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[SOURCE: https://en.wikipedia.org/wiki/SYCL] | [TOKENS: 2620] |
Contents SYCL SYCL (pronounced "sickle") is a higher-level programming model to improve programming productivity on various hardware accelerators. It is a single-source embedded domain-specific language (eDSL) based on pure C++17. It is a standard developed by Khronos Group, announced in March 2014. Origin of the name SYCL (pronounced ‘sickle’) originally stood for System-wide Compute Language, but since 2020 SYCL developers have stated that SYCL is a name and have made clear that it is no longer an acronym and contains no reference to OpenCL. Purpose SYCL is a royalty-free, cross-platform abstraction layer that builds on the underlying concepts, portability and efficiency inspired by OpenCL that enables code for heterogeneous processors to be written in a “single-source” style using completely standard C++. SYCL enables single-source development where C++ template functions can contain both host and device code to construct complex algorithms that use hardware accelerators, and then re-use them throughout their source code on different types of data. While the SYCL standard started as the higher-level programming model sub-group of the OpenCL working group and was originally developed for use with OpenCL and SPIR, SYCL is a Khronos Group workgroup independent from the OpenCL working group since September 20, 2019 and starting with SYCL 2020, SYCL has been generalized as a more general heterogeneous framework able to target other systems. This is now possible with the concept of a generic backend to target any acceleration API while enabling full interoperability with the target API, like using existing native libraries to reach the maximum performance along with simplifying the programming effort. For example, the AdaptiveCPP implementation targets ROCm and CUDA via AMD's cross-vendor HIP. Versions SYCL was introduced at GDC in March 2014 with provisional version 1.2, then the SYCL 1.2 final version was introduced at IWOCL 2015 in May 2015. The latest version for the previous SYCL 1.2.1 series is SYCL 1.2.1 revision 7 which was published on April 27, 2020 (the first version was published on December 6, 2017). SYCL 2.2 provisional was introduced at IWOCL 2016 in May 2016 targeting C++14 and OpenCL 2.2. But the SYCL committee preferred not to finalize this version and to move towards a more flexible SYCL specification to address the increasing diversity of current hardware accelerators, including artificial intelligence engines, which led to SYCL 2020. The latest version is SYCL 2020 revision 6 which was published on November 13, 2022, an evolution from first release of revision 2 which was published on February 9, 2021, taking into account the feedback from users and implementors on the SYCL 2020 Provisional Specification revision 1 published on June 30, 2020. C++17 and OpenCL 3.0 support are main targets of this release. Unified shared memory (USM) is one main feature for GPUs with OpenCL and CUDA support. At IWOCL 2021 a roadmap was presented. DPC++, ComputeCpp, AdaptiveCPP, triSYCL and neoSYCL are the main implementations of SYCL. Next Target in development is support of C++20 in future SYCL 202x. Implementations Extensions In March 2023 the Khronos Group announced the creation of the SYCL SC Working Group, with the objective of creating a high-level heterogeneous computing framework for safety-critical systems. These systems span various fields, including avionics, automotive, industrial, and medical sectors. The SYCL Safety Critical framework will comply with several industry standards to ensure its reliability and safety. These standards include MISRA C++ 202X, which provides guidelines for the use of C++ in critical systems, RTCA DO-178C / EASA ED-12C, which are standards for software considerations in airborne systems and equipment certification, ISO 26262/21448, which pertains to the functional safety of road vehicles, IEC 61508, which covers the functional safety of electrical/electronic/programmable electronic safety-related systems, and IEC 62304, which relates to the lifecycle requirements for medical device software. Software Some notable software fields that make use of SYCL include the following (with examples): Resources Khronos Maintains a list of SYCL resource. Codeplay Software also provides tutorials on the website sycl.tech along with other information and news on the SYCL ecosystem. License The source files for building the specification, such as Makefiles and some scripts, the SYCL headers and the SYCL code samples are under the Apache 2.0 license. Comparison with other Tools The open standards SYCL and OpenCL are similar to the programming models of the proprietary stack CUDA from Nvidia and HIP from the open-source stack ROCm, supported by AMD. In the Khronos Group realm, OpenCL and Vulkan are the low-level non-single source APIs, providing fine-grained control over hardware resources and operations. OpenCL is widely used for parallel programming across various hardware types, while Vulkan primarily focuses on high-performance graphics and computing tasks. SYCL, on the other hand, is the high-level single-source C++ embedded domain-specific language (eDSL). It enables developers to write code for heterogeneous computing systems, including CPUs, GPUs, and other accelerators, using a single-source approach. This means that both host and device code can be written in the same C++ source file. By comparison, the single-source C++ embedded domain-specific language version of CUDA, which is named "CUDA Runtime API," is somewhat similar to SYCL. In fact, Intel released a tool called SYCLOMATIC that automatically translated code from CUDA to SYCL. However, there is a less known non-single-source version of CUDA, which is called "CUDA Driver API," similar to OpenCL, and used, for example, by the CUDA Runtime API implementation itself. SYCL extends the C++ AMP features, relieving the programmer from explicitly transferring data between the host and devices by using buffers and accessors. This is in contrast to CUDA (prior to the introduction of Unified Memory in CUDA 6), where explicit data transfers were required. Starting with SYCL 2020, it is also possible to use Unified Shared Memory (USM) to augment, rather than replace, the buffer-based interfaces, providing a lower-level programming model similar to Unified Memory in CUDA. SYCL is higher-level than C++ AMP and CUDA since you do not need to build an explicit dependency graph between all the kernels, and it provides you with automatic asynchronous scheduling of the kernels with communication and computation overlap. This is all done by using the concept of accessors without requiring any compiler support. Unlike C++ AMP and CUDA, SYCL is a pure C++ eDSL without any C++ extension. This allows for a basic CPU implementation that relies on pure runtime without any specific compiler. Both DPC++ and AdaptiveCpp compilers provide a backend to NVIDIA GPUs, similar to how CUDA does. This allows SYCL code to be compiled and run on NVIDIA hardware, allowing developers to leverage SYCL's high-level abstractions on CUDA-capable GPUs. Intel offers a freeware "DPC++ Compatibility Tool" (dpct) for automatically converting CUDA C++ code bases to SYCL C++. There is an open source version of the tool called SYCLomatic. ROCm HIP targets Nvidia GPU, AMD GPU, and x86 CPU. HIP is a lower-level API that closely resembles CUDA's APIs. For example, AMD released a tool called HIPIFY that can automatically translate CUDA code to HIP. Therefore, many of the points mentioned in the comparison between CUDA and SYCL also apply to the comparison between HIP and SYCL. ROCm HIP has some similarities to SYCL in the sense that it can target various vendors (AMD and Nvidia) and accelerator types (GPU and CPU). However, SYCL can target a broader range of accelerators and vendors. SYCL supports multiple types of accelerators simultaneously within a single application through the concept of backends. Additionally, SYCL is written in pure C++, whereas HIP, like CUDA, uses some language extensions. These extensions prevent HIP from being compiled with a standard C++ compiler. Both DPC++ and AdaptiveCpp compilers provide backends for NVIDIA and AMD GPUs, similar to how HIP does. This enables SYCL code to be compiled and executed on hardware from these vendors, offering developers the flexibility to leverage SYCL's high-level abstractions across a diverse range of devices and platforms. SYCL has many similarities to the Kokkos programming model, including the use of opaque multi-dimensional array objects (SYCL buffers and Kokkos arrays), multi-dimensional ranges for parallel execution, and reductions (added in SYCL 2020). Numerous features in SYCL 2020 were added in response to feedback from the Kokkos community. SYCL focuses more on heterogeneous systems; thanks to its integration with OpenCL, it can be adopted on a wide range of devices. Kokkos, on the other hand, targets most of the HPC platforms, thus it is more HPC-oriented for performance. As of 2024, the Kokkos team is developing a SYCL backend, which enables Kokkos to target Intel hardware in addition to the platforms it already supports. This development broadens the applicability of Kokkos and allows for greater flexibility in leveraging different hardware architectures within HPC applications. Raja is a library of C++ software abstractions to enable the architecture and programming portability of HPC applications. Like SYCL, it provides portable code across heterogeneous platforms. However, unlike SYCL, Raja introduces an abstraction layer over other programming models like CUDA, HIP, OpenMP, and others. This allows developers to write their code once and run it on various backends without modifying the core logic. Raja is maintained and developed at Lawrence Livermore National Laboratory (LLNL), whereas SYCL is an open standard maintained by the community. Similar to Kokkos, Raja is more tailored for HPC use cases, focusing on performance and scalability in high-performance computing environments. In contrast, SYCL supports a broader range of devices, making it more versatile for different types of applications beyond just HPC. As of 2024, the Raja team is developing a SYCL backend, which will enable Raja to also target Intel hardware. This development will enhance Raja's portability and flexibility, allowing it to leverage SYCL's capabilities and expand its applicability across a wider array of hardware platforms. OpenMP targets computational offloading to external accelerators, primarily focusing on multi-core architectures and GPUs. SYCL, on the other hand, is oriented towards a broader range of devices due to its integration with OpenCL, which enables support for various types of hardware accelerators. OpenMP uses a pragma-based approach, where the programmer annotates the code with directives, and the compiler handles the complexity of parallel execution and memory management. This high-level abstraction makes it easier for developers to parallelize their applications without dealing with the intricate details of memory transfers and synchronization. Both OpenMP and SYCL support C++ and are standardized. OpenMP is standardized by the OpenMP Architecture Review Board (ARB), while SYCL is standardized by the Khronos Group. OpenMP has wide support from various compilers, like GCC and Clang. std::par is part of the C++17 standard and is designed to facilitate the parallel execution of standard algorithms on C++ standard containers. It provides a standard way to take advantage of external accelerators by allowing developers to specify an execution policy for parallel operations, such as std::for_each, std::transform, and std::reduce. This enables efficient use of multi-core processors and other parallel hardware without requiring significant changes to the code. SYCL can be used as a backend for std::par, enabling the execution of standard algorithms on a wide range of external accelerators, including GPUs from Intel, AMD, and NVIDIA, as well as other types of accelerators. By leveraging SYCL's capabilities, developers can write standard C++ code that seamlessly executes on heterogeneous computing environments. This integration allows for greater flexibility and performance optimization across different hardware platforms. The use of SYCL as a backend for std::par is compiler-dependent, meaning it requires a compiler that supports both SYCL and the parallel execution policies introduced in C++17. Examples of such compilers include DPC++ and other SYCL-compliant compilers. With these compilers, developers can take advantage of SYCL's abstractions for memory management and parallel execution while still using the familiar C++ standard algorithms and execution policies. See also References External links |
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[SOURCE: https://en.wikipedia.org/wiki/Maor_Farid#cite_note-19] | [TOKENS: 1458] |
Contents Maor Farid Dr. Maor Farid (Hebrew: מאור פריד; born April 20, 1992) is an Israeli scientist, engineer and artificial intelligence researcher at Massachusetts Institute of Technology, social activist, and author. He is the founder and CEO of Learn to Succeed (Hebrew: ללמוד להצליח) for empowering of youths from the Israeli socio-economic periphery and youths at risk, a regional manager of the Israeli center of ScienceAbroad at MIT, and an activist in the American Technion Society. He is an alumnus of Unit 8200, and a fellow of Fulbright Program and the Israel Scholarship Educational Foundation [he]. Dr. Farid was elected to the Forbes 30 Under 30 list of 2019, and won the Moskowitz Prize for Zionism. Early life Maor was born in Ness Ziona, a city in central Israel, as the eldest son for parents from immigrating families of Mizrahi Jews from Iraq and Libya. Maor suffered from Attention deficit hyperactivity disorder (ADHD) from a young age, and was classified as a problematic and violent student. His ADHD issues were diagnosed only after he began his university studies. However, inspired by his parents' background, he aspired to excel at school for a better future for his family. During elementary school, Maor attended local quizzes about Jewish history and Zionism, which significantly shaped his identity and national perspective. Farid graduated high school with the highest GPA in school. Later he was recruited to the Israel Defense Forces and drafted to the Brakim Program [he] – an excellence program of the Israeli Intelligence Corps for training leading R&D officers for the Israeli military and defense industry. Maor graduated the program with honors and was elected by the Israeli Prime Minister's Office and Unit 8200, where he served as an artificial intelligence researcher, officer, and commander. During his Military service, he received various honors and awards, such as the Excellent Scientist Award, given to the top three academics serving in the Israel Defense Forces. In 2019, Farid completed his military service in the rank of a Captain. Education and academic career As part of the (4 years) Brakim Program, Maor completed his Bachelor's and Master's degrees at the Technion in Mechanical Engineering with honors. Then, he initiated his Ph.D. research as a collaboration with the Israel Atomic Energy Commission (IAEC) in parallel to his duty military service. The main goals of his Ph.D. research were predicting irreversible effects of major earthquakes on Israel's nuclear facilities, and improving their seismic resistance using energy absorption technologies. The mathematical models developed by Farid were able to forecast earthquake effects on facilities with major hazard potential, and predicted the failure of liquid storage tanks due to earthquakes took place in Italy (2012) and Mexico (2017). The energy absorption technologies used, increased in up to 90% the seismic resistance abilities of those sensitive facilities. The research results were published in multiple papers in peer-reviewed academic journals and presented in international academic conferences. Later, this research expanded to an official collaboration between the Technion and the Shimon Peres Negev Nuclear Research Center, which aims to implement the findings obtained on existing sensitive systems, and won funding of 1.5 million NIS from the Pazy foundation of the Israel Atomic Energy Commission and the Council for Higher Education. In 2017, Farid completed his Ph.D. and as the youngest graduate at the Technion for that year, at the age of 24. In the graduation ceremonies, he honored his parents to receive the diplomas on his behalf. At the same year, he served as a lecturer at Ben-Gurion University in an original course he developed as a solution for knowledge gaps he identified in the Israeli defense industry. In 2018, Dr. Farid served as an artificial intelligence researcher at a Data Science team of Unit 8200, where he developed machine learning-based solutions for military and operational needs. In 2019, Farid won the Fulbright and the Israel Scholarship Educational Foundation scholarships, and was accepted to post-doctoral position at Massachusetts Institute of Technology where he develops real-time methods for predicting earthquake effects using machine learning techniques. In 2020, Farid was accepted to the Emerging Leaders Program at Harvard Kennedy School in Cambridge, Massachusetts. At the same year, he received the excellence research grant of the Israel Academy of Sciences and Humanities for leading his research in collaboration between MIT and the Technion. Social activism Farid social activism focuses on empowering youths from disadvantaged backgrounds from an early age. In 2010–2015, he served as a mentor of a robotics team from Dimona in FIRST Robotics Competition, a mathematics tutor in "Aharai!" [he] program for high-school students at risk in Dimona and Be'er Sheva, and a mentor and private tutor of adolescence and reserve duty soldiers from disadvantaged backgrounds. In 2010, he initiated "Learn to Succeed" (Hebrew: ללמוד להצליח) project, for mitigating the social gaps in the Israeli society by empowering youths from the social, economical, and geographical periphery for excellence, self-fulfillment and gaining formal education. In 2018, Learn to Succeed became an official non-profit organization. At the same year, Farid led a crowdfunding project of 150,000 NIS in order to expand the organization to a national scale. In 2019, he published the book "Learn to Succeed", in which he describes his struggle with ADHD, the violent environment in which he grew up, and the changing process he went through from being a violent teenager to becoming the youngest Ph.D. graduate at the Technion. The book was given to more than two thousand youths at risk and became a top seller in Israel shortly after its publication. Maor dedicated the book to his parents and to the memorial of his friend Captain Tal Nachman who was killed in operational activity during his military service in 2014. The organization consists of hundreds of volunteers, gives full scholarships to STEM students from the periphery who serve as mentors of youths, both Jews and Arabs, from disadvantaged backgrounds, runs a hotline which gives online practical and mental support to hundreds of youths, parents and educators, initiates inspirational activities with military orientation to increase the motivation of its teen-age members for significant military service, and gives inspirational lectures to more than 5,000 youths each year. In 2019, Maor initiated a collaboration with Unit 8200 in which tens of the program's members are being interviewed to the unit. This opportunity is usually given to students with the highest grades in the matriculate exams in each class. In 2020, Dr. Farid established the ScienceAbroad center at MIT, aiming to strengthen the connections between Israeli researchers in the institute and the state of Israel. Moreover, he serves as a volunteer in the American Technion Society. Honors and awards Personal life Farid is married to Michal. Interviews and articles References External links |
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[SOURCE: https://en.wikipedia.org/wiki/E-government] | [TOKENS: 10901] |
Contents E-government E-government (short for electronic government) involves the use of technological devices, such as computers and the Internet, for faster means of delivering public services to citizens and other persons in a country or region. E-government offers new opportunities for more direct and convenient citizen access to government and for government provision of services directly to citizens. E-government involves digital interactions across various levels and stakeholders (C2G), between governments and other government agencies (G2G), between government and citizens (G2C), between government and employees (G2E), and between government and businesses/commerces (G2B). E-government delivery models can be broken down into the following categories: This interaction consists of citizens communicating with all levels of government (city, state/province, national, and international), facilitating citizen involvement in governance using information and communication technology (ICT) (such as computers and websites) and business process re-engineering (BPR). Brabham and Guth (2017) interviewed the third-party designers of e-government tools in North America about the ideals of user interaction that they build into their technologies, which include progressive values, ubiquitous participation, geolocation, and education of the public. Other definitions stray from the idea that technology is an object and defines e-government simply as facilitators or instruments and focus on specific changes in public administration issues. The internal transformation of a government is the definition that established the specialist technologist Mauro D. Ríos. In his paper "In Search of a Definition of Electronic Government", he says: "Digital government is a new way of organization and management of public affairs, introducing positive transformational processes in management and the structure itself of the organization chart, adding value to the procedures and services provided, all through the introduction and continued appropriation of information and communication technologies as a facilitator of these transformations." Terminology E-government is also known as e-gov, electronic government, Internet governance, digital government, online government, connected government. As of 2014, the OECD used the term digital government, and distinguishes it from e-government in the recommendation produced there for the Network on E-Government of the Public Governance Committee. Several governments have started to use the term digital government to a wide range of services involving contemporary technology, such as big data, automation or predictive analytics. E-gov strategies (or digital government) is defined as "The employment of the Internet and the world-wide-web for delivering government information and services to the citizens." (United Nations, 2006; AOEMA, 2005). Electronic government (or e-government) essentially refers to "utilization of Information Technology (IT), Information and Communication Technologies (ICTs), and other web-based telecommunication technologies to improve and/or enhance on the efficiency and effectiveness of service delivery in the public sector". E-government is often described as promoting broader stakeholder participation to national and community development, as well as deepen the governance process. In electronic government systems, government operations are supported by Web-based services. It involves the use of information technology, specifically the Internet, to facilitate the communication between the government and its citizens. Transformational government or also transformational e-government is the use of computer-based information and communications technologies (ICT) to change the way governments work. The term is commonly used to describe a government reform strategy which attempts to radically change the way people understand the government, especially those working within the government. For example, it is often associated with a whole-of-government viewpoint, which tries to foster cross-department collaboration and provide one-stop-shop convenience in the delivery of services to citizens. The term transformational government is usually used aspirationally, as denoting the highest level of what e-government can achieve: Government 2.0 or Gov 2.0 refers to government policies that aim to harness collaborative technologies and interactive Internet tools to create an open-source computing platform in which government, citizens, and innovative companies can improve transparency and efficiency. Put simply, Gov 2.0 is about "putting government in the hands of citizens". Gov 2.0 combines interactive Web 2.0 fundamentals with e-government and increases citizen participation by using open-source platforms, which allow development of innovative apps, websites, and widgets. The government's role is to provide open data, web services, and platforms as an infrastructure. E-government should enable anyone visiting a city website to communicate and interact with city employees via the Internet with graphical user interfaces (GUI), instant messaging (IM), learn about government issues through audio/video presentations, and in any way more sophisticated than a simple email letter to the address provided at the site. The essence of e-governance is "The enhanced value for stakeholders through transformation" and "the use of technology to enhance the access to and delivery of government services to benefit citizens, business partners and employees". The focus should be on: Whilst e-government has traditionally been understood as being centered around the operations of government, e-governance is understood to extend the scope by including citizen engagement and participation in governance. As such, following in line with the OECD definition of e-government, e-governance can be defined as the use of ICTs as a tool to achieve better governance. While e-government is often thought of as "online government" or "Internet-based government," many non-Internet "electronic government" technologies can be used in this context. Some non-Internet forms include telephone, fax, PDA, SMS text messaging, MMS, wireless networks and services, Bluetooth, CCTV, tracking systems, RFID, biometric identification, road traffic management and regulatory enforcement, identity cards, smart cards and other near-field communication applications; polling station technology (where non-online e-voting is being considered), TV and radio-based delivery of government services (e.g., CSMW), email, online community facilities, newsgroups and electronic mailing lists, online chat, and instant messaging technologies. History One of the first references to the term "electronic government" happened alongside the term electronic democracy in 1992. During the last two decades,[vague] governments around the world have invested in ICT with the aim of increasing the quality and decreasing the cost of public services. But over that time, as even the least developed countries have moved to websites, e-services and e-government strategies, it has become increasingly clear that e-government has not delivered all the benefits that were hoped for it. One study found that 35% of e-government projects in developing countries resulted in total failures; and that 50% were partial failures. In reaction to these poor outcomes, there has been a shift of perspective to transformational government, aiming beyond purely technical aspects of better enabling e-government processes towards addressing the cultural and organisational barriers which have hindered public service benefits realisation. Researchers have defined the rationale for transformational government as "the exploitation of e-government such that benefits can be realized". In 2010, the Organization for the Advancement of Structured Information Standards (OASIS) published a report which identified a wide range of common pitfalls which have hampered many governments in achieving significant impacts through their technology investments. However, OASIS also noted that OASIS cites the UK and Australia as two of the leaders in this area: UN e-Government Development Index The Division of a Public Administration and Development Management (DPAPM) of the United Nations Department of Economic and Social Affairs (UN-DESA) conducts a biannual e-government survey which includes a section titled e-Government Development Index (EGDI). It is a comparative ranking of 193 countries of the world according to three primary indicators: i) the OSI – Online Service Index that measures the online presence of the government in terms of service delivery; ii) the TII – Telecommunication Infrastructure Index; and iii) HCI – Human Capital Index. Constructing a model for the measurement of digitized services, the survey assesses the 193 member states of the UN according to a quantitative composite index of e-government readiness based on website assessment, telecommunication infrastructure, and human resource endowment. The e-Government Development Index can serve as a benchmarking tool for countries to identify their strengths and weaknesses and shape their policies along these findings in the area of e-government. The e-Government Development Index (EGDI) is calculated with the following method: EGDI = 1/3 (OSI normalized + TII normalized + HCI normalized). A diverse group of 100 researchers online volunteers from across the globe engaged with the United Nations Department of Economic Affairs (UN DESA) to process 386 research surveys carried out across 193 UN Member States for the 2016 UN e-Government Survey. The diversity of nationalities and languages of the online volunteers—more than 65 languages, 15 nationalities, of which half are from developing countries—mirrors perfectly the mission of the survey. The survey has been criticized not including an index of digital inclusion levels. Delivery models and activities of e-government The primary delivery models of e-government can be divided into Within each of these interaction domains, four kinds of activities take place: Examples of online transactional services, employed in e-governments include Controversies The main disadvantages concerning e-government are that there exists a digital divide and digital inequalities that bar certain people from accessing the full benefits of digitization. When presented as the only option to access an essential service, those who do not have public access to computers and the Internet, or do not have adequate knowledge on how to use them, suffer. Other disadvantages include the reliability of information on the Web and issues that could influence and bias public opinions. There are many considerations and potential implications of implementing and designing e-government, including disintermediation of the government and its citizens, digital self-determination of citizens in a global Internet network, impacts on economic, social, and political factors, vulnerability to cyberattacks, and disturbances to the status quo in these areas. The political nature of public sector forms are also cited as disadvantages to e-government systems. Although "a prodigious amount of money has been spent" on the development and implementation of e-government, some say[who?] it has yielded only a mediocre result. The outcomes and effects of trial Internet-based government services are often difficult to gauge or users find them unsatisfactory. According to Gartner, worldwide IT spending is estimated to total $3.6 trillion in 2011, which is 5.1% increase from the year 2010 ($3.4 trillion). Because e-government is in the early stages of development in many countries and jurisdictions, it is hard to be applied to forms of government that have been institutionalized. Age-old bureaucratic practices being delivered in new mediums or using new technologies can lead to problems of miscommunication. An example of such a practice was the automation of the Indiana welfare program that began in 2006. An audit commissioned by then Indiana Governor Mitch Daniels in 2005 found that several Family and Social Service Administration (FSSA) employees and welfare recipients were committing welfare fraud. The bureaucratic nature of Indiana's welfare system allowed people to cheat the system and cost the state large amounts of money. Daniels characterized the system as "irretrievably broken," stating that it was at a state where employees could not fix it on their own. He cited many issues that directly tie into the fact that the system had not been automated. In hopes to reap the many benefits of e-government, Daniels signed into law a bill privatizing and automating the enrollment service for Indiana's welfare programs. Daniels aimed to streamline benefits applications, privatize casework, and identify fraud. It was believed that moving away from face-to-face casework and toward electronic communication would fix the aforementioned problems and improve efficiency. Indiana's welfare enrollment facilities were replaced with online applications and call centers operated by IBM. These ran into issues almost immediately. The mainly face-to-face and personalized practice was modernized essentially overnight, blindsiding many people who relied on those features. The automated system worked upon a one-size-fits-all approach that attributed errors to the recipient over anything else. Problems that were previously solvable through a single phone call with a recipient's caseworker became increasingly complicated due to the private call center workers not being adequately trained. Welfare recipients were denied their benefits due to lack of direct help, system errors out of their control, or simply an inability to use the technology meant to speed up the process. The transition overwhelmed not only recipients but also the employees. In October 2009, even Daniels admitted to the project being flawed and problematic, cancelling the contract with IBM. Indiana began rolling out a hybrid system starting in 2010, including caseworkers and some automation where appropriate. Opponents of e-government argue that online governmental transparency is dubious because it is maintained by the governments themselves. Information can be added or removed from the public eye. To this day, very few organizations monitor and provide accountability for these modifications. Those that do so, like the United States' OMBWatch and Government Accountability Project, are often nonprofit volunteers. Even the governments themselves do not always keep track of the information they insert and delete. Increased electronic contact and data exchange between government and its citizens goes both ways. Once e-government technologies become more sophisticated, citizens will be likely be encouraged to interact electronically with the government for more transactions, as e-services are much less costly than brick-and-mortar service offices (physical buildings) staffed by civil servants. This could potentially lead to a decrease in privacy for civilians as the government obtains more and more information about their activities. Without safeguards, government agencies might share information on citizens. In a worst-case scenario, with so much information being passed electronically between government and civilians, a totalitarian-like system could develop. When the government has easy access to countless information on its citizens, personal privacy is lost. An e-government website that provides government services often does not offer the "potential to reach many users including those who live in remote areas [without Internet access], are homebound, have low literacy levels, exist on poverty line incomes." Homeless people, people in poverty and elderly people may not have access. Trust in e-governance is very highly dependent on its performance and execution, which can be measured through the effectiveness of current actions. This is much riskier and prone to fluctuation than a system of trust that is based on reputation because performance does not consider past actions. With the automation of institutionalized government services, trust can go both ways: the trust that people have for the government, and the trust the government places in its people. In the case of Indiana's automated welfare system, the less skilled call center workers defaulted their decisions to the automated system and favored solutions that best fit the system rather than the people. When too much trust is put in e-governance, errors and mistakes are not caught. A crucial part of the Indiana welfare system was the relationship between caseworkers and their clients. It was the main way for Hoosiers to interact with this public institution and receive the help they want. However, Daniels and many others saw a potential invitation to fraud. There were indeed instances of welfare fraud occurring between caseworkers and clients, such as this case from Marion County, December 2009. But the motivation to automate was an attempt to catch people taking advantage of the system rather than trying to deliver the services to as many people as possible. Welfare recipients were being considered as criminals rather than people in need. Such treatment of the poor is similar to that of poorhouses from the 19th and 20th centuries. Both developed flawed systems with an intent to punish, creating more burdens than the initially marketed benefits. The ultimate goal of the e-government is to be able to offer an increased portfolio of public services to citizens in an efficient and cost-effective manner. E-government allows for government transparency. Government transparency is important because it allows the public to be informed about what the government is working on as well as the policies they are trying to implement. Simple tasks may be easier to perform through electronic government access. Many changes, such as marital status or address changes, can be a long process and take a lot of paperwork for citizens. E-government allows these tasks to be performed efficiently with more convenience to individuals. E-government is an easy way for the public to be more involved in political campaigns. It could increase voter awareness, which could lead to an increase in citizen participation in elections. It is convenient and cost-effective for businesses, and the public benefits by obtaining easy access to the most current information available without having to spend time, energy and money to obtain it. E-government helps simplify processes and makes government information more easily accessible for public sector agencies and citizens. For example, the Indiana Bureau of Motor Vehicles simplified the process of certifying driver records to be admitted in county court proceedings.[failed verification] Indiana became the first state to allow government records to be digitally signed, legally certified and delivered electronically by using Electronic Postmark technology. In addition to its simplicity, e-democracy services can reduce costs. Alabama Department of Conservation & Natural Resources, Wal-Mart and NIC developed an online hunting and fishing license service utilizing an existing computer to automate the licensing process. More than 140,000 licenses were purchased at Wal-Mart stores during the first hunting season and the agency estimates it will save $200,000 annually from service. The anticipated benefits of e-government include efficiency, improved services, better accessibility of public services, sustainable community development and more transparency and accountability. One goal of some e-government initiatives is greater citizen participation. Through the Internet's Web 2.0 interactive features, people from all over the country can provide input to politicians or public servants and make their voices heard. Blogging and interactive surveys allow politicians or public servants to see the views of the people on any issue. Chat rooms can place citizens in real-time contact with elected officials or their office staff or provide them with the means to interact directly with public servants, allowing voters to have a direct impact and influence in their government. These technologies can create a more transparent government, allowing voters to immediately see how and why their representatives in the capital are voting the way they are. This helps voters decide whom to vote for in the future or how to help the public servants become more productive. A government could theoretically move more towards a true democracy with the proper application of e-government. Government transparency will give insight to the public on how decisions are made and hold elected officials or public servants accountable for their actions. The public could become a direct and prominent influence in government legislature to some degree. Proponents of e-government argue that online government services would lessen the need for hard copy paper forms. Due to recent pressures from environmentalist groups, the media, and the public, some governments and organizations have turned to the Internet to reduce paper use. The United States government utilizes the website Government Forms, by Agency | A | USAGov to provide "internal government forms for federal employees" and thus "produce significant savings in paper. As well, if citizens can apply for government services or permits online, they may not need to drive into a government office, which could lead to less air pollution from gas- and diesel-fueled vehicles. E-government allows citizens to interact with computers to achieve objectives at any time and any location and eliminates the necessity for physical travel to government agents sitting behind desks and windows. Many e-government services are available to citizens with computers and Internet access 24 hours a day and seven days a week, in contrast to brick-and-mortar government offices, which tend to be only open during business hours (notable exceptions are police stations and hospitals, which are usually open 24 hours a day so that staff can deal with emergencies). Organizations like GovTools focus on speed, efficiency and convenience by providing e-government services designed to improve city communications, constituent relationship management (CRM) for political teams and municipalities, civic event coordination, engagement tools, customizable news feeds, and case management systems. The platform incorporates artificial intelligence to enhance operational efficiency and user experience. Improved accounting and recordkeeping can be noted through computerization, and information and forms can be easily accessed by citizens with computers and Internet access, which may enable quicker processing time for applications and find information. On the administrative side, access to help find or retrieve files and linked information can now be stored in electronic databases versus hard copies (paper copies) stored in various locations. Individuals with disabilities or conditions that affect their mobility no longer have to be mobile to be active in government and can access public services in the comfort of their own homes (as long as they have a computer and Internet and any accessibility equipment they may need). Recent trials of e-government have been met with acceptance and eagerness from the public. Citizens participate in online discussions of political issues with increasing frequency, and young people, who traditionally display minimal interest in government affairs, are drawn to electronic voting procedures. Although Internet-based governmental programs have been criticized for lack of reliable privacy policies, studies have shown that people value prosecution of offenders over personal confidentiality. Ninety percent of United States adults approve of Internet tracking systems of criminals, and 57% are willing to forgo some of their personal Internet privacy if it leads to the prosecution of criminals or terrorists. Technology-specific e-government There are also some technology-specific sub-categories of e-government, such as m-government (mobile government), u-government (ubiquitous government), and g-government (GIS/GPS applications for e-government). The previous concern about developments in e-government concerning technology are due to the limited use of online platforms for political reasons by citizens in local political participations. The primary delivery models of e-government are classified depending on who benefits. In the development of the public sector or private sector portals and platforms, a system is created that benefits all constituents. Citizens needing to renew their vehicle registration have a convenient way to accomplish it while already engaged in meeting the regulatory inspection requirement. On behalf of a government partner, the business provides what has traditionally, and solely, managed by the government and can use this service to generate profit or attract new customers. Government agencies are relieved of the cost and complexity of having to process the transactions. To develop these public sector portals or platforms, governments have the choice to internally develop and manage, outsource, or sign a self-funding contract. The self-funding model creates portals that pay for themselves through convenience fees for certain e-government transactions, known as self-funding portals. Social networking services and websites are an emerging area for e-democracy. The social networking entry point is within the citizens' environment and the engagement is on the citizens' terms. Proponents of e-government perceive the government's use of social networking as a medium to help the government act more like the public it serves. Examples can be found at almost every state government portal through Facebook, Twitter, and YouTube widgets. Government and its agents also have the opportunity to follow citizens to monitor satisfaction with services they receive. Through ListServs, RSS feeds, mobile messaging, microblogging services and blogs, government and its agencies can share information to citizens who share common interests and concerns. Government is also beginning to employ the use of Twitter. In the state of Rhode Island, Treasurer Frank T. Caprio is offering daily tweets of the state's cash flow.[when?][non-primary source needed] For a full list of state agencies with Twitter feeds, visit NIC. For more information, visit transparent-gov.com. Several local governments in the United States have allowed online e-signatures for candidate nominating petitions and signature requirements for ballot initiatives. In 2012, Arizona launched a prototype system called E-qual, which allowed statewide candidates running for office to collect signatures online and share the link on other forms on social media. E-qual was expanded in 2016 to cover candidates in local elections within the state, but it was not used at the local level before the 2020 state election. The city of Boulder, Colorado, has implemented a similar system in 2020 to collect signatures for city ballot questions. By country Since the election of the current president Abdel-Fattah El-Sisi, he has invested large sums of money towards sustainable energy and digitalization of the government system. Some of the problems faced are privacy, security concerns, lack of citizens' awareness, and lack of technical unified standards. Egypt has a population of approximately 100 million with various backgrounds and living conditions and access to resources. Not only does the education level of citizens vary between cities and rural areas but also within Cairo. Compared to other Arab or Middle Eastern countries, Egypt is quite behind in terms of technological developments and utilization. Recently[when?], the government issued a law that all businesses must have electronic receipts and that all pension payments or government-citizen expenditure must be done through electronic transfers. This shows their initiative to leave behind the cash-driven economy to an electronic one. Following the transition from the longstanding Kenya African National Union government to the National Rainbow Coalition government in December 2002, a Directorate of e-government was established after an executive (cabinet) session in January 2004. The newly created department had the duty to draw the plan of action for future ICT implementations. Like many other African nations, Kenya has embraced the high mobile penetration rate within its population. Even people living in remote areas that did not have access to traditional telecommunications' networks can now communicate with ease. The fact of the same has, and continues to have, a great impact on the governments' strategies in reaching out to its citizens. Given that about 70% of the population owns mobile phones, leading mobile network operators like Safaricom have taken a great step in offering services that meet citizens' demands. Such services include Kipokezi (which allows subscribers to do online chatting and also exchange electronic mails via standard mobile phones), and M-Pesa (which allows the subscribers to send and receive electronic cash). Such services have even appealed to the majority of Kenyans, as they support the branchless members of the society too, in undertaking normal and secure businesses via M-Pesa. The recent IMF report reveals that MPESA transactions in Kenya exceeded those carried out by the Western Union worldwide. Website: Open Kenya | Transparent Africa Armenian e-government was established in 2004. E-government brings together all tools and databases created by Armenian state agencies and provides a user-friendly online environment for users. It includes more than twenty services and tools. Under this initiative, "Interactive Budget" and "State Non-Commercial Organisations' Financing" sections are available for the first time. There are also twenty other tools, including search engines, allowing to find the Government's and the Prime Minister's decisions, the agenda of the next cabinet sitting, information on the state purchases, the electronic tax reporting system, the online application system of the Intellectual Property Agency, the information search system of the Intellectual Property Agency, as well as the Electronic Signature and Electronic Visa (e-visa) sections. It is worth mentioning that the Electronic Signature is used in several other services when a user wants to submit an application or receive information. The Electronic Signature is universal system and is used both by the state officials and by citizens, legal entities. The "e-government" framework was established in accordance with the "National Strategy on Information-Communication Technologies in the Development of the Republic of Azerbaijan (2003–2012)" and implemented in the framework of the "E-Azerbaijan" Program. The project is aimed to increase the convenience and efficiency of the activity of state agencies, simplify interactions between population, businesses, and government agencies, contribute to creating new citizen-official relations framework and ensure transparency and free flow of information. The main components of the e-government infrastructure are integrated network infrastructure for state bodies, e-government portal, e-government gateway, State register of information resources and systems, e-signature, e-document circulation and e-government data center (under preparation). State portal www.e-gov.az was established to facilitate citizens in benefiting from e-services provided by government agencies on a "single-window" principle with the combination of services. Through e-government portal, citizens can use more than 140 e-services of 27 state agencies. Besides, a gateway between government agencies was established to ensure the mutual exchange of information, and most state agencies are connected to this infrastructure. The gateway allows users to efficiently use the existing government information systems and safe contact between them, issuing requests and rendering e-services, liberates citizens from providing same information or documents which are already available in information databases. On 14 March 2018, it launched the E-government Development Center. It is a public legal entity that is subordinated to State Agency for Public Service and Social Innovations under the President of the Republic of Azerbaijan. The service tries to utilize digital technologies, establish e-government to make state services operate more efficiently, ensure public services availability, and improve the living standards of the citizens of the country. It is a government-to-citizen type of e-governance. The e-government web portal has been developed to provide more convenient access to various government services and information through one window. Services can now be delivered to people at their convenience, and more importantly, now have a lot more weight on transparency and accountability of public services. According to State-owned Assets Supervision and Administration Commission of the State Council (国务院国有资产监督管理委员会) of Fujian Province, digital Transformation was firstly proposed by IBM in 2012, which enhances the application of digital technology to reshape customer value propositions and emphasizes the customer interaction and collaboration. The Chinese government has added "Digital Economy" to its "Government Work Report" (政府工作报告) for four consecutive years from 2017, and proposed in the 14th Five-Year Plan to outline the "Use digital transformation to drive changes in production methods, lifestyles and governance methods as a whole". Furthermore, Digital Transformation has been elevated to a national strategy from enterprise (organization) level. The Chinese government also has its official website for e-government is eGovernment.gov.cn, and maintained by Central Party School of the Chinese Communist Party (中共中央党校) or National Academy of Governance (国家行政学院) (these two names are for one institute but with two different names). Ever since the sovereign handover in 1997, Hong Kong has been improving in technology and e-governance. The E-Governance initiatives and programs in India are undertaken by the Ministry of Electronics and Information Technology (MeitY www.meity.gov.in). The current umbrella program for e-governance of Government of India is known by the title "DIGITAL INDIA" (www.digitalindia.gov.in) Indian government has launched many e-governance initiatives, including a portal for public grievance, MCA21 Mission Mode Project, e-Filing of income tax, e-gazette, Project Nemmadi, and their overall digital India policy. E-government in Indonesia is developing, especially in central and regional/local government offices. E-government was officially introduced to public administration by Presidential Directive No 6/2001 on Telematics, which states that the government of Indonesia has to use telematics technology to support good governance. Furthermore, e-government should have been introduced for different purposes in government offices. As one of the ISO member countries, Indonesia gives more attention to facilitating the activities of standardization. Among of the facilities provided are building the National information system of standardization (SISTANAS) and Indonesia Standardization Information Network (INSTANET). As of 2017, ministries, institutions and local governments of Indonesia used to run separate e-government systems, which is now integrated into a centrally based system. In 2017, the government has also undertaken programs for digitization of SMEs and the informal sector. Many of the cities across Indonesia, including Jakarta, Bandung, Surabaya, and Makassar, are implementing smart city concepts, consisting of e-government, e-health, e-education, e-logistics and e-procurement as priority areas. In 2002, Iran published a detailed report named TAKFA (Barnameye Tose-e va Karborde Fanavaie Etela’at) in which it was predicted that most of the government bodies would try to virtualize their services as soon as possible. However, based on the reports by UN bodies, Iran has failed in recent years to meet the average standards of e-government. In 2008, the Supreme Council of Information released a report which criticized the government for its poor advancement in employing new communication technologies for administration purposes. In 2016, Iran launched the National Information Network and improved the quality and speed of Internet access. In 2017, Iran introduced phase one of e-government including E-Tax, E-Customs, E-Visa, E-Government Portal, and a mobile application to modernize Iran's government services. The Iranian government plans to introduce other phases of e-gov soon. The Iraqi e-government citizen program was established to "eliminate bribery and favoritism and end the citizens' suffering in going back repeatedly to directories". The interface lets the citizen send requests and complaints; it can also be used for issuing identity cards, driving licenses and passports. Jordan established its e-government program in 2002. Many governmental services are provisioned online. The e-government portal egov.kz was launched in 2012 as part of Kazakhstan's effort to modernize how citizens access government services and information. It offers all possible services that can be provided by the state for citizens and businesses such as education, health care, social security, job placement and employment, tax issues, legal assistance. It is currently at the transformational stage of development. The main goal of egov.kz is to maximize efficiency. For instance, users can register birth of a child, while simultaneously resolving all related issues—applying for benefits and putting the child on the waiting list for kindergarten. The egov.kz mobile app was recognized as best app in the GovTechioneers competition at the 2017 World Government Summit in Dubai. At the WSIS Prizes 2017 (World Summit on the Information Society contest), three projects from the Republic of Kazakhstan were announced champions: e-Government, Open Government, and Integrated Call Center 1414. Projects of the e-government: In Malaysia, the e-government efforts are undertaken by the Malaysian government, under the umbrella of Multimedia Super Corridor (MSC) and e-government flagships, which was launched in mid-1996, by Mahathir Mohamad (1981–2003), by the then Prime Minister of Malaysia (Jeong & Nor Fadzlina, 2007). Electronic government is an initiative aimed at reinventing how the government works. It seeks to improve how the government operates, as well as how it delivers services to the people (Ibrahim Ariff & Goh Chen Chuan, 2000). The Yangon City Development Committee (Burmese- ရန်ကုန်မြို့တော်စည်ပင်သာယာရေးကော်မတီ) (YCDC) is the administrative body of Yangon, and Yangon is the largest city and former capital of Myanmar (Burma). The Yangon City Development Committee consists of 20 departments. Its headquarters was on the Yangon City Hall. The committee's chairman is also the city's mayor.[citation needed] In 2003, YCDC was organized to provide e-government for Yangon City. The main purposes of the city's e-government program are to provide easy access between the government and the city's citizens via the Internet, to reduce paper usage, to reduce the city budget, to build the city's fiber ring, to provide timely public information, to store public data and to develop and expand G2G, G2C, G2B, and G2E programs.[citation needed] In January 2013, responsibility for e-government was divided between the e-Government Administration Committee and the e-Government Processing Committee. The e-Government Administration Committee includes the Mayor of Yangon City as Chief, the General Secretary of Yangon City as Sub-Chief, and the other 20 head of department officers as chairmen. The e-Government Processing Committee includes the Head of Public Relation and Information Department as Chief and the other 20 deputy head of department officers as chairmen.[citation needed] The official web-portal is www.ycdc.gov.mm. Mandalay is the second-largest city and the last royal capital of Myanmar (Burma). In 2014, Mandalay Region Government developed www.mdyregion.gov.mm to know about regional government and their activities to people. Mandalay Region Government organized the e-Government Steering Committee on 23 June 2016. That committee chairman was U Sai Kyaw Zaw, Minister, Ministry of Ethnic Affairs. On 21 July 2017, www.emandalay.gov.mm web portal was opened by Dr. Zaw Myint Maung, Prime Minister of Mandalay Region Government. That portal includes 2 e-services, 199 topics from 70 agencies. The committee develops a Regional Data Center, too. That Datacenter will be opened in 2018. The e-government planning and conceptual framework has been presented to Nepal in extensive support from the Government of Korea (KIPA). E-government Vision is "The Value Networking Nepal" through Nepal's e-government mission statement is "Improve the quality of people's lives without any discrimination, transcending regional and racial differences, and realize socio-economic development by building a transparent government and providing value-added quality services through ICT." The e-government practice has been slow both in adoption and practice in Nepal. However, local government bodies now have dedicated team of ICT Volunteers working towards implementing e-government in the country through an extensive ICT for Local Bodies initiatives. In 2015, the Ministry of Interior of Saudi Arabia launched the e-service application known as Absher. The application allows the people of the Kingdom to access more than 279 different government services from their smartphones, without the need to queue or for the inefficiencies of bureaucracy. Some e-services that can be completed by way of the application include Another application that has been launched is Tawakkalna. This application was created by the Saudi Data and Artificial Intelligence Authority (SDAIA) in order for the government to better counteract against COVID-19. Initially, the application was created so as to issue permits to those who were required to commute to work during lockdown. Now, it is being used for travel; entering commercial buildings, hospitals, and schools within the Kingdom; setting vaccine appointments; and COVID-19 tracing. Announced in 2013 with "an ambitious plan to allow wider public access to government data to improve the transparency of state affairs", this initiative includes citizen-centered government innovation, core values of openness, sharing, communication, collaboration for all areas of governing, customized services to individual citizens, which will create jobs and support creative economy. Sri Lanka have taken some initiative actions to provide the benefits of e-government to the citizens. To implement the principles of e-government, the Ministry of Information and Telecommunication Technologies of Thailand developed a plan for creating a modern e-services system during 2009–2014. The next stage was the five-year project of the digital government, which began in 2016 and will be completed in 2021. This project assumes that within five years, more than 80% of Thai government agencies will use electronic documents for identification. There is the Unified State Portal of e-Government of Thailand, developed by the Ministry of Information and Telecommunications Technology in 2008. In 2018, Thailand ranks 73rd in the UN e-government ranking. In the United Arab Emirates, the Emirates eGovernment is designed for e-government operations. In 2014, the Government of Pakistan created the National Information Technology Board under the Ministry of Information Technology & Telecom to enable a digital eco-system for government services to the citizens of Pakistan. NITB was formed as a result of a merger between Pakistan Computer Bureau (PCB) and Electronic Government Directorate (EGD). The key functions identified by the NITB are NITB rolled out an e-Office Suite across various ministries in the Government of Pakistan. While it clearly pursued efficiency gains and improved transparency, it also hoped to deliver "efficient and cost-effective public services to citizens of Pakistan." The suite primarily included five modules or applications across all the ministries. Description of each module listed are NITB released a high-level diagram that describes the process of transforming federal government agencies and ministries to e-office environments. Criticism: NITB's rollout of the e-Office suite across almost all federal agencies is not only overly ambitious but also likely to fail. It seems to put together a lot of lofty organizational efficiency goals with a set of delivery or citizen-facing targets. In fact, most of the services NITB has provided have been largely conceptual and not sufficient concrete. The process outlined in the adoption process diagram seems devoid of any user-centric design or value proposition formulation. Instead of creating many MVPs (Minimum Viable Products) and taking advantage of an iterative and validated learning the process, the e-Office Suite seems to incorporate all the features and functions that various ministries and divisions may need or use. It seems to focus more on the needs of the bureaucrats and government agencies rather than the needs of the end-user (citizens of Pakistan) and what services would they need that a ministry or division can provide. E-government (from (en) electronic government, (de) e-government, rarely eGovernment) refers to the simplification, implementation and support of processes for information, communication and transaction within and between state, municipal and other official institutions and between these institutions and citizens or companies and organizations through the use of digital information and communication technologies (ICT). The legal basis in Germany for federal authorities is the Electronic Government Act (EGovG). Some of the federal states have their own e-government laws. The first discussions in Poland on e-government in Europe began with a report published in 1994 by the European Commission, entitled "Europe and the Global Information Society Recommendations to the Council of Europe" (named after one of the authors of the Bangemann Report). It showed the direction of the development of the global information society in Europe. Since then, the concept of e-government has become a permanent fixture in the issues raised in the EU as a component of eEurope. In Poland, the year 2000 should be considered the beginning of e-government. It was then that the Scientific Research Committee prepared a document based on seven expert opinions, which was published under the collective title "Global Information Society in the conditions of Poland's Accession to the European Union". Today, we know the material as an official document of the Scientific Research Committee and the Ministry of Communications entitled "Goals and directions of development of the information society in Poland". In 2000, the Sejm also adopted a resolution on building the information society, and then in 2001, passed an act important for the development of e-government: introducing the Public Information Bulletin (BIP), the Act on access to public information, and the act on electronic signature, regulating the issue of e-signature. The next step in the development of e-management was the preparation of the ePoland document, containing an action plan for the development of the information society in Poland, which was modeled on the European eEurope development plan. This document was last updated in 2002. The next version of this strategy was called ePolska-2006. The adoption of this document resulted in the preparation by the Scientific Research Committee of the preliminary concept of the Gateway to Poland project (a central IT system, the task of which was to provide administrative services for citizens and business entities by electronic means) and the document The Strategy for Informatisation of the Republic of Poland-ePoland. On the Federal Law "On providing state and municipal services" (2010), the strategy on development of Information Society in the Russian Federation, approved by the President (2008), the Federal target programme "Electronic Russia" (2002 – 2010 years), approved by the government (2002), the State Programme "Information Society" (2010), the Procedure on development and approval of administrative regulations execution of public functions (public services), approved by the government (2005), the concept of administrative reform in the Russian Federation in 2006 - 2010 respectively, approved by the government (2005), on other orders, resolutions and acts in the Russian Federation was created electronic government (or e-government).[citation needed] The main target on creating e-government lies in the field of providing equal opportunities for all the Russians in spite of their living place and their incomes and make a more effective system of public administration. So e-government is created for reaching the useful system of public management accommodating the individual interests of every citizen by participation through ICTs in public policymaking.[citation needed] Nowadays, Russian e-government includes such systems as 1. The united interagency interacting system using for providing of state and municipal services, exchange of information and data between participants of interagency interacting, quick approval of state and municipal decisions, etc. 2. The united system for authentication and authorization providing evidence of the rights of all participants of e-government. 3. The united portal of state and municipal services and functions which are the "single window" for all information and services assured by government and municipals. The portal of public services is one of the key elements of the project to create an "electronic government" in the country. The portal provides a single point of access to all references on state and municipal services through the Internet and provides citizens and organizations the opportunity to receive these services electronically. Monthly visits by users of the public services portal range between 200,000 and 700,000. For example, citizens are now able to obtain or exchange a driver's license through this portal. 4. Head system providing utilization of electronic signature. Other systems located on cloud services, since cloud computing has been a useful tool for e-government according to researchers.[citation needed] Today, Russian e-government elements are demanded in the spheres of e-governance, e-services (e-health, e-education, e-library, etc.), e-commerce, e-democracy (web-election, Russian public initiative). By the United Nations E-Government Survey 2012, e-Government for the People Russia became one of the 7 emerging leaders in e-government development, took ninth place in rating of e-government development in largest population countries, and took 8th rank in top e-participation leaders, after Norway, Sweden and Chile, Advancing 32 positions in the world rankings, the Russian Federation became the leader of e-government in Eastern Europe. Evolution of ICT in the Russian Federation provided the raising of Russia in e-government development index to the 27 places. E-government in Turkey is the use of digital technology to improve service efficiency and effectiveness in Turkey. As of December 2020, 700 government agencies offers 5,338 applications to 51,757,237 million users. The mobile application offers 2,850 services. The main coordinating government body in matters of e-government is Ministry of Digital Transformation established in 2019. In 2020, it launched the Diia app and web portal which allows Ukrainians to use various kinds of documents (including ID cards and passports) via their smartphones as well as to access various government services with the plans to make all governmental services available by 2023. Transformational Government: Enabled by Technology, 2005, stated that "the future of public services has to use technology to give citizens choice, with personalised services designed around their needs not the needs of the provider". A major report published by the House of Commons Public Administration Select Committee in July 2011 addressed procurement of Information Technology by the government and found there was an overreliance "on a small 'oligopoly' of large suppliers". The report introduced its summary with the observation that [D]espite a number of successful initiatives, government's overall record in developing and implementing new IT systems is appalling. However, an initiative introduced in 2011 which enables people to notify a number of central and local government departments about a birth or death at the same time, called "Tell Us Once", has been welcomed as "a fine example of innovation and best practice, a dynamic and inspiring model". The current Clerk of the Privy Council – the head of the federal public service has made workplace renewal a pillar of overall public service renewal. The key to workplace renewal is the adoption of collaborative networked tools. An example of such a tool is GCPEDIA – a wiki platform for federal public servants. Other tools include GCconnex, a social networking tool, and GCforums, a discussion board system. Report of the Auditor General of Canada: Chapter 1 Information Technology: Government On-Line 2003: "One of the key principles of Government On-Line is that programs and services will be transformed to reflect the needs and expectations of clients and citizens. From the government's perspective, the overall objective of the GOL initiative is full service transformation – to fundamentally change the way the government operates and to deliver better services to Canadians." The election of Barack Obama as President of the United States became associated with the effective use of Internet technologies during his campaign and in the implementation of his new administration in 2009. On January 21, 2009, the President signed one of his first memorandums – the Memorandum for the Heads of Executive Departments and Agencies on Transparency and Open Government. The memo called for an unprecedented level of openness in government, asking agencies to "ensure the public trust and establish a system of transparency, public participation, and collaboration." The memo further "directs the Chief Technology Officer, in coordination with the Director of the Office of Management and Budget (OMB) and the Administrator of General Services (GSA), to coordinate the development by appropriate executive departments and agencies [and] to take specific actions implementing the principles set forth in the memorandum." President Obama's memorandum centered around the idea of increasing transparency throughout various different federal departments and agencies. By enabling public websites like recovery.gov and data.gov to distribute more information to the American population, the administration believes that it will gain greater citizen participation. In 2009, the U.S. federal government launched Data.gov to make more government data available to the public. With data from Data.Gov, the public can build apps, websites, and mashups. Although "Gov 2.0", as a concept and as a term, had been in existence since the mid-2000s, it was the launch of Data.gov that made it "go viral". In August 2009, the City of San Francisco launched DataSF.org with more than a hundred datasets. Just weeks after the DataSF.org launch, new apps and websites were developed. Using data feeds available on DataSF.org, civic-minded developers built programs to display public transportation arrival and departure times, where to recycle hazardous materials, and crime patterns. Since the launch of DataSF.org, there have been more than seventy apps created with San Francisco's data. In March 2009, former San Francisco Mayor Gavin Newsom was at Twitter headquarters for a conversation about technology in government. During the town hall, Newsom received a tweet about a pothole. He turned to Twitter co-founders Biz Stone and Evan Williams and said, "Let's find a way for people to tweet their service requests directly to San Francisco's 311 customer service center." Three months later, San Francisco launched the first Twitter 311 service, called @SF311, allowing residents to tweet, text, and send photos of potholes and other requests directly to the city. Working with Twitter and using the open-source platform, CoTweet turned @SF311 into reality. The software procurement process for something like this would normally have taken months, but in this case, it took less than three months. The @SF311 is saving the city money in call center costs. In 2011, The United States Government Accountability Office passed the Electronic Government Act in 2002 to promote better use of Internet and information technology; and additionally, to improve government services for citizens, internal government operations, and opportunities for citizen participation in government. Presidential Innovation Fellows program where "teams of government experts and private-sector doers take a user-centric approach to issues at the intersection of people, processes, products, and policy to achieve lasting impact" launched in 2012. 18F, a new digital government delivery service, was formed in early 2014 and the United States Digital Service (USDS) was launched later in 2014. The goal defined in the Digital Government Strategy is to reach the total digitization of services by the end of 2022. "The main objective of the digital government is to bring citizens closer to the State. Technologies allow us to see each Brazilian better, including those who feel excluded, to direct public policies in a much more agile and efficient way and to reach mainly those who need it most", emphasizes the Digital Government secretary of the Ministry of Economy, Luís Felipe Monteiro. International initiatives The early pioneering work by some governments is now being picked up by a range of global organizations which offer support to governments in moving to a transformational government approach. For example: See also References External links |
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Contents Rho Orionis Rho Orionis, Latinised from ρ Orionis, is the Bayer designation for an orange-hued binary star system in the equatorial constellation of Orion. It is visible to the naked eye with an apparent visual magnitude of +4.44. The star shows an annual parallax shift of 9.32 mas due to the orbital motion of the Earth, which provides a distance estimate of roughly 350 light-years from the Sun. It is moving away from the Sun with a radial velocity of +40.5 km/s. About 2.6 million years ago, Rho Orionis made its perihelion passage at a distance of around 10 light-years (3.1 parsecs). This is a single-lined spectroscopic binary system with an orbital period of 2.8 years and an eccentricity of 0.1. The visible component is an evolved giant star of type K with a stellar classification of K0 III. Its measured angular diameter is 2.19±0.02 mas, which, at its estimated distance yields a physical size of about 25 times the radius of the Sun. It has 2.67 times the mass of the Sun and is about 650 million years old. The star is radiating 251 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,533 K. Notes References |
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Contents Sebile Sebile, alternatively written as Sedile, Sebille, Sibilla, Sibyl, Sybilla, and other similar names, is a mythical medieval queen or princess who is frequently portrayed as a fairy or an enchantress in the Arthurian legend and Italian folklore. She appears in a variety of roles, from the most faithful and noble lady to a wicked seductress, often in relation with or substituting for the character of Morgan le Fay. Some tales feature her as a wife of either King Charlemagne or Prince Lancelot, and even as an ancestor of King Arthur. Origins The character of Sebile has her earliest roots in the Ancient Greek figure of the virgin priestess and prophetess known as the Cumaean Sibyl. This Classic motif was later transmuted into a Christianized character named Sibyl featured in the Christian mythology of the Early Middle Ages. A further transformation during the Late Middle Ages eventually turned her (as summed up by Alfred Foulet) from ...the sibyl of antiquity, a god-possessed human prophetess, into the fay of mediaeval, particularly Arthurian romance, a queen and enchantress, only rarely virginal and prophetic, usually a lustful magician who entices heroes to her otherworld lair for prodigiously prolonged sessions of love-making. In the late mediaeval legend Sybil/Sybilla/Sebille comes to resemble Morgan le Fay so closely as to be conflated with her in those places in which she is not Morgan's rival or companion. Matter of France Queen Sebile first appears in text in the Matter of France's Chanson des Saisnes (Song of the Saxons, written c. 1200) as the young and beautiful second wife (a daughter in later versions) of the Saxon king named Guiteclin or Geteclin (representing the historical Widukind), who fights against the Franks. Queen Sebile falls in love with the Frankish king Charlemagne's nephew and Roland's brother, Baudoin, for whom she betrays her husband. After Guiteclin is killed, she marries Baudoin, who thus becomes the King of Saxony. Later versions from various countries present her instead as a daughter of either King Desiderius of Lombardy in Macaire ou la Reine Sebile, the Emperor of Constantinople in La Chanson de la Reine Sibile and Willem Vorsterman's Historie vander coninghinnen Sibilla, or the pagan king Agolant in La Reine Sebile. This Sebile marries not Baudoin, but Charlemagne himself. In the early 13th-century French epic poem Huon de Bordeaux, Sebile is a cousin of the story's eponymous hero, the Frankish knight Huon of Bordeaux. She uses her magical abilities to aid Huon in slaying her captor: a monstrous, 17-foot-tall giant named Pride (l'Orgueilleux), whom Huon defeats and beheads after a terrible duel. In La Chanson d'Esclarmonde, one of the continuations of Huon, Sebile is one of the three fay mentioned by name when summoned by the fairy queen Morgue (Morgan), Lady of the Hidden Isle (Avalon), to welcome Huon and Esclarmonde, his lover and daughter of the Emir of Babylon. Matter of Britain Sebile makes her first known appearance in an Arthurian legend in Ulrich von Zatzikhoven's late 12th-century German poem Lanzelet, in which the loving fairy mistress of Prince Lancelot is named Iblis (or Yblis), an anagram for Sibil/Sybil. There, she is the only daughter of Iweret of the Beautiful Forest (Beforet), an enemy of the family of Lancelot's foster mother, the sea fairy Queen of the Maidenland. Iblis is the most virtuous woman, as proven by a magic cloak test (an arguably central motif of the entire tale), who falls in love with Lancelot in a prophetic dream before even meeting him. After Lancelot slays her father in combat (she faints when he fights and instantly forgives him after his victory) and he learns his name and real identity, Princess Iblis marries him as the new king of this realm. Lancelot later leaves to defeat a hundred knights and marry the Queen of Pluris (marrying for the fourth time), but eventually escapes from her and returns to the faithful Iblis and their kingdom. Ruling their combined lands together, they have four children, and later they both die on the same day. In the early 13th-century French Lancelot-Grail prose cycle, Queen Sebile (Sedile le roine) or Sebile the enchantress (Sebile l'enchanteresse) becomes a villainous character. She takes part in the kidnapping of Lancelot by her, Morgan le Fay (Morgue la fee), and the Queen of Sorestan. This story was made well known through Thomas Malory's retelling in his popular Le Morte d'Arthur, where the three queens became four: Queen Morgan of Gorre (Rheged), and the unnamed trio of the Queen of Norgales (North Galys, meaning North Wales), the Queen of Eastland, and the Queen of the Outer Isles (identified by Malory as the Hebrides). The queens of Eastland and Sorestan appear identical in both versions, so Sebile seems to be the Queen either of North Galys or the Outer Isles in Malory's tale. They all are described as the most powerful female mages in the world after the Lady of the Lake. Sebile, the youngest of them, is noted as so expert at sorcery that she had managed to render Cerberus harmless during her visit to Hell. In a well-known episode from Lancelot-Grail, found largely unchanged in Malory's compilation, the queens are riding together when they find the young Lancelot asleep by an apple tree (apples being a symbol of enchantment in the legends). Amazed by how fairylike handsome Lancelot is, they argue over who among them would be the most deserving of his love for reasons other than their equal social rank and magical powers (at least in the French original version, as Malory turns Morgan into a clearly dominant leader of the group). Each of them states different reasons to be chosen, with Sebile emphasizing her merry character, youth and beauty. The Queens consider waking up Lancelot to ask him to choose among them, but Morgan advises that they take him still asleep to their castle,[note 1] where they can hold him in their power. The next day, the Queens appear before the awoken Lancelot in their finest clothes and ask him to choose one of them as a lover; if he refuses, he will never leave his prison. Despite this threat, Lancelot, faithful to his secret beloved, Queen Guinevere, categorically and with contempt refuses all three. Humiliated by his response, the angry queens throw Lancelot into a dungeon, but he is soon freed by the daughter of the King of Norgales' enemy (either King Bagdemagus of Gorre or the Duke of Rochedon) who asks him to fight for her father in an upcoming tournament. In the Venician Les Prophéties de Merlin (written c. 1276), Sebile is part of a quartet of enchantresses: besides Sebile and Morgan (Morgain), here being her only lover among all the women, they include also the Queen of Norgales and the Lady of Avalon (Dame d'Avalon). They all are former students of Merlin, who had received dark magic powers through his demonic origin, and are also in good relations with the extremely villainous knight Brehus without Mercy (Brehus sans Pitié). Sebile remains a powerful sorceress, whose special skills include invisibility, but is clearly inferior to the Lady; this is evidenced in the episode where Sebile and the Queen of the Norgales together attack the Lady's castle with their magic (in Sebile's case, trying to set it on fire) without any real effect, while the Lady retaliates by effortlessly taking their clothes off and making the naked Sebile visible for all. Morgan too is greater in her magic and seems to be in a master-to-disciple relationship with the younger Sebile, but they are equal in their lust. The two are usually inseparable companions, but this is tested when they become rivals to seduce the widowed knight known as Berengier of Gomeret or Bielengier the Handsome (Bielengiers li Biaus), who first spends a night with Sebile but then leaves to marry one of Morgan's ladies, the virgin Lily Flower (Flour de Lis), who had kidnapped his child for Morgan. This results in a quarrel that goes from an exchange of worst insults to a physical brawl that leaves Morgan battered half to death by the younger Sebile; the Queen of Norgales then saves the remorseful and terrified Sebile from Morgan's revenge by reminding Morgan how they both stole Lancelot's brother Ector de Maris from her but she had forgiven them, and Morgan and Sebile soon fully reconcile. There are also other knights that Sebile is known to desire, especially Lamorak. In the French text known as the Livre d'Artus (Book of Arthur, written c. 1280), Sebile (Sebille) is a beautiful pagan queen of the Fairy Realm (la Terre Fae) Sarmenie,[note 2] who has just lost her husband. Queen Sebile has an affair with Arthur's knight Sagramore (Sagremor), who is at first her prisoner until he seduces her. Sagramore converts Sebile to Christianity when she hastily baptizes herself after he refuses to sleep with a heathen. An evil knight known as the Faery Black Knight (Le Noir Chevalier Faé, Cheualiers Faez) or Baruc the Black (Baruc li Noirs) is revealed as the one who had killed her previous husband in order to marry her himself. The villain is then defeated in great battle and captured after a personal duel against Sagramore with Sebile's help. After that, Sebile marries Sagramore, who stays with her for 15 days before leaving to resume his quest. Sagramor and Sebille are also paired in Jean Froissart's Roman de Meliador. In the anonymous French prose romance Perceforest, a massive quasi-prequel to the Arthurian legend written c. 1330, the most beautiful, wise and honorable enchantress Sebile is known variably as Sebile of the Lake (Sebile du Lac) or the Lady of the Lake, Sebile of the Red Castle (Dame du Lac, Sebile du Chastel Vermei). It is a different character yet a symbolic namesake, which is a recurring theme in Perceforest. In this tale, King Arthur is the descendant from the union of Sebile and Alexander the Great. Alexander is at first a young knight before becoming King Alexander of England and then battling to conquer the world. Sebile falls in love with Alexander on sight; she incites him into her mist-concealed Castle of the Lake (later the Red Castle) by magic and keeps him there through seduction. Their mutual love then grows, especially after Sebile nurses him back to health from a grave wound and Alexander lifts a siege of her castle by defeating her enemies. In one episode, travelling Sebile is attacked by four evil knights who want to rape her, but the Scottish knight Tor of Pedrac arrives at the last moment and slays the villains (their severed heads are then preserved with a spell and given to him as a memorial of this deed). After Alexander dies, Sebile marries Vestige of Joy, also known as the Knight of the Black Eagle, and gives him a daughter named Alexandre, also known as the Maiden of the Two Dragons. Other characters include her cousin Gloriane, the lady of Castle Darnant. Italian folklore and other classic literature Another Sebile later appears at the end of the 14th century in the French Le Roman d'Eledus et Serene as a maidservant of the heroine Serene, "versed in the science of love". Serene and Sebile are considered doublets. In central Italy, Sebile features in a local version of the Venusberg motif from Germanic mythology. In The Paradise of Queen Sebile (Le Paradis de la Reine Sebile, Il paradise della regina Sibilla), Antoine de la Sale records a folk legend that he heard from locals at the aptly-named mountain Monte Sibilla in 1420: Sebile/Sibilla is depicted as a demonic fay sorceress who lives with an entourage of amorous nymphs in magnificent palaces and lush gardens within a subterranean, paradise-like enchanted realm (inspired by Morgan's Avalon). She welcomes guests to her kingdom of carnal pleasure (voluttà), but, if, entangled in the delights, they spend more than a year there, the guests are trapped forever in sinful bliss, waiting for the Last Judgment with the fairies. In de la Sale's La Salade (written c. 1440), a German knight and his squire enter Queen Sebile's kingdom out of curiosity and revel for a year in its forbidden pleasures. Before it is too late for him, the knight realizes the sinfulness of this by witnessing how the fair ladies transform each week into adders and scorpions for a night, so he escapes and hurries to Rome to confess to the Pope just in time. The squire, who regrets having left the pleasures of the fairy realm, flees him and returns to the Sebile's earthly paradise; the Pope sends out messengers with the news of his absolution, but they arrive too late. Sibilla is gifted with her famed prophetic powers, but tells only bad news, never good. In a similar story included within Andrea da Barberino's prose chivalric romance Il Guerrin Meschino (the part written c. 1391), a pious knight, advised to seek out the fay Sebile (fée Sébile) in her abode in the mountain near Norcia, goes through a cave to her realm; he stays there for a year, but refuses all temptation and only attempts to learn about his parentage, without success. He boldly resists the flattering advances of the fay and her damsels, whose sinister nature he suspects, but later too receives an absolution after confessing to the Pope in any case. Sebile is also a recurring character in Italian works of the 16th century, such as in Gian Giorgio Trissino's L'Italia liberata dai Goti (1547). The names and characters of Sebile (Sibilla), Morgan le Fay (Fata Morgana) and the fairy queen Alcina are often interchangeable in Italian tales of fairies; for example, Morgan substitutes for Sebile in P.A. Caracciolo's 15th-century Magico. Pietro Aretino's 16th-century Ragionamenti mentions a certain "sister of Sibilla of Norcia and aunt of Morgan the Fairy (Fata Morgana)". Modern fiction See also Notes Further reading References |
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Contents Elon Musk Elon Reeve Musk (/ˈiːlɒn/ EE-lon; born June 28, 1971) is a businessman and entrepreneur known for his leadership of Tesla, SpaceX, Twitter, and xAI. Musk has been the wealthiest person in the world since 2025; as of February 2026,[update] Forbes estimates his net worth to be around US$852 billion. Born into a wealthy family in Pretoria, South Africa, Musk emigrated in 1989 to Canada; he has Canadian citizenship since his mother was born there. He received bachelor's degrees in 1997 from the University of Pennsylvania before moving to California to pursue business ventures. In 1995, Musk co-founded the software company Zip2. Following its sale in 1999, he co-founded X.com, an online payment company that later merged to form PayPal, which was acquired by eBay in 2002. Musk also became an American citizen in 2002. In 2002, Musk founded the space technology company SpaceX, becoming its CEO and chief engineer; the company has since led innovations in reusable rockets and commercial spaceflight. Musk joined the automaker Tesla as an early investor in 2004 and became its CEO and product architect in 2008; it has since become a leader in electric vehicles. In 2015, he co-founded OpenAI to advance artificial intelligence (AI) research, but later left; growing discontent with the organization's direction and their leadership in the AI boom in the 2020s led him to establish xAI, which became a subsidiary of SpaceX in 2026. In 2022, he acquired the social network Twitter, implementing significant changes, and rebranding it as X in 2023. His other businesses include the neurotechnology company Neuralink, which he co-founded in 2016, and the tunneling company the Boring Company, which he founded in 2017. In November 2025, a Tesla pay package worth $1 trillion for Musk was approved, which he is to receive over 10 years if he meets specific goals. Musk was the largest donor in the 2024 U.S. presidential election, where he supported Donald Trump. After Trump was inaugurated as president in early 2025, Musk served as Senior Advisor to the President and as the de facto head of the Department of Government Efficiency (DOGE). After a public feud with Trump, Musk left the Trump administration and returned to managing his companies. Musk is a supporter of global far-right figures, causes, and political parties. His political activities, views, and statements have made him a polarizing figure. Musk has been criticized for COVID-19 misinformation, promoting conspiracy theories, and affirming antisemitic, racist, and transphobic comments. His acquisition of Twitter was controversial due to a subsequent increase in hate speech and the spread of misinformation on the service, following his pledge to decrease censorship. His role in the second Trump administration attracted public backlash, particularly in response to DOGE. The emails he sent to Jeffrey Epstein are included in the Epstein files, which were published between 2025–26 and became a topic of worldwide debate. Early life Elon Reeve Musk was born on June 28, 1971, in Pretoria, South Africa's administrative capital. He is of British and Pennsylvania Dutch ancestry. His mother, Maye (née Haldeman), is a model and dietitian born in Saskatchewan, Canada, and raised in South Africa. Musk therefore holds both South African and Canadian citizenship from birth. His father, Errol Musk, is a South African electromechanical engineer, pilot, sailor, consultant, emerald dealer, and property developer, who partly owned a rental lodge at Timbavati Private Nature Reserve. His maternal grandfather, Joshua N. Haldeman, who died in a plane crash when Elon was a toddler, was an American-born Canadian chiropractor, aviator and political activist in the technocracy movement who moved to South Africa in 1950. Elon has a younger brother, Kimbal, a younger sister, Tosca, and four paternal half-siblings. Musk was baptized as a child in the Anglican Church of Southern Africa. Despite both Elon and Errol previously stating that Errol was a part owner of a Zambian emerald mine, in 2023, Errol recounted that the deal he made was to receive "a portion of the emeralds produced at three small mines". Errol was elected to the Pretoria City Council as a representative of the anti-apartheid Progressive Party and has said that his children shared their father's dislike of apartheid. After his parents divorced in 1979, Elon, aged around 9, chose to live with his father because Errol Musk had an Encyclopædia Britannica and a computer. Elon later regretted his decision and became estranged from his father. Elon has recounted trips to a wilderness school that he described as a "paramilitary Lord of the Flies" where "bullying was a virtue" and children were encouraged to fight over rations. In one incident, after an altercation with a fellow pupil, Elon was thrown down concrete steps and beaten severely, leading to him being hospitalized for his injuries. Elon described his father berating him after he was discharged from the hospital. Errol denied berating Elon and claimed, "The [other] boy had just lost his father to suicide, and Elon had called him stupid. Elon had a tendency to call people stupid. How could I possibly blame that child?" Elon was an enthusiastic reader of books, and had attributed his success in part to having read The Lord of the Rings, the Foundation series, and The Hitchhiker's Guide to the Galaxy. At age ten, he developed an interest in computing and video games, teaching himself how to program from the VIC-20 user manual. At age twelve, Elon sold his BASIC-based game Blastar to PC and Office Technology magazine for approximately $500 (equivalent to $1,600 in 2025). Musk attended Waterkloof House Preparatory School, Bryanston High School, and then Pretoria Boys High School, where he graduated. Musk was a decent but unexceptional student, earning a 61/100 in Afrikaans and a B on his senior math certification. Musk applied for a Canadian passport through his Canadian-born mother to avoid South Africa's mandatory military service, which would have forced him to participate in the apartheid regime, as well as to ease his path to immigration to the United States. While waiting for his application to be processed, he attended the University of Pretoria for five months. Musk arrived in Canada in June 1989, connected with a second cousin in Saskatchewan, and worked odd jobs, including at a farm and a lumber mill. In 1990, he entered Queen's University in Kingston, Ontario. Two years later, he transferred to the University of Pennsylvania, where he studied until 1995. Although Musk has said that he earned his degrees in 1995, the University of Pennsylvania did not award them until 1997 – a Bachelor of Arts in physics and a Bachelor of Science in economics from the university's Wharton School. He reportedly hosted large, ticketed house parties to help pay for tuition, and wrote a business plan for an electronic book-scanning service similar to Google Books. In 1994, Musk held two internships in Silicon Valley: one at energy storage startup Pinnacle Research Institute, which investigated electrolytic supercapacitors for energy storage, and another at Palo Alto–based startup Rocket Science Games. In 1995, he was accepted to a graduate program in materials science at Stanford University, but did not enroll. Musk decided to join the Internet boom of the 1990s, applying for a job at Netscape, to which he reportedly never received a response. The Washington Post reported that Musk lacked legal authorization to remain and work in the United States after failing to enroll at Stanford. In response, Musk said he was allowed to work at that time and that his student visa transitioned to an H1-B. According to numerous former business associates and shareholders, Musk said he was on a student visa at the time. Business career In 1995, Musk, his brother Kimbal, and Greg Kouri founded the web software company Zip2 with funding from a group of angel investors. They housed the venture at a small rented office in Palo Alto. Replying to Rolling Stone, Musk denounced the notion that they started their company with funds borrowed from Errol Musk, but in a tweet, he recognized that his father contributed 10% of a later funding round. The company developed and marketed an Internet city guide for the newspaper publishing industry, with maps, directions, and yellow pages. According to Musk, "The website was up during the day and I was coding it at night, seven days a week, all the time." To impress investors, Musk built a large plastic structure around a standard computer to create the impression that Zip2 was powered by a small supercomputer. The Musk brothers obtained contracts with The New York Times and the Chicago Tribune, and persuaded the board of directors to abandon plans for a merger with CitySearch. Musk's attempts to become CEO were thwarted by the board. Compaq acquired Zip2 for $307 million in cash in February 1999 (equivalent to $590,000,000 in 2025), and Musk received $22 million (equivalent to $43,000,000 in 2025) for his 7-percent share. In 1999, Musk co-founded X.com, an online financial services and e-mail payment company. The startup was one of the first federally insured online banks, and, in its initial months of operation, over 200,000 customers joined the service. The company's investors regarded Musk as inexperienced and replaced him with Intuit CEO Bill Harris by the end of the year. The following year, X.com merged with online bank Confinity to avoid competition. Founded by Max Levchin and Peter Thiel, Confinity had its own money-transfer service, PayPal, which was more popular than X.com's service. Within the merged company, Musk returned as CEO. Musk's preference for Microsoft software over Unix created a rift in the company and caused Thiel to resign. Due to resulting technological issues and lack of a cohesive business model, the board ousted Musk and replaced him with Thiel in 2000.[b] Under Thiel, the company focused on the PayPal service and was renamed PayPal in 2001. In 2002, PayPal was acquired by eBay for $1.5 billion (equivalent to $2,700,000,000 in 2025) in stock, of which Musk—the largest shareholder with 11.72% of shares—received $175.8 million (equivalent to $320,000,000 in 2025). In 2017, Musk purchased the domain X.com from PayPal for an undisclosed amount, stating that it had sentimental value. In 2001, Musk became involved with the nonprofit Mars Society and discussed funding plans to place a growth-chamber for plants on Mars. Seeking a way to launch the greenhouse payloads into space, Musk made two unsuccessful trips to Moscow to purchase intercontinental ballistic missiles (ICBMs) from Russian companies NPO Lavochkin and Kosmotras. Musk instead decided to start a company to build affordable rockets. With $100 million of his early fortune, (equivalent to $180,000,000 in 2025) Musk founded SpaceX in May 2002 and became the company's CEO and Chief Engineer. SpaceX attempted its first launch of the Falcon 1 rocket in 2006. Although the rocket failed to reach Earth orbit, it was awarded a Commercial Orbital Transportation Services program contract from NASA, then led by Mike Griffin. After two more failed attempts that nearly caused Musk to go bankrupt, SpaceX succeeded in launching the Falcon 1 into orbit in 2008. Later that year, SpaceX received a $1.6 billion NASA contract (equivalent to $2,400,000,000 in 2025) for Falcon 9-launched Dragon spacecraft flights to the International Space Station (ISS), replacing the Space Shuttle after its 2011 retirement. In 2012, the Dragon vehicle docked with the ISS, a first for a commercial spacecraft. Working towards its goal of reusable rockets, in 2015 SpaceX successfully landed the first stage of a Falcon 9 on a land platform. Later landings were achieved on autonomous spaceport drone ships, an ocean-based recovery platform. In 2018, SpaceX launched the Falcon Heavy; the inaugural mission carried Musk's personal Tesla Roadster as a dummy payload. Since 2019, SpaceX has been developing Starship, a reusable, super heavy-lift launch vehicle intended to replace the Falcon 9 and Falcon Heavy. In 2020, SpaceX launched its first crewed flight, the Demo-2, becoming the first private company to place astronauts into orbit and dock a crewed spacecraft with the ISS. In 2024, NASA awarded SpaceX an $843 million (equivalent to $865,000,000 in 2025) contract to build a spacecraft that NASA will use to deorbit the ISS at the end of its lifespan. In 2015, SpaceX began development of the Starlink constellation of low Earth orbit satellites to provide satellite Internet access. After the launch of prototype satellites in 2018, the first large constellation was deployed in May 2019. As of May 2025[update], over 7,600 Starlink satellites are operational, comprising 65% of all operational Earth satellites. The total cost of the decade-long project to design, build, and deploy the constellation was estimated by SpaceX in 2020 to be $10 billion (equivalent to $12,000,000,000 in 2025).[c] During the Russian invasion of Ukraine, Musk provided free Starlink service to Ukraine, permitting Internet access and communication at a yearly cost to SpaceX of $400 million (equivalent to $440,000,000 in 2025). However, Musk refused to block Russian state media on Starlink. In 2023, Musk denied Ukraine's request to activate Starlink over Crimea to aid an attack against the Russian navy, citing fears of a nuclear response. Tesla, Inc., originally Tesla Motors, was incorporated in July 2003 by Martin Eberhard and Marc Tarpenning. Both men played active roles in the company's early development prior to Musk's involvement. Musk led the Series A round of investment in February 2004; he invested $6.35 million (equivalent to $11,000,000 in 2025), became the majority shareholder, and joined Tesla's board of directors as chairman. Musk took an active role within the company and oversaw Roadster product design, but was not deeply involved in day-to-day business operations. Following a series of escalating conflicts in 2007 and the 2008 financial crisis, Eberhard was ousted from the firm.[page needed] Musk assumed leadership of the company as CEO and product architect in 2008. A 2009 lawsuit settlement with Eberhard designated Musk as a Tesla co-founder, along with Tarpenning and two others. Tesla began delivery of the Roadster, an electric sports car, in 2008. With sales of about 2,500 vehicles, it was the first mass production all-electric car to use lithium-ion battery cells. Under Musk, Tesla has since launched several well-selling electric vehicles, including the four-door sedan Model S (2012), the crossover Model X (2015), the mass-market sedan Model 3 (2017), the crossover Model Y (2020), and the pickup truck Cybertruck (2023). In May 2020, Musk resigned as chairman of the board as part of the settlement of a lawsuit from the SEC over him tweeting that funding had been "secured" for potentially taking Tesla private. The company has also constructed multiple lithium-ion battery and electric vehicle factories, called Gigafactories. Since its initial public offering in 2010, Tesla stock has risen significantly; it became the most valuable carmaker in summer 2020, and it entered the S&P 500 later that year. In October 2021, it reached a market capitalization of $1 trillion (equivalent to $1,200,000,000,000 in 2025), the sixth company in U.S. history to do so. Musk provided the initial concept and financial capital for SolarCity, which his cousins Lyndon and Peter Rive founded in 2006. By 2013, SolarCity was the second largest provider of solar power systems in the United States. In 2014, Musk promoted the idea of SolarCity building an advanced production facility in Buffalo, New York, triple the size of the largest solar plant in the United States. Construction of the factory started in 2014 and was completed in 2017. It operated as a joint venture with Panasonic until early 2020. Tesla acquired SolarCity for $2 billion in 2016 (equivalent to $2,700,000,000 in 2025) and merged it with its battery unit to create Tesla Energy. The deal's announcement resulted in a more than 10% drop in Tesla's stock price; at the time, SolarCity was facing liquidity issues. Multiple shareholder groups filed a lawsuit against Musk and Tesla's directors, stating that the purchase of SolarCity was done solely to benefit Musk and came at the expense of Tesla and its shareholders. Tesla directors settled the lawsuit in January 2020, leaving Musk the sole remaining defendant. Two years later, the court ruled in Musk's favor. In 2016, Musk co-founded Neuralink, a neurotechnology startup, with an investment of $100 million. Neuralink aims to integrate the human brain with artificial intelligence (AI) by creating devices that are embedded in the brain. Such technology could enhance memory or allow the devices to communicate with software. The company also hopes to develop devices to treat neurological conditions like spinal cord injuries. In 2022, Neuralink announced that clinical trials would begin by the end of the year. In September 2023, the Food and Drug Administration approved Neuralink to initiate six-year human trials. Neuralink has conducted animal testing on macaques at the University of California, Davis. In 2021, the company released a video in which a macaque played the video game Pong via a Neuralink implant. The company's animal trials—which have caused the deaths of some monkeys—have led to claims of animal cruelty. The Physicians Committee for Responsible Medicine has alleged that Neuralink violated the Animal Welfare Act. Employees have complained that pressure from Musk to accelerate development has led to botched experiments and unnecessary animal deaths. In 2022, a federal probe was launched into possible animal welfare violations by Neuralink.[needs update] In 2017, Musk founded the Boring Company to construct tunnels; he also revealed plans for specialized, underground, high-occupancy vehicles that could travel up to 150 miles per hour (240 km/h) and thus circumvent above-ground traffic in major cities. Early in 2017, the company began discussions with regulatory bodies and initiated construction of a 30-foot (9.1 m) wide, 50-foot (15 m) long, and 15-foot (4.6 m) deep "test trench" on the premises of SpaceX's offices, as that required no permits. The Los Angeles tunnel, less than two miles (3.2 km) in length, debuted to journalists in 2018. It used Tesla Model Xs and was reported to be a rough ride while traveling at suboptimal speeds. Two tunnel projects announced in 2018, in Chicago and West Los Angeles, have been canceled. A tunnel beneath the Las Vegas Convention Center was completed in early 2021. Local officials have approved further expansions of the tunnel system. April 14, 2022 In early 2017, Musk expressed interest in buying Twitter and had questioned the platform's commitment to freedom of speech. By 2022, Musk had reached 9.2% stake in the company, making him the largest shareholder.[d] Musk later agreed to a deal that would appoint him to Twitter's board of directors and prohibit him from acquiring more than 14.9% of the company. Days later, Musk made a $43 billion offer to buy Twitter. By the end of April Musk had successfully concluded his bid for approximately $44 billion. This included approximately $12.5 billion in loans and $21 billion in equity financing. Having backtracked on his initial decision, Musk bought the company on October 27, 2022. Immediately after the acquisition, Musk fired several top Twitter executives including CEO Parag Agrawal; Musk became the CEO instead. Under Elon Musk, Twitter instituted monthly subscriptions for a "blue check", and laid off a significant portion of the company's staff. Musk lessened content moderation and hate speech also increased on the platform after his takeover. In late 2022, Musk released internal documents relating to Twitter's moderation of Hunter Biden's laptop controversy in the lead-up to the 2020 presidential election. Musk also promised to step down as CEO after a Twitter poll, and five months later, Musk stepped down as CEO and transitioned his role to executive chairman and chief technology officer (CTO). Despite Musk stepping down as CEO, X continues to struggle with challenges such as viral misinformation, hate speech, and antisemitism controversies. Musk has been accused of trying to silence some of his critics such as Twitch streamer Asmongold, who criticized him during one of his streams. Musk has been accused of removing their accounts' blue checkmarks, which hinders visibility and is considered a form of shadow banning, or suspending their accounts without justification. Other activities In August 2013, Musk announced plans for a version of a vactrain, and assigned engineers from SpaceX and Tesla to design a transport system between Greater Los Angeles and the San Francisco Bay Area, at an estimated cost of $6 billion. Later that year, Musk unveiled the concept, dubbed the Hyperloop, intended to make travel cheaper than any other mode of transport for such long distances. In December 2015, Musk co-founded OpenAI, a not-for-profit artificial intelligence (AI) research company aiming to develop artificial general intelligence, intended to be safe and beneficial to humanity. Musk pledged $1 billion of funding to the company, and initially gave $50 million. In 2018, Musk left the OpenAI board. Since 2018, OpenAI has made significant advances in machine learning. In July 2023, Musk launched the artificial intelligence company xAI, which aims to develop a generative AI program that competes with existing offerings like OpenAI's ChatGPT. Musk obtained funding from investors in SpaceX and Tesla, and xAI hired engineers from Google and OpenAI. December 16, 2022 Musk uses a private jet owned by Falcon Landing LLC, a SpaceX-linked company, and acquired a second jet in August 2020. His heavy use of the jets and the consequent fossil fuel usage have received criticism. Musk's flight usage is tracked on social media through ElonJet. In December 2022, Musk banned the ElonJet account on Twitter, and made temporary bans on the accounts of journalists that posted stories regarding the incident, including Donie O'Sullivan, Keith Olbermann, and journalists from The New York Times, The Washington Post, CNN, and The Intercept. In October 2025, Musk's company xAI launched Grokipedia, an AI-generated online encyclopedia that he promoted as an alternative to Wikipedia. Articles on Grokipedia are generated and reviewed by xAI's Grok chatbot. Media coverage and academic analysis described Grokipedia as frequently reusing Wikipedia content but framing contested political and social topics in line with Musk's own views and right-wing narratives. A study by Cornell University researchers and NBC News stated that Grokipedia cites sources that are blacklisted or considered "generally unreliable" on Wikipedia, for example, the conspiracy site Infowars and the neo-Nazi forum Stormfront. Wired, The Guardian and Time criticized Grokipedia for factual errors and for presenting Musk himself in unusually positive terms while downplaying controversies. Politics Musk is an outlier among business leaders who typically avoid partisan political advocacy. Musk was a registered independent voter when he lived in California. Historically, he has donated to both Democrats and Republicans, many of whom serve in states in which he has a vested interest. Since 2022, his political contributions have mostly supported Republicans, with his first vote for a Republican going to Mayra Flores in the 2022 Texas's 34th congressional district special election. In 2024, he started supporting international far-right political parties, activists, and causes, and has shared misinformation and numerous conspiracy theories. Since 2024, his views have been generally described as right-wing. Musk supported Barack Obama in 2008 and 2012, Hillary Clinton in 2016, Joe Biden in 2020, and Donald Trump in 2024. In the 2020 Democratic Party presidential primaries, Musk endorsed candidate Andrew Yang and expressed support for Yang's proposed universal basic income, and endorsed Kanye West's 2020 presidential campaign. In 2021, Musk publicly expressed opposition to the Build Back Better Act, a $3.5 trillion legislative package endorsed by Joe Biden that ultimately failed to pass due to unanimous opposition from congressional Republicans and several Democrats. In 2022, gave over $50 million to Citizens for Sanity, a conservative political action committee. In 2023, he supported Republican Ron DeSantis for the 2024 U.S. presidential election, giving $10 million to his campaign, and hosted DeSantis's campaign announcement on a Twitter Spaces event. From June 2023 to January 2024, Musk hosted a bipartisan set of X Spaces with Republican and Democratic candidates, including Robert F. Kennedy Jr., Vivek Ramaswamy, and Dean Phillips. In October 2025, former vice-president Kamala Harris commented that it was a mistake from the Democratic side to not invite Musk to a White House electric vehicle event organized in August 2021 and featuring executives from General Motors, Ford and Stellantis, despite Tesla being "the major American manufacturer of extraordinary innovation in this space." Fortune remarked that this was a nod to United Auto Workers and organized labor. Harris said presidents should put aside political loyalties when it came to recognizing innovation, and guessed that the non-invitation impacted Musk's perspective. Fortune noted that, at the time, Musk said, "Yeah, seems odd that Tesla wasn't invited." A month later, he criticized Biden as "not the friendliest administration." Jacob Silverman, author of the book Gilded Rage: Elon Musk and the Radicalization of Silicon Valley, said that the tech industry represented by Musk, Thiel, Andreessen and other capitalists, actually flourished under Biden, but the tech leaders chose Trump for their common ground on cultural issues. By early 2024, Musk had become a vocal and financial supporter of Donald Trump. In July 2024, minutes after the attempted assassination of Donald Trump, Musk endorsed him for president saying; "I fully endorse President Trump and hope for his rapid recovery." During the presidential campaign, Musk joined Trump on stage at a campaign rally, and during the campaign promoted conspiracy theories and falsehoods about Democrats, election fraud and immigration, in support of Trump. Musk was the largest individual donor of the 2024 election. In 2025, Musk contributed $19 million to the Wisconsin Supreme Court race, hoping to influence the state's future redistricting efforts and its regulations governing car manufacturers and dealers. In 2023, Musk said he shunned the World Economic Forum because it was boring. The organization commented that they had not invited him since 2015. He has participated in Dialog, dubbed "Tech Bilderberg" and organized by Peter Thiel and Auren Hoffman, though. Musk's international political actions and comments have come under increasing scrutiny and criticism, especially from the governments and leaders of France, Germany, Norway, Spain and the United Kingdom, particularly due to his position in the U.S. government as well as ownership of X. An NBC News analysis found he had boosted far-right political movements to cut immigration and curtail regulation of business in at least 18 countries on six continents since 2023. During his speech after the second inauguration of Donald Trump, Musk twice made a gesture interpreted by many as a Nazi or a fascist Roman salute.[e] He thumped his right hand over his heart, fingers spread wide, and then extended his right arm out, emphatically, at an upward angle, palm down and fingers together. He then repeated the gesture to the crowd behind him. As he finished the gestures, he said to the crowd, "My heart goes out to you. It is thanks to you that the future of civilization is assured." It was widely condemned as an intentional Nazi salute in Germany, where making such gestures is illegal. The Anti-Defamation League said it was not a Nazi salute, but other Jewish organizations disagreed and condemned the salute. American public opinion was divided on partisan lines as to whether it was a fascist salute. Musk dismissed the accusations of Nazi sympathies, deriding them as "dirty tricks" and a "tired" attack. Neo-Nazi and white supremacist groups celebrated it as a Nazi salute. Multiple European political parties demanded that Musk be banned from entering their countries. The concept of DOGE emerged in a discussion between Musk and Donald Trump, and in August 2024, Trump committed to giving Musk an advisory role, with Musk accepting the offer. In November and December 2024, Musk suggested that the organization could help to cut the U.S. federal budget, consolidate the number of federal agencies, and eliminate the Consumer Financial Protection Bureau, and that its final stage would be "deleting itself". In January 2025, the organization was created by executive order, and Musk was designated a "special government employee". Musk led the organization and was a senior advisor to the president, although his official role is not clear. In sworn statement during a lawsuit, the director of the White House Office of Administration stated that Musk "is not an employee of the U.S. DOGE Service or U.S. DOGE Service Temporary Organization", "is not the U.S. DOGE Service administrator", and has "no actual or formal authority to make government decisions himself". Trump said two days later that he had put Musk in charge of DOGE. A federal judge has ruled that Musk acted as the de facto leader of DOGE. Musk's role in the second Trump administration, particularly in response to DOGE, has attracted public backlash. He was criticized for his treatment of federal government employees, including his influence over the mass layoffs of the federal workforce. He has prioritized secrecy within the organization and has accused others of violating privacy laws. A Senate report alleged that Musk could avoid up to $2 billion in legal liability as a result of DOGE's actions. In May 2025, Bill Gates accused Musk of "killing the world's poorest children" through his cuts to USAID, which modeling by Boston University estimated had resulted in 300,000 deaths by this time, most of them of children. By November 2025, the estimated death toll had increased to 400,000 children and 200,000 adults. Musk announced on May 28, 2025, that he would depart from the Trump administration as planned when the special government employee's 130 day deadline expired, with a White House official confirming that Musk's offboarding from the Trump administration was already underway. His departure was officially confirmed during a joint Oval Office press conference with Trump on May 30, 2025. @realDonaldTrump is in the Epstein files. That is the real reason they have not been made public. June 5, 2025 After leaving office, Musk criticized the Trump administration's Big Beautiful Bill, calling it a "disgusting abomination" due to its provisions increasing the deficit. A feud began between Musk and Trump, with its most notable event being Musk alleging Trump had ties to sex offender Jeffrey Epstein on X (formerly Twitter) on June 5, 2025. Trump responded on Truth Social stating that Musk went "CRAZY" after the "EV Mandate" was purportedly taken away and threatened to cut Musk's government contracts. Musk then called for a third Trump impeachment. The next day, Trump stated that he did not wish to reconcile with Musk, and added that Musk would face "very serious consequences" if he funds Democratic candidates. On June 11, Musk publicly apologized for the tweets against Trump, saying they "went too far". Views November 6, 2022 Rejecting the conservative label, Musk has described himself as a political moderate, even as his views have become more right-wing over time. His views have been characterized as libertarian and far-right, and after his involvement in European politics, they have received criticism from world leaders such as Emmanuel Macron and Olaf Scholz. Within the context of American politics, Musk supported Democratic candidates up until 2022, at which point he voted for a Republican for the first time. He has stated support for universal basic income, gun rights, freedom of speech, a tax on carbon emissions, and H-1B visas. Musk has expressed concern about issues such as artificial intelligence (AI) and climate change, and has been a critic of wealth tax, short-selling, and government subsidies. An immigrant himself, Musk has been accused of being anti-immigration, and regularly blames immigration policies for illegal immigration. He is also a pronatalist who believes population decline is the biggest threat to civilization, and identifies as a cultural Christian. Musk has long been an advocate for space colonization, especially the colonization of Mars. He has repeatedly pushed for humanity colonizing Mars, in order to become an interplanetary species and lower the risks of human extinction. Musk has promoted conspiracy theories and made controversial statements that have led to accusations of racism, sexism, antisemitism, transphobia, disseminating disinformation, and support of white pride. While describing himself as a "pro-Semite", his comments regarding George Soros and Jewish communities have been condemned by the Anti-Defamation League and the Biden White House. Musk was criticized during the COVID-19 pandemic for making unfounded epidemiological claims, defying COVID-19 lockdowns restrictions, and supporting the Canada convoy protest against vaccine mandates. He has amplified false claims of white genocide in South Africa. Musk has been critical of Israel's actions in the Gaza Strip during the Gaza war, praised China's economic and climate goals, suggested that Taiwan and China should resolve cross-strait relations, and was described as having a close relationship with the Chinese government. In Europe, Musk expressed support for Ukraine in 2022 during the Russian invasion, recommended referendums and peace deals on the annexed Russia-occupied territories, and supported the far-right Alternative for Germany political party in 2024. Regarding British politics, Musk blamed the 2024 UK riots on mass migration and open borders, criticized Prime Minister Keir Starmer for what he described as a "two-tier" policing system, and was subsequently attacked as being responsible for spreading misinformation and amplifying the far-right. He has also voiced his support for far-right activist Tommy Robinson and pledged electoral support for Reform UK. In February 2026, Musk described Spanish Prime Minister Pedro Sánchez as a "tyrant" following Sánchez's proposal to prohibit minors under the age of 16 from accessing social media platforms. Legal affairs In 2018, Musk was sued by the U.S. Securities and Exchange Commission (SEC) for a tweet stating that funding had been secured for potentially taking Tesla private.[f] The securities fraud lawsuit characterized the tweet as false, misleading, and damaging to investors, and sought to bar Musk from serving as CEO of publicly traded companies. Two days later, Musk settled with the SEC, without admitting or denying the SEC's allegations. As a result, Musk and Tesla were fined $20 million each, and Musk was forced to step down for three years as Tesla chairman but was able to remain as CEO. Shareholders filed a lawsuit over the tweet, and in February 2023, a jury found Musk and Tesla not liable. Musk has stated in interviews that he does not regret posting the tweet that triggered the SEC investigation. In 2019, Musk stated in a tweet that Tesla would build half a million cars that year. The SEC reacted by asking a court to hold him in contempt for violating the terms of the 2018 settlement agreement. A joint agreement between Musk and the SEC eventually clarified the previous agreement details, including a list of topics about which Musk needed preclearance. In 2020, a judge blocked a lawsuit that claimed a tweet by Musk regarding Tesla stock price ("too high imo") violated the agreement. Freedom of Information Act (FOIA)-released records showed that the SEC concluded Musk had subsequently violated the agreement twice by tweeting regarding "Tesla's solar roof production volumes and its stock price". In October 2023, the SEC sued Musk over his refusal to testify a third time in an investigation into whether he violated federal law by purchasing Twitter stock in 2022. In February 2024, Judge Laurel Beeler ruled that Musk must testify again. In January 2025, the SEC filed a lawsuit against Musk for securities violations related to his purchase of Twitter. In January 2024, Delaware judge Kathaleen McCormick ruled in a 2018 lawsuit that Musk's $55 billion pay package from Tesla be rescinded. McCormick called the compensation granted by the company's board "an unfathomable sum" that was unfair to shareholders. The Delaware Supreme Court overturned McCormick's decision in December 2025, restoring Musk's compensation package and awarding $1 in nominal damages. Personal life Musk became a U.S. citizen in 2002. From the early 2000s until late 2020, Musk resided in California, where both Tesla and SpaceX were founded. He then relocated to Cameron County, Texas, saying that California had become "complacent" about its economic success. While hosting Saturday Night Live in 2021, Musk stated that he has Asperger syndrome (an outdated term for autism spectrum disorder). When asked about his experience growing up with Asperger's syndrome in a TED2022 conference in Vancouver, Musk stated that "the social cues were not intuitive ... I would just tend to take things very literally ... but then that turned out to be wrong — [people were not] simply saying exactly what they mean, there's all sorts of other things that are meant, and [it] took me a while to figure that out." Musk suffers from back pain and has undergone several spine-related surgeries, including a disc replacement. In 2000, he contracted a severe case of malaria while on vacation in South Africa. Musk has stated he uses doctor-prescribed ketamine for occasional depression and that he doses "a small amount once every other week or something like that"; since January 2024, some media outlets have reported that he takes ketamine, marijuana, LSD, ecstasy, mushrooms, cocaine and other drugs. Musk at first refused to comment on his alleged drug use, before responding that he had not tested positive for drugs, and that if drugs somehow improved his productivity, "I would definitely take them!". The New York Times' investigations revealed Musk's overuse of ketamine and numerous other drugs, as well as strained family relationships and concerns from close associates who have become troubled by his public behavior as he became more involved in political activities and government work. According to The Washington Post, President Trump described Musk as "a big-time drug addict". Through his own label Emo G Records, Musk released a rap track, "RIP Harambe", on SoundCloud in March 2019. The following year, he released an EDM track, "Don't Doubt Ur Vibe", featuring his own lyrics and vocals. Musk plays video games, which he stated has a "'restoring effect' that helps his 'mental calibration'". Some games he plays include Quake, Diablo IV, Elden Ring, and Polytopia. Musk once claimed to be one of the world's top video game players but has since admitted to "account boosting", or cheating by hiring outside services to achieve top player rankings. Musk has justified the boosting by claiming that all top accounts do it so he has to as well to remain competitive. In 2024 and 2025, Musk criticized the video game Assassin's Creed Shadows and its creator Ubisoft for "woke" content. Musk posted to X that "DEI kills art" and specified the inclusion of the historical figure Yasuke in the Assassin's Creed game as offensive; he also called the game "terrible". Ubisoft responded by saying that Musk's comments were "just feeding hatred" and that they were focused on producing a game not pushing politics. Musk has fathered at least 14 children, one of whom died as an infant. The Wall Street Journal reported in 2025 that sources close to Musk suggest that the "true number of Musk's children is much higher than publicly known". He had six children with his first wife, Canadian author Justine Wilson, whom he met while attending Queen's University in Ontario, Canada; they married in 2000. In 2002, their first child Nevada Musk died of sudden infant death syndrome at the age of 10 weeks. After his death, the couple used in vitro fertilization (IVF) to continue their family; they had twins in 2004, followed by triplets in 2006. The couple divorced in 2008 and have shared custody of their children. The elder twin he had with Wilson came out as a trans woman and, in 2022, officially changed her name to Vivian Jenna Wilson, adopting her mother's surname because she no longer wished to be associated with Musk. Musk began dating English actress Talulah Riley in 2008. They married two years later at Dornoch Cathedral in Scotland. In 2012, the couple divorced, then remarried the following year. After briefly filing for divorce in 2014, Musk finalized a second divorce from Riley in 2016. Musk then dated the American actress Amber Heard for several months in 2017; he had reportedly been "pursuing" her since 2012. In 2018, Musk and Canadian musician Grimes confirmed they were dating. Grimes and Musk have three children, born in 2020, 2021, and 2022.[g] Musk and Grimes originally gave their eldest child the name "X Æ A-12", which would have violated California regulations as it contained characters that are not in the modern English alphabet; the names registered on the birth certificate are "X" as a first name, "Æ A-Xii" as a middle name, and "Musk" as a last name. They received criticism for choosing a name perceived to be impractical and difficult to pronounce; Musk has said the intended pronunciation is "X Ash A Twelve". Their second child was born via surrogacy. Despite the pregnancy, Musk confirmed reports that the couple were "semi-separated" in September 2021; in an interview with Time in December 2021, he said he was single. In October 2023, Grimes sued Musk over parental rights and custody of X Æ A-Xii. Elon Musk has taken X Æ A-Xii to multiple official events in Washington, D.C. during Trump's second term in office. Also in July 2022, The Wall Street Journal reported that Musk allegedly had an affair with Nicole Shanahan, the wife of Google co-founder Sergey Brin, in 2021, leading to their divorce the following year. Musk denied the report. Musk also had a relationship with Australian actress Natasha Bassett, who has been described as "an occasional girlfriend". In October 2024, The New York Times reported Musk bought a Texas compound for his children and their mothers, though Musk denied having done so. Musk also has four children with Shivon Zilis, director of operations and special projects at Neuralink: twins born via IVF in 2021, a child born in 2024 via surrogacy and a child born in 2025.[h] On February 14, 2025, Ashley St. Clair, an influencer and author, posted on X claiming to have given birth to Musk's son Romulus five months earlier, which media outlets reported as Musk's supposed thirteenth child.[i] On February 22, 2025, it was reported that St Clair had filed for sole custody of her five-month-old son and for Musk to be recognised as the child's father. On March 31, 2025, Musk wrote that, while he was unsure if he was the father of St. Clair's child, he had paid St. Clair $2.5 million and would continue paying her $500,000 per year.[j] Later reporting from the Wall Street Journal indicated that $1 million of these payments to St. Clair were structured as a loan. In 2014, Musk and Ghislaine Maxwell appeared together in a photograph taken at an Academy Awards after-party, which Musk later described as a "photobomb". The January 2026 Epstein files contain emails between Musk and Epstein from 2012 to 2013, after Epstein's first conviction. Emails released on January 30, 2026, indicated that Epstein invited Musk to visit his private island on multiple occasions. The correspondence showed that while Epstein repeatedly encouraged Musk to attend, Musk did not visit the island. In one instance, Musk discussed the possibility of attending a party with his then-wife Talulah Riley and asked which day would be the "wildest party"; according to the emails, the visit did not take place after Epstein later cancelled the plans.[k] On Christmas day in 2012, Musk emailed Epstein asking "Do you have any parties planned? I’ve been working to the edge of sanity this year and so, once my kids head home after Christmas, I really want to hit the party scene in St Barts or elsewhere and let loose. The invitation is much appreciated, but a peaceful island experience is the opposite of what I’m looking for". Epstein replied that the "ratio on my island" might make Musk's wife uncomfortable to which Musk responded, "Ratio is not a problem for Talulah". On September 11, 2013, Epstein sent an email asking Musk if he had any plans for coming to New York for the opening of the United Nations General Assembly where many "interesting people" would be coming to his house to which Musk responded that "Flying to NY to see UN diplomats do nothing would be an unwise use of time". Epstein responded by stating "Do you think i am retarded. Just kidding, there is no one over 25 and all very cute." Musk has denied any close relationship with Epstein and described him as a "creep" who attempted to ingratiate himself with influential people. When Musk was asked in 2019 if he introduced Epstein to Mark Zuckerberg, Musk responded: "I don’t recall introducing Epstein to anyone, as I don’t know the guy well enough to do so." The released emails nonetheless showed cordial exchanges on a range of topics, including Musk's inquiry about parties on the island. The correspondence also indicated that Musk suggested hosting Epstein at SpaceX, while Epstein separately discussed plans to tour SpaceX and bring "the girls", though there is no evidence that such a visit occurred. Musk has described the release of the files a "distraction", later accusing the second Trump administration of suppressing them to protect powerful individuals, including Trump himself.[l] Wealth Elon Musk is the wealthiest person in the world, with an estimated net worth of US$690 billion as of January 2026, according to the Bloomberg Billionaires Index, and $852 billion according to Forbes, primarily from his ownership stakes in SpaceX and Tesla. Having been first listed on the Forbes Billionaires List in 2012, around 75% of Musk's wealth was derived from Tesla stock in November 2020, although he describes himself as "cash poor". According to Forbes, he became the first person in the world to achieve a net worth of $300 billion in 2021; $400 billion in December 2024; $500 billion in October 2025; $600 billion in mid-December 2025; $700 billion later that month; and $800 billion in February 2026. In November 2025, a Tesla pay package worth potentially $1 trillion for Musk was approved, which he is to receive over 10 years if he meets specific goals. Public image Although his ventures have been highly influential within their separate industries starting in the 2000s, Musk only became a public figure in the early 2010s. He has been described as an eccentric who makes spontaneous and impactful decisions, while also often making controversial statements, contrary to other billionaires who prefer reclusiveness to protect their businesses. Musk's actions and his expressed views have made him a polarizing figure. Biographer Ashlee Vance described people's opinions of Musk as polarized due to his "part philosopher, part troll" persona on Twitter. He has drawn denouncement for using his platform to mock the self-selection of personal pronouns, while also receiving praise for bringing international attention to matters like British survivors of grooming gangs. Musk has been described as an American oligarch due to his extensive influence over public discourse, social media, industry, politics, and government policy. After Trump's re-election, Musk's influence and actions during the transition period and the second presidency of Donald Trump led some to call him "President Musk", the "actual president-elect", "shadow president" or "co-president". Awards for his contributions to the development of the Falcon rockets include the American Institute of Aeronautics and Astronautics George Low Transportation Award in 2008, the Fédération Aéronautique Internationale Gold Space Medal in 2010, and the Royal Aeronautical Society Gold Medal in 2012. In 2015, he received an honorary doctorate in engineering and technology from Yale University and an Institute of Electrical and Electronics Engineers Honorary Membership. Musk was elected a Fellow of the Royal Society (FRS) in 2018.[m] In 2022, Musk was elected to the National Academy of Engineering. Time has listed Musk as one of the most influential people in the world in 2010, 2013, 2018, and 2021. Musk was selected as Time's "Person of the Year" for 2021. Then Time editor-in-chief Edward Felsenthal wrote that, "Person of the Year is a marker of influence, and few individuals have had more influence than Musk on life on Earth, and potentially life off Earth too." Notes References Works cited Further reading External links |
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Contents Python (programming language) Python is a high-level, general-purpose programming language. Its design philosophy emphasizes code readability with the use of significant indentation. Python is dynamically type-checked and garbage-collected. It supports multiple programming paradigms, including structured (particularly procedural), object-oriented and functional programming. Guido van Rossum began working on Python in the late 1980s as a successor to the ABC programming language. Python 3.0, released in 2008, was a major revision and not completely backward-compatible with earlier versions. Beginning with Python 3.5, capabilities and keywords for typing were added to the language, allowing optional static typing. As of 2026[update], the Python Software Foundation supports Python 3.10, 3.11, 3.12, 3.13, and 3.14, following the project's annual release cycle and five-year support policy. Python 3.15 is currently in the alpha development phase, and the stable release is expected to come out in October 2026. Earlier versions in the 3.x series have reached end-of-life and no longer receive security updates. Python has gained widespread use in the machine learning community. It is widely taught as an introductory programming language. Since 2003, Python has consistently ranked in the top ten of the most popular programming languages in the TIOBE Programming Community Index, which ranks based on searches in 24 platforms. History Python was conceived in the late 1980s by Guido van Rossum at Centrum Wiskunde & Informatica (CWI) in the Netherlands. It was designed as a successor to the ABC programming language, which was inspired by SETL, capable of exception handling and interfacing with the Amoeba operating system. Python implementation began in December 1989. Van Rossum first released it in 1991 as Python 0.9.0. Van Rossum assumed sole responsibility for the project, as the lead developer, until 12 July 2018, when he announced his "permanent vacation" from responsibilities as Python's "benevolent dictator for life" (BDFL); this title was bestowed on him by the Python community to reflect his long-term commitment as the project's chief decision-maker. (He has since come out of retirement and is self-titled "BDFL-emeritus".) In January 2019, active Python core developers elected a five-member Steering Council to lead the project. The name Python derives from the British comedy series Monty Python's Flying Circus. (See § Naming.) Python 2.0 was released on 16 October 2000, featuring many new features such as list comprehensions, cycle-detecting garbage collection, reference counting, and Unicode support. Python 2.7's end-of-life was initially set for 2015, and then postponed to 2020 out of concern that a large body of existing code could not easily be forward-ported to Python 3. It no longer receives security patches or updates. While Python 2.7 and older versions are officially unsupported, a different unofficial Python implementation, PyPy, continues to support Python 2, i.e., "2.7.18+" (plus 3.11), with the plus signifying (at least some) "backported security updates". Python 3.0 was released on 3 December 2008, and was a major revision and not completely backward-compatible with earlier versions, with some new semantics and changed syntax. Python 2.7.18, released in 2020, was the last release of Python 2. Several releases in the Python 3.x series have added new syntax to the language, and made a few (considered very minor) backward-incompatible changes. As of January 2026[update], Python 3.14.3 is the latest stable release. All older 3.x versions had a security update down to Python 3.9.24 then again with 3.9.25, the final version in 3.9 series. Python 3.10 is, since November 2025, the oldest supported branch. Python 3.15 has an alpha released, and Android has an official downloadable executable available for Python 3.14. Releases receive two years of full support followed by three years of security support. Design philosophy and features Python is a multi-paradigm programming language. Object-oriented programming and structured programming are fully supported, and many of their features support functional programming and aspect-oriented programming – including metaprogramming and metaobjects. Many other paradigms are supported via extensions, including design by contract and logic programming. Python is often referred to as a 'glue language' because it is purposely designed to be able to integrate components written in other languages. Python uses dynamic typing and a combination of reference counting and a cycle-detecting garbage collector for memory management. It uses dynamic name resolution (late binding), which binds method and variable names during program execution. Python's design offers some support for functional programming in the "Lisp tradition". It has filter, map, and reduce functions; list comprehensions, dictionaries, sets, and generator expressions. The standard library has two modules (itertools and functools) that implement functional tools borrowed from Haskell and Standard ML. Python's core philosophy is summarized in the Zen of Python (PEP 20) written by Tim Peters, which includes aphorisms such as these: However, Python has received criticism for violating these principles and adding unnecessary language bloat. Responses to these criticisms note that the Zen of Python is a guideline rather than a rule. The addition of some new features had been controversial: Guido van Rossum resigned as Benevolent Dictator for Life after conflict about adding the assignment expression operator in Python 3.8. Nevertheless, rather than building all functionality into its core, Python was designed to be highly extensible via modules. This compact modularity has made it particularly popular as a means of adding programmable interfaces to existing applications. Van Rossum's vision of a small core language with a large standard library and easily extensible interpreter stemmed from his frustrations with ABC, which represented the opposite approach. Python claims to strive for a simpler, less-cluttered syntax and grammar, while giving developers a choice in their coding methodology. Python lacks do .. while loops, which Rossum considered harmful. In contrast to Perl's motto "there is more than one way to do it", Python advocates an approach where "there should be one – and preferably only one – obvious way to do it". In practice, however, Python provides many ways to achieve a given goal. There are at least three ways to format a string literal, with no certainty as to which one a programmer should use. Alex Martelli is a Fellow at the Python Software Foundation and Python book author; he wrote that "To describe something as 'clever' is not considered a compliment in the Python culture." Python's developers typically prioritize readability over performance. For example, they reject patches to non-critical parts of the CPython reference implementation that would offer increases in speed that do not justify the cost of clarity and readability.[failed verification] Execution speed can be improved by moving speed-critical functions to extension modules written in languages such as C, or by using a just-in-time compiler like PyPy. Also, it is possible to transpile to other languages. However, this approach either fails to achieve the expected speed-up, since Python is a very dynamic language, or only a restricted subset of Python is compiled (with potential minor semantic changes). Python is meant to be a fun language to use. This goal is reflected in the name – a tribute to the British comedy group Monty Python – and in playful approaches to some tutorials and reference materials. For instance, some code examples use the terms "spam" and "eggs" (in reference to a Monty Python sketch), rather than the typical terms "foo" and "bar". A common neologism in the Python community is pythonic, which has a broad range of meanings related to program style: Pythonic code may use Python idioms well; be natural or show fluency in the language; or conform with Python's minimalist philosophy and emphasis on readability. Syntax and semantics Python is meant to be an easily readable language. Its formatting is visually uncluttered and often uses English keywords where other languages use punctuation. Unlike many other languages, it does not use curly brackets to delimit blocks, and semicolons after statements are allowed but rarely used. It has fewer syntactic exceptions and special cases than C or Pascal. Python uses whitespace indentation, rather than curly brackets or keywords, to delimit blocks. An increase in indentation comes after certain statements; a decrease in indentation signifies the end of the current block. Thus, the program's visual structure accurately represents its semantic structure. This feature is sometimes termed the off-side rule. Some other languages use indentation this way; but in most, indentation has no semantic meaning. The recommended indent size is four spaces. Python's statements include the following: The assignment statement (=) binds a name as a reference to a separate, dynamically allocated object. Variables may subsequently be rebound at any time to any object. In Python, a variable name is a generic reference holder without a fixed data type; however, it always refers to some object with a type. This is called dynamic typing—in contrast to statically-typed languages, where each variable may contain only a value of a certain type. Python does not support tail call optimization or first-class continuations; according to Van Rossum, the language never will. However, better support for coroutine-like functionality is provided by extending Python's generators. Before 2.5, generators were lazy iterators; data was passed unidirectionally out of the generator. From Python 2.5 on, it is possible to pass data back into a generator function; and from version 3.3, data can be passed through multiple stack levels. Python's expressions include the following: In Python, a distinction between expressions and statements is rigidly enforced, in contrast to languages such as Common Lisp, Scheme, or Ruby. This distinction leads to duplicating some functionality, for example: A statement cannot be part of an expression; because of this restriction, expressions such as list and dict comprehensions (and lambda expressions) cannot contain statements. As a particular case, an assignment statement such as a = 1 cannot be part of the conditional expression of a conditional statement. Python uses duck typing, and it has typed objects but untyped variable names. Type constraints are not checked at definition time; rather, operations on an object may fail at usage time, indicating that the object is not of an appropriate type. Despite being dynamically typed, Python is strongly typed, forbidding operations that are poorly defined (e.g., adding a number and a string) rather than quietly attempting to interpret them. Python allows programmers to define their own types using classes, most often for object-oriented programming. New instances of classes are constructed by calling the class, for example, SpamClass() or EggsClass()); the classes are instances of the metaclass type (which is an instance of itself), thereby allowing metaprogramming and reflection. Before version 3.0, Python had two kinds of classes, both using the same syntax: old-style and new-style. Current Python versions support the semantics of only the new style. Python supports optional type annotations. These annotations are not enforced by the language, but may be used by external tools such as mypy to catch errors. Python includes a module typing including several type names for type annotations. Also, mypy supports a Python compiler called mypyc, which leverages type annotations for optimization. 1.33333 frozenset() Python includes conventional symbols for arithmetic operators (+, -, *, /), the floor-division operator //, and the modulo operator %. (With the modulo operator, a remainder can be negative, e.g., 4 % -3 == -2.) Also, Python offers the ** symbol for exponentiation, e.g. 5**3 == 125 and 9**0.5 == 3.0. Also, it offers the matrix‑multiplication operator @ . These operators work as in traditional mathematics; with the same precedence rules, the infix operators + and - can also be unary, to represent positive and negative numbers respectively. Division between integers produces floating-point results. The behavior of division has changed significantly over time: In Python terms, the / operator represents true division (or simply division), while the // operator represents floor division. Before version 3.0, the / operator represents classic division. Rounding towards negative infinity, though a different method than in most languages, adds consistency to Python. For instance, this rounding implies that the equation (a + b)//b == a//b + 1 is always true. Also, the rounding implies that the equation b*(a//b) + a%b == a is valid for both positive and negative values of a. As expected, the result of a%b lies in the half-open interval [0, b), where b is a positive integer; however, maintaining the validity of the equation requires that the result must lie in the interval (b, 0] when b is negative. Python provides a round function for rounding a float to the nearest integer. For tie-breaking, Python 3 uses the round to even method: round(1.5) and round(2.5) both produce 2. Python versions before 3 used the round-away-from-zero method: round(0.5) is 1.0, and round(-0.5) is −1.0. Python allows Boolean expressions that contain multiple equality relations to be consistent with general usage in mathematics. For example, the expression a < b < c tests whether a is less than b and b is less than c. C-derived languages interpret this expression differently: in C, the expression would first evaluate a < b, resulting in 0 or 1, and that result would then be compared with c. Python uses arbitrary-precision arithmetic for all integer operations. The Decimal type/class in the decimal module provides decimal floating-point numbers to a pre-defined arbitrary precision with several rounding modes. The Fraction class in the fractions module provides arbitrary precision for rational numbers. Due to Python's extensive mathematics library and the third-party library NumPy, the language is frequently used for scientific scripting in tasks such as numerical data processing and manipulation. Functions are created in Python by using the def keyword. A function is defined similarly to how it is called, by first providing the function name and then the required parameters. Here is an example of a function that prints its inputs: To assign a default value to a function parameter in case no actual value is provided at run time, variable-definition syntax can be used inside the function header. Code examples "Hello, World!" program: Program to calculate the factorial of a non-negative integer: Libraries Python's large standard library is commonly cited as one of its greatest strengths. For Internet-facing applications, many standard formats and protocols such as MIME and HTTP are supported. The language includes modules for creating graphical user interfaces, connecting to relational databases, generating pseudorandom numbers, arithmetic with arbitrary-precision decimals, manipulating regular expressions, and unit testing. Some parts of the standard library are covered by specifications—for example, the Web Server Gateway Interface (WSGI) implementation wsgiref follows PEP 333—but most parts are specified by their code, internal documentation, and test suites. However, because most of the standard library is cross-platform Python code, only a few modules must be altered or rewritten for variant implementations. As of 13 March 2025,[update] the Python Package Index (PyPI), the official repository for third-party Python software, contains over 614,339 packages. Development environments Most[which?] Python implementations (including CPython) include a read–eval–print loop (REPL); this permits the environment to function as a command line interpreter, with which users enter statements sequentially and receive results immediately. Also, CPython is bundled with an integrated development environment (IDE) called IDLE, which is oriented toward beginners.[citation needed] Other shells, including IDLE and IPython, add additional capabilities such as improved auto-completion, session-state retention, and syntax highlighting. Standard desktop IDEs include PyCharm, Spyder, and Visual Studio Code; there are web browser-based IDEs, such as the following environments: Implementations CPython is the reference implementation of Python. This implementation is written in C, meeting the C11 standard since version 3.11. Older versions use the C89 standard with several select C99 features, but third-party extensions are not limited to older C versions—e.g., they can be implemented using C11 or C++. CPython compiles Python programs into an intermediate bytecode, which is then executed by a virtual machine. CPython is distributed with a large standard library written in a combination of C and native Python. CPython is available for many platforms, including Windows and most modern Unix-like systems, including macOS (and Apple M1 Macs, since Python 3.9.1, using an experimental installer). Starting with Python 3.9, the Python installer intentionally fails to install on Windows 7 and 8; Windows XP was supported until Python 3.5, with unofficial support for VMS. Platform portability was one of Python's earliest priorities. During development of Python 1 and 2, even OS/2 and Solaris were supported; since that time, support has been dropped for many platforms. All current Python versions (since 3.7) support only operating systems that feature multithreading, by now supporting not nearly as many operating systems (dropping many outdated) than in the past. All alternative implementations have at least slightly different semantics. For example, an alternative may include unordered dictionaries, in contrast to other current Python versions. As another example in the larger Python ecosystem, PyPy does not support the full C Python API. Creating an executable with Python often is done by bundling an entire Python interpreter into the executable, which causes binary sizes to be massive for small programs, yet there exist implementations that are capable of truly compiling Python. Alternative implementations include the following: Stackless Python is a significant fork of CPython that implements microthreads. This implementation uses the call stack differently, thus allowing massively concurrent programs. PyPy also offers a stackless version. Just-in-time Python compilers have been developed, but are now unsupported: There are several compilers/transpilers to high-level object languages; the source language is unrestricted Python, a subset of Python, or a language similar to Python: There are also specialized compilers: Some older projects existed, as well as compilers not designed for use with Python 3.x and related syntax: A performance comparison among various Python implementations, using a non-numerical (combinatorial) workload, was presented at EuroSciPy '13. In addition, Python's performance relative to other programming languages is benchmarked by The Computer Language Benchmarks Game. There are several approaches to optimizing Python performance, despite the inherent slowness of an interpreted language. These approaches include the following strategies or tools: Language Development Python's development is conducted mostly through the Python Enhancement Proposal (PEP) process; this process is the primary mechanism for proposing major new features, collecting community input on issues, and documenting Python design decisions. Python coding style is covered in PEP 8. Outstanding PEPs are reviewed and commented on by the Python community and the steering council. Enhancement of the language corresponds with development of the CPython reference implementation. The mailing list python-dev is the primary forum for the language's development. Specific issues were originally discussed in the Roundup bug tracker hosted by the foundation. In 2022, all issues and discussions were migrated to GitHub. Development originally took place on a self-hosted source-code repository running Mercurial, until Python moved to GitHub in January 2017. CPython's public releases have three types, distinguished by which part of the version number is incremented: Many alpha, beta, and release-candidates are also released as previews and for testing before final releases. Although there is a rough schedule for releases, they are often delayed if the code is not ready yet. Python's development team monitors the state of the code by running a large unit test suite during development. The major academic conference on Python is PyCon. Also, there are special Python mentoring programs, such as PyLadies. Naming Python's name is inspired by the British comedy group Monty Python, whom Python creator Guido van Rossum enjoyed while developing the language. Monty Python references appear frequently in Python code and culture; for example, the metasyntactic variables often used in Python literature are spam and eggs, rather than the traditional foo and bar. Also, the official Python documentation contains various references to Monty Python routines. Python users are sometimes referred to as "Pythonistas". Languages influenced by Python See also Notes References Further reading External links |
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Contents Redshift In physics, a redshift is an increase in the wavelength, or equivalently, a decrease in the frequency, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and energy, is known as a blueshift. Three forms of redshift occur in astronomy and cosmology: Doppler redshifts due to the relative motions of radiation sources, gravitational redshift as radiation escapes from gravitational potentials, and cosmological redshifts caused by the universe expanding. The value of a redshift is often denoted by the letter z, corresponding to the fractional change in wavelength (positive for redshifts, negative for blueshifts), and by the wavelength ratio 1 + z (which is greater than 1 for redshifts and less than 1 for blueshifts). Automated astronomical redshift surveys are an important tool for learning about the large-scale structure of the universe. Redshift and blueshift can also be related to photon energy and, via Planck's law, to a corresponding blackbody temperature. Examples of strong redshifting are a gamma ray perceived as an X-ray, or initially visible light perceived as radio waves. The initial 3000 kelvin (K) radiation from the Big Bang has redshifted far down to become the 3 K cosmic microwave background. Subtler redshifts are seen in the spectroscopic observations of astronomical objects, and are used in terrestrial technologies such as Doppler radar and radar guns. Gravitational waves, which also travel at the speed of light, are subject to the same redshift phenomena. Other physical processes exist that can lead to a shift in the frequency of electromagnetic radiation, including scattering and optical effects; however, the resulting changes are distinguishable from (astronomical) redshift and are not generally referred to as such. Concept Using a telescope and a spectrometer, the variation in intensity of star light with frequency can be measured. The resulting spectrum can be compared to the spectrum from hot gases expected in stars, such as hydrogen, in a laboratory on Earth. As illustrated with the idealised spectrum in the top-right, to determine the redshift, features in the two spectra such as absorption lines, emission lines, or other variations in light intensity may be shifted. Redshift (and blueshift) may be characterised by the relative difference between the observed and emitted wavelengths (or frequency) of an object. In astronomy, it is customary to refer to this change using a dimensionless quantity called z. If λ represents wavelength and f represents frequency (note, λf = c where c is the speed of light), then z is defined by the equations: Doppler effect blueshifts (z < 0) are associated with objects approaching (moving closer to) the observer with the light shifting to greater energies. Conversely, Doppler effect redshifts (z > 0) are associated with objects receding (moving away) from the observer with the light shifting to lower energies. Likewise, gravitational blueshifts are associated with light emitted from a source residing within a weaker gravitational field as observed from within a stronger gravitational field, while gravitational redshifting implies the opposite conditions. History The history of the subject began in the 19th century, with the development of classical wave mechanics and the exploration of phenomena which are associated with the Doppler effect. The effect is named after the Austrian mathematician Christian Doppler, who offered the first known physical explanation for the phenomenon in 1842.: 107 In 1845, the hypothesis was tested and confirmed for sound waves by the Dutch scientist Christophorus Buys Ballot. Doppler correctly predicted that the phenomenon would apply to all waves and, in particular, suggested that the varying colors of stars could be attributed to their motion with respect to the Earth. Unaware of Doppler's work, French physicist Hippolyte Fizeau suggested in 1848 that a shift in spectral lines from stars might be used to measure their motion relative to Earth.: 109 In 1850, François-Napoléon-Marie Moigno analysed both Doppler's and Fizeau's ideas in a publication read by both James Clerk Maxwell and William Huggins, who initially stuck to the idea that the color of stars related to their chemistry, however by 1868, Huggins was the first to determine the velocity of a star moving away from the Earth by the analysis of spectral shifts.: 111 In 1871, optical redshift was confirmed when the phenomenon was observed in Fraunhofer lines, using solar rotation, about 0.1 Å in the red. In 1887, Hermann Carl Vogel and Julius Scheiner discovered the "annual Doppler effect", the yearly change in the Doppler shift of stars located near the ecliptic, due to the orbital velocity of the Earth. In 1901, Aristarkh Belopolsky verified optical redshift in the laboratory using a system of rotating mirrors. Beginning with observations in 1912, Vesto Slipher discovered that the Andromeda Galaxy had a blue shift, indicating that it was moving towards the Earth. Slipher first reported his measurement in the inaugural volume of the Lowell Observatory Bulletin. Three years later, he wrote a review in the journal Popular Astronomy. In it he stated that "the early discovery that the great Andromeda spiral had the quite exceptional velocity of –300 km[/s] showed the means then available, capable of investigating not only the spectra of the spirals but their velocities as well." Slipher reported the velocities for 15 spiral nebulae spread across the entire celestial sphere, all but three having observable "positive" (that is recessional) velocities. Until 1923 the nature of the nebulae was unclear. By that year Edwin Hubble had established that these were galaxies and worked out a procedure to measure distance based on the period-luminosity relation of variable Cepheids stars. This made it possible to test a prediction by Willem de Sitter in 1917 that redshift would be correlated with distance. In 1929 Hubble combined his distance estimates with redshift data from Slipher's reports and measurements by Milton Humason to report an approximate relationship between the redshift and distance, a result now called Hubble's law.: 64 Theories relating to the redshift-distance relation also evolved during the 1920s. The solution to the equations of general relativity described by de Sitter contained no matter, but in 1922 Alexander Friedmann derived dynamic solutions, now called the Friedmann equations, based on frictionless fluid models. Independently Georges Lemaître derived similar equations in 1927 and his analysis became widely known around the time of Hubble's key publication.: 77 By early 1930 the combination of the redshift measurements and theoretical models established a major breakthrough in the new science of cosmology: the universe had a history and its expansion could be investigated with physical models backed up with observational astronomy.: 99 When cosmological redshifts were first discovered, Fritz Zwicky proposed an effect known as tired light. However this model has largely been ruled out by timescale stretch observations in type Ia supernovae. Arthur Eddington used the term "red shift" as early as 1923, which is the oldest example of the term reported by the Oxford English Dictionary. Willem de Sitter used the single-word version redshift in 1934. In the 1960s the discovery of quasars, which appear as very blue point sources and thus were initially thought to be unusual stars, led to the idea that they were as bright as they were because they were closer than their redshift data indicated. A flurry of theoretical and observational work concluded that these objects were very powerful but distant astronomical objects.: 261 Physical origins Redshifts are differences between two wavelength measurements and wavelengths are a property of both the photons and the measuring equipment. Thus redshifts characterise differences between two measurement locations. These differences are commonly organised in three groups, attributed to relative motion between the source and the observer, to the expansion of the universe, and to gravity. The following sections explain these groups. If a source of the light is moving away from an observer, then redshift (z > 0) occurs; if the source moves towards the observer, then blueshift (z < 0) occurs. This is true for all electromagnetic waves and is explained by the Doppler effect. Consequently, this type of redshift is called the Doppler redshift. If the source moves away from the observer with velocity v, which is much less than the speed of light (v ≪ c), the redshift is given by z ≈ v c {\displaystyle z\approx {\frac {v}{c}}} where c is the speed of light (since γ ≈ 1 {\displaystyle \gamma \approx 1} ). In the classical Doppler effect, the frequency of the source is not modified, but the recessional motion causes the illusion of a lower frequency. A more complete treatment of the Doppler redshift requires considering relativistic effects associated with motion of sources close to the speed of light. A complete derivation of the effect can be found in the article on the relativistic Doppler effect. In brief, objects moving close to the speed of light will experience deviations from the above formula due to the time dilation of special relativity which can be corrected for by introducing the Lorentz factor γ into the classical Doppler formula as follows (for motion solely in the line of sight): 1 + z = ( 1 + v c ) γ . {\displaystyle 1+z=\left(1+{\frac {v}{c}}\right)\gamma .} This phenomenon was first observed in a 1938 experiment performed by Herbert E. Ives and G. R. Stilwell, called the Ives–Stilwell experiment. Since the Lorentz factor is dependent only on the magnitude of the velocity, this causes the redshift associated with the relativistic correction to be independent of the orientation of the source movement. In contrast, the classical part of the formula is dependent on the projection of the movement of the source into the line-of-sight which yields different results for different orientations. If θ is the angle between the direction of relative motion and the direction of emission in the observer's frame (zero angle is directly away from the observer), the full form for the relativistic Doppler effect becomes: 1 + z = 1 + v cos ( θ ) / c 1 − v 2 / c 2 {\displaystyle 1+z={\frac {1+v\cos(\theta )/c}{\sqrt {1-v^{2}/c^{2}}}}} and for motion solely in the line of sight (θ = 0°), this equation reduces to: 1 + z = 1 + v / c 1 − v / c {\displaystyle 1+z={\sqrt {\frac {1+v/c}{1-v/c}}}} For the special case that the light is moving at right angle (θ = 90°) to the direction of relative motion in the observer's frame, the relativistic redshift is known as the transverse redshift, and a redshift: 1 + z = 1 1 − v 2 / c 2 {\displaystyle 1+z={\frac {1}{\sqrt {1-v^{2}/c^{2}}}}} is measured, even though the object is not moving away from the observer. Even when the source is moving towards the observer, if there is a transverse component to the motion then there is some speed at which the dilation just cancels the expected blueshift and at higher speed the approaching source will be redshifted. The observations of increasing redshifts from more and more distant galaxies can be modelled assuming a homogeneous and isotropic universe combined with general relativity. This cosmological redshift can be written as a function of a, the time-dependent cosmic scale factor:: 72 1 + z = a n o w a t h e n = a 0 a ( t ) {\displaystyle 1+z={\frac {a_{\mathrm {now} }}{a_{\mathrm {then} }}}={\frac {a_{0}}{a(t)}}} The scale factor is monotonically increasing as time passes. Thus z is positive, close to zero for local stars, and increasing for distant galaxies that appear redshifted. Using a Friedmann–Robertson–Walker model of the expansion of the universe, redshift can be related to the age of an observed object, the so-called cosmic time–redshift relation. Denote a density ratio as Ω0: Ω 0 = ρ ρ crit , {\displaystyle \Omega _{0}={\frac {\rho }{\rho _{\text{crit}}}}\ ,} with ρcrit the critical density demarcating a universe that eventually crunches from one that simply expands. This density is about three hydrogen atoms per cubic meter of space. At large redshifts, 1 + z > Ω0−1, one finds: t ( z ) ≈ 2 3 H 0 Ω 0 1 / 2 ( 1 z 3 / 2 ) , {\displaystyle t(z)\approx {\frac {2}{3H_{0}{\Omega _{0}}^{1/2}}}({\frac {1}{z^{3/2}}}\ ),} where t is age of the object after the big bang, H0 is the present-day Hubble constant, and z is the redshift. For these large redshifts, the age of the universe, t(z), is small, meaning that the light was emitted when the universe was young. The cosmological redshift is commonly attributed to stretching of the wavelengths of photons due to the stretching of space. This interpretation can be misleading. As required by general relativity, the cosmological expansion of space has no effect on local physics. There is no term related to expansion in Maxwell's equations that govern light propagation. The cosmological redshift can be interpreted as an accumulation of infinitesimal Doppler shifts along the trajectory of the light. There are several websites for calculating various times and distances from redshift, as the precise calculations require numerical integrals for most values of the parameters. The redshift of a galaxy includes both a component related to recessional velocity from expansion of the universe, and a component related to the peculiar motion of the galaxy with respect to its local universe. The redshift due to expansion of the universe depends upon the recessional velocity in a fashion determined by the cosmological model chosen to describe the expansion of the universe, which is very different from how Doppler redshift depends upon local velocity. Describing the cosmological expansion origin of redshift, cosmologist Edward Robert Harrison said, "Light leaves a galaxy, which is stationary in its local region of space, and is eventually received by observers who are stationary in their own local region of space. Between the galaxy and the observer, light travels through vast regions of expanding space. As a result, all wavelengths of the light are stretched by the expansion of space. It is as simple as that..." Steven Weinberg clarified, "The increase of wavelength from emission to absorption of light does not depend on the rate of change of a(t) [the scale factor] at the times of emission or absorption, but on the increase of a(t) in the whole period from emission to absorption." In the theory of general relativity, there is time dilation within a gravitational well. Light emitted within the well will appear to have fewer cycles per second when measured outside of the well, due to differences in the two clocks.: 284 This is known as the gravitational redshift or Einstein shift. The theoretical derivation of this effect follows from the Schwarzschild solution of the Einstein equations which yields the following formula for redshift associated with a photon travelling in the gravitational field of an uncharged, nonrotating, spherically symmetric mass: 1 + z = 1 1 − 2 G M r c 2 , {\displaystyle 1+z={\frac {1}{\sqrt {1-{\frac {2GM}{rc^{2}}}}}},} where This gravitational redshift result can be derived from the assumptions of special relativity and the equivalence principle; the full theory of general relativity is not required. The effect is very small but measurable on Earth using the Mössbauer effect and was first observed in the Pound–Rebka experiment. However, it is significant near a black hole, and as an object approaches the event horizon the red shift becomes infinite. It is also the dominant cause of large angular-scale temperature fluctuations in the cosmic microwave background radiation (see Sachs–Wolfe effect). Several important special-case formulae for redshift in certain special spacetime geometries are summarised in the following table. In all cases the magnitude of the shift (the value of z) is independent of the wavelength. For motion completely in the radial orline-of-sight direction: 1 + z = γ ( 1 + v ∥ c ) = 1 + v ∥ c 1 − v ∥ c {\displaystyle 1+z=\gamma \left(1+{\frac {v_{\parallel }}{c}}\right)={\sqrt {\frac {1+{\frac {v_{\parallel }}{c}}}{1-{\frac {v_{\parallel }}{c}}}}}} z ≈ v ∥ c {\displaystyle z\approx {\frac {v_{\parallel }}{c}}} for small v ∥ {\displaystyle v_{\parallel }} For motion completely in the transverse direction: 1 + z = 1 1 − v ⊥ 2 c 2 {\displaystyle 1+z={\frac {1}{\sqrt {1-{\frac {v_{\perp }^{2}}{c^{2}}}}}}} z ≈ 1 2 ( v ⊥ c ) 2 {\displaystyle z\approx {\frac {1}{2}}\left({\frac {v_{\perp }}{c}}\right)^{2}} for small v ⊥ {\displaystyle v_{\perp }} 1 + z = a n o w a t h e n {\displaystyle 1+z={\frac {a_{\mathrm {now} }}{a_{\mathrm {then} }}}} Hubble's law: z ≈ H 0 D c {\displaystyle z\approx {\frac {H_{0}D}{c}}} for D ≪ c H 0 {\displaystyle D\ll {\frac {c}{H_{0}}}} 1 + z = g t t ( receiver ) g t t ( source ) {\displaystyle 1+z={\sqrt {\frac {g_{tt}({\text{receiver}})}{g_{tt}({\text{source}})}}}} For the Schwarzschild geometry: 1 + z = 1 − r S r receiver 1 − r S r source = 1 − 2 G M c 2 r receiver 1 − 2 G M c 2 r source {\displaystyle 1+z={\sqrt {\frac {1-{\frac {r_{S}}{r_{\text{receiver}}}}}{1-{\frac {r_{S}}{r_{\text{source}}}}}}}={\sqrt {\frac {1-{\frac {2GM}{c^{2}r_{\text{receiver}}}}}{1-{\frac {2GM}{c^{2}r_{\text{source}}}}}}}} z ≈ 1 2 ( r S r source − r S r receiver ) {\displaystyle z\approx {\frac {1}{2}}\left({\frac {r_{S}}{r_{\text{source}}}}-{\frac {r_{S}}{r_{\text{receiver}}}}\right)} for r ≫ r S {\displaystyle r\gg r_{S}} In terms of escape velocity: z ≈ 1 2 ( v e c ) source 2 − 1 2 ( v e c ) receiver 2 {\displaystyle z\approx {\frac {1}{2}}\left({\frac {v_{\text{e}}}{c}}\right)_{\text{source}}^{2}-{\frac {1}{2}}\left({\frac {v_{\text{e}}}{c}}\right)_{\text{receiver}}^{2}} for v e ≪ c {\displaystyle v_{\text{e}}\ll c} Observations in astronomy The redshift observed in astronomy can be measured because the emission and absorption spectra for atoms are distinctive and well known, calibrated from spectroscopic experiments in laboratories on Earth. When the redshifts of various absorption and emission lines from a single astronomical object are measured, z is found to be remarkably constant. Although distant objects may be slightly blurred and lines broadened, it is by no more than can be explained by thermal or mechanical motion of the source. For these reasons and others, the consensus among astronomers is that the redshifts they observe are due to some combination of the three established forms of Doppler-like redshifts. Spectroscopy, as a measurement, is considerably more difficult than simple photometry, which measures the brightness of astronomical objects through certain filters. When photometric data is all that is available (for example, the Hubble Deep Field and the Hubble Ultra Deep Field), astronomers rely on a technique for measuring photometric redshifts. Due to the broad wavelength ranges in photometric filters and the necessary assumptions about the nature of the spectrum at the light-source, errors for these sorts of measurements can range up to δz = 0.5, and are much less reliable than spectroscopic determinations. However, photometry does at least allow a qualitative characterisation of a redshift. For example, if a Sun-like spectrum had a redshift of z = 1, it would be brightest in the infrared (1000 nm) rather than at the blue-green (500 nm) color associated with the peak of its blackbody spectrum, and the light intensity will be reduced in the filter by a factor of four, (1 + z)2. Both the photon count rate and the photon energy are redshifted. (See K correction for more details on the photometric consequences of redshift.) Determining the redshift of an object with spectroscopy requires the wavelength of the emitted light in the rest frame of the source. Astronomical applications rely on distinct spectral lines. Redshifts cannot be calculated by looking at unidentified features whose rest-frame frequency is unknown, or with a spectrum that is featureless or white noise (random fluctuations in a spectrum). Thus gamma-ray bursts themselves cannot be used for reliable redshift measurements, but optical afterglow associated with the burst can be analysed for redshifts. In nearby objects (within our Milky Way galaxy) observed redshifts are almost always related to the line-of-sight velocities associated with the objects being observed. Observations of such redshifts and blueshifts enable astronomers to measure velocities and parametrise the masses of the orbiting stars in spectroscopic binaries. Similarly, small redshifts and blueshifts detected in the spectroscopic measurements of individual stars are one way astronomers have been able to diagnose and measure the presence and characteristics of planetary systems around other stars and have even made very detailed differential measurements of redshifts during planetary transits to determine precise orbital parameters. Some approaches are able to track the redshift variations in multiple objects at once. Finely detailed measurements of redshifts are used in helioseismology to determine the precise movements of the photosphere of the Sun. Redshifts have also been used to make the first measurements of the rotation rates of planets, velocities of interstellar clouds, the rotation of galaxies, and the dynamics of accretion onto neutron stars and black holes which exhibit both Doppler and gravitational redshifts. The temperatures of various emitting and absorbing objects can be obtained by measuring Doppler broadening—effectively redshifts and blueshifts over a single emission or absorption line. By measuring the broadening and shifts of the 21-centimeter hydrogen line in different directions, astronomers have been able to measure the recessional velocities of interstellar gas, which in turn reveals the rotation curve of our Milky Way. Similar measurements have been performed on other galaxies, such as Andromeda. The most distant objects exhibit larger redshifts corresponding to the Hubble flow of the universe. The largest-observed redshift, corresponding to the greatest distance and furthest back in time, is that of the cosmic microwave background radiation; the numerical value of its redshift is about z = 1089 (z = 0 corresponds to present time), and it shows the state of the universe about 13.8 billion years ago, and 379,000 years after the initial moments of the Big Bang. The luminous point-like cores of quasars were the first "high-redshift" (z > 0.1) objects discovered before the improvement of telescopes allowed for the discovery of other high-redshift galaxies. For galaxies more distant than the Local Group and the nearby Virgo Cluster, but within a thousand megaparsecs or so, the redshift is approximately proportional to the galaxy's distance. This correlation was first observed by Edwin Hubble and has come to be known as Hubble's law. Vesto Slipher was the first to discover galactic redshifts, in about 1912, while Hubble correlated Slipher's measurements with distances he measured by other means to formulate his law. Because it is usually not known how luminous objects are, measuring the redshift is easier than more direct distance measurements, so redshift is sometimes in practice converted to a crude distance measurement using Hubble's law. Gravitational interactions of galaxies with each other and clusters cause a significant scatter in the normal plot of the Hubble diagram. The peculiar velocities associated with galaxies superimpose a rough trace of the mass of virialised objects in the universe. This effect leads to such phenomena as nearby galaxies (such as the Andromeda Galaxy) exhibiting blueshifts as we fall towards a common barycenter, and redshift maps of clusters showing a fingers of god effect due to the scatter of peculiar velocities in a roughly spherical distribution. These "redshift-space distortions" can be used as a cosmological probe in their own right, providing information on how structure formed in the universe, and how gravity behaves on large scales. The Hubble law's linear relationship between distance and redshift assumes that the rate of expansion of the universe is constant. However, when the universe was much younger, the expansion rate, and thus the Hubble "constant", was larger than it is today. For more distant galaxies, then, whose light has been travelling to us for much longer times, the approximation of constant expansion rate fails, and the Hubble law becomes a non-linear integral relationship and dependent on the history of the expansion rate since the emission of the light from the galaxy in question. Observations of the redshift-distance relationship can be used, then, to determine the expansion history of the universe and thus the matter and energy content. It was long believed that the expansion rate has been continuously decreasing since the Big Bang, but observations beginning in 1988 of the redshift-distance relationship using Type Ia supernovae have suggested that in comparatively recent times the expansion rate of the universe has begun to accelerate. The most reliable redshifts are from spectroscopic data, and the highest-confirmed spectroscopic redshift of a galaxy is that of JADES-GS-z14-0 with a redshift of z = 14.32, corresponding to 290 million years after the Big Bang. The previous record was held by GN-z11, with a redshift of z = 11.1, corresponding to 400 million years after the Big Bang. Slightly less reliable are Lyman-break redshifts, the highest of which is the lensed galaxy A1689-zD1 at a redshift z = 7.5 and the next highest being z = 7.0. The most distant-observed gamma-ray burst with a spectroscopic redshift measurement was GRB 090423, which had a redshift of z = 8.2. The most distant-known quasar, ULAS J1342+0928, is at z = 7.54. The highest-known redshift radio galaxy (TGSS1530) is at a redshift z = 5.72 and the highest-known redshift molecular material is the detection of emission from the CO molecule from the quasar SDSS J1148+5251 at z = 6.42. Extremely red objects (EROs) are astronomical sources of radiation that radiate energy in the red and near infrared part of the electromagnetic spectrum. These may be starburst galaxies that have a high redshift accompanied by reddening from intervening dust, or they could be highly redshifted elliptical galaxies with an older (and therefore redder) stellar population. Objects that are even redder than EROs are termed hyper extremely red objects (HEROs). In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it. Nonetheless, relic sources post far higher redshifts than even the furthest astronomical objects observed. The cosmic microwave background has a redshift of z = 1089, corresponding to an age of approximately 379,000 years after the Big Bang and a proper distance of more than 46 billion light-years. This redshift corresponds to a shift in average temperature from 3000 K down to 3 K. The yet-to-be-observed first light from the oldest Population III stars, not long after atoms first formed and the CMB ceased to be absorbed almost completely, may have redshifts in the range of 20 < z < 100. Other high-redshift events predicted by physics but not presently observable are the cosmic neutrino background from about two seconds after the Big Bang (and a redshift in excess of z > 1010) and the cosmic gravitational wave background emitted directly from inflation at a redshift in excess of z > 1025. With advent of automated telescopes and improvements in spectroscopes, a number of collaborations have been made to map the universe in redshift space. By combining redshift with angular position data, a redshift survey maps the 3D distribution of matter within a field of the sky. These observations are used to measure properties of the large-scale structure of the universe. The Great Wall, a vast supercluster of galaxies over 500 million light-years wide, provides a dramatic example of a large-scale structure that redshift surveys can detect. The first redshift survey was the CfA Redshift Survey, started in 1977 with the initial data collection completed in 1982. More recently, the 2dF Galaxy Redshift Survey determined the large-scale structure of one section of the universe, measuring redshifts for over 220,000 galaxies; data collection was completed in 2002, and the final data set was released 30 June 2003. The Sloan Digital Sky Survey (SDSS) began collecting data in 1998 and published its eighteenth data release in 2023. SSDS has measured redshifts for galaxies as high as 0.8, and has recorded over 100,000 quasars at z = 3 and beyond. The DEEP2 Redshift Survey used the Keck telescopes with the "DEIMOS" spectrograph; a follow-up to the pilot program DEEP1, DEEP2 was designed to measure faint galaxies with redshifts 0.7 and above, and it recorded redshifts of over 38,000 objects by its conclusion in 2013. Effects from physical optics or radiative transfer The interactions and phenomena summarised in the subjects of radiative transfer and physical optics can result in shifts in the wavelength and frequency of electromagnetic radiation. In such cases, the shifts correspond to a physical energy transfer to matter or other photons rather than being by a transformation between reference frames. Such shifts can be from such physical phenomena as coherence effects or the scattering of electromagnetic radiation whether from charged elementary particles, from particulates, or from fluctuations of the index of refraction in a dielectric medium as occurs in the radio phenomenon of radio whistlers. While such phenomena are sometimes referred to as "redshifts" and "blueshifts", in astrophysics light–matter interactions that result in energy shifts in the radiation field are generally referred to as "reddening" rather than "redshifting" which, as a term, is normally reserved for the effects discussed above. In many circumstances scattering causes radiation to redden because entropy results in the predominance of many low-energy photons over few high-energy ones (while conserving total energy). Except possibly under carefully controlled conditions, scattering does not produce the same relative change in wavelength across the whole spectrum; that is, any calculated z is generally a function of wavelength. Furthermore, scattering from random media generally occurs at many angles, and z is a function of the scattering angle. If multiple scattering occurs, or the scattering particles have relative motion, then there is generally distortion of spectral lines as well. In interstellar astronomy, visible spectra can appear redder due to scattering processes in a phenomenon referred to as interstellar reddening—similarly Rayleigh scattering causes the atmospheric reddening of the Sun seen in the sunrise or sunset and causes the rest of the sky to have a blue colour. This phenomenon is distinct from redshifting because the spectroscopic lines are not shifted to other wavelengths in reddened objects and there is an additional dimming and distortion associated with the phenomenon due to photons being scattered in and out of the line of sight. Blueshift The opposite of a redshift is a blueshift. A blueshift is any decrease in wavelength (increase in energy), with a corresponding increase in frequency, of an electromagnetic wave. In visible light, this shifts a color towards the blue end of the spectrum. Doppler blueshift is caused by movement of a source towards the observer. The term applies to any decrease in wavelength and increase in frequency caused by relative motion, even outside the visible spectrum. Only objects moving at near-relativistic speeds toward the observer are noticeably bluer to the naked eye, but the wavelength of any reflected or emitted photon or other particle is shortened in the direction of travel. Doppler blueshift is used in astronomy to determine relative motion: Unlike the relative Doppler blueshift, caused by movement of a source towards the observer and thus dependent on the received angle of the photon, gravitational blueshift is absolute and does not depend on the received angle of the photon: Photons climbing out of a gravitating object become less energetic. This loss of energy is known as a "redshifting", as photons in the visible spectrum would appear more red. Similarly, photons falling into a gravitational field become more energetic and exhibit a blueshifting. ... Note that the magnitude of the redshifting (blueshifting) effect is not a function of the emitted angle or the received angle of the photon—it depends only on how far radially the photon had to climb out of (fall into) the potential well. It is a natural consequence of conservation of energy and mass–energy equivalence, and was confirmed experimentally in 1959 with the Pound–Rebka experiment. Gravitational blueshift contributes to cosmic microwave background (CMB) anisotropy via the Sachs–Wolfe effect: when a gravitational well evolves while a photon is passing, the amount of blueshift on approach will differ from the amount of gravitational redshift as it leaves the region. There are far-away active galaxies that show a blueshift in their [O III] emission lines. One of the largest blueshifts is found in the narrow-line quasar, PG 1543+489, which has a relative velocity of −1150 km/s. These types of galaxies are called "blue outliers". In a hypothetical universe undergoing a runaway Big Crunch contraction, a cosmological blueshift would be observed, with galaxies further away being increasingly blueshifted—the exact opposite of the actually observed cosmological redshift in the present expanding universe. See also References Sources External links |
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Contents Weak artificial intelligence Weak artificial intelligence (weak AI) is artificial intelligence that implements a limited part of the mind, or, as narrow AI, artificial narrow intelligence (ANI), is focused on one narrow task. Weak AI is contrasted with strong AI, which can be interpreted in various ways: Narrow AI can be classified as being "limited to a single, narrowly defined task. Most modern AI systems would be classified in this category." Artificial general intelligence is conversely the opposite. Applications and risks Some examples of narrow AI are AlphaGo, self-driving cars, robot systems used in the medical field, and diagnostic doctors. Narrow AI systems are sometimes dangerous if unreliable. And the behavior that it follows can become inconsistent. It could be difficult for the AI to grasp complex patterns and get to a solution that works reliably in various environments. This "brittleness" can cause it to fail in unpredictable ways. Narrow AI failures can sometimes have significant consequences. It could for example cause disruptions in the electric grid, damage nuclear power plants, cause global economic problems, and misdirect autonomous vehicles. Medicines could be incorrectly sorted and distributed. Also, medical diagnoses can ultimately have serious and sometimes deadly consequences if the AI is faulty or biased. Simple AI programs have already worked their way into society, oftentimes unnoticed by the public. Autocorrection for typing, speech recognition for speech-to-text programs, and vast expansions in the data science fields are examples. Narrow AI has also been the subject of some controversy, including resulting in unfair prison sentences, discrimination against women in the workplace for hiring, resulting in death via autonomous driving, among other cases. Despite being "narrow" AI, recommender systems are efficient at predicting user reactions based their posts, patterns, or trends. For instance, TikTok's "For You" algorithm can determine a user's interests or preferences in less than an hour. Some other social media AI systems are used to detect bots that may be involved in propaganda or other potentially malicious activities. Weak AI versus strong AI John Searle contests the possibility of strong AI (by which he means conscious AI). He further believes that the Turing test (created by Alan Turing and originally called the "imitation game", used to assess whether a machine can converse indistinguishably from a human) is not accurate or appropriate for testing whether an AI is "strong". Scholars such as Antonio Lieto have argued that the current research on both AI and cognitive modelling are perfectly aligned with the weak-AI hypothesis (that should not be confused with the "general" vs "narrow" AI distinction) and that the popular assumption that cognitively inspired AI systems espouse the strong AI hypothesis is ill-posed and problematic since "artificial models of brain and mind can be used to understand mental phenomena without pretending that that they are the real phenomena that they are modelling" (as, on the other hand, implied by the strong AI assumption). See also References |
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Contents Abraham Abraham[a] (originally Abram)[b] is the common Hebrew patriarch of the Abrahamic religions, including Judaism, Christianity, and Islam. In Judaism, he is the founding father who began the covenantal relationship between the Jewish people and God; in Christianity, he is the spiritual progenitor of all believers, whether Jewish or non-Jewish;[c] and in Islam, he is a link in the chain of Islamic prophets that begins with Adam and culminates in Muhammad. Abraham is also revered in other Abrahamic religions such as the Baháʼí Faith and the Druze faith. The story of the life of Abraham, as told in the narrative of the Book of Genesis in the Hebrew Bible, revolves around the themes of posterity and land. He is said to have been called by God to leave the house of his father Terah and settle in the land of Canaan, which God now promises to Abraham and his progeny. This promise is subsequently inherited by Isaac, Abraham's son by his wife Sarah, while Isaac's half-brother Ishmael is also promised that he will be the founder of a great nation. Abraham purchases a tomb (the Cave of the Patriarchs) at Hebron to be Sarah's grave, thus establishing his right to the land; and, in the second generation, his heir Isaac is married to a woman from his own kin to earn his parents' approval. Abraham later marries Keturah and has six more sons; but, on his death, when he is buried beside Sarah, it is Isaac who receives "all Abraham's goods" while the other sons receive only "gifts". Most scholars view the patriarchal age, along with the Exodus and the period of the biblical judges, as a late literary construct that does not relate to any particular historical era. It is largely concluded that the Torah, the series of books that includes Genesis, was composed during the Persian period, as a result of tensions between Jewish landowners who had stayed in Judah during the Babylonian captivity and traced their right to the land through their "father Abraham", and the returning exiles who based their counterclaim on Moses and the Exodus tradition of the Israelites. The Abraham Cycle The Abraham cycle (Genesis 11:27–Genesis 25:11) unfolds as a narrative of mounting tension, centered on the conflict between God's promise that Abram would father a lineage and become the ancestor of numerous nations, and a succession of crises that jeopardize this divine commitment. The storytelling method used here is the “obstacle story,” a literary device renowned for its enduring and universal popularity across cultures and eras. The Abraham cycle is not structured by a unified plot centered on a conflict and its resolution or a problem and its solution. The episodes are often only loosely linked, and the sequence is not always logical, but it is unified by the presence of Abraham himself, as either actor or witness, and by the themes of posterity and land. These themes form "narrative programs" set out in Genesis 11:27–31 concerning the sterility of Sarah and Genesis 12:1–3 in which Abraham is ordered to leave the land of his birth for the land God will show him. Terah, the ninth in descent from Noah, was the father of Abram, Nahor, Haran (Hebrew: הָרָן Hārān) and Sarah. Haran was the father of Lot, who was Abram's nephew; the family lived in Ur of the Chaldees. Haran died there while Terah was still alive. Abram married Sarah (Sarai) but they were childless. Genesis 11 records that Terah, Abram, Sarai, and Lot departed for Canaan, but settled in a place named Haran (Hebrew: חָרָן Ḥārān), where Terah died at the age of 205. Then the narrative in Genesis 12 shows that God told Abram to leave his country and his kindred, and go to a land that God would show him, and promised to make of him a great nation, bless him, make his name great, bless them that bless him, and curse them who may curse him. Abram was 75 years old when he and Sarai left Haran with his nephew Lot, and their possessions and people that they had acquired, and they traveled to Shechem in Canaan. Abram built an altar to God in Shechem, and later he built another altar between Bethel and Ai. From there the party travelled to the Negev, or to the south. According to some exegetes, like Nahmanides, Abram was actually born in Haran and he later relocated to Ur, while some of his family remained in Haran. There was a severe famine in the land of Canaan, so that Abram, Lot, and their households traveled to Egypt. On the way Abram told Sarai to say that she was his sister, so that the Egyptians would not kill him. When they entered Egypt, the Pharaoh's officials praised Sarai's beauty to Pharaoh, and they took her into the palace and gave Abram goods in exchange. God afflicted Pharaoh and his household with plagues, which led Pharaoh to try to find out what was wrong. Upon discovering that Sarai was a married woman, Pharaoh demanded that Abram and Sarai leave. When they lived for a while in the Negev after being banished from Egypt and came back to the Bethel and Ai area, Abram's and Lot's sizable herds occupied the same pastures. This became a problem for the herdsmen, who were assigned to each family's cattle. The conflicts between herdsmen had become so troublesome that Abram suggested that Lot choose a separate area, either on the left hand or on the right hand, that there be no conflict between them. Lot decided to go eastward to the plain of Jordan, where the land was well watered everywhere as far as Zoara, and he dwelled in the cities of the plain toward Sodom. Abram went south to Hebron and settled in the plain of Mamre, where he built another altar to worship God. During the rebellion of the Jordan River cities, Sodom and Gomorrah, against Elam, Abram's nephew, Lot, was taken prisoner along with his entire household by the invading Elamite forces. The Elamite army came to collect the spoils of war, after having just defeated the king of Sodom's armies. Lot and his family, at the time, were settled on the outskirts of the Kingdom of Sodom which made them a visible target. One person who escaped capture came and told Abram what happened. Once Abram received this news, he immediately assembled 318 trained servants. Abram's force headed north in pursuit of the Elamite army, who were already worn down from the Battle of Siddim. When they caught up with them at Dan, Abram devised a battle plan by splitting his group into more than one unit, and launched a night raid. Not only were they able to free the captives, Abram's unit chased and slaughtered the Elamite King Chedorlaomer at Hobah, just north of Damascus. They freed Lot, as well as his household and possessions, and recovered all of the goods from Sodom that had been taken. Upon Abram's return, Sodom's king came out to meet with him in the Valley of Shaveh, the "king's dale". Also, Melchizedek king of Salem (Jerusalem), a priest of El Elyon, brought out bread and wine and blessed Abram and God. Abram then gave Melchizedek a tenth of everything. The king of Sodom then offered to let Abram keep all the possessions if he would merely return his people. Abram declined to accept anything other than the share to which his allies were entitled. The voice of the Lord came to Abram in a vision and repeated the promise of the land and descendants as numerous as the stars. Abram and God made a covenant ceremony, and God told of the future bondage of Israel in Egypt. God described to Abram the land that his offspring would claim: the land of the Kenites, Kenizzites, Kadmonites, Hittites, Perizzites, Rephaims, Amorites, Canaanites, Girgashites, and Jebusites. Abram and Sarai tried to make sense of how he would become a progenitor of nations, because after 10 years of living in Canaan, no child had been born. Sarai then offered her Egyptian slave, Hagar, to Abram with the intention that she would bear him a son. After Hagar found she was pregnant, she began to despise her mistress, Sarai. Sarai responded by mistreating Hagar, and Hagar fled into the wilderness. An angel spoke with Hagar at the fountain on the way to Shur. He instructed her to return to Abram's camp and that her son would be "a wild ass of a man; his hand shall be against every man, and every man's hand against him; and he shall dwell in the face of all his brethren." She was told to call her son Ishmael. Hagar then called God who spoke to her "El-roi", ("Thou God seest me:" KJV). From that day onward, the well was called Beer-lahai-roi, ("The well of him that liveth and seeth me." KJV margin), located between Kadesh and Bered. She then did as she was instructed by returning to her mistress in order to have her child. Abram was 86 years of age when Ishmael was born. Thirteen years later, when Abram was 99 years of age, God declared Abram's new name: "Abraham" – "a father of many nations". Abraham then received the instructions for the covenant of the pieces, of which circumcision was to be the sign. God declared Sarai's new name: "Sarah", blessed her, and told Abraham, "I will give thee a son also of her". Abraham laughed, and "said in his heart, 'Shall a child be born unto him that is a hundred years old? and shall Sarah, that is ninety years old, bear [a child]?'" Immediately after Abraham's encounter with God, he had his entire household of men, including himself (age 99) and Ishmael (age 13), circumcised. Not long afterward, during the heat of the day, Abraham had been sitting at the entrance of his tent by the terebinths of Mamre. He looked up and saw three men in the presence of God. Then he ran and bowed to the ground to welcome them. Abraham then offered to wash their feet and fetch them a morsel of bread, to which they assented. Abraham rushed to Sarah's tent to order ash cakes made from choice flour, then he ordered a servant-boy to prepare a choice calf. When all was prepared, he set curds, milk and the calf before them, waiting on them, under a tree, as they ate. One of the visitors told Abraham that upon his return next year, Sarah would have a son. While at the tent entrance, Sarah overheard what was said and she laughed to herself about the prospect of having a child at their ages. The visitor inquired of Abraham why Sarah laughed at bearing a child at her age, as nothing is too hard for God. Frightened, Sarah denied laughing. After eating, Abraham and the three visitors got up. They walked over to the peak that overlooked the 'cities of the plain' to discuss the fate of Sodom and Gomorrah for their detestable sins that were so great, it moved God to action. Because Abraham's nephew was living in Sodom, God revealed plans to confirm and judge these cities. At this point, the two other visitors left for Sodom. Then Abraham turned to God and pleaded decrementally with Him (from fifty persons to less) that "if there were at least ten righteous men found in the city, would not God spare the city?" For the sake of ten righteous people, God declared that he would not destroy the city. When the two visitors arrived in Sodom to conduct their report, they planned on staying in the city square. However, Abraham's nephew, Lot, met with them and strongly insisted that these two "men" stay at his house for the night. A rally of men stood outside of Lot's home and demanded that Lot bring out his guests so that they may "know" (v. 5) them. However, Lot objected and offered his virgin daughters who had not "known" (v. 8) man to the rally of men instead. They rejected that notion and sought to break down Lot's door to get to his male guests, thus confirming the wickedness of the city and portending their imminent destruction. Early the next morning, Abraham went to the place where he stood before God. He "looked out toward Sodom and Gomorrah" and saw what became of the cities of the plain, where not even "ten righteous" (v. 18:32) had been found, as "the smoke of the land went up as the smoke of a furnace." Abraham settled between Kadesh and Shur in what the Bible anachronistically calls "the land of the Philistines". While he was living in Gerar, Abraham openly claimed that Sarah was his sister. Upon discovering this news, King Abimelech had her brought to him. God then came to Abimelech in a dream and declared that taking her would result in death because she was a man's wife. Abimelech had not laid hands on her, so he inquired if he would also slay a righteous nation, especially since Abraham had claimed that he and Sarah were siblings. In response, God told Abimelech that he did indeed have a blameless heart and that is why he continued to exist. However, should he not return the wife of Abraham back to him, God would surely destroy Abimelech and his entire household. Abimelech was informed that Abraham was a prophet who would pray for him. Early next morning, Abimelech informed his servants of his dream and approached Abraham inquiring as to why he had brought such great guilt upon his kingdom. Abraham stated that he thought there was no fear of God in that place, and that they might kill him for his wife. Then Abraham defended what he had said as not being a lie at all: "And yet indeed she is my sister; she is the daughter of my father, but not the daughter of my mother; and she became my wife." Abimelech returned Sarah to Abraham, and gave him gifts of sheep, oxen, and servants; and invited him to settle wherever he pleased in Abimelech's lands. Further, Abimelech gave Abraham a thousand pieces of silver to serve as Sarah's vindication before all. Abraham then prayed for Abimelech and his household, since God had stricken the women with infertility because of the taking of Sarah. After living for some time in the land of the Philistines, Abimelech and Phicol, the chief of his troops, approached Abraham because of a dispute that resulted in a violent confrontation at a well. Abraham then reproached Abimelech due to his Philistine servant's aggressive attacks and the seizing of Abraham's Well. Abimelech claimed ignorance of the incident. Then Abraham offered a pact by providing sheep and oxen to Abimelech. Further, to attest that Abraham was the one who dug the well, he also gave Abimelech seven ewes for proof. Because of this sworn oath, they called the place of this well: Beersheba. After Abimelech and Phicol headed back to Philistia, Abraham planted a tamarisk grove in Beersheba and called upon "the name of the LORD, the everlasting God." As had been prophesied in Mamre the previous year, Sarah became pregnant and bore a son to Abraham, on the first anniversary of the covenant of circumcision. Abraham was "an hundred years old", when his son whom he named Isaac was born; and he circumcised him when he was eight days old. For Sarah, the thought of giving birth and nursing a child, at such an old age, also brought her much laughter, as she declared, "God hath made me to laugh, so that all who hear will laugh with me." Isaac continued to grow and on the day he was weaned, Abraham held a great feast to honor the occasion. During the celebration, however, Sarah found Ishmael mocking; an observation that would begin to clarify the birthright of Isaac. Ishmael was fourteen years old when Abraham's son Isaac was born to Sarah. When she found Ishmael teasing Isaac, Sarah told Abraham to send both Ishmael and Hagar away. She declared that Ishmael would not share in Isaac's inheritance. Abraham was greatly distressed by his wife's words and sought the advice of his God. God told Abraham not to be distressed but to do as his wife commanded. God reassured Abraham that "in Isaac shall seed be called to thee." He also said Ishmael would make a nation, "because he is thy seed". Early the next morning, Abraham brought Hagar and Ishmael out together. He gave her bread and water and sent them away. The two wandered in the wilderness of Beersheba until her bottle of water was completely consumed. In a moment of despair, she burst into tears. After God heard the boy's voice, an angel of the Lord confirmed to Hagar that he would become a great nation, and will be "living on his sword". A well of water then appeared so that it saved their lives. As the boy grew, he became a skilled archer living in the wilderness of Paran. Eventually his mother found a wife for Ishmael from her home country, the land of Egypt. At some point in Isaac's youth, Abraham was commanded by God to offer his son up as a sacrifice in the land of Moriah. The patriarch traveled three days until he came to the mount that God told him of. He then commanded the servants to remain while he and Isaac proceeded alone into the mount. Isaac carried the wood upon which he would be sacrificed. Along the way, Isaac asked his father where the animal for the burnt offering was, to which Abraham replied "God will provide himself a lamb for a burnt offering". Just as Abraham was about to sacrifice his son, he was interrupted by the angel of the Lord, and he saw behind him a "ram caught in a thicket by his horns", which he sacrificed instead of his son. The place was later named as Jehovah-jireh. For his obedience he received another promise of numerous descendants and abundant prosperity. After this event, Abraham went to Beersheba. Sarah died, and Abraham buried her in the Cave of the Patriarchs (the "cave of Machpelah"), near Hebron which he had purchased along with the adjoining field from Ephron the Hittite. After the death of Sarah, Abraham took another wife, a concubine named Keturah, by whom he had six sons: Zimran, Jokshan, Medan, Midian, Ishbak, and Shuah. According to the Bible, reflecting the change of his name to "Abraham" meaning "a father of many nations", Abraham is considered to be the progenitor of many nations mentioned in the Bible, among others the Israelites, Ishmaelites, Edomites, Amalekites, Kenizzites, Midianites and Assyrians, and through his nephew Lot he was also related to the Moabites and Ammonites. Abraham lived to see Isaac marry Rebekah, and to see the birth of his twin grandsons Jacob and Esau. He died at age 175, and was buried in the cave of Machpelah by his sons Isaac and Ishmael. Historical context In the early and middle 20th century, leading archaeologists such as William F. Albright and G. Ernest Wright and biblical scholars such as Albrecht Alt and John Bright believed that the patriarchs and matriarchs were either real individuals or believable composites of people who lived in the "patriarchal age", the 2nd millennium BCE. However, in the 1970s, new arguments concerning Israel's past and the biblical texts challenged these views; these arguments can be found in Thomas L. Thompson's The Historicity of the Patriarchal Narratives (1974), and John Van Seters' Abraham in History and Tradition (1975). Thompson, a literary scholar, based his argument on archaeology and ancient texts. His thesis centered on the lack of compelling evidence that the patriarchs lived in the 2nd millennium BCE, and noted how certain biblical texts reflected first millennium conditions and concerns. Van Seters examined the patriarchal stories and argued that their names, social milieu, and messages strongly suggested that they were Iron Age creations. Van Seters' and Thompson's works were a paradigm shift in biblical scholarship and archaeology, which gradually led scholars to no longer consider the patriarchal narratives as historical. Some conservative scholars attempted to defend the Patriarchal narratives in the following years, but this has not found acceptance among scholars. By the beginning of the 21st century, archaeologists had stopped trying to recover any context that would make Abraham, Isaac or Jacob credible historical figures. Abraham's story, like those of the other patriarchs, most likely had a substantial oral prehistory (he is mentioned in the Book of Ezekiel and the Book of Isaiah). As with Moses, Abraham's name is apparently very ancient, as the tradition found in the Book of Genesis no longer understands its original meaning, which is likely "father is exalted" – the meaning offered in Genesis 17:5, "Father of a multitude", is a folk etymology. At some stage the oral traditions became part of the written tradition of the Pentateuch; a majority of scholars believe this stage belongs to the Persian period, roughly 520–320 BCE. The mechanisms by which this came about remain unknown, but there are currently at least two hypotheses. The first, called Persian Imperial authorisation, is that the post-Exilic community devised the Torah as a legal basis on which to function within the Persian Imperial system; the second is that the Pentateuch was written to provide the criteria for determining who would belong to the post-Exilic Jewish community and to establish the power structures and relative positions of its various groups, notably the priesthood and the lay "elders". The completion of the Torah and its elevation to the centre of post-Exilic Judaism was as much or more about combining older texts as writing new ones – the final Pentateuch was based on existing traditions. In the Book of Ezekiel, written during the Exile (i.e., in the first half of the 6th century BCE), Ezekiel, an exile in Babylon, tells how those who remained in Judah are claiming ownership of the land based on inheritance from Abraham; but the prophet tells them they have no claim because they do not observe Torah. The Book of Isaiah similarly testifies of tension between the people of Judah and the returning post-Exilic Jews (the "gôlâ"), stating that God is the father of Israel and that Israel's history begins with the Exodus and not with Abraham. The conclusion to be inferred from this and similar evidence (e.g., Ezra–Nehemiah), is that the figure of Abraham must have been preeminent among the great landowners of Judah at the time of the Exile and after, serving to support their claims to the land in opposition to those of the returning exiles. According to Nissim Amzallag, the Book of Genesis portrays Abraham as having an Amorite origin, arguing that the patriarch's provenance from the region of Harran as described in Genesis 11:31 associates him with the territory of the Amorite homeland. He also notes parallels between the biblical narrative and the Amorite migration into the Southern Levant in the 2nd millennium BCE. Likewise, some scholars like Daniel E. Fleming and Alice Mandell have argued that the biblical portrayal of the Patriarchs' lifestyle appears to reflect the Amorite culture of the 2nd millennium BCE as attested in texts from the ancient city-state of Mari, suggesting that the Genesis stories retain historical memories of the ancestral origins of some of the Israelites. Alan Millard argues that the name Abram is of Amorite origin and that it is attested in Mari as ʾabī-rām. He also suggests that the Patriarch's name corresponds to a form typical of the Middle Bronze Age and not of later periods. Some papers identify Abraham with the Amorite chieftain Abum, and his son Ishmael with Sumulael. The earliest possible reference to Abraham may be the name of a town in the Negev listed in the Bubastite Portal inscription of Pharaoh Sheshonq I (biblical Shishak), which is referred as "the Fortress of Abraham" (i-bi-ra-ma), suggesting the possible existence of an Abraham tradition in the 10th century BCE. The orientalist Mario Liverani has proposed to see in the name Abraham the eponymous ancestor of a 13th-century BCE tribe, the Raham, mentioned in a stele of Seti I found at Beth-Shean and dating back to around 1289 BCE. The tribe probably lived in the area surrounding or close to Beth-Shean, in Galilee (the stele in fact refers to battles that took place in the area). Liverani hypothesized that the members of the tribe of Raham called themselves "sons of Raham" (*Banu-Raham), so that the name of their eponymous ancestor would have been "father of Raham" (*Abu-Raham), that being the name of the patriarch Abraham. Israel Finkelstein and Thomas Römer suggested that the oldest Abraham traditions originated in the Iron Age (monarchic period) and that they contained an autochthonous hero story, as the oldest biblical references to Abraham outside the book of Genesis (Ezekiel 33 and Isaiah 51) do not have an indication of a Mesopotamian origin of Abraham and present only two main themes of the Abraham narrative in Genesis—land and offspring. Finkelstein and Römer considered Abraham as ancestor who was worshiped in Hebron, with the oldest tradition of him possibly being about the altar he built in Hebron. Religious traditions Abraham is given a high position of respect in three major world faiths, Judaism, Christianity, and Islam. In Judaism, he is the founding father of the covenant, the special relationship between the Jewish people and God—leading to the belief that the Jews are the chosen people of God. In Christianity, Paul the Apostle taught that Abraham's faith in God—preceding the Mosaic law—made him the prototype of all believers, Jewish or gentile; and in Islam, he is seen as a link in the chain of prophets that begins with Adam and culminates in Muhammad. In Jewish tradition, Abraham is called Avraham Avinu (אברהם אבינו), "our father Abraham", signifying that he is both the biological progenitor of the Jews and the father of Judaism, the first Jew. His story is read in the weekly Torah reading portions, predominantly in the parashot: Lech-Lecha (לֶךְ-לְךָ), Vayeira (וַיֵּרָא), Chayei Sarah (חַיֵּי שָׂרָה), and Toledot (תּוֹלְדֹת). Hanan bar Rava taught in Abba Arikha's name that Abraham's mother was named ʾĂmatlaʾy bat Karnebo.[d] Hiyya bar Abba taught that Abraham worked in Teraḥ's idol shop in his youth. In Legends of the Jews, God created heaven and earth for the sake of the merits of Abraham. After the biblical flood, Abraham was the only one among the pious who solemnly swore never to forsake God, studied in the house of Noah and Shem to learn about the "Ways of God", and continued the line of High Priest from Noah and Shem, assigning the office to Levi and his seed forever. Before leaving his father's land, Abraham was miraculously saved from the fiery furnace of Nimrod following his brave action of breaking the idols of the Chaldeans into pieces. During his sojourning in Canaan, Abraham was accustomed to extend hospitality to travelers and strangers and taught how to praise God also knowledge of God to those who had received his kindness. Along with Isaac and Jacob, he is the one whose name would appear united with God, as God in Judaism is called Elohei Avraham, Elohei Yitzchak, vEilohei Ya'akov ("God of Abraham, God of Isaac, and God of Jacob"). He was also mentioned as the father of thirty nations. In Mandaeism, Abraham (Classical Mandaic: ࡀࡁࡓࡀࡄࡉࡌ, romanized: Abrahim) is mentioned in Book 18 of the Right Ginza as the patriarch of the Jewish people. Mandaeans consider Abraham to have been originally a Mandaean priest, however they differ with Abraham and Jews regarding circumcision which they consider to be bodily mutilation and therefore forbidden.: 18, 185 In Christianity, Abraham is revered as the prophet to whom God chose to reveal himself and with whom God initiated a covenant (cf. Covenant Theology). Paul the Apostle declared that all who believe in Jesus (Christians) are "included in the seed of Abraham and are inheritors of the promise made to Abraham." In Romans 4, Abraham is praised for his "unwavering faith" in God, which is tied into the concept of partakers of the covenant of grace being those "who demonstrate faith in the saving power of Christ". Throughout history, church leaders, following Paul, have emphasized Abraham as the spiritual father of all Christians. Augustine of Hippo declared that Christians are "children (or "seed") of Abraham by faith", Ambrose stated that "by means of their faith Christians possess the promises made to Abraham", and Martin Luther recalled Abraham as "a paradigm of the man of faith."[e] The Roman Catholic Church, the largest Christian denomination, calls Abraham "our father in Faith" in the Eucharistic prayer of the Roman Canon, recited during the Mass. He is also commemorated in the calendars of saints of several denominations: on 20 August by the Maronite Church, 28 August in the Coptic Church and the Assyrian Church of the East (with the full office for the latter), and on 9 October by the Roman Catholic Church and the Lutheran Church–Missouri Synod. In the introduction to his 15th-century translation of the Golden Legend's account of Abraham, William Caxton noted that this patriarch's life was read in church on Quinquagesima Sunday. He is the patron saint of those in the hospitality industry. The Eastern Orthodox Church commemorates him as the "Righteous Forefather Abraham", with two feast days in its liturgical calendar. The first time is on 9 October (for those churches which follow the traditional Julian Calendar, 9 October falls on 22 October of the modern Gregorian Calendar), where he is commemorated together with his nephew "Righteous Lot". The other is on the "Sunday of the Forefathers" (two Sundays before Christmas), when he is commemorated together with other ancestors of Jesus. Abraham is also mentioned in the Divine Liturgy of Basil the Great, just before the Anaphora, and Abraham and Sarah are invoked in the prayers said by the priest over a newly married couple. A popular hymn sung in many English-speaking Sunday Schools by children is known as "Father Abraham" and emphasizes the patriarch as the spiritual progenitor of Christians. Islam regards ʾIbrāhīm (Abraham) as a link in the chain of prophets that begins with Adam and culminates in Muhammad via ʾIsmāʿīl (Ishmael). Abraham is mentioned in 35 chapters of the Quran, more often than any other biblical personage apart from Moses. He is called both a hanif (monotheist) and muslim (one who submits), and Muslims regard him as a prophet and patriarch, the archetype of the perfect Muslim, and the revered reformer of the Kaaba in Mecca. Islamic tradition considers Abraham the first "pioneer of Islam" (which is also called millat ʾIbrāhīm, the 'religion of Abraham'), and that his purpose and mission throughout his life was to proclaim the oneness of God. In Islam, Abraham holds an exalted position among the major prophets and he is referred to as Khalīlullāh, meaning 'Friend of God'. Besides Ishaq and Yaqub (Isaac and Jacob), Abraham is among the most excellent and honorable men in the view of God. He is also mentioned in Quran as the "Father of Muslims", and is put forward as a role model for the community. The Druze regard Abraham as the third spokesman (natiq) after Adam and Noah, who helped transmit the foundational teachings of monotheism (tawhid) intended for the larger audience. He is also among the seven prophets who appeared in different periods of history according to the Druze faith. Baháʼís considered Abraham as a Manifestation of God, and as the originator of monotheistic religion. ʻAbdu'l-Bahá states that Abraham was born in Mesopotamia, and Bahá'u'lláh states that the language which Abraham spoke, when "he crossed the Jordan", is Hebrew ('Ibrání), so "the language of the crossing." To ʻAbdu'l-Bahá, the Abraham was born to a family that was ignorant of the oneness of God. Abraham opposed his own people and government, and even his own kin, he rejected all their gods, and, alone and single-handed, he withstood a powerful nation. These people believed not in one God but in many gods, to whom they ascribed miracles, and hence they all rose up against Abraham. No one supported him except his nephew Lot and "one or two other individuals of no consequence". At last the intensity of his enemies' opposition obliged him, utterly wronged, to forsake his native land. Abraham then came to "these regions", that is, to the Holy Land. To Bahá'u'lláh, the "Voice of God" commanded Abraham to offer up Ishmael as a sacrifice, so that his steadfastness in the faith of God and his detachment from all else but him may be demonstrated unto men. The purpose of God, moreover, was to sacrifice him as a ransom for the sins and iniquities of all the peoples of the earth. In the Baháʼí texts, like the Islamic texts, Abraham is often referred to as "the Friend of God". 'Abdu'l-Bahá described Abraham as the founder of monotheism. ʻAbdu'l-Bahá also suggested the "holy manifestations who have been the sources or founders of the various religious systems" were united and agreed in purpose and teaching, and the Abraham, Moses, Zoroaster, the Buddha, Jesus, Muhammad, the Báb and Bahá'u'lláh are one in "spirit and reality". Artistic depictions Paintings on the life of Abraham tend to focus on only a few incidents: the sacrifice of Isaac; meeting Melchizedek; entertaining the three angels; Hagar in the desert; and a few others.[f] Additionally, Martin O'Kane, a professor of Biblical Studies, writes that the parable of Lazarus resting in the "Bosom of Abraham", as described in the Gospel of Luke, became an iconic image in Christian works. According to O'Kane, artists often chose to divert from the common literary portrayal of Lazarus sitting next to Abraham at a banquet in Heaven and instead focus on the "somewhat incongruous notion of Abraham, the most venerated of patriarchs, holding a naked and vulnerable child in his bosom". Several artists have been inspired by the life of Abraham, including Albrecht Dürer (1471–1528), Caravaggio (1573–1610), Donatello, Raphael, Philip van Dyck (Dutch painter, 1680–1753), and Claude Lorrain (French painter, 1600–1682). Rembrandt (Dutch, 1606–1669) created at least seven works on Abraham, Peter Paul Rubens (1577–1640) did several, Marc Chagall did at least five on Abraham, Gustave Doré (French illustrator, 1832–1883) did six, and James Tissot (French painter and illustrator, 1836–1902) did over twenty works on the subject.[f] The Sarcophagus of Junius Bassus depicts a set of biblical stories, including Abraham about to sacrifice Isaac. These sculpted scenes are on the outside of a marble Early Christian sarcophagus used for the burial of Junius Bassus. He died in 359. This sarcophagus has been described as "probably the single most famous piece of early Christian relief sculpture." The sarcophagus was originally placed in or under Old St. Peter's Basilica, was rediscovered in 1597, and is now below the modern basilica in the Museo Storico del Tesoro della Basilica di San Pietro (Museum of St. Peter's Basilica) in the Vatican. The base is approximately 4 ft × 8 ft × 4 ft (1.2 m × 2.4 m × 1.2 m). George Segal created figural sculptures by molding plastered gauze strips over live models in his 1987 work Abraham's Farewell to Ishmael. The human condition was central to his concerns, and Segal used the Old Testament as a source for his imagery. This sculpture depicts the dilemma faced by Abraham when Sarah demanded that he expel Hagar and Ishmael. In the sculpture, the father's tenderness, Sarah's rage, and Hagar's resigned acceptance portray a range of human emotions. The sculpture was donated to the Miami Art Museum after the artist's death in 2000. Abraham can sometimes be identified by the context of the image – the meeting with Melchizedek, the three visitors, or the sacrifice of Isaac. In solo portraits a sword or knife may be used as his accessory, as in this statue by Giovanni Maria Morlaiter or this painting by Lorenzo Monaco. As early as the beginning of the 3rd century, Christian art followed Christian typology in making the sacrifice of Isaac a foreshadowing of Christ's sacrifice on the cross, and its memorial in the sacrifice of the Mass. See for example this 11th-century Christian altar engraved with Abraham's and other sacrifices taken to prefigure that of Christ in the Eucharist. Some early Christian writers interpreted the three visitors as the triune God. Thus in Santa Maria Maggiore, Rome, a 5th-century mosaic portrays only the visitors against a gold ground and puts semitransparent copies of them in the "heavenly" space above the scene. In Eastern Orthodox art, the visit is the chief means by which the Trinity is pictured (example). Some images do not include Abraham and Sarah, like Andrei Rublev's Trinity, which shows only the three visitors as beardless youths at a table. Fear and Trembling (original Danish title: Frygt og Bæven) is an influential philosophical work by Søren Kierkegaard, published in 1843 under the pseudonym Johannes de silentio (John the Silent). Kierkegaard wanted to understand the anxiety that must have been present in Abraham when God asked him to sacrifice his son. W. G. Hardy's novel Father Abraham (1935) tells the fictionalized life story of Abraham. In her short story collection Sarah and After, Lynne Reid Banks tells the story of Abraham and Sarah, with an emphasis on Sarah's view of events. In 1681, Marc-Antoine Charpentier released a Dramatic motet (Oratorio), Sacrificim Abrahae H.402 – 402 a – 402 b, for soloists, chorus, doubling instruments and continuo. Sébastien de Brossard composed a cantata Abraham ou le sacrifice d'Isaac between 1703 and 1708. In 1994, Steve Reich released an opera named The Cave. The title refers to the Cave of the Patriarchs. The narrative of the opera is based on the story of Abraham, and his immediate family, as it is recounted in religious texts, and understood by individuals from different cultures and religious traditions. The eponymous track on Bob Dylan's 1965 album Highway 61 Revisited contains five stanzas, with someone in each describing an unusual problem that is ultimately resolved on Highway 61. In the first stanza, God tells Abraham to "kill me a son". God wants the killing done on Highway 61. Abram, the birth name of Abraham, is also the name of Dylan's father. In 2004, Rolling Stone magazine ranked "Highway 61 Revisited" at number 364 in their 500 Greatest Songs of All Time. See also Footnotes References Bibliography External links |
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Contents OpenAI OpenAI is an American artificial intelligence research organization comprising both a non-profit foundation and a controlled for-profit public benefit corporation (PBC), headquartered in San Francisco. It aims to develop "safe and beneficial" artificial general intelligence (AGI), which it defines as "highly autonomous systems that outperform humans at most economically valuable work". OpenAI is widely recognized for its development of the GPT family of large language models, the DALL-E series of text-to-image models, and the Sora series of text-to-video models, which have influenced industry research and commercial applications. Its release of ChatGPT in November 2022 has been credited with catalyzing widespread interest in generative AI. The organization was founded in 2015 in Delaware but evolved a complex corporate structure. As of October 2025, following restructuring approved by California and Delaware regulators, the non-profit OpenAI Foundation holds 26% of the for-profit OpenAI Group PBC, with Microsoft holding 27% and employees/other investors holding 47%. Under its governance arrangements, the OpenAI Foundation holds the authority to appoint the board of the for-profit OpenAI Group PBC, a mechanism designed to align the entity’s strategic direction with the Foundation’s charter. Microsoft previously invested over $13 billion into OpenAI, and provides Azure cloud computing resources. In October 2025, OpenAI conducted a $6.6 billion share sale that valued the company at $500 billion. In 2023 and 2024, OpenAI faced multiple lawsuits for alleged copyright infringement against authors and media companies whose work was used to train some of OpenAI's products. In November 2023, OpenAI's board removed Sam Altman as CEO, citing a lack of confidence in him, but reinstated him five days later following a reconstruction of the board. Throughout 2024, roughly half of then-employed AI safety researchers left OpenAI, citing the company's prominent role in an industry-wide problem. Founding In December 2015, OpenAI was founded as a not for profit organization by Sam Altman, Elon Musk, Ilya Sutskever, Greg Brockman, Trevor Blackwell, Vicki Cheung, Andrej Karpathy, Durk Kingma, John Schulman, Pamela Vagata, and Wojciech Zaremba, with Sam Altman and Elon Musk as the co-chairs. A total of $1 billion in capital was pledged by Sam Altman, Greg Brockman, Elon Musk, Reid Hoffman, Jessica Livingston, Peter Thiel, Amazon Web Services (AWS), and Infosys. However, the actual capital collected significantly lagged pledges. According to company disclosures, only $130 million had been received by 2019. In its founding charter, OpenAI stated an intention to collaborate openly with other institutions by making certain patents and research publicly available, but later restricted access to its most capable models, citing competitive and safety concerns. OpenAI was initially run from Brockman's living room. It was later headquartered at the Pioneer Building in the Mission District, San Francisco. According to OpenAI's charter, its founding mission is "to ensure that artificial general intelligence (AGI)—by which we mean highly autonomous systems that outperform humans at most economically valuable work—benefits all of humanity." Musk and Altman stated in 2015 that they were partly motivated by concerns about AI safety and existential risk from artificial general intelligence. OpenAI stated that "it's hard to fathom how much human-level AI could benefit society", and that it is equally difficult to comprehend "how much it could damage society if built or used incorrectly". The startup also wrote that AI "should be an extension of individual human wills and, in the spirit of liberty, as broadly and evenly distributed as possible", and that "because of AI's surprising history, it's hard to predict when human-level AI might come within reach. When it does, it'll be important to have a leading research institution which can prioritize a good outcome for all over its own self-interest." Co-chair Sam Altman expected a decades-long project that eventually surpasses human intelligence. Brockman met with Yoshua Bengio, one of the "founding fathers" of deep learning, and drew up a list of great AI researchers. Brockman was able to hire nine of them as the first employees in December 2015. OpenAI did not pay AI researchers salaries comparable to those of Facebook or Google. It also did not pay stock options which AI researchers typically get. Nevertheless, OpenAI spent $7 million on its first 52 employees in 2016. OpenAI's potential and mission drew these researchers to the firm; a Google employee said he was willing to leave Google for OpenAI "partly because of the very strong group of people and, to a very large extent, because of its mission." OpenAI co-founder Wojciech Zaremba stated that he turned down "borderline crazy" offers of two to three times his market value to join OpenAI instead. In April 2016, OpenAI released a public beta of "OpenAI Gym", its platform for reinforcement learning research. Nvidia gifted its first DGX-1 supercomputer to OpenAI in August 2016 to help it train larger and more complex AI models with the capability of reducing processing time from six days to two hours. In December 2016, OpenAI released "Universe", a software platform for measuring and training an AI's general intelligence across the world's supply of games, websites, and other applications. Corporate structure In 2019, OpenAI transitioned from non-profit to "capped" for-profit, with the profit being capped at 100 times any investment. According to OpenAI, the capped-profit model allows OpenAI Global, LLC to legally attract investment from venture funds and, in addition, to grant employees stakes in the company. Many top researchers work for Google Brain, DeepMind, or Facebook, which offer equity that a nonprofit would be unable to match. Before the transition, OpenAI was legally required to publicly disclose the compensation of its top employees. The company then distributed equity to its employees and partnered with Microsoft, announcing an investment package of $1 billion into the company. Since then, OpenAI systems have run on an Azure-based supercomputing platform from Microsoft. OpenAI Global, LLC then announced its intention to commercially license its technologies. It planned to spend $1 billion "within five years, and possibly much faster". Altman stated that even a billion dollars may turn out to be insufficient, and that the lab may ultimately need "more capital than any non-profit has ever raised" to achieve artificial general intelligence. The nonprofit, OpenAI, Inc., is the sole controlling shareholder of OpenAI Global, LLC, which, despite being a for-profit company, retains a formal fiduciary responsibility to OpenAI, Inc.'s nonprofit charter. A majority of OpenAI, Inc.'s board is barred from having financial stakes in OpenAI Global, LLC. In addition, minority members with a stake in OpenAI Global, LLC are barred from certain votes due to conflict of interest. Some researchers have argued that OpenAI Global, LLC's switch to for-profit status is inconsistent with OpenAI's claims to be "democratizing" AI. On February 29, 2024, Elon Musk filed a lawsuit against OpenAI and CEO Sam Altman, accusing them of shifting focus from public benefit to profit maximization—a case OpenAI dismissed as "incoherent" and "frivolous," though Musk later revived legal action against Altman and others in August. On April 9, 2024, OpenAI countersued Musk in federal court, alleging that he had engaged in "bad-faith tactics" to slow the company's progress and seize its innovations for his personal benefit. OpenAI also argued that Musk had previously supported the creation of a for-profit structure and had expressed interest in controlling OpenAI himself. The countersuit seeks damages and legal measures to prevent further alleged interference. On February 10, 2025, a consortium of investors led by Elon Musk submitted a $97.4 billion unsolicited bid to buy the nonprofit that controls OpenAI, declaring willingness to match or exceed any better offer. The offer was rejected on 14 February 2025, with OpenAI stating that it was not for sale, but the offer complicated Altman's restructuring plan by suggesting a lower bar for how much the nonprofit should be valued. OpenAI, Inc. was originally designed as a nonprofit in order to ensure that AGI "benefits all of humanity" rather than "the private gain of any person". In 2019, it created OpenAI Global, LLC, a capped-profit subsidiary controlled by the nonprofit. In December 2024, OpenAI proposed a restructuring plan to convert the capped-profit into a Delaware-based public benefit corporation (PBC), and to release it from the control of the nonprofit. The nonprofit would sell its control and other assets, getting equity in return, and would use it to fund and pursue separate charitable projects, including in science and education. OpenAI's leadership described the change as necessary to secure additional investments, and claimed that the nonprofit's founding mission to ensure AGI "benefits all of humanity" would be better fulfilled. The plan has been criticized by former employees. A legal letter named "Not For Private Gain" asked the attorneys general of California and Delaware to intervene, stating that the restructuring is illegal and would remove governance safeguards from the nonprofit and the attorneys general. The letter argues that OpenAI's complex structure was deliberately designed to remain accountable to its mission, without the conflicting pressure of maximizing profits. It contends that the nonprofit is best positioned to advance its mission of ensuring AGI benefits all of humanity by continuing to control OpenAI Global, LLC, whatever the amount of equity that it could get in exchange. PBCs can choose how they balance their mission with profit-making. Controlling shareholders have a large influence on how closely a PBC sticks to its mission. On October 28, 2025, OpenAI announced that it had adopted the new PBC corporate structure after receiving approval from the attorneys general of California and Delaware. Under the new structure, OpenAI's for-profit branch became a public benefit corporation known as OpenAI Group PBC, while the non-profit was renamed to the OpenAI Foundation. The OpenAI Foundation holds a 26% stake in the PBC, while Microsoft holds a 27% stake and the remaining 47% is owned by employees and other investors. All members of the OpenAI Group PBC board of directors will be appointed by the OpenAI Foundation, which can remove them at any time. Members of the Foundation's board will also serve on the for-profit board. The new structure allows the for-profit PBC to raise investor funds like most traditional tech companies, including through an initial public offering, which Altman claimed was the most likely path forward. In January 2023, OpenAI Global, LLC was in talks for funding that would value the company at $29 billion, double its 2021 value. On January 23, 2023, Microsoft announced a new US$10 billion investment in OpenAI Global, LLC over multiple years, partially needed to use Microsoft's cloud-computing service Azure. From September to December, 2023, Microsoft rebranded all variants of its Copilot to Microsoft Copilot, and they added MS-Copilot to many installations of Windows and released Microsoft Copilot mobile apps. Following OpenAI's 2025 restructuring, Microsoft owns a 27% stake in the for-profit OpenAI Group PBC, valued at $135 billion. In a deal announced the same day, OpenAI agreed to purchase $250 billion of Azure services, with Microsoft ceding their right of first refusal over OpenAI's future cloud computing purchases. As part of the deal, OpenAI will continue to share 20% of its revenue with Microsoft until it achieves AGI, which must now be verified by an independent panel of experts. The deal also loosened restrictions on both companies working with third parties, allowing Microsoft to pursue AGI independently and allowing OpenAI to develop products with other companies. In 2017, OpenAI spent $7.9 million, a quarter of its functional expenses, on cloud computing alone. In comparison, DeepMind's total expenses in 2017 were $442 million. In the summer of 2018, training OpenAI's Dota 2 bots required renting 128,000 CPUs and 256 GPUs from Google for multiple weeks. In October 2024, OpenAI completed a $6.6 billion capital raise with a $157 billion valuation including investments from Microsoft, Nvidia, and SoftBank. On January 21, 2025, Donald Trump announced The Stargate Project, a joint venture between OpenAI, Oracle, SoftBank and MGX to build an AI infrastructure system in conjunction with the US government. The project takes its name from OpenAI's existing "Stargate" supercomputer project and is estimated to cost $500 billion. The partners planned to fund the project over the next four years. In July, the United States Department of Defense announced that OpenAI had received a $200 million contract for AI in the military, along with Anthropic, Google, and xAI. In the same month, the company made a deal with the UK Government to use ChatGPT and other AI tools in public services. OpenAI subsequently began a $50 million fund to support nonprofit and community organizations. In April 2025, OpenAI raised $40 billion at a $300 billion post-money valuation, which was the highest-value private technology deal in history. The financing round was led by SoftBank, with other participants including Microsoft, Coatue, Altimeter and Thrive. In July 2025, the company reported annualized revenue of $12 billion. This was an increase from $3.7 billion in 2024, which was driven by ChatGPT subscriptions, which reached 20 million paid subscribers by April 2025, up from 15.5 million at the end of 2024, alongside a rapidly expanding enterprise customer base that grew to five million business users. The company’s cash burn remains high because of the intensive computational costs required to train and operate large language models. It projects an $8 billion operating loss in 2025. OpenAI reports revised long-term spending projections totaling approximately $115 billion through 2029, with annual expenditures projected to escalate significantly, reaching $17 billion in 2026, $35 billion in 2027, and $45 billion in 2028. These expenditures are primarily allocated toward expanding compute infrastructure, developing proprietary AI chips, constructing data centers, and funding intensive model training programs, with more than half of the spending through the end of the decade expected to support research-intensive compute for model training and development. The company's financial strategy prioritizes market expansion and technological advancement over near-term profitability, with OpenAI targeting cash-flow-positive operations by 2029 and projecting revenue of approximately $200 billion by 2030. This aggressive spending trajectory underscores both the enormous capital requirements of scaling cutting-edge AI technology and OpenAI's commitment to maintaining its position as a leader in the artificial intelligence industry. In October 2025, OpenAI completed an employee share sale of up to $10 billion to existing investors which valued the company at $500 billion. The deal values OpenAI as the most valuable privately owned company in the world—surpassing SpaceX as the world's most valuable private company. On November 17, 2023, Sam Altman was removed as CEO when its board of directors (composed of Helen Toner, Ilya Sutskever, Adam D'Angelo and Tasha McCauley) cited a lack of confidence in him. Chief Technology Officer Mira Murati took over as interim CEO. Greg Brockman, the president of OpenAI, was also removed as chairman of the board and resigned from the company's presidency shortly thereafter. Three senior OpenAI researchers subsequently resigned: director of research and GPT-4 lead Jakub Pachocki, head of AI risk Aleksander Mądry, and researcher Szymon Sidor. On November 18, 2023, there were reportedly talks of Altman returning as CEO amid pressure placed upon the board by investors such as Microsoft and Thrive Capital, who objected to Altman's departure. Although Altman himself spoke in favor of returning to OpenAI, he has since stated that he considered starting a new company and bringing former OpenAI employees with him if talks to reinstate him didn't work out. The board members agreed "in principle" to resign if Altman returned. On November 19, 2023, negotiations with Altman to return failed and Murati was replaced by Emmett Shear as interim CEO. The board initially contacted Anthropic CEO Dario Amodei (a former OpenAI executive) about replacing Altman, and proposed a merger of the two companies, but both offers were declined. On November 20, 2023, Microsoft CEO Satya Nadella announced Altman and Brockman would be joining Microsoft to lead a new advanced AI research team, but added that they were still committed to OpenAI despite recent events. Before the partnership with Microsoft was finalized, Altman gave the board another opportunity to negotiate with him. About 738 of OpenAI's 770 employees, including Murati and Sutskever, signed an open letter stating they would quit their jobs and join Microsoft if the board did not rehire Altman and then resign. This prompted OpenAI investors to consider legal action against the board as well. In response, OpenAI management sent an internal memo to employees stating that negotiations with Altman and the board had resumed and would take some time. On November 21, 2023, after continued negotiations, Altman and Brockman returned to the company in their prior roles along with a reconstructed board made up of new members Bret Taylor (as chairman) and Lawrence Summers, with D'Angelo remaining. According to subsequent reporting, shortly before Altman’s firing, some employees raised concerns to the board about how he had handled the safety implications of a recent internal AI capability discovery. On November 29, 2023, OpenAI announced that an anonymous Microsoft employee had joined the board as a non-voting member to observe the company's operations; Microsoft resigned from the board in July 2024. In February 2024, the Securities and Exchange Commission subpoenaed OpenAI's internal communication to determine if Altman's alleged lack of candor misled investors. In 2024, following the temporary removal of Sam Altman and his return, many employees gradually left OpenAI, including most of the original leadership team and a significant number of AI safety researchers. In August 2023, it was announced that OpenAI had acquired the New York-based start-up Global Illumination, a company that deploys AI to develop digital infrastructure and creative tools. In June 2024, OpenAI acquired Multi, a startup focused on remote collaboration. In March 2025, OpenAI reached a deal with CoreWeave to acquire $350 million worth of CoreWeave shares and access to AI infrastructure, in return for $11.9 billion paid over five years. Microsoft was already CoreWeave's biggest customer in 2024. Alongside their other business dealings, OpenAI and Microsoft were renegotiating the terms of their partnership to facilitate a potential future initial public offering by OpenAI, while ensuring Microsoft's continued access to advanced AI models. On May 21, OpenAI announced the $6.5 billion acquisition of io, an AI hardware start-up founded by former Apple designer Jony Ive in 2024. In September 2025, OpenAI agreed to acquire the product testing startup Statsig for $1.1 billion in an all-stock deal and appointed Statsig's founding CEO Vijaye Raji as OpenAI's chief technology officer of applications. The company also announced development of an AI-driven hiring service designed to rival LinkedIn. OpenAI acquired personal finance app Roi in October 2025. In October 2025, OpenAI acquired Software Applications Incorporated, the developer of Sky, a macOS-based natural language interface designed to operate across desktop applications. The Sky team joined OpenAI, and the company announced plans to integrate Sky’s capabilities into ChatGPT. In December 2025, it was announced OpenAI had agreed to acquire Neptune, an AI tooling startup that helps companies track and manage model training, for an undisclosed amount. In January 2026, it was announced OpenAI had acquired healthcare technology startup Torch for approximately $60 million. The acquisition followed the launch of OpenAI’s ChatGPT Health product and was intended to strengthen the company’s medical data and healthcare artificial intelligence capabilities. OpenAI has been criticized for outsourcing the annotation of data sets to Sama, a company based in San Francisco that employed workers in Kenya. These annotations were used to train an AI model to detect toxicity, which could then be used to moderate toxic content, notably from ChatGPT's training data and outputs. However, these pieces of text usually contained detailed descriptions of various types of violence, including sexual violence. The investigation uncovered that OpenAI began sending snippets of data to Sama as early as November 2021. The four Sama employees interviewed by Time described themselves as mentally scarred. OpenAI paid Sama $12.50 per hour of work, and Sama was redistributing the equivalent of between $1.32 and $2.00 per hour post-tax to its annotators. Sama's spokesperson said that the $12.50 was also covering other implicit costs, among which were infrastructure expenses, quality assurance and management. In 2024, OpenAI began collaborating with Broadcom to design a custom AI chip capable of both training and inference, targeted for mass production in 2026 and to be manufactured by TSMC on a 3 nm process node. This initiative intended to reduce OpenAI's dependence on Nvidia GPUs, which are costly and face high demand in the market. In January 2024, Arizona State University purchased ChatGPT Enterprise in OpenAI's first deal with a university. In June 2024, Apple Inc. signed a contract with OpenAI to integrate ChatGPT features into its products as part of its new Apple Intelligence initiative. In June 2025, OpenAI began renting Google Cloud's Tensor Processing Units (TPUs) to support ChatGPT and related services, marking its first meaningful use of non‑Nvidia AI chips. In September 2025, it was revealed that OpenAI signed a contract with Oracle to purchase $300 billion in computing power over the next five years. In September 2025, OpenAI and NVIDIA announced a memorandum of understanding that included a potential deployment of at least 10 gigawatts of NVIDIA systems and a $100 billion investment from NVIDIA in OpenAI. OpenAI expected the negotiations to be completed within weeks. As of January 2026, this has not been realized, and the two sides are rethinking the future of their partnership. In October 2025, OpenAI announced a multi-billion dollar deal with AMD. OpenAI committed to purchasing six gigawatts worth of AMD chips, starting with the MI450. OpenAI will have the option to buy up to 160 million shares of AMD, about 10% of the company, depending on development, performance and share price targets. In December 2025, Disney said it would make a $1 billion investment in OpenAI, and signed a three-year licensing deal that will let users generate videos using Sora—OpenAI's short-form AI video platform. More than 200 Disney, Marvel, Star Wars and Pixar characters will be available to OpenAI users. In early 2026, Amazon entered advanced discussions to invest up to $50 billion in OpenAI as part of a potential artificial intelligence partnership. Under the proposed agreement, OpenAI’s models could be integrated into Amazon’s digital assistant Alexa and other internal projects. OpenAI provides LLMs to the Artificial Intelligence Cyber Challenge and to the Advanced Research Projects Agency for Health. In October 2024, The Intercept revealed that OpenAI's tools are considered "essential" for AFRICOM's mission and included in an "Exception to Fair Opportunity" contractual agreement between the United States Department of Defense and Microsoft. In December 2024, OpenAI said it would partner with defense-tech company Anduril to build drone defense technologies for the United States and its allies. In 2025, OpenAI's Chief Product Officer, Kevin Weil, was commissioned lieutenant colonel in the U.S. Army to join Detachment 201 as senior advisor. In June 2025, the U.S. Department of Defense awarded OpenAI a $200 million one-year contract to develop AI tools for military and national security applications. OpenAI announced a new program, OpenAI for Government, to give federal, state, and local governments access to its models, including ChatGPT. Services In February 2019, GPT-2 was announced, which gained attention for its ability to generate human-like text. In 2020, OpenAI announced GPT-3, a language model trained on large internet datasets. GPT-3 is aimed at natural language answering questions, but it can also translate between languages and coherently generate improvised text. It also announced that an associated API, named the API, would form the heart of its first commercial product. Eleven employees left OpenAI, mostly between December 2020 and January 2021, in order to establish Anthropic. In 2021, OpenAI introduced DALL-E, a specialized deep learning model adept at generating complex digital images from textual descriptions, utilizing a variant of the GPT-3 architecture. In December 2022, OpenAI received widespread media coverage after launching a free preview of ChatGPT, its new AI chatbot based on GPT-3.5. According to OpenAI, the preview received over a million signups within the first five days. According to anonymous sources cited by Reuters in December 2022, OpenAI Global, LLC was projecting $200 million of revenue in 2023 and $1 billion in revenue in 2024. After ChatGPT was launched, Google announced a similar chatbot, Bard, amid internal concerns that ChatGPT could threaten Google’s position as a primary source of online information. On February 7, 2023, Microsoft announced that it was building AI technology based on the same foundation as ChatGPT into Microsoft Bing, Edge, Microsoft 365 and other products. On March 14, 2023, OpenAI released GPT-4, both as an API (with a waitlist) and as a feature of ChatGPT Plus. On November 6, 2023, OpenAI launched GPTs, allowing individuals to create customized versions of ChatGPT for specific purposes, further expanding the possibilities of AI applications across various industries. On November 14, 2023, OpenAI announced they temporarily suspended new sign-ups for ChatGPT Plus due to high demand. Access for newer subscribers re-opened a month later on December 13. In December 2024, the company launched the Sora model. It also launched OpenAI o1, an early reasoning model that was internally codenamed strawberry. Additionally, ChatGPT Pro—a $200/month subscription service offering unlimited o1 access and enhanced voice features—was introduced, and preliminary benchmark results for the upcoming OpenAI o3 models were shared. On January 23, 2025, OpenAI released Operator, an AI agent and web automation tool for accessing websites to execute goals defined by users. The feature was only available to Pro users in the United States. OpenAI released deep research agent, nine days later. It scored a 27% accuracy on the benchmark Humanity's Last Exam (HLE). Altman later stated GPT-4.5 would be the last model without full chain-of-thought reasoning. In July 2025, reports indicated that AI models by both OpenAI and Google DeepMind solved mathematics problems at the level of top-performing students in the International Mathematical Olympiad. OpenAI's large language model was able to achieve gold medal-level performance, reflecting significant progress in AI's reasoning abilities. On October 6, 2025, OpenAI unveiled its Agent Builder platform during the company's DevDay event. The platform includes a visual drag-and-drop interface that lets developers and businesses design, test, and deploy agentic workflows with limited coding. On October 21, 2025, OpenAI introduced ChatGPT Atlas, a browser integrating the ChatGPT assistant directly into web navigation, to compete with existing browsers such as Google Chrome and Apple Safari. On December 11, 2025, OpenAI announced GPT-5.2. This model will be better at creating spreadsheets, building presentations, perceiving images, writing code and understanding long context. On January 27, 2026, OpenAI introduced Prism, a LaTeX-native workspace meant to assist scientists to help with research and writing. The platform utilizes GPT-5.2 as a backend to automate the process of drafting for scientific papers, including features for managing citations, complex equation formatting, and real-time collaborative editing. In March 2023, the company was criticized for disclosing particularly few technical details about products like GPT-4, contradicting its initial commitment to openness and making it harder for independent researchers to replicate its work and develop safeguards. OpenAI cited competitiveness and safety concerns to justify this repudiation. OpenAI's former chief scientist Ilya Sutskever argued in 2023 that open-sourcing increasingly capable models was increasingly risky, and that the safety reasons for not open-sourcing the most potent AI models would become "obvious" in a few years. In September 2025, OpenAI published a study on how people use ChatGPT for everyday tasks. The study found that "non-work tasks" (according to an LLM-based classifier) account for more than 72 percent of all ChatGPT usage, with a minority of overall usage related to business productivity. In July 2023, OpenAI launched the superalignment project, aiming within four years to determine how to align future superintelligent systems. OpenAI promised to dedicate 20% of its computing resources to the project, although the team denied receiving anything close to 20%. OpenAI ended the project in May 2024 after its co-leaders Ilya Sutskever and Jan Leike left the company. In August 2025, OpenAI was criticized after thousands of private ChatGPT conversations were inadvertently exposed to public search engines like Google due to an experimental "share with search engines" feature. The opt-in toggle, intended to allow users to make specific chats discoverable, resulted in some discussions including personal details such as names, locations, and intimate topics appearing in search results when users accidentally enabled it while sharing links. OpenAI announced the feature's permanent removal on August 1, 2025, and the company began coordinating with search providers to remove the exposed content, emphasizing that it was not a security breach but a design flaw that heightened privacy risks. CEO Sam Altman acknowledged the issue in a podcast, noting users often treat ChatGPT as a confidant for deeply personal matters, which amplified concerns about AI handling sensitive data. Management In 2018, Musk resigned from his Board of Directors seat, citing "a potential future conflict [of interest]" with his role as CEO of Tesla due to Tesla's AI development for self-driving cars. OpenAI stated that Musk's financial contributions were below $45 million. On March 3, 2023, Reid Hoffman resigned from his board seat, citing a desire to avoid conflicts of interest with his investments in AI companies via Greylock Partners, and his co-founding of the AI startup Inflection AI. Hoffman remained on the board of Microsoft, a major investor in OpenAI. In May 2024, Chief Scientist Ilya Sutskever resigned and was succeeded by Jakub Pachocki. Co-leader Jan Leike also departed amid concerns over safety and trust. OpenAI then signed deals with Reddit, News Corp, Axios, and Vox Media. Paul Nakasone then joined the board of OpenAI. In August 2024, cofounder John Schulman left OpenAI to join Anthropic, and OpenAI's president Greg Brockman took extended leave until November. In September 2024, CTO Mira Murati left the company. In November 2025, Lawrence Summers resigned from the board of directors. Governance and legal issues In May 2023, Sam Altman, Greg Brockman and Ilya Sutskever posted recommendations for the governance of superintelligence. They stated that superintelligence could happen within the next 10 years, allowing a "dramatically more prosperous future" and that "given the possibility of existential risk, we can't just be reactive". They proposed creating an international watchdog organization similar to IAEA to oversee AI systems above a certain capability threshold, suggesting that relatively weak AI systems on the other side should not be overly regulated. They also called for more technical safety research for superintelligences, and asked for more coordination, for example through governments launching a joint project which "many current efforts become part of". In July 2023, the FTC issued a civil investigative demand to OpenAI to investigate whether the company's data security and privacy practices to develop ChatGPT were unfair or harmed consumers (including by reputational harm) in violation of Section 5 of the Federal Trade Commission Act of 1914. These are typically preliminary investigative matters and are nonpublic, but the FTC's document was leaked. In July 2023, the FTC launched an investigation into OpenAI over allegations that the company scraped public data and published false and defamatory information. They asked OpenAI for comprehensive information about its technology and privacy safeguards, as well as any steps taken to prevent the recurrence of situations in which its chatbot generated false and derogatory content about people. The agency also raised concerns about ‘circular’ spending arrangements—for example, Microsoft extending Azure credits to OpenAI while both companies shared engineering talent—and warned that such structures could negatively affect the public. In September 2024, OpenAI's global affairs chief endorsed the UK's "smart" AI regulation during testimony to a House of Lords committee. In February 2025, OpenAI CEO Sam Altman stated that the company is interested in collaborating with the People's Republic of China, despite regulatory restrictions imposed by the U.S. government. This shift comes in response to the growing influence of the Chinese artificial intelligence company DeepSeek, which has disrupted the AI market with open models, including DeepSeek V3 and DeepSeek R1. Following DeepSeek's market emergence, OpenAI enhanced security protocols to protect proprietary development techniques from industrial espionage. Some industry observers noted similarities between DeepSeek's model distillation approach and OpenAI's methodology, though no formal intellectual property claim was filed. According to Oliver Roberts, in March 2025, the United States had 781 state AI bills or laws. OpenAI advocated for preempting state AI laws with federal laws. According to Scott Kohler, OpenAI has opposed California's AI legislation and suggested that the state bill encroaches on a more competent federal government. Public Citizen opposed a federal preemption on AI and pointed to OpenAI's growth and valuation as evidence that existing state laws have not hampered innovation. Before May 2024, OpenAI required departing employees to sign a lifelong non-disparagement agreement forbidding them from criticizing OpenAI and acknowledging the existence of the agreement. Daniel Kokotajlo, a former employee, publicly stated that he forfeited his vested equity in OpenAI in order to leave without signing the agreement. Sam Altman stated that he was unaware of the equity cancellation provision, and that OpenAI never enforced it to cancel any employee's vested equity. However, leaked documents and emails refute this claim. On May 23, 2024, OpenAI sent a memo releasing former employees from the agreement. OpenAI was sued for copyright infringement by authors Sarah Silverman, Matthew Butterick, Paul Tremblay and Mona Awad in July 2023. In September 2023, 17 authors, including George R. R. Martin, John Grisham, Jodi Picoult and Jonathan Franzen, joined the Authors Guild in filing a class action lawsuit against OpenAI, alleging that the company's technology was illegally using their copyrighted work. The New York Times also sued the company in late December 2023. In May 2024 it was revealed that OpenAI had destroyed its Books1 and Books2 training datasets, which were used in the training of GPT-3, and which the Authors Guild believed to have contained over 100,000 copyrighted books. In 2021, OpenAI developed a speech recognition tool called Whisper. OpenAI used it to transcribe more than one million hours of YouTube videos into text for training GPT-4. The automated transcription of YouTube videos raised concerns within OpenAI employees regarding potential violations of YouTube's terms of service, which prohibit the use of videos for applications independent of the platform, as well as any type of automated access to its videos. Despite these concerns, the project proceeded with notable involvement from OpenAI's president, Greg Brockman. The resulting dataset proved instrumental in training GPT-4. In February 2024, The Intercept as well as Raw Story and Alternate Media Inc. filed lawsuit against OpenAI on copyright litigation ground. The lawsuit is said to have charted a new legal strategy for digital-only publishers to sue OpenAI. On April 30, 2024, eight newspapers filed a lawsuit in the Southern District of New York against OpenAI and Microsoft, claiming illegal harvesting of their copyrighted articles. The suing publications included The Mercury News, The Denver Post, The Orange County Register, St. Paul Pioneer Press, Chicago Tribune, Orlando Sentinel, Sun Sentinel, and New York Daily News. In June 2023, a lawsuit claimed that OpenAI scraped 300 billion words online without consent and without registering as a data broker. It was filed in San Francisco, California, by sixteen anonymous plaintiffs. They also claimed that OpenAI and its partner as well as customer Microsoft continued to unlawfully collect and use personal data from millions of consumers worldwide to train artificial intelligence models. On May 22, 2024, OpenAI entered into an agreement with News Corp to integrate news content from The Wall Street Journal, the New York Post, The Times, and The Sunday Times into its AI platform. Meanwhile, other publications like The New York Times chose to sue OpenAI and Microsoft for copyright infringement over the use of their content to train AI models. In November 2024, a coalition of Canadian news outlets, including the Toronto Star, Metroland Media, Postmedia, The Globe and Mail, The Canadian Press and CBC, sued OpenAI for using their news articles to train its software without permission. In October 2024 during a New York Times interview, Suchir Balaji accused OpenAI of violating copyright law in developing its commercial LLMs which he had helped engineer. He was a likely witness in a major copyright trial against the AI company, and was one of several of its current or former employees named in court filings as potentially having documents relevant to the case. On November 26, 2024, Balaji died by suicide. His death prompted the circulation of conspiracy theories alleging that he had been deliberately silenced. California Congressman Ro Khanna endorsed calls for an investigation. On April 24, 2025, Ziff Davis sued OpenAI in Delaware federal court for copyright infringement. Ziff Davis is known for publications such as ZDNet, PCMag, CNET, IGN and Lifehacker. In April 2023, the EU's European Data Protection Board (EDPB) formed a dedicated task force on ChatGPT "to foster cooperation and to exchange information on possible enforcement actions conducted by data protection authorities" based on the "enforcement action undertaken by the Italian data protection authority against OpenAI about the ChatGPT service". In late April 2024 NOYB filed a complaint with the Austrian Datenschutzbehörde against OpenAI for violating the European General Data Protection Regulation. A text created with ChatGPT gave a false date of birth for a living person without giving the individual the option to see the personal data used in the process. A request to correct the mistake was denied. Additionally, neither the recipients of ChatGPT's work nor the sources used, could be made available, OpenAI claimed. OpenAI was criticized for lifting its ban on using ChatGPT for "military and warfare". Up until January 10, 2024, its "usage policies" included a ban on "activity that has high risk of physical harm, including", specifically, "weapons development" and "military and warfare". Its new policies prohibit "[using] our service to harm yourself or others" and to "develop or use weapons". In August 2025, the parents of a 16-year-old boy who died by suicide filed a wrongful death lawsuit against OpenAI (and CEO Sam Altman), alleging that months of conversations with ChatGPT about mental health and methods of self-harm contributed to their son's death and that safeguards were inadequate for minors. OpenAI expressed condolences and said it was strengthening protections (including updated crisis response behavior and parental controls). Coverage described it as a first-of-its-kind wrongful death case targeting the company's chatbot. The complaint was filed in California state court in San Francisco. In November 2025, the Social Media Victims Law Center and Tech Justice Law Project filed seven lawsuits against OpenAI, of which four lawsuits alleged wrongful death. The suits were filed on behalf of Zane Shamblin, 23, of Texas; Amaurie Lacey, 17, of Georgia; Joshua Enneking, 26, of Florida; and Joe Ceccanti, 48, of Oregon, who each committed suicide after prolonged ChatGPT usage. In December 2025, Stein-Erik Soelberg, who was 56 years old at the time, allegedly murdered his mother Suzanne Adams. In the months prior the paranoid, delusional man often discussed his ideas with ChatGPT. Adam's estate then sued OpenAI claiming that the company shared responsibility due to the risk of chatbot psychosis despite the fact that chatbot psychosis is not a real medical diagnosis. OpenAI responded saying they will make ChatGPT safer for users disconnected from reality. See also References Further reading External links |
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[SOURCE: https://en.wikipedia.org/w/index.php?title=Climate_change_in_the_Middle_East_and_North_Africa&action=edit] | [TOKENS: 1454] |
Editing Climate change in the Middle East and North Africa Copy and paste: – — ° ′ ″ ≈ ≠ ≤ ≥ ± − × ÷ ← → · § Cite your sources: <ref></ref> {{}} {{{}}} | [] [[]] [[Category:]] #REDIRECT [[]] <s></s> <sup></sup> <sub></sub> <code></code> <pre></pre> <blockquote></blockquote> <ref></ref> <ref name="" /> {{Reflist}} <references /> <includeonly></includeonly> <noinclude></noinclude> {{DEFAULTSORT:}} <nowiki></nowiki> <!-- --> <span class="plainlinks"></span> Symbols: ~ | ¡ ¿ † ‡ ↔ ↑ ↓ • ¶ # ∞ ‹› «» ¤ ₳ ฿ ₵ ¢ ₡ ₢ $ ₫ ₯ € ₠ ₣ ƒ ₴ ₭ ₤ ℳ ₥ ₦ ₧ ₰ £ ៛ ₨ ₪ ৳ ₮ ₩ ¥ ♠ ♣ ♥ ♦ 𝄫 ♭ ♮ ♯ 𝄪 © ¼ ½ ¾ Latin: A a Á á À à  â Ä ä Ǎ ǎ Ă ă Ā ā à ã Å å Ą ą Æ æ Ǣ ǣ B b C c Ć ć Ċ ċ Ĉ ĉ Č č Ç ç D d Ď ď Đ đ Ḍ ḍ Ð ð E e É é È è Ė ė Ê ê Ë ë Ě ě Ĕ ĕ Ē ē Ẽ ẽ Ę ę Ẹ ẹ Ɛ ɛ Ǝ ǝ Ə ə F f G g Ġ ġ Ĝ ĝ Ğ ğ Ģ ģ H h Ĥ ĥ Ħ ħ Ḥ ḥ I i İ ı Í í Ì ì Î î Ï ï Ǐ ǐ Ĭ ĭ Ī ī Ĩ ĩ Į į Ị ị J j Ĵ ĵ K k Ķ ķ L l Ĺ ĺ Ŀ ŀ Ľ ľ Ļ ļ Ł ł Ḷ ḷ Ḹ ḹ M m Ṃ ṃ N n Ń ń Ň ň Ñ ñ Ņ ņ Ṇ ṇ Ŋ ŋ O o Ó ó Ò ò Ô ô Ö ö Ǒ ǒ Ŏ ŏ Ō ō Õ õ Ǫ ǫ Ọ ọ Ő ő Ø ø Œ œ Ɔ ɔ P p Q q R r Ŕ ŕ Ř ř Ŗ ŗ Ṛ ṛ Ṝ ṝ S s Ś ś Ŝ ŝ Š š Ş ş Ș ș Ṣ ṣ ß T t Ť ť Ţ ţ Ț ț Ṭ ṭ Þ þ U u Ú ú Ù ù Û û Ü ü Ǔ ǔ Ŭ ŭ Ū ū Ũ ũ Ů ů Ų ų Ụ ụ Ű ű Ǘ ǘ Ǜ ǜ Ǚ ǚ Ǖ ǖ V v W w Ŵ ŵ X x Y y Ý ý Ŷ ŷ Ÿ ÿ Ỹ ỹ Ȳ ȳ Z z Ź ź Ż ż Ž ž ß Ð ð Þ þ Ŋ ŋ Ə ə Greek: Ά ά Έ έ Ή ή Ί ί Ό ό Ύ ύ Ώ ώ Α α Β β Γ γ Δ δ Ε ε Ζ ζ Η η Θ θ Ι ι Κ κ Λ λ Μ μ Ν ν Ξ ξ Ο ο Π π Ρ ρ Σ σ ς Τ τ Υ υ Φ φ Χ χ Ψ ψ Ω ω {{Polytonic|}} Cyrillic: А а Б б В в Г г Ґ ґ Ѓ ѓ Д д Ђ ђ Е е Ё ё Є є Ж ж З з Ѕ ѕ И и І і Ї ї Й й Ј ј К к Ќ ќ Л л Љ љ М м Н н Њ њ О о П п Р р С с Т т Ћ ћ У у Ў ў Ф ф Х х Ц ц Ч ч Џ џ Ш ш Щ щ Ъ ъ Ы ы Ь ь Э э Ю ю Я я ́ IPA: t̪ d̪ ʈ ɖ ɟ ɡ ɢ ʡ ʔ ɸ β θ ð ʃ ʒ ɕ ʑ ʂ ʐ ç ʝ ɣ χ ʁ ħ ʕ ʜ ʢ ɦ ɱ ɳ ɲ ŋ ɴ ʋ ɹ ɻ ɰ ʙ ⱱ ʀ ɾ ɽ ɫ ɬ ɮ ɺ ɭ ʎ ʟ ɥ ʍ ɧ ʼ ɓ ɗ ʄ ɠ ʛ ʘ ǀ ǃ ǂ ǁ ɨ ʉ ɯ ɪ ʏ ʊ ø ɘ ɵ ɤ ə ɚ ɛ œ ɜ ɝ ɞ ʌ ɔ æ ɐ ɶ ɑ ɒ ʰ ʱ ʷ ʲ ˠ ˤ ⁿ ˡ ˈ ˌ ː ˑ ̪ {{IPA|}} Wikidata entities used in this page Pages transcluded onto the current version of this page (help): This page is a member of 8 hidden categories (help): |
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[SOURCE: https://en.wikipedia.org/wiki/Weak_artificial_intelligence#cite_ref-15] | [TOKENS: 594] |
Contents Weak artificial intelligence Weak artificial intelligence (weak AI) is artificial intelligence that implements a limited part of the mind, or, as narrow AI, artificial narrow intelligence (ANI), is focused on one narrow task. Weak AI is contrasted with strong AI, which can be interpreted in various ways: Narrow AI can be classified as being "limited to a single, narrowly defined task. Most modern AI systems would be classified in this category." Artificial general intelligence is conversely the opposite. Applications and risks Some examples of narrow AI are AlphaGo, self-driving cars, robot systems used in the medical field, and diagnostic doctors. Narrow AI systems are sometimes dangerous if unreliable. And the behavior that it follows can become inconsistent. It could be difficult for the AI to grasp complex patterns and get to a solution that works reliably in various environments. This "brittleness" can cause it to fail in unpredictable ways. Narrow AI failures can sometimes have significant consequences. It could for example cause disruptions in the electric grid, damage nuclear power plants, cause global economic problems, and misdirect autonomous vehicles. Medicines could be incorrectly sorted and distributed. Also, medical diagnoses can ultimately have serious and sometimes deadly consequences if the AI is faulty or biased. Simple AI programs have already worked their way into society, oftentimes unnoticed by the public. Autocorrection for typing, speech recognition for speech-to-text programs, and vast expansions in the data science fields are examples. Narrow AI has also been the subject of some controversy, including resulting in unfair prison sentences, discrimination against women in the workplace for hiring, resulting in death via autonomous driving, among other cases. Despite being "narrow" AI, recommender systems are efficient at predicting user reactions based their posts, patterns, or trends. For instance, TikTok's "For You" algorithm can determine a user's interests or preferences in less than an hour. Some other social media AI systems are used to detect bots that may be involved in propaganda or other potentially malicious activities. Weak AI versus strong AI John Searle contests the possibility of strong AI (by which he means conscious AI). He further believes that the Turing test (created by Alan Turing and originally called the "imitation game", used to assess whether a machine can converse indistinguishably from a human) is not accurate or appropriate for testing whether an AI is "strong". Scholars such as Antonio Lieto have argued that the current research on both AI and cognitive modelling are perfectly aligned with the weak-AI hypothesis (that should not be confused with the "general" vs "narrow" AI distinction) and that the popular assumption that cognitively inspired AI systems espouse the strong AI hypothesis is ill-posed and problematic since "artificial models of brain and mind can be used to understand mental phenomena without pretending that that they are the real phenomena that they are modelling" (as, on the other hand, implied by the strong AI assumption). See also References |
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[SOURCE: https://en.wikipedia.org/wiki/Elon_Musk#cite_note-:1-251] | [TOKENS: 10515] |
Contents Elon Musk Elon Reeve Musk (/ˈiːlɒn/ EE-lon; born June 28, 1971) is a businessman and entrepreneur known for his leadership of Tesla, SpaceX, Twitter, and xAI. Musk has been the wealthiest person in the world since 2025; as of February 2026,[update] Forbes estimates his net worth to be around US$852 billion. Born into a wealthy family in Pretoria, South Africa, Musk emigrated in 1989 to Canada; he has Canadian citizenship since his mother was born there. He received bachelor's degrees in 1997 from the University of Pennsylvania before moving to California to pursue business ventures. In 1995, Musk co-founded the software company Zip2. Following its sale in 1999, he co-founded X.com, an online payment company that later merged to form PayPal, which was acquired by eBay in 2002. Musk also became an American citizen in 2002. In 2002, Musk founded the space technology company SpaceX, becoming its CEO and chief engineer; the company has since led innovations in reusable rockets and commercial spaceflight. Musk joined the automaker Tesla as an early investor in 2004 and became its CEO and product architect in 2008; it has since become a leader in electric vehicles. In 2015, he co-founded OpenAI to advance artificial intelligence (AI) research, but later left; growing discontent with the organization's direction and their leadership in the AI boom in the 2020s led him to establish xAI, which became a subsidiary of SpaceX in 2026. In 2022, he acquired the social network Twitter, implementing significant changes, and rebranding it as X in 2023. His other businesses include the neurotechnology company Neuralink, which he co-founded in 2016, and the tunneling company the Boring Company, which he founded in 2017. In November 2025, a Tesla pay package worth $1 trillion for Musk was approved, which he is to receive over 10 years if he meets specific goals. Musk was the largest donor in the 2024 U.S. presidential election, where he supported Donald Trump. After Trump was inaugurated as president in early 2025, Musk served as Senior Advisor to the President and as the de facto head of the Department of Government Efficiency (DOGE). After a public feud with Trump, Musk left the Trump administration and returned to managing his companies. Musk is a supporter of global far-right figures, causes, and political parties. His political activities, views, and statements have made him a polarizing figure. Musk has been criticized for COVID-19 misinformation, promoting conspiracy theories, and affirming antisemitic, racist, and transphobic comments. His acquisition of Twitter was controversial due to a subsequent increase in hate speech and the spread of misinformation on the service, following his pledge to decrease censorship. His role in the second Trump administration attracted public backlash, particularly in response to DOGE. The emails he sent to Jeffrey Epstein are included in the Epstein files, which were published between 2025–26 and became a topic of worldwide debate. Early life Elon Reeve Musk was born on June 28, 1971, in Pretoria, South Africa's administrative capital. He is of British and Pennsylvania Dutch ancestry. His mother, Maye (née Haldeman), is a model and dietitian born in Saskatchewan, Canada, and raised in South Africa. Musk therefore holds both South African and Canadian citizenship from birth. His father, Errol Musk, is a South African electromechanical engineer, pilot, sailor, consultant, emerald dealer, and property developer, who partly owned a rental lodge at Timbavati Private Nature Reserve. His maternal grandfather, Joshua N. Haldeman, who died in a plane crash when Elon was a toddler, was an American-born Canadian chiropractor, aviator and political activist in the technocracy movement who moved to South Africa in 1950. Elon has a younger brother, Kimbal, a younger sister, Tosca, and four paternal half-siblings. Musk was baptized as a child in the Anglican Church of Southern Africa. Despite both Elon and Errol previously stating that Errol was a part owner of a Zambian emerald mine, in 2023, Errol recounted that the deal he made was to receive "a portion of the emeralds produced at three small mines". Errol was elected to the Pretoria City Council as a representative of the anti-apartheid Progressive Party and has said that his children shared their father's dislike of apartheid. After his parents divorced in 1979, Elon, aged around 9, chose to live with his father because Errol Musk had an Encyclopædia Britannica and a computer. Elon later regretted his decision and became estranged from his father. Elon has recounted trips to a wilderness school that he described as a "paramilitary Lord of the Flies" where "bullying was a virtue" and children were encouraged to fight over rations. In one incident, after an altercation with a fellow pupil, Elon was thrown down concrete steps and beaten severely, leading to him being hospitalized for his injuries. Elon described his father berating him after he was discharged from the hospital. Errol denied berating Elon and claimed, "The [other] boy had just lost his father to suicide, and Elon had called him stupid. Elon had a tendency to call people stupid. How could I possibly blame that child?" Elon was an enthusiastic reader of books, and had attributed his success in part to having read The Lord of the Rings, the Foundation series, and The Hitchhiker's Guide to the Galaxy. At age ten, he developed an interest in computing and video games, teaching himself how to program from the VIC-20 user manual. At age twelve, Elon sold his BASIC-based game Blastar to PC and Office Technology magazine for approximately $500 (equivalent to $1,600 in 2025). Musk attended Waterkloof House Preparatory School, Bryanston High School, and then Pretoria Boys High School, where he graduated. Musk was a decent but unexceptional student, earning a 61/100 in Afrikaans and a B on his senior math certification. Musk applied for a Canadian passport through his Canadian-born mother to avoid South Africa's mandatory military service, which would have forced him to participate in the apartheid regime, as well as to ease his path to immigration to the United States. While waiting for his application to be processed, he attended the University of Pretoria for five months. Musk arrived in Canada in June 1989, connected with a second cousin in Saskatchewan, and worked odd jobs, including at a farm and a lumber mill. In 1990, he entered Queen's University in Kingston, Ontario. Two years later, he transferred to the University of Pennsylvania, where he studied until 1995. Although Musk has said that he earned his degrees in 1995, the University of Pennsylvania did not award them until 1997 – a Bachelor of Arts in physics and a Bachelor of Science in economics from the university's Wharton School. He reportedly hosted large, ticketed house parties to help pay for tuition, and wrote a business plan for an electronic book-scanning service similar to Google Books. In 1994, Musk held two internships in Silicon Valley: one at energy storage startup Pinnacle Research Institute, which investigated electrolytic supercapacitors for energy storage, and another at Palo Alto–based startup Rocket Science Games. In 1995, he was accepted to a graduate program in materials science at Stanford University, but did not enroll. Musk decided to join the Internet boom of the 1990s, applying for a job at Netscape, to which he reportedly never received a response. The Washington Post reported that Musk lacked legal authorization to remain and work in the United States after failing to enroll at Stanford. In response, Musk said he was allowed to work at that time and that his student visa transitioned to an H1-B. According to numerous former business associates and shareholders, Musk said he was on a student visa at the time. Business career In 1995, Musk, his brother Kimbal, and Greg Kouri founded the web software company Zip2 with funding from a group of angel investors. They housed the venture at a small rented office in Palo Alto. Replying to Rolling Stone, Musk denounced the notion that they started their company with funds borrowed from Errol Musk, but in a tweet, he recognized that his father contributed 10% of a later funding round. The company developed and marketed an Internet city guide for the newspaper publishing industry, with maps, directions, and yellow pages. According to Musk, "The website was up during the day and I was coding it at night, seven days a week, all the time." To impress investors, Musk built a large plastic structure around a standard computer to create the impression that Zip2 was powered by a small supercomputer. The Musk brothers obtained contracts with The New York Times and the Chicago Tribune, and persuaded the board of directors to abandon plans for a merger with CitySearch. Musk's attempts to become CEO were thwarted by the board. Compaq acquired Zip2 for $307 million in cash in February 1999 (equivalent to $590,000,000 in 2025), and Musk received $22 million (equivalent to $43,000,000 in 2025) for his 7-percent share. In 1999, Musk co-founded X.com, an online financial services and e-mail payment company. The startup was one of the first federally insured online banks, and, in its initial months of operation, over 200,000 customers joined the service. The company's investors regarded Musk as inexperienced and replaced him with Intuit CEO Bill Harris by the end of the year. The following year, X.com merged with online bank Confinity to avoid competition. Founded by Max Levchin and Peter Thiel, Confinity had its own money-transfer service, PayPal, which was more popular than X.com's service. Within the merged company, Musk returned as CEO. Musk's preference for Microsoft software over Unix created a rift in the company and caused Thiel to resign. Due to resulting technological issues and lack of a cohesive business model, the board ousted Musk and replaced him with Thiel in 2000.[b] Under Thiel, the company focused on the PayPal service and was renamed PayPal in 2001. In 2002, PayPal was acquired by eBay for $1.5 billion (equivalent to $2,700,000,000 in 2025) in stock, of which Musk—the largest shareholder with 11.72% of shares—received $175.8 million (equivalent to $320,000,000 in 2025). In 2017, Musk purchased the domain X.com from PayPal for an undisclosed amount, stating that it had sentimental value. In 2001, Musk became involved with the nonprofit Mars Society and discussed funding plans to place a growth-chamber for plants on Mars. Seeking a way to launch the greenhouse payloads into space, Musk made two unsuccessful trips to Moscow to purchase intercontinental ballistic missiles (ICBMs) from Russian companies NPO Lavochkin and Kosmotras. Musk instead decided to start a company to build affordable rockets. With $100 million of his early fortune, (equivalent to $180,000,000 in 2025) Musk founded SpaceX in May 2002 and became the company's CEO and Chief Engineer. SpaceX attempted its first launch of the Falcon 1 rocket in 2006. Although the rocket failed to reach Earth orbit, it was awarded a Commercial Orbital Transportation Services program contract from NASA, then led by Mike Griffin. After two more failed attempts that nearly caused Musk to go bankrupt, SpaceX succeeded in launching the Falcon 1 into orbit in 2008. Later that year, SpaceX received a $1.6 billion NASA contract (equivalent to $2,400,000,000 in 2025) for Falcon 9-launched Dragon spacecraft flights to the International Space Station (ISS), replacing the Space Shuttle after its 2011 retirement. In 2012, the Dragon vehicle docked with the ISS, a first for a commercial spacecraft. Working towards its goal of reusable rockets, in 2015 SpaceX successfully landed the first stage of a Falcon 9 on a land platform. Later landings were achieved on autonomous spaceport drone ships, an ocean-based recovery platform. In 2018, SpaceX launched the Falcon Heavy; the inaugural mission carried Musk's personal Tesla Roadster as a dummy payload. Since 2019, SpaceX has been developing Starship, a reusable, super heavy-lift launch vehicle intended to replace the Falcon 9 and Falcon Heavy. In 2020, SpaceX launched its first crewed flight, the Demo-2, becoming the first private company to place astronauts into orbit and dock a crewed spacecraft with the ISS. In 2024, NASA awarded SpaceX an $843 million (equivalent to $865,000,000 in 2025) contract to build a spacecraft that NASA will use to deorbit the ISS at the end of its lifespan. In 2015, SpaceX began development of the Starlink constellation of low Earth orbit satellites to provide satellite Internet access. After the launch of prototype satellites in 2018, the first large constellation was deployed in May 2019. As of May 2025[update], over 7,600 Starlink satellites are operational, comprising 65% of all operational Earth satellites. The total cost of the decade-long project to design, build, and deploy the constellation was estimated by SpaceX in 2020 to be $10 billion (equivalent to $12,000,000,000 in 2025).[c] During the Russian invasion of Ukraine, Musk provided free Starlink service to Ukraine, permitting Internet access and communication at a yearly cost to SpaceX of $400 million (equivalent to $440,000,000 in 2025). However, Musk refused to block Russian state media on Starlink. In 2023, Musk denied Ukraine's request to activate Starlink over Crimea to aid an attack against the Russian navy, citing fears of a nuclear response. Tesla, Inc., originally Tesla Motors, was incorporated in July 2003 by Martin Eberhard and Marc Tarpenning. Both men played active roles in the company's early development prior to Musk's involvement. Musk led the Series A round of investment in February 2004; he invested $6.35 million (equivalent to $11,000,000 in 2025), became the majority shareholder, and joined Tesla's board of directors as chairman. Musk took an active role within the company and oversaw Roadster product design, but was not deeply involved in day-to-day business operations. Following a series of escalating conflicts in 2007 and the 2008 financial crisis, Eberhard was ousted from the firm.[page needed] Musk assumed leadership of the company as CEO and product architect in 2008. A 2009 lawsuit settlement with Eberhard designated Musk as a Tesla co-founder, along with Tarpenning and two others. Tesla began delivery of the Roadster, an electric sports car, in 2008. With sales of about 2,500 vehicles, it was the first mass production all-electric car to use lithium-ion battery cells. Under Musk, Tesla has since launched several well-selling electric vehicles, including the four-door sedan Model S (2012), the crossover Model X (2015), the mass-market sedan Model 3 (2017), the crossover Model Y (2020), and the pickup truck Cybertruck (2023). In May 2020, Musk resigned as chairman of the board as part of the settlement of a lawsuit from the SEC over him tweeting that funding had been "secured" for potentially taking Tesla private. The company has also constructed multiple lithium-ion battery and electric vehicle factories, called Gigafactories. Since its initial public offering in 2010, Tesla stock has risen significantly; it became the most valuable carmaker in summer 2020, and it entered the S&P 500 later that year. In October 2021, it reached a market capitalization of $1 trillion (equivalent to $1,200,000,000,000 in 2025), the sixth company in U.S. history to do so. Musk provided the initial concept and financial capital for SolarCity, which his cousins Lyndon and Peter Rive founded in 2006. By 2013, SolarCity was the second largest provider of solar power systems in the United States. In 2014, Musk promoted the idea of SolarCity building an advanced production facility in Buffalo, New York, triple the size of the largest solar plant in the United States. Construction of the factory started in 2014 and was completed in 2017. It operated as a joint venture with Panasonic until early 2020. Tesla acquired SolarCity for $2 billion in 2016 (equivalent to $2,700,000,000 in 2025) and merged it with its battery unit to create Tesla Energy. The deal's announcement resulted in a more than 10% drop in Tesla's stock price; at the time, SolarCity was facing liquidity issues. Multiple shareholder groups filed a lawsuit against Musk and Tesla's directors, stating that the purchase of SolarCity was done solely to benefit Musk and came at the expense of Tesla and its shareholders. Tesla directors settled the lawsuit in January 2020, leaving Musk the sole remaining defendant. Two years later, the court ruled in Musk's favor. In 2016, Musk co-founded Neuralink, a neurotechnology startup, with an investment of $100 million. Neuralink aims to integrate the human brain with artificial intelligence (AI) by creating devices that are embedded in the brain. Such technology could enhance memory or allow the devices to communicate with software. The company also hopes to develop devices to treat neurological conditions like spinal cord injuries. In 2022, Neuralink announced that clinical trials would begin by the end of the year. In September 2023, the Food and Drug Administration approved Neuralink to initiate six-year human trials. Neuralink has conducted animal testing on macaques at the University of California, Davis. In 2021, the company released a video in which a macaque played the video game Pong via a Neuralink implant. The company's animal trials—which have caused the deaths of some monkeys—have led to claims of animal cruelty. The Physicians Committee for Responsible Medicine has alleged that Neuralink violated the Animal Welfare Act. Employees have complained that pressure from Musk to accelerate development has led to botched experiments and unnecessary animal deaths. In 2022, a federal probe was launched into possible animal welfare violations by Neuralink.[needs update] In 2017, Musk founded the Boring Company to construct tunnels; he also revealed plans for specialized, underground, high-occupancy vehicles that could travel up to 150 miles per hour (240 km/h) and thus circumvent above-ground traffic in major cities. Early in 2017, the company began discussions with regulatory bodies and initiated construction of a 30-foot (9.1 m) wide, 50-foot (15 m) long, and 15-foot (4.6 m) deep "test trench" on the premises of SpaceX's offices, as that required no permits. The Los Angeles tunnel, less than two miles (3.2 km) in length, debuted to journalists in 2018. It used Tesla Model Xs and was reported to be a rough ride while traveling at suboptimal speeds. Two tunnel projects announced in 2018, in Chicago and West Los Angeles, have been canceled. A tunnel beneath the Las Vegas Convention Center was completed in early 2021. Local officials have approved further expansions of the tunnel system. April 14, 2022 In early 2017, Musk expressed interest in buying Twitter and had questioned the platform's commitment to freedom of speech. By 2022, Musk had reached 9.2% stake in the company, making him the largest shareholder.[d] Musk later agreed to a deal that would appoint him to Twitter's board of directors and prohibit him from acquiring more than 14.9% of the company. Days later, Musk made a $43 billion offer to buy Twitter. By the end of April Musk had successfully concluded his bid for approximately $44 billion. This included approximately $12.5 billion in loans and $21 billion in equity financing. Having backtracked on his initial decision, Musk bought the company on October 27, 2022. Immediately after the acquisition, Musk fired several top Twitter executives including CEO Parag Agrawal; Musk became the CEO instead. Under Elon Musk, Twitter instituted monthly subscriptions for a "blue check", and laid off a significant portion of the company's staff. Musk lessened content moderation and hate speech also increased on the platform after his takeover. In late 2022, Musk released internal documents relating to Twitter's moderation of Hunter Biden's laptop controversy in the lead-up to the 2020 presidential election. Musk also promised to step down as CEO after a Twitter poll, and five months later, Musk stepped down as CEO and transitioned his role to executive chairman and chief technology officer (CTO). Despite Musk stepping down as CEO, X continues to struggle with challenges such as viral misinformation, hate speech, and antisemitism controversies. Musk has been accused of trying to silence some of his critics such as Twitch streamer Asmongold, who criticized him during one of his streams. Musk has been accused of removing their accounts' blue checkmarks, which hinders visibility and is considered a form of shadow banning, or suspending their accounts without justification. Other activities In August 2013, Musk announced plans for a version of a vactrain, and assigned engineers from SpaceX and Tesla to design a transport system between Greater Los Angeles and the San Francisco Bay Area, at an estimated cost of $6 billion. Later that year, Musk unveiled the concept, dubbed the Hyperloop, intended to make travel cheaper than any other mode of transport for such long distances. In December 2015, Musk co-founded OpenAI, a not-for-profit artificial intelligence (AI) research company aiming to develop artificial general intelligence, intended to be safe and beneficial to humanity. Musk pledged $1 billion of funding to the company, and initially gave $50 million. In 2018, Musk left the OpenAI board. Since 2018, OpenAI has made significant advances in machine learning. In July 2023, Musk launched the artificial intelligence company xAI, which aims to develop a generative AI program that competes with existing offerings like OpenAI's ChatGPT. Musk obtained funding from investors in SpaceX and Tesla, and xAI hired engineers from Google and OpenAI. December 16, 2022 Musk uses a private jet owned by Falcon Landing LLC, a SpaceX-linked company, and acquired a second jet in August 2020. His heavy use of the jets and the consequent fossil fuel usage have received criticism. Musk's flight usage is tracked on social media through ElonJet. In December 2022, Musk banned the ElonJet account on Twitter, and made temporary bans on the accounts of journalists that posted stories regarding the incident, including Donie O'Sullivan, Keith Olbermann, and journalists from The New York Times, The Washington Post, CNN, and The Intercept. In October 2025, Musk's company xAI launched Grokipedia, an AI-generated online encyclopedia that he promoted as an alternative to Wikipedia. Articles on Grokipedia are generated and reviewed by xAI's Grok chatbot. Media coverage and academic analysis described Grokipedia as frequently reusing Wikipedia content but framing contested political and social topics in line with Musk's own views and right-wing narratives. A study by Cornell University researchers and NBC News stated that Grokipedia cites sources that are blacklisted or considered "generally unreliable" on Wikipedia, for example, the conspiracy site Infowars and the neo-Nazi forum Stormfront. Wired, The Guardian and Time criticized Grokipedia for factual errors and for presenting Musk himself in unusually positive terms while downplaying controversies. Politics Musk is an outlier among business leaders who typically avoid partisan political advocacy. Musk was a registered independent voter when he lived in California. Historically, he has donated to both Democrats and Republicans, many of whom serve in states in which he has a vested interest. Since 2022, his political contributions have mostly supported Republicans, with his first vote for a Republican going to Mayra Flores in the 2022 Texas's 34th congressional district special election. In 2024, he started supporting international far-right political parties, activists, and causes, and has shared misinformation and numerous conspiracy theories. Since 2024, his views have been generally described as right-wing. Musk supported Barack Obama in 2008 and 2012, Hillary Clinton in 2016, Joe Biden in 2020, and Donald Trump in 2024. In the 2020 Democratic Party presidential primaries, Musk endorsed candidate Andrew Yang and expressed support for Yang's proposed universal basic income, and endorsed Kanye West's 2020 presidential campaign. In 2021, Musk publicly expressed opposition to the Build Back Better Act, a $3.5 trillion legislative package endorsed by Joe Biden that ultimately failed to pass due to unanimous opposition from congressional Republicans and several Democrats. In 2022, gave over $50 million to Citizens for Sanity, a conservative political action committee. In 2023, he supported Republican Ron DeSantis for the 2024 U.S. presidential election, giving $10 million to his campaign, and hosted DeSantis's campaign announcement on a Twitter Spaces event. From June 2023 to January 2024, Musk hosted a bipartisan set of X Spaces with Republican and Democratic candidates, including Robert F. Kennedy Jr., Vivek Ramaswamy, and Dean Phillips. In October 2025, former vice-president Kamala Harris commented that it was a mistake from the Democratic side to not invite Musk to a White House electric vehicle event organized in August 2021 and featuring executives from General Motors, Ford and Stellantis, despite Tesla being "the major American manufacturer of extraordinary innovation in this space." Fortune remarked that this was a nod to United Auto Workers and organized labor. Harris said presidents should put aside political loyalties when it came to recognizing innovation, and guessed that the non-invitation impacted Musk's perspective. Fortune noted that, at the time, Musk said, "Yeah, seems odd that Tesla wasn't invited." A month later, he criticized Biden as "not the friendliest administration." Jacob Silverman, author of the book Gilded Rage: Elon Musk and the Radicalization of Silicon Valley, said that the tech industry represented by Musk, Thiel, Andreessen and other capitalists, actually flourished under Biden, but the tech leaders chose Trump for their common ground on cultural issues. By early 2024, Musk had become a vocal and financial supporter of Donald Trump. In July 2024, minutes after the attempted assassination of Donald Trump, Musk endorsed him for president saying; "I fully endorse President Trump and hope for his rapid recovery." During the presidential campaign, Musk joined Trump on stage at a campaign rally, and during the campaign promoted conspiracy theories and falsehoods about Democrats, election fraud and immigration, in support of Trump. Musk was the largest individual donor of the 2024 election. In 2025, Musk contributed $19 million to the Wisconsin Supreme Court race, hoping to influence the state's future redistricting efforts and its regulations governing car manufacturers and dealers. In 2023, Musk said he shunned the World Economic Forum because it was boring. The organization commented that they had not invited him since 2015. He has participated in Dialog, dubbed "Tech Bilderberg" and organized by Peter Thiel and Auren Hoffman, though. Musk's international political actions and comments have come under increasing scrutiny and criticism, especially from the governments and leaders of France, Germany, Norway, Spain and the United Kingdom, particularly due to his position in the U.S. government as well as ownership of X. An NBC News analysis found he had boosted far-right political movements to cut immigration and curtail regulation of business in at least 18 countries on six continents since 2023. During his speech after the second inauguration of Donald Trump, Musk twice made a gesture interpreted by many as a Nazi or a fascist Roman salute.[e] He thumped his right hand over his heart, fingers spread wide, and then extended his right arm out, emphatically, at an upward angle, palm down and fingers together. He then repeated the gesture to the crowd behind him. As he finished the gestures, he said to the crowd, "My heart goes out to you. It is thanks to you that the future of civilization is assured." It was widely condemned as an intentional Nazi salute in Germany, where making such gestures is illegal. The Anti-Defamation League said it was not a Nazi salute, but other Jewish organizations disagreed and condemned the salute. American public opinion was divided on partisan lines as to whether it was a fascist salute. Musk dismissed the accusations of Nazi sympathies, deriding them as "dirty tricks" and a "tired" attack. Neo-Nazi and white supremacist groups celebrated it as a Nazi salute. Multiple European political parties demanded that Musk be banned from entering their countries. The concept of DOGE emerged in a discussion between Musk and Donald Trump, and in August 2024, Trump committed to giving Musk an advisory role, with Musk accepting the offer. In November and December 2024, Musk suggested that the organization could help to cut the U.S. federal budget, consolidate the number of federal agencies, and eliminate the Consumer Financial Protection Bureau, and that its final stage would be "deleting itself". In January 2025, the organization was created by executive order, and Musk was designated a "special government employee". Musk led the organization and was a senior advisor to the president, although his official role is not clear. In sworn statement during a lawsuit, the director of the White House Office of Administration stated that Musk "is not an employee of the U.S. DOGE Service or U.S. DOGE Service Temporary Organization", "is not the U.S. DOGE Service administrator", and has "no actual or formal authority to make government decisions himself". Trump said two days later that he had put Musk in charge of DOGE. A federal judge has ruled that Musk acted as the de facto leader of DOGE. Musk's role in the second Trump administration, particularly in response to DOGE, has attracted public backlash. He was criticized for his treatment of federal government employees, including his influence over the mass layoffs of the federal workforce. He has prioritized secrecy within the organization and has accused others of violating privacy laws. A Senate report alleged that Musk could avoid up to $2 billion in legal liability as a result of DOGE's actions. In May 2025, Bill Gates accused Musk of "killing the world's poorest children" through his cuts to USAID, which modeling by Boston University estimated had resulted in 300,000 deaths by this time, most of them of children. By November 2025, the estimated death toll had increased to 400,000 children and 200,000 adults. Musk announced on May 28, 2025, that he would depart from the Trump administration as planned when the special government employee's 130 day deadline expired, with a White House official confirming that Musk's offboarding from the Trump administration was already underway. His departure was officially confirmed during a joint Oval Office press conference with Trump on May 30, 2025. @realDonaldTrump is in the Epstein files. That is the real reason they have not been made public. June 5, 2025 After leaving office, Musk criticized the Trump administration's Big Beautiful Bill, calling it a "disgusting abomination" due to its provisions increasing the deficit. A feud began between Musk and Trump, with its most notable event being Musk alleging Trump had ties to sex offender Jeffrey Epstein on X (formerly Twitter) on June 5, 2025. Trump responded on Truth Social stating that Musk went "CRAZY" after the "EV Mandate" was purportedly taken away and threatened to cut Musk's government contracts. Musk then called for a third Trump impeachment. The next day, Trump stated that he did not wish to reconcile with Musk, and added that Musk would face "very serious consequences" if he funds Democratic candidates. On June 11, Musk publicly apologized for the tweets against Trump, saying they "went too far". Views November 6, 2022 Rejecting the conservative label, Musk has described himself as a political moderate, even as his views have become more right-wing over time. His views have been characterized as libertarian and far-right, and after his involvement in European politics, they have received criticism from world leaders such as Emmanuel Macron and Olaf Scholz. Within the context of American politics, Musk supported Democratic candidates up until 2022, at which point he voted for a Republican for the first time. He has stated support for universal basic income, gun rights, freedom of speech, a tax on carbon emissions, and H-1B visas. Musk has expressed concern about issues such as artificial intelligence (AI) and climate change, and has been a critic of wealth tax, short-selling, and government subsidies. An immigrant himself, Musk has been accused of being anti-immigration, and regularly blames immigration policies for illegal immigration. He is also a pronatalist who believes population decline is the biggest threat to civilization, and identifies as a cultural Christian. Musk has long been an advocate for space colonization, especially the colonization of Mars. He has repeatedly pushed for humanity colonizing Mars, in order to become an interplanetary species and lower the risks of human extinction. Musk has promoted conspiracy theories and made controversial statements that have led to accusations of racism, sexism, antisemitism, transphobia, disseminating disinformation, and support of white pride. While describing himself as a "pro-Semite", his comments regarding George Soros and Jewish communities have been condemned by the Anti-Defamation League and the Biden White House. Musk was criticized during the COVID-19 pandemic for making unfounded epidemiological claims, defying COVID-19 lockdowns restrictions, and supporting the Canada convoy protest against vaccine mandates. He has amplified false claims of white genocide in South Africa. Musk has been critical of Israel's actions in the Gaza Strip during the Gaza war, praised China's economic and climate goals, suggested that Taiwan and China should resolve cross-strait relations, and was described as having a close relationship with the Chinese government. In Europe, Musk expressed support for Ukraine in 2022 during the Russian invasion, recommended referendums and peace deals on the annexed Russia-occupied territories, and supported the far-right Alternative for Germany political party in 2024. Regarding British politics, Musk blamed the 2024 UK riots on mass migration and open borders, criticized Prime Minister Keir Starmer for what he described as a "two-tier" policing system, and was subsequently attacked as being responsible for spreading misinformation and amplifying the far-right. He has also voiced his support for far-right activist Tommy Robinson and pledged electoral support for Reform UK. In February 2026, Musk described Spanish Prime Minister Pedro Sánchez as a "tyrant" following Sánchez's proposal to prohibit minors under the age of 16 from accessing social media platforms. Legal affairs In 2018, Musk was sued by the U.S. Securities and Exchange Commission (SEC) for a tweet stating that funding had been secured for potentially taking Tesla private.[f] The securities fraud lawsuit characterized the tweet as false, misleading, and damaging to investors, and sought to bar Musk from serving as CEO of publicly traded companies. Two days later, Musk settled with the SEC, without admitting or denying the SEC's allegations. As a result, Musk and Tesla were fined $20 million each, and Musk was forced to step down for three years as Tesla chairman but was able to remain as CEO. Shareholders filed a lawsuit over the tweet, and in February 2023, a jury found Musk and Tesla not liable. Musk has stated in interviews that he does not regret posting the tweet that triggered the SEC investigation. In 2019, Musk stated in a tweet that Tesla would build half a million cars that year. The SEC reacted by asking a court to hold him in contempt for violating the terms of the 2018 settlement agreement. A joint agreement between Musk and the SEC eventually clarified the previous agreement details, including a list of topics about which Musk needed preclearance. In 2020, a judge blocked a lawsuit that claimed a tweet by Musk regarding Tesla stock price ("too high imo") violated the agreement. Freedom of Information Act (FOIA)-released records showed that the SEC concluded Musk had subsequently violated the agreement twice by tweeting regarding "Tesla's solar roof production volumes and its stock price". In October 2023, the SEC sued Musk over his refusal to testify a third time in an investigation into whether he violated federal law by purchasing Twitter stock in 2022. In February 2024, Judge Laurel Beeler ruled that Musk must testify again. In January 2025, the SEC filed a lawsuit against Musk for securities violations related to his purchase of Twitter. In January 2024, Delaware judge Kathaleen McCormick ruled in a 2018 lawsuit that Musk's $55 billion pay package from Tesla be rescinded. McCormick called the compensation granted by the company's board "an unfathomable sum" that was unfair to shareholders. The Delaware Supreme Court overturned McCormick's decision in December 2025, restoring Musk's compensation package and awarding $1 in nominal damages. Personal life Musk became a U.S. citizen in 2002. From the early 2000s until late 2020, Musk resided in California, where both Tesla and SpaceX were founded. He then relocated to Cameron County, Texas, saying that California had become "complacent" about its economic success. While hosting Saturday Night Live in 2021, Musk stated that he has Asperger syndrome (an outdated term for autism spectrum disorder). When asked about his experience growing up with Asperger's syndrome in a TED2022 conference in Vancouver, Musk stated that "the social cues were not intuitive ... I would just tend to take things very literally ... but then that turned out to be wrong — [people were not] simply saying exactly what they mean, there's all sorts of other things that are meant, and [it] took me a while to figure that out." Musk suffers from back pain and has undergone several spine-related surgeries, including a disc replacement. In 2000, he contracted a severe case of malaria while on vacation in South Africa. Musk has stated he uses doctor-prescribed ketamine for occasional depression and that he doses "a small amount once every other week or something like that"; since January 2024, some media outlets have reported that he takes ketamine, marijuana, LSD, ecstasy, mushrooms, cocaine and other drugs. Musk at first refused to comment on his alleged drug use, before responding that he had not tested positive for drugs, and that if drugs somehow improved his productivity, "I would definitely take them!". The New York Times' investigations revealed Musk's overuse of ketamine and numerous other drugs, as well as strained family relationships and concerns from close associates who have become troubled by his public behavior as he became more involved in political activities and government work. According to The Washington Post, President Trump described Musk as "a big-time drug addict". Through his own label Emo G Records, Musk released a rap track, "RIP Harambe", on SoundCloud in March 2019. The following year, he released an EDM track, "Don't Doubt Ur Vibe", featuring his own lyrics and vocals. Musk plays video games, which he stated has a "'restoring effect' that helps his 'mental calibration'". Some games he plays include Quake, Diablo IV, Elden Ring, and Polytopia. Musk once claimed to be one of the world's top video game players but has since admitted to "account boosting", or cheating by hiring outside services to achieve top player rankings. Musk has justified the boosting by claiming that all top accounts do it so he has to as well to remain competitive. In 2024 and 2025, Musk criticized the video game Assassin's Creed Shadows and its creator Ubisoft for "woke" content. Musk posted to X that "DEI kills art" and specified the inclusion of the historical figure Yasuke in the Assassin's Creed game as offensive; he also called the game "terrible". Ubisoft responded by saying that Musk's comments were "just feeding hatred" and that they were focused on producing a game not pushing politics. Musk has fathered at least 14 children, one of whom died as an infant. The Wall Street Journal reported in 2025 that sources close to Musk suggest that the "true number of Musk's children is much higher than publicly known". He had six children with his first wife, Canadian author Justine Wilson, whom he met while attending Queen's University in Ontario, Canada; they married in 2000. In 2002, their first child Nevada Musk died of sudden infant death syndrome at the age of 10 weeks. After his death, the couple used in vitro fertilization (IVF) to continue their family; they had twins in 2004, followed by triplets in 2006. The couple divorced in 2008 and have shared custody of their children. The elder twin he had with Wilson came out as a trans woman and, in 2022, officially changed her name to Vivian Jenna Wilson, adopting her mother's surname because she no longer wished to be associated with Musk. Musk began dating English actress Talulah Riley in 2008. They married two years later at Dornoch Cathedral in Scotland. In 2012, the couple divorced, then remarried the following year. After briefly filing for divorce in 2014, Musk finalized a second divorce from Riley in 2016. Musk then dated the American actress Amber Heard for several months in 2017; he had reportedly been "pursuing" her since 2012. In 2018, Musk and Canadian musician Grimes confirmed they were dating. Grimes and Musk have three children, born in 2020, 2021, and 2022.[g] Musk and Grimes originally gave their eldest child the name "X Æ A-12", which would have violated California regulations as it contained characters that are not in the modern English alphabet; the names registered on the birth certificate are "X" as a first name, "Æ A-Xii" as a middle name, and "Musk" as a last name. They received criticism for choosing a name perceived to be impractical and difficult to pronounce; Musk has said the intended pronunciation is "X Ash A Twelve". Their second child was born via surrogacy. Despite the pregnancy, Musk confirmed reports that the couple were "semi-separated" in September 2021; in an interview with Time in December 2021, he said he was single. In October 2023, Grimes sued Musk over parental rights and custody of X Æ A-Xii. Elon Musk has taken X Æ A-Xii to multiple official events in Washington, D.C. during Trump's second term in office. Also in July 2022, The Wall Street Journal reported that Musk allegedly had an affair with Nicole Shanahan, the wife of Google co-founder Sergey Brin, in 2021, leading to their divorce the following year. Musk denied the report. Musk also had a relationship with Australian actress Natasha Bassett, who has been described as "an occasional girlfriend". In October 2024, The New York Times reported Musk bought a Texas compound for his children and their mothers, though Musk denied having done so. Musk also has four children with Shivon Zilis, director of operations and special projects at Neuralink: twins born via IVF in 2021, a child born in 2024 via surrogacy and a child born in 2025.[h] On February 14, 2025, Ashley St. Clair, an influencer and author, posted on X claiming to have given birth to Musk's son Romulus five months earlier, which media outlets reported as Musk's supposed thirteenth child.[i] On February 22, 2025, it was reported that St Clair had filed for sole custody of her five-month-old son and for Musk to be recognised as the child's father. On March 31, 2025, Musk wrote that, while he was unsure if he was the father of St. Clair's child, he had paid St. Clair $2.5 million and would continue paying her $500,000 per year.[j] Later reporting from the Wall Street Journal indicated that $1 million of these payments to St. Clair were structured as a loan. In 2014, Musk and Ghislaine Maxwell appeared together in a photograph taken at an Academy Awards after-party, which Musk later described as a "photobomb". The January 2026 Epstein files contain emails between Musk and Epstein from 2012 to 2013, after Epstein's first conviction. Emails released on January 30, 2026, indicated that Epstein invited Musk to visit his private island on multiple occasions. The correspondence showed that while Epstein repeatedly encouraged Musk to attend, Musk did not visit the island. In one instance, Musk discussed the possibility of attending a party with his then-wife Talulah Riley and asked which day would be the "wildest party"; according to the emails, the visit did not take place after Epstein later cancelled the plans.[k] On Christmas day in 2012, Musk emailed Epstein asking "Do you have any parties planned? I’ve been working to the edge of sanity this year and so, once my kids head home after Christmas, I really want to hit the party scene in St Barts or elsewhere and let loose. The invitation is much appreciated, but a peaceful island experience is the opposite of what I’m looking for". Epstein replied that the "ratio on my island" might make Musk's wife uncomfortable to which Musk responded, "Ratio is not a problem for Talulah". On September 11, 2013, Epstein sent an email asking Musk if he had any plans for coming to New York for the opening of the United Nations General Assembly where many "interesting people" would be coming to his house to which Musk responded that "Flying to NY to see UN diplomats do nothing would be an unwise use of time". Epstein responded by stating "Do you think i am retarded. Just kidding, there is no one over 25 and all very cute." Musk has denied any close relationship with Epstein and described him as a "creep" who attempted to ingratiate himself with influential people. When Musk was asked in 2019 if he introduced Epstein to Mark Zuckerberg, Musk responded: "I don’t recall introducing Epstein to anyone, as I don’t know the guy well enough to do so." The released emails nonetheless showed cordial exchanges on a range of topics, including Musk's inquiry about parties on the island. The correspondence also indicated that Musk suggested hosting Epstein at SpaceX, while Epstein separately discussed plans to tour SpaceX and bring "the girls", though there is no evidence that such a visit occurred. Musk has described the release of the files a "distraction", later accusing the second Trump administration of suppressing them to protect powerful individuals, including Trump himself.[l] Wealth Elon Musk is the wealthiest person in the world, with an estimated net worth of US$690 billion as of January 2026, according to the Bloomberg Billionaires Index, and $852 billion according to Forbes, primarily from his ownership stakes in SpaceX and Tesla. Having been first listed on the Forbes Billionaires List in 2012, around 75% of Musk's wealth was derived from Tesla stock in November 2020, although he describes himself as "cash poor". According to Forbes, he became the first person in the world to achieve a net worth of $300 billion in 2021; $400 billion in December 2024; $500 billion in October 2025; $600 billion in mid-December 2025; $700 billion later that month; and $800 billion in February 2026. In November 2025, a Tesla pay package worth potentially $1 trillion for Musk was approved, which he is to receive over 10 years if he meets specific goals. Public image Although his ventures have been highly influential within their separate industries starting in the 2000s, Musk only became a public figure in the early 2010s. He has been described as an eccentric who makes spontaneous and impactful decisions, while also often making controversial statements, contrary to other billionaires who prefer reclusiveness to protect their businesses. Musk's actions and his expressed views have made him a polarizing figure. Biographer Ashlee Vance described people's opinions of Musk as polarized due to his "part philosopher, part troll" persona on Twitter. He has drawn denouncement for using his platform to mock the self-selection of personal pronouns, while also receiving praise for bringing international attention to matters like British survivors of grooming gangs. Musk has been described as an American oligarch due to his extensive influence over public discourse, social media, industry, politics, and government policy. After Trump's re-election, Musk's influence and actions during the transition period and the second presidency of Donald Trump led some to call him "President Musk", the "actual president-elect", "shadow president" or "co-president". Awards for his contributions to the development of the Falcon rockets include the American Institute of Aeronautics and Astronautics George Low Transportation Award in 2008, the Fédération Aéronautique Internationale Gold Space Medal in 2010, and the Royal Aeronautical Society Gold Medal in 2012. In 2015, he received an honorary doctorate in engineering and technology from Yale University and an Institute of Electrical and Electronics Engineers Honorary Membership. Musk was elected a Fellow of the Royal Society (FRS) in 2018.[m] In 2022, Musk was elected to the National Academy of Engineering. Time has listed Musk as one of the most influential people in the world in 2010, 2013, 2018, and 2021. Musk was selected as Time's "Person of the Year" for 2021. Then Time editor-in-chief Edward Felsenthal wrote that, "Person of the Year is a marker of influence, and few individuals have had more influence than Musk on life on Earth, and potentially life off Earth too." Notes References Works cited Further reading External links |
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[SOURCE: https://en.wikipedia.org/wiki/T_(programming_language)] | [TOKENS: 316] |
Contents T (programming language) T is a dialect of the Scheme programming language developed in the early 1980s by Jonathan A. Rees, Kent M. Pitman, and Norman I. Adams of Yale University as an experiment in language design and implementation. Rationale T's purpose is to test the thesis developed by Guy L. Steele Jr. and Gerald Jay Sussman in their series of papers about Scheme: that Scheme may be used as the basis for a practical programming language of exceptional expressive power, and that implementations of Scheme could perform better than other Lisp systems, and competitively with implementations of programming languages, such as C and BLISS, which are usually considered to be inherently more efficient than Lisp on conventional machine architectures. Much of this occurs via an optimizing compiler named Orbit. T contains some features that modern Scheme lacks. For example, T is object-oriented, and it has first-class environments, called locales, which can be modified non-locally and used as a module system. T has several extra special forms for lazy evaluation and flow control, and an equivalent to Common Lisp's setf. T, like Scheme, supports call-with-current-continuation (call/cc), but it also has a more limited form called catch. From the T manual, a hypothetical implementation of cons could be: This example shows that objects in T are intimately related to closures and message-passing. A primitive called join puts two objects together, allowing for something resembling inheritance. Ports T was ported to many hardware platforms and operating systems, including: See also References External links |
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[SOURCE: https://en.wikipedia.org/wiki/2020_Democratic_Party_presidential_primaries] | [TOKENS: 2773] |
Contents 2020 Democratic Party presidential primaries Hillary Clinton Joe Biden Presidential primaries and caucuses were organized by the Democratic Party to select delegates to the 2020 Democratic National Convention to determine the party's nominee for president in the 2020 election. The primaries and caucuses took place in all 50 U.S. states, in the District of Columbia, in five U.S. territories, and through Democrats Abroad. They occurred between February 3 and August 11, 2020. Former Vice President Joe Biden led in the polls throughout most of 2019. The 2020 Iowa Democratic presidential caucuses were marred by technical problems; certified results of the caucus eventually showed Mayor Pete Buttigieg winning the most delegates, while Senator Bernie Sanders won the popular vote in the state. Sanders then won New Hampshire and Nevada. Biden, whose campaign fortunes had suffered from losses in Iowa, New Hampshire and Nevada, made a comeback by overwhelmingly winning the South Carolina primary. After Biden won South Carolina, and one day before the Super Tuesday primaries, several candidates dropped out of the race and endorsed Biden. Biden then won 10 out of 15 contests on Super Tuesday. On April 8, after Sanders withdrew from the race, Biden became the presumptive Democratic presidential nominee. Biden and his running mate, U.S. senator Kamala Harris of California, were nominated for president and vice president by delegates at the Democratic National Convention. Biden and Harris won the presidency and vice presidency in the general election on November 3, defeating incumbent President Donald Trump and incumbent Vice President Mike Pence. Overview A total of 29 major candidates declared their 2020 Democratic presidential candidacies. With the exception of a brief period in October 2019 when Senator Elizabeth Warren experienced a surge in support, former vice president Joe Biden led in the polls throughout 2019. Eighteen of the 29 declared candidates withdrew before the first primary contest. The first primary was marred by controversy, as technical issues with vote reporting resulted in a three-day delay in vote counting in the Iowa caucuses. The certified results of the caucuses showed Mayor Pete Buttigieg winning the most delegates, while Senator Bernie Sanders won the popular vote in the state. Sanders then won the New Hampshire primary in a narrow victory over Buttigieg before comfortably winning the Nevada caucus, solidifying his status as the front-runner for the nomination. Sanders received significant support from Asian, Hispanic, and young voters. Biden, whose campaign fortunes had suffered from losses in Iowa, New Hampshire and Nevada, made a comeback by overwhelmingly winning the South Carolina primary. Biden was helped by strong support from African American voters, an endorsement from South Carolina U.S. Representative Jim Clyburn, and Democratic establishment concerns about nominating Sanders. After Biden won South Carolina, and one day before the Super Tuesday primaries, several candidates dropped out of the race and endorsed Biden; before that time, polling saw Sanders leading with a plurality in most Super Tuesday states. Biden then won 10 out of 15 contests on Super Tuesday, beating back challenges from Sanders, Warren, and former New York City Mayor Michael Bloomberg and solidifying his lead. As the primaries proceeded, they were overshadowed by the COVID-19 pandemic, which was declared to be a global pandemic on March 11, 2020. Between March 19 and April 7, most states in the country issued stay-at-home orders, and the overwhelming majority of campaign activity was suspended. On April 8, 2020, Biden became the presumptive Democratic nominee after Sanders (the only other candidate remaining) withdrew from the race. In early June, Biden passed the threshold of 1,991 delegates to win the nomination. Seven candidates received pledged delegates: Biden, Sanders, Warren, Bloomberg, Buttigieg, Senator Amy Klobuchar and U.S. Representative Tulsi Gabbard. On August 11, Biden announced that former presidential candidate Senator Kamala Harris would be his running mate. Biden and Harris were nominated for president and vice president by delegates at the Democratic National Convention on August 18 and 19. Biden and Harris won the presidency and vice presidency in the general election on November 3, defeating the Republican ticket of President Donald Trump and Vice President Mike Pence. Background After Hillary Clinton's loss in the previous election, many felt the Democratic Party lacked a clear leading figure. Divisions remained in the party following the 2016 primaries, which pitted Clinton against Bernie Sanders. Between the 2016 election and the 2018 midterm elections, Senate Democrats generally shifted to the political left in relation to college tuition, healthcare, and immigration. The 2018 elections saw the Democratic Party regain the House of Representatives for the first time in eight years, picking up seats in both urban and suburban districts. On August 25, 2018, the Democratic National Committee (DNC) members passed reforms to the Democratic Party's primary process in order to increase participation and ensure transparency. State parties are encouraged to use a government-run primary whenever available and increase the accessibility of their primary through same-day or automatic registration and same-day party switching. Caucuses are required to have absentee voting, or to otherwise allow those who cannot participate in person to be included. Independent of the results of the primaries and caucuses, the Democratic Party, from its group of party leaders and elected officials, also appointed 771[a] unpledged delegates (superdelegates) to participate in its national convention. In contrast to all previous election cycles since superdelegates were introduced in 1984, superdelegates will no longer have the right to cast decisive votes on the convention's first ballot for the presidential nomination. They will be allowed to cast non-decisive votes if a candidate has clinched the nomination before the first ballot, or decisive votes on subsequent ballots in a contested convention. In that case, the number of votes required shall increase to a majority of pledged and superdelegates combined. Superdelegates are not precluded from publicly endorsing a candidate before the convention. There were a number of changes to the process of nomination at the state level. A decline in the number of caucuses occurred after 2016. Democrats in Colorado, Hawaii, Idaho, Kansas, Maine, Minnesota, Nebraska, North Dakota, and Washington all switched from various forms of caucuses to primaries. Hawaii, Kansas, and North Dakota switched to party-run "firehouse primaries". This resulted in the lowest number of caucuses in the Democratic Party's recent history. Only three states (Iowa, Nevada, and Wyoming) and four territories (American Samoa, Guam, Northern Marianas, and U.S. Virgin Islands) used them. Six states were approved in 2019 by the DNC to use ranked-choice voting in the primaries: Alaska, Hawaii, Kansas, and Wyoming for all voters; Iowa and Nevada for absentee voters. Rather than eliminating candidates until a single winner is chosen, voters' choices were reallocated until all remaining candidates have at least 15%, the threshold to receive delegates to the convention. Several states which did not use paper ballots widely in 2016 and 2018, adopted them for the 2020 primary and general elections, to minimize potential interference in vote tallies, a concern raised by intelligence officials, election officials and the public. The move to paper ballots enabled audits to start where they had not been possible before, and in 2020 about half the states audit samples of primary ballots to measure accuracy of the reported results. Audits of caucus results depend on party rules, and the Iowa Democratic party investigated inaccuracies in precinct reports, resolved enough to be sure the delegate allocations were correct, and decided it did not have authority or time to correct all errors. The number of pledged delegates from each state is proportional to the state's share of the electoral college, and to the state's past Democratic votes for president. Thus less weight is given to swing states and Republican states, while more weight is given to strongly Democratic states, in choosing a nominee. Six pledged delegates are assigned to each territory, 44 to Puerto Rico, and 12 to Democrats Abroad. Each jurisdiction can also earn bonus delegates by holding primaries after March or in clusters of three or more neighboring states. Within states, a quarter of pledged delegates are allocated to candidates based on statewide vote totals, and the rest typically based on votes in each congressional district, although some states use divisions other than congressional districts. For example, Texas uses state Senate districts. Districts which have voted Democratic in the past get more delegates, and fewer delegates are allocated for swing districts and Republican districts. For example, House Speaker Pelosi's strongly Democratic district 12 has 7 delegates, or one per 109,000 people, and a swing district, CA-10, which became Democratic in 2018, has 4 delegates, or one per 190,000 people. Candidates who received under 15% of the votes in a state or district didn't get any delegates from that area. Candidates who got 15% or more of the votes divided delegates in proportion to their votes. These rules apply at the state level to state delegates and within each district for those delegates. The 15% threshold was established in 1992 to limit "fringe" candidates. The threshold now means that any sector of the party (moderate, progressive, etc.) which produces many candidates, thus dividing supporters' votes, may win few delegates, even if it wins a majority of votes. Schedule and results February March 3 (Super Tuesday) March 10 March 14–17 March 24–29 April 4–7 April 28 May June February March 3 (Super Tuesday) March 10 March 14–17 April 7–17 April 28 May June July–August Election day postponements and cancellations Due to the COVID-19 pandemic in the United States, a number of presidential primaries were rescheduled. On April 27, New York canceled its primary altogether on the grounds that there was only one candidate left with an active campaign. Andrew Yang responded with a lawsuit, arguing that the decision infringes on voting rights, and in early May, the judge ruled in favor of Yang. In addition, the DNC elected to delay the 2020 Democratic National Convention from July 13–16 to August 17–20. Candidates Major candidates in the 2020 Democratic presidential primaries had held significant elective office or received substantial media coverage. Nearly 300 candidates who did not receive significant media coverage also filed with the Federal Election Commission to run for president in the primary. Other notable individuals who were not major candidates terminated their campaigns during the primaries: Other notable individuals who were not major candidates terminated their campaigns before the primaries: A number of individuals considered a run, either publicly or privately, but ultimately decided against it. Political positions Debates and forums In December 2018, the Democratic National Committee (DNC) announced the schedule for 12 official DNC-sanctioned debates, set to begin in June 2019, with six debates in 2019 and the remaining six during the first four months of 2020. Candidates were allowed to participate in forums featuring multiple other candidates as long as only one candidate appeared on stage at a time. Any presidential candidates who participated in unsanctioned debates with each other would have lost their invitations to the next DNC-sanctioned debate. No unsanctioned debates took place during the 2019–2020 debate season. The DNC also announced that it would not partner with Fox News as a media sponsor for any debates. Fox News last held a Democratic debate in 2003. All media sponsors selected to host a debate were as a new rule required to appoint at least one female moderator for each debate, to ensure there would not be a gender-skewed treatment of the candidates and debate topics. Primary election polling The following graph depicts the standing of each candidate in the poll aggregators from December 2018 to April 2020. Timeline Ballot access Filing for the primaries began in October 2019. indicates that the candidate was on the ballot for the primary contest, indicates that the candidate was a recognized write-in candidate, and indicates that the candidate did not appear on the ballot in that state's contest. indicates that a candidate withdrew before the election but was still listed on the ballot. Candidates listed in italics have suspended their campaigns. National convention The 2020 Democratic National Convention was scheduled to take place in Milwaukee, Wisconsin, on July 13–16, 2020, but was postponed and rescheduled to take place on August 17–20 due to the COVID-19 pandemic. The event became a virtual "Convention Across America" with voting held online before the opening gavel, and the non-televised events held remotely over ZOOM. Endorsements Campaign finance This is an overview of the money being raised and spent by each campaign for the entire period running from January 1, 2017, to March 31, 2020, as it was reported to the Federal Election Commission (FEC). Total raised is the sum of all individual contributions (large and small), loans from the candidate, and transfers from other campaign committees. The last column, Cash On Hand (COH), has been calculated by subtracting the "spent" amount from the "raised" amount, thereby showing the remaining cash each campaign had available for its future spending as of February 29, 2020.[update] As of February 29, 2020, the major candidates have raised $989,234,992.08. Maps See also Notes Further reading References |
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[SOURCE: https://en.wikipedia.org/wiki/Jim_Crow_laws] | [TOKENS: 6755] |
Contents Jim Crow laws The Jim Crow laws were state and local laws introduced in the Southern United States in the late 19th and early 20th centuries that enforced racial segregation. The origin of the term Jim Crow is obscure, but probably refers to a minstrel show song called "Jump Jim Crow". The last of the Jim Crow laws were generally overturned in 1965 by the Voting Rights Act of 1965. Formal and informal racial segregation policies were present in other areas of the United States as well, even as several states outside the South had banned discrimination in public accommodations and voting. Southern laws were enacted by white-dominated state legislatures (Redeemers) to disenfranchise and remove political and economic gains made by African Americans during the Reconstruction era. Such continuing racial segregation was also supported by the successful Lily-white movement. In practice, Jim Crow laws mandated racial segregation in all public facilities in the South, beginning in the 1870s. Jim Crow laws were upheld in 1896 in the case of Plessy v. Ferguson, in which the Supreme Court laid out its "separate but equal" legal doctrine concerning facilities for African Americans. Public education had essentially been segregated since it began during the Reconstruction era after 1863. Companion laws excluded most African Americans from the vote in the South. Although in theory the "equal" segregation doctrine governed public facilities and transportation, facilities for African Americans were consistently inferior and underfunded compared to facilities for white Americans; sometimes, there were no facilities for the black community at all. Far from equality, as a body of law, Jim Crow institutionalized economic, educational, political and social disadvantages and second-class citizenship for most African Americans living in the United States. After the NAACP (National Association for the Advancement of Colored People) was founded in 1909, it became involved in a sustained public protest and campaigns against the Jim Crow laws, and the so-called "separate but equal" doctrine. In 1954, segregation of public schools (state-sponsored) was declared unconstitutional by the U.S. Supreme Court in the landmark case Brown v. Board of Education of Topeka. In some states, it took many years to implement this decision, while the Warren Court continued to rule against Jim Crow legislation in other cases such as Heart of Atlanta Motel, Inc. v. United States (1964). In general, the remaining Jim Crow laws were generally overturned by the Civil Rights Act of 1964 and the Voting Rights Act of 1965. Southern state anti-miscegenation laws were generally overturned in the 1967 case of Loving v. Virginia. Etymology The origin of the term "Jim Crow" is obscure, but probably refers to slave singing that incorporated an African dance called "Jump Jim Crow". "Jump Jim Crow" became a minstrel show dance performed by white actor Thomas D. Rice in blackface, first performed in 1828. Many other white minstrel dancers in blackface copied it for white audiences. According to The Jim Crow Encyclopedia: The routine was immensely popular during the antebellum period, and the figure of Jim Crow became a recognizable and enduring icon in American popular culture. In the 1840s, abolitionists used the phrase Jim Crow to describe segregated railroad cars. By the end of the nineteenth century, the term came to signify the social separation of the races. The earliest known use of the phrase "Jim Crow law" can be dated to 1884 in a newspaper article summarizing congressional debate. The term appears in 1892 in the title of a New York Times article about Louisiana requiring segregated railroad cars. Origins In January 1865, an amendment to the Constitution abolishing slavery in the United States was proposed by Congress and ratified as the Thirteenth Amendment on December 18, 1865. During the Reconstruction era of 1865–1877, federal laws provided civil rights protections in the U.S. South for freedmen, African Americans who were former slaves, and the minority of black people who had been free before the war. In the 1870s, Democrats gradually regained power in the Southern legislatures as violent insurgent paramilitary groups, such as the Ku Klux Klan, White League, and Red Shirts disrupted Republican organizing, ran Republican officeholders out of town, and lynched black voters as an intimidation tactic to suppress the black vote. Extensive voter fraud was also used. In one instance, an outright coup or insurrection in coastal North Carolina led to the violent removal of democratically elected Republican party executive and representative officials, who were either hunted down or hounded out. Gubernatorial elections were close and had been disputed in Louisiana for years, with increasing violence against black Americans during campaigns from 1868 onward. The Compromise of 1877 to gain Southern support in the presidential election resulted in the government withdrawing the last of the federal troops from the South. White Democrats had regained political power in every Southern state. These Southern, white, "Redeemer" governments legislated Jim Crow laws, officially segregating the country's population. Jim Crow laws were a manifestation of authoritarian rule specifically directed at one racial group. Black people were still elected to local offices throughout the 1880s in local areas with large black populations, but their voting was suppressed for state and national elections. States passed laws to make voter registration and electoral rules more restrictive, with the result that political participation by most black people and many poor white people began to decrease. Between 1890 and 1910, ten of the eleven former Confederate states, beginning with Mississippi, passed new constitutions or amendments that effectively disenfranchised most black people and tens of thousands of poor white people through a combination of poll taxes, literacy and comprehension tests, and residency and record-keeping requirements. Grandfather clauses temporarily permitted some illiterate white people to vote but gave no relief to most black people. Voter turnout dropped dramatically through the South as a result of these measures. In Louisiana, by 1900, black voters were reduced to 5,320 on the rolls, although they comprised the majority of the state's population. By 1910, only 730 black people were registered, less than 0.5% of eligible black men. "In 27 of the state's 60 parishes, not a single black voter was registered any longer; in 9 more parishes, only one black voter was." The cumulative effect in North Carolina meant that black voters were eliminated from voter rolls during the period from 1896 to 1904. The growth of their thriving middle class was slowed. In North Carolina and other Southern states, black people suffered from being made invisible in the political system: "[W]ithin a decade of disfranchisement, the white supremacy campaign had erased the image of the black middle class from the minds of white North Carolinians." In Alabama, tens of thousands of poor whites were also disenfranchised, although initially legislators had promised them they would not be affected adversely by the new restrictions. Those who could not vote were not eligible to serve on juries and could not run for local offices. They effectively disappeared from political life, as they could not influence the state legislatures, and their interests were overlooked. While public schools had been established by Reconstruction legislatures for the first time in most Southern states, those for black children were consistently underfunded compared to schools for white children, even when considered within the strained finances of the postwar South where the decreasing price of cotton kept the agricultural economy at a low. Like schools, public libraries for black people were underfunded, if they existed at all, and they were often stocked with secondhand books and other resources. These facilities were not introduced for African Americans in the South until the first decade of the 20th century. Throughout the Jim Crow era, libraries were only available sporadically. Prior to the 20th century, most libraries established for African Americans were school-library combinations. Many public libraries for both European-American and African-American patrons in this period were founded as the result of middle-class activism aided by matching grants from the Carnegie Foundation. In some cases, progressive measures intended to reduce election fraud, such as the Eight Box Law in South Carolina, acted against black and white voters who were illiterate, as they could not follow the directions. While the separation of African Americans from the white general population was becoming legalized and formalized during the Progressive Era (1890s–1920s), it was also becoming customary. Even in cases in which Jim Crow laws did not expressly forbid black people from participating in sports or recreation, a segregated culture had become common. In the Jim Crow context, the presidential election of 1912 was steeply slanted against the interests of African Americans. Most black Americans still lived in the South, where they had been effectively disfranchised, so they could not vote at all. While poll taxes and literacy requirements banned many poor or illiterate people from voting, these stipulations frequently had loopholes that exempted European Americans from meeting the requirements. In Oklahoma, for instance, anyone qualified to vote before 1866, or related to someone qualified to vote before 1866 (a kind of "grandfather clause"), was exempted from the literacy requirement; but the only men who had the franchise before that year were white or European-American. European Americans were effectively exempted from the literacy testing, whereas black Americans were effectively singled out by the law. Woodrow Wilson was a Democrat elected from New Jersey, but he was born and raised in the South, and was the first Southern-born president of the post-Civil War period. He appointed Southerners to his Cabinet. Some quickly began to press for segregated workplaces, although the city of Washington, D.C., and federal offices had been integrated since after the Civil War. In 1913, Secretary of the Treasury William Gibbs McAdoo – an appointee of the President – was heard to express his opinion of black and white women working together in one government office: "I feel sure that this must go against the grain of the white women. Is there any reason why the white women should not have only white women working across from them on the machines?" The Wilson administration introduced segregation in federal offices, despite much protest from African-American leaders and white progressive groups in the north and midwest. He appointed segregationist Southern politicians because of his own firm belief that racial segregation was in the best interest of black and European Americans alike. At the Great Reunion of 1913 at Gettysburg, Wilson addressed the crowd on July 4, the semi-centennial of Abraham Lincoln's declaration that "all men are created equal": How complete the union has become and how dear to all of us, how unquestioned, how benign and majestic, as state after state has been added to this, our great family of free men! In sharp contrast to Wilson, a Washington Bee editorial wondered if the "reunion" of 1913 was a reunion of those who fought for "the extinction of slavery" or a reunion of those who fought to "perpetuate slavery and who are now employing every artifice and argument known to deceit" to present emancipation as a failed venture. Historian David W. Blight observed that the "Peace Jubilee" at which Wilson presided at Gettysburg in 1913 "was a Jim Crow reunion, and white supremacy might be said to have been the silent, invisible master of ceremonies". In Texas, several towns adopted residential segregation laws between 1910 and the 1920s. Legal strictures called for segregated water fountains and restrooms. The exclusion of African Americans also found support in the Republican Lily-white movement. Historical development The Civil Rights Act of 1875, introduced by Charles Sumner and Benjamin Butler, stipulated a guarantee that everyone, regardless of race, color, or previous condition of servitude, was entitled to the same treatment in public accommodations, such as inns, public transportation, theaters, and other places of recreation. This Act had little effect in practice. An 1883 Supreme Court decision ruled that the act was unconstitutional in some respects, saying Congress was not afforded control over private persons or corporations. With white southern Democrats forming a solid voting bloc in Congress, due to having outsize power from keeping seats apportioned for the total population in the South (although hundreds of thousands had been disenfranchised), Congress did not pass another civil rights law until 1957. In 1887, Rev. William Henry Heard lodged a complaint with the Interstate Commerce Commission against the Georgia Railroad and Banking Company for discrimination, citing its provision of different cars for white and black/colored passengers. The company successfully appealed for relief on the grounds it offered "separate but equal" accommodation. In 1890, Louisiana passed a law requiring separate accommodations for colored and white passengers on railroads. Louisiana law distinguished between "white", "black" and "colored" (that is, people of mixed European and African ancestry). The law had already specified that black people could not ride with white people, but colored people could ride with white people before 1890. A group of concerned black, colored and white citizens in New Orleans formed an association dedicated to rescinding the law. The group persuaded Homer Plessy to test it; he was a man of color who was of fair complexion and one-eighth "Negro" in ancestry. In 1892, Plessy bought a first-class ticket from New Orleans on the East Louisiana Railway. Once he had boarded the train, he informed the train conductor of his racial lineage and took a seat in the whites-only car. He was directed to leave that car and sit instead in the "coloreds only" car. Plessy refused and was immediately arrested. The Citizens Committee of New Orleans fought the case all the way to the United States Supreme Court. They lost in Plessy v. Ferguson (1896), in which the Court ruled that "separate but equal" facilities were constitutional. The finding contributed to 58 more years of legalized discrimination against black and colored people in the United States. In 1908, Congress defeated an attempt to introduce segregated streetcars into the capital. White Southerners encountered problems in learning free labor management after the end of slavery, and they resented African Americans, who represented the Confederacy's Civil War defeat: "With white supremacy being challenged throughout the South, many whites sought to protect their former status by threatening African Americans who exercised their new rights." White Southerners used their power to segregate public spaces and facilities in law and reestablish social dominance over black people in the South. One rationale for the systematic exclusion of African Americans from southern public society was that it was for their own protection. An early 20th-century scholar suggested that allowing black people to attend white schools would mean "constantly subjecting them to adverse feeling and opinion", which might lead to "a morbid race consciousness". This perspective took anti-black sentiment for granted, because bigotry was widespread in the South after slavery became a racial caste system. Justifications for white supremacy were provided by scientific racism and negative stereotypes of African Americans. Social segregation, from housing to laws against interracial chess games, was justified as a way to prevent black men from having sex with white women and in particular the rapacious Black Buck stereotype. In 1944, Associate justice Frank Murphy introduced the word "racism" into the lexicon of U.S. Supreme Court opinions in Korematsu v. United States, 323 U.S. 214 (1944). In his dissenting opinion, Murphy stated that by upholding the forced relocation of Japanese Americans during World War II, the Court was sinking into "the ugly abyss of racism". This was the first time that "racism" was used in Supreme Court opinion (Murphy used it twice in a concurring opinion in Steele v Louisville & Nashville Railway Co 323 192 (1944) issued that day). Murphy used the word in five separate opinions, but after he left the court, "racism" was not used again in an opinion for two decades. It next appeared in the landmark decision of Loving v. Virginia, 388 U.S. 1 (1967). Numerous boycotts and demonstrations against segregation had occurred throughout the 1930s and 1940s. The National Association for the Advancement of Colored People (NAACP) had been engaged in a series of litigation cases since the early 20th century in efforts to combat laws that disenfranchised black voters across the South. Some of the early demonstrations achieved positive results, strengthening political activism, especially in the post-World War II years. Black veterans were impatient with social oppression after having fought for the United States and freedom across the world. In 1947 K. Leroy Irvis of Pittsburgh's Urban League, for instance, led a demonstration against employment discrimination by the city's department stores. It was the beginning of his own influential political career. After World War II, people of color increasingly challenged segregation, as they believed they had more than earned the right to be treated as full citizens because of their military service and sacrifices. The civil rights movement was energized by a number of flashpoints, including the 1946 police beating and blinding of World War II veteran Isaac Woodard while he was in U.S. Army uniform. In 1948 President Harry S. Truman issued Executive Order 9981, ending racial discrimination in the armed services. That same year, Silas Herbert Hunt enrolled in the University of Arkansas, effectively starting the desegregation of education in the South. As the civil rights movement gained momentum and used federal courts to attack Jim Crow statutes, the white-dominated governments of many of the southern states countered by passing alternative forms of resistance. Decline and removal Historian William Chafe has explored the defensive techniques developed inside the African American community to avoid the worst features of Jim Crow as expressed in the legal system, unbalanced economic power, and intimidation and psychological pressure. Chafe says "protective socialization by black people themselves" was created inside the community in order to accommodate white-imposed sanctions while subtly encouraging challenges to those sanctions. Known as "walking the tightrope", such efforts at bringing about change were only slightly effective before the 1920s. However, this did build the foundation for later generations to advance racial equality and de-segregation. Chafe argued that the places essential for change to begin were institutions, particularly black churches, which functioned as centers for community-building and discussion of politics. Additionally, some all-black communities, such as Mound Bayou, Mississippi, and Ruthville, Virginia, served as sources of pride and inspiration for black society as a whole. Over time, pushback and open defiance of the oppressive existing laws grew, until it reached a boiling point in the aggressive, large-scale activism of the 1950s civil rights movement. The NAACP Legal Defense Committee (a group that became independent of the NAACP) – and its lawyer, Thurgood Marshall – brought the landmark case Brown v. Board of Education of Topeka, 347 U.S. 483 (1954) before the U.S. Supreme Court under Chief Justice Earl Warren. In its pivotal 1954 decision, the Warren Court unanimously (9–0) overturned the 1896 Plessy decision. The Supreme Court found that legally mandated (de jure) public school segregation was unconstitutional. The decision had far-reaching social ramifications. Racial integration of all-white collegiate sports teams was high on the Southern agenda in the 1950s and 1960s. Involved were issues of equality, racism, and the alumni demand for the top players needed to win high-profile games. The Atlantic Coast Conference (ACC) of flagship state universities in the Southeast took the lead. First they started to schedule integrated teams from the North. Finally, ACC schools – typically under pressure from boosters and civil rights groups – integrated their teams. With an alumni base that dominated local and state politics, society and business, the ACC schools were successful in their endeavor – as Pamela Grundy argues, they had learned how to win: In 1955, Rosa Parks refused to give up her seat on a city bus to a white man in Montgomery, Alabama. This was not the first time this happened – for example, Parks was inspired by 15-year-old Claudette Colvin doing the same thing nine months earlier – but the Parks act of civil disobedience was chosen, symbolically, as an important catalyst in the growth of the post-1954 civil rights movement; activists built the Montgomery bus boycott around it, which lasted more than a year and resulted in desegregation of the privately run buses in the city. Civil rights protests and actions, together with legal challenges, resulted in a series of legislative and court decisions which contributed to undermining the Jim Crow system. The decisive action ending segregation came when Congress in bipartisan fashion overcame Southern filibusters to pass the Civil Rights Act of 1964 and the Voting Rights Act of 1965. A complex interaction of factors came together unexpectedly in the period 1954–1965 to make the momentous changes possible. The Supreme Court had taken the first initiative in Brown v. Board of Education (1954), declaring segregation of public schools unconstitutional. Enforcement was rapid in the North and border states, but was deliberately stopped in the South by the movement called Massive Resistance, sponsored by rural segregationists who largely controlled the state legislatures. Southern liberals, who counseled moderation, were shouted down by both sides and had limited impact. Much more significant was the civil rights movement, especially the Southern Christian Leadership Conference (SCLC) headed by Martin Luther King Jr. It largely displaced the old, much more moderate NAACP in taking leadership roles. King organized massive demonstrations, that seized massive media attention in an era when network television news was an innovative and universally watched phenomenon. SCLC, student activists and smaller local organizations staged demonstrations across the South. National attention focused on Birmingham, Alabama, where protesters (mostly young teenagers), faced off against Commissioner of Public Safety Bull Connor, Connor arrested 900 on one day alone. The next day Connor unleashed billy clubs, police dogs, and high-pressure water hoses to disperse and punish the young demonstrators with a brutality that horrified the nation. The brutality undermined the image of a modernizing progressive urban South. President John F. Kennedy, who had been calling for moderation, threatened to use federal troops to restore order in Birmingham. The result in Birmingham was compromise by which the new mayor opened the library, golf courses, and other city facilities to both races, against the backdrop of church bombings and assassinations. In summer 1963, there were 800 demonstrations in 200 southern cities and towns, with over 100,000 participants, and 15,000 arrests. In Alabama in June 1963, Governor George Wallace escalated the crisis by defying court orders to admit the first two black students to the University of Alabama. Kennedy responded by sending Congress a comprehensive civil rights bill, and ordered Attorney General Robert F. Kennedy to file federal lawsuits against segregated schools, and to deny funds for discriminatory programs. Martin Luther King launched a huge march on Washington in August 1963, bringing out 200,000 demonstrators in front of the Lincoln Memorial, at the time the largest political assembly in the nation's history. The Kennedy administration now gave full-fledged support to the civil rights movement, but powerful southern congressmen blocked any legislation. After Kennedy was assassinated, President Lyndon B. Johnson called for immediate passage of Kennedy's civil rights legislation as a memorial to the martyred president. Johnson formed a coalition with Northern Republicans that led to passage in the House, and with the help of Republican Senate leader Everett Dirksen with passage in the Senate early in 1964. For the first time in history, the southern filibuster was broken and the Senate finally passed its version on June 19 by vote of 73 to 27. The Civil Rights Act of 1964 was the most powerful affirmation of equal rights ever made by Congress. It guaranteed access to public accommodations such as restaurants and places of amusement, authorized the Justice Department to bring suits to desegregate facilities in schools, gave new powers to the Civil Rights Commission; and allowed federal funds to be cut off in cases of discrimination. Furthermore, racial, religious and gender discrimination was outlawed for businesses with 25 or more employees, as well as apartment houses. The South resisted until the last moment, but as soon as the new law was signed by President Johnson on July 2, 1964, it was widely accepted across the nation. There was only a scattering of diehard opposition, typified by restaurant owner Lester Maddox in Georgia. In January 1964, President Lyndon Johnson met with civil rights leaders. On January 8, during his first State of the Union address, Johnson asked Congress to "let this session of Congress be known as the session which did more for civil rights than the last hundred sessions combined." On June 21, civil rights workers Michael Schwerner, Andrew Goodman, and James Chaney disappeared in Neshoba County, Mississippi, where they were volunteering in the registration of African American voters as part of the Freedom Summer project. The disappearance of the three activists captured national attention and the ensuing outrage was used by Johnson and civil rights activists to build a coalition of northern and western Democrats and Republicans and push Congress to pass the Civil Rights Act of 1964. On July 2, 1964, Johnson signed the historic Civil Rights Act of 1964. It invoked the Commerce Clause to outlaw discrimination in public accommodations (privately owned restaurants, hotels, and stores, and in private schools and workplaces). This use of the Commerce Clause was upheld by the Warren Court in the landmark case Heart of Atlanta Motel v. United States 379 US 241 (1964). By 1965, efforts to break the grip of state disenfranchisement by education for voter registration in southern counties had been underway for some time, but had achieved only modest success overall. In some areas of the Deep South, white resistance made these efforts almost entirely ineffectual. The murder of the three voting-rights activists in Mississippi in 1964 and the state's refusal to prosecute the murderers, along with numerous other acts of violence and terrorism against black people, had gained national attention. Finally, the unprovoked attack on March 7, 1965, by county and state troopers on peaceful Alabama marchers crossing the Edmund Pettus Bridge en route from Selma to the state capital of Montgomery, persuaded the President and Congress to overcome Southern legislators' resistance to effective voting rights enforcement legislation. President Johnson issued a call for a strong voting rights law and hearings soon began on the bill that would become the Voting Rights Act. The Voting Rights Act of 1965 ended legally sanctioned state barriers to voting for all federal, state and local elections. It also provided for federal oversight and monitoring of counties with historically low minority voter turnout. Years of enforcement have been needed to overcome resistance, and additional legal challenges have been made in the courts to ensure the ability of voters to elect candidates of their choice. For instance, many cities and counties introduced at-large election of council members, which resulted in many cases of diluting minority votes and preventing election of minority-supported candidates. After passage of the act, Martin Luther King, Jr., began to turn his attentions to a fledgling Poor People's Campaign. His ill-fated proposal for an Economic Bills of Rights was met with hostility from southern Democrats as well as northern and southern Republicans in Congress. In 2013, the Roberts Court, in Shelby County v. Holder, removed the requirement established by the Voting Rights Act that Southern states needed Federal approval for changes in voting policies. Several states immediately made changes in their laws restricting voting access. Influence and aftermath The Jim Crow laws were factors that led to the Great Migration during the first half of the 20th century. Because job opportunities were very limited in the rural South, African Americans moved in great numbers to cities in Northeastern, Midwestern, and Western states to seek better lives. African American athletes faced much discrimination during the Jim Crow era with white opposition leading to their exclusion from most organized sporting competitions. The boxers Jack Johnson and Joe Louis (both of whom became world heavyweight boxing champions) and track and field athlete Jesse Owens (who won four gold medals at the 1936 Summer Olympics in Berlin) gained prominence during the era. In baseball, a color line instituted in the 1880s had informally barred black people from playing in the major leagues, leading to the development of the Negro leagues, which featured many famous players. A major breakthrough occurred in 1947, when Jackie Robinson was hired as the first African American to play in Major League Baseball; he permanently broke the color bar. Baseball teams continued to integrate in the following years, leading to the full participation of black baseball players in the Major Leagues in the 1960s.[citation needed] Although sometimes counted among Jim Crow laws of the South, statutes such as anti-miscegenation laws were also passed by other states. Anti-miscegenation laws were not repealed by the Civil Rights Act of 1964, but were declared unconstitutional by the U.S. Supreme Court (the Warren Court) in a unanimous ruling Loving v. Virginia (1967). Chief Justice Earl Warren wrote in the court opinion that "the freedom to marry, or not marry, a person of another race resides with the individual, and cannot be infringed by the State." The Sixth Amendment to the United States Constitution grants criminal defendants the right to a trial by a jury of their peers. While federal law required that convictions could only be granted by a unanimous jury for federal crimes, states were free to set their own jury requirements. All but two states, Oregon and Louisiana, opted for unanimous juries for conviction. Oregon and Louisiana, however, allowed juries of at least 10–2 to decide a criminal conviction. Louisiana's law was amended in 2018 to require a unanimous jury for criminal convictions, effective in 2019. Prior to that amendment, the law had been seen as a remnant of Jim Crow laws, because it allowed minority voices on a jury to be marginalized. In 2020, the Supreme Court found, in Ramos v. Louisiana, that unanimous jury votes are required for criminal convictions at state levels, thereby nullifying Oregon's remaining law, and overturning previous cases in Louisiana. In 1971, the U.S. Supreme Court (the Burger Court), in Swann v. Charlotte-Mecklenburg Board of Education, upheld desegregation busing of students to achieve integration. Interpretation of the Constitution and its application to minority rights continues to be controversial as Court membership changes. Observers such as Ian F. Lopez believe that in the 2000s, the Supreme Court has become more protective of the status quo. Mississippi Today discusses the present-day Jim Crow legacy of felony disenfranchisement, and states that part of Mississippi's 1890 constitution was not erased by the Civil Rights Movement during the 1960s. The article states the constitutional felony disenfranchisement clause "takes away – for life – the right to vote upon conviction for several low-level crimes, like theft and bribery, that the 1890 drafters felt would be mostly committed by Black people." In 2017, Ford Foundation Professor of Law James Whitman contended that, during sessions culminating in the Nuremberg Laws, Nazi officials such as Franz Gürtner and Bernhard Lösener discussed a memorandum by Heinrich Krieger, a former graduate student at the University of Arkansas. Krieger had published an article on "Principles of Indian [Native American] law" (1935) in the Washington Law Review, focusing on the Dawes Act and Indian Reorganization Act. The memorandum, based on research into the history of United States immigration and Jim Crow laws, became the basis for Krieger's Race Law in the United States (1936). Scholars such as Michael Livingston, while lauding Whitman's analysis of the memorandum and his comparisons between U.S. and German state-sponsored eugenics legislation, demanded more evaluation and evidence for any additional contentions. In 2023, Darren Walker, president of the Ford Foundation endowment for Whitman's chair, opined that "Henry Ford, our founder, was among the twentieth century's most virulent American antisemites. And yet, to me, our past confers a special obligation to engage, not to retreat – no matter the complications or the consequences." Remembrance Ferris State University in Big Rapids, Michigan, houses the Jim Crow Museum of Racist Memorabilia, an extensive collection of everyday items that promoted racial segregation or presented racial stereotypes of African Americans, for the purpose of academic research and education about their cultural influence. See also Footnotes Further reading External links |
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Contents China China,[h] officially the People's Republic of China (PRC),[i] is a country in East Asia. It is the second-most populous country after India, with a population exceeding 1.4 billion, representing 17% of the world's population. China borders fourteen countries by land[j] across an area of 9.6 million square kilometers (3,700,000 sq mi), making it the third-largest country by area.[k] The country is divided into 33 province-level divisions: 22 provinces,[l] 5 autonomous regions, 4 municipalities, and 2 semi-autonomous special administrative regions. Beijing is the capital, while Shanghai is the most populous city by urban area and largest financial center. The first humans in China arrived during the Paleolithic era. By the 2nd millennium BCE dynastic states had emerged in the Yellow River basin. The 8th–3rd centuries BCE saw a breakdown in the authority of the Zhou dynasty, accompanied by the emergence of administrative and military techniques, literature and philosophy. In 221 BCE, China was unified under an emperor, ushering in two millennia of imperial rule. Chinese achievements include the invention of gunpowder, paper, printing and the compass, the establishment of the Silk Road, and the building of the Great Wall. Chinese culture has flourished and has had a great influence on the region and beyond. China began to cede parts of the country in the 19th century, to European powers through a series of unequal treaties. The 1911 Revolution overthrew the Qing dynasty and the Republic of China was established the following year. The country was unstable and fragmented during the Warlord Era, this came to an end with the Northern Expedition conducted by the Kuomintang to reunify the country. The Chinese Civil War began in 1927, when Kuomintang forces purged members of the Chinese Communist Party (CCP). China was invaded by the Empire of Japan in 1937, leading the CCP and Kuomintang to form the Second United Front to fight the Japanese. The Second Sino-Japanese War ended in a Chinese victory; however, the CCP and the Kuomintang resumed their civil war. In 1949, the CCP proclaimed the People's Republic of China and forced the Kuomintang-led government to retreat to the island of Taiwan. The country was split, with both sides claiming to be the legitimate government. Following the implementation of land reforms, attempts by the CCP to realize communism failed: the Great Leap Forward was responsible for the Great Chinese Famine which resulted in millions of deaths, and the Cultural Revolution was a period of turmoil and persecution. The reform and opening up that began in 1978 moved the country away from a planned economy towards a market-based economy, spurring an economic boom. A movement for political liberalization stalled after the 1989 Tiananmen Square protests and massacre. Since 1949, China has been a unitary communist state with the CCP as its sole ruling party. It is one of the five permanent members of the UN Security Council and a member of numerous multilateral and regional organizations. Making up around one-fifth of the world's economy, China is the second-wealthiest country in the world, with the Chinese economy being the largest when adjusted for PPP. However, China ranks poorly in measures of democracy and human rights. China has been one of the fastest-growing modern economies and is the world's largest manufacturer and exporter, as well as the second-largest importer. China is a nuclear-weapon state with the world's largest standing army and the second-largest defense budget. It is described as either a potential or established superpower due to its influence in the fields of geopolitics, technology, manufacturing, economics and culture. China is known for its cuisine and culture. It is a megadiverse country, and has 60 UNESCO World Heritage Sites. Etymology The word "China" has been used in English since the 16th century; however, it was not used by the Chinese themselves during this period. Its origin has been traced through Portuguese, Malay, and Persian back to the Sanskrit word Cīna, used in ancient India. "China" appears in Richard Eden's 1555 translation[m] of the 1516 journal of the Portuguese explorer Duarte Barbosa.[n] Barbosa's usage was derived from Persian Chīn (چین), which in turn derived from Sanskrit Cīna (चीन). The origin of the Sanskrit word is a matter of debate. Cīna was first used in early Hindu scripture, including the Mahabharata (3rd century BCE–4th century CE) and the Laws of Manu (2nd century BCE–2nd century CE). In 1655, Martino Martini suggested that the word China is derived ultimately from the name of the Qin dynasty (221–206 BCE) or the prior state of Qin. Although use in Indian sources precedes this dynasty, though not the state, this derivation is still given in various sources. Alternative suggestions include the names for Yelang and the Jing or Chu state. The official name of the modern state is the "People's Republic of China" (simplified Chinese: 中华人民共和国; traditional Chinese: 中華人民共和國; pinyin: Zhōnghuá rénmín gònghéguó). The shorter form is "China" (中国; 中國; Zhōngguó), from zhōng ('central') and guó ('state'), a term which developed under the Western Zhou dynasty in reference to its royal demesne.[o][p] It was used in official documents as an synonym for the state under the Qing. The name Zhongguo is also translated as 'Middle Kingdom' in English. China is sometimes referred to as mainland China or "the Mainland" when distinguishing it from the Republic of China or the PRC's Special Administrative Regions. History Archaeological evidence suggests that early hominids inhabited China 2.25 million years ago. The hominid fossils of Peking Man, a Homo erectus who used fire, have been dated to between 680,000 and 780,000 years ago. The fossilized teeth of Homo sapiens (dated to 125,000–80,000 years ago) have been discovered in Fuyan Cave. Chinese proto-writing existed in Jiahu around 6600 BCE, at Damaidi around 6000 BCE, Dadiwan from 5800 to 5400 BCE, and Banpo dating from the 5th millennium BCE. Some scholars have suggested that the Jiahu symbols (7th millennium BCE) constituted the earliest Chinese writing system. According to traditional Chinese historiography, the Xia dynasty was established during the late 3rd millennium BCE, marking the beginning of the dynastic cycle that was understood to underpin China's entire political history. In the modern era, the Xia's historicity came under increasing scrutiny, in part due to the earliest known attestation of the Xia being written millennia after the date given for their collapse. In 1958, archaeologists discovered sites belonging to the Erlitou culture that existed during the early Bronze Age; they have since been characterized as the remains of the historical Xia, but this conception is often rejected. The Shang dynasty that traditionally succeeded the Xia is the earliest for which there are both contemporary written records and undisputed archaeological evidence. The Shang ruled much of the Yellow River valley until the 11th century BCE, with the earliest hard evidence dated c. 1300 BCE. The oracle bone script, attested from c. 1250 BCE but generally assumed to be considerably older, represents the oldest known form of written Chinese, and is the direct ancestor of modern Chinese characters. The Shang were overthrown by the Zhou, who ruled between the 11th and 5th centuries BCE, though the centralized authority of Son of Heaven was slowly eroded by fengjian lords. Some principalities eventually emerged from the weakened Zhou and continually waged war with each other during the 300-year Spring and Autumn period. By the time of the Warring States period of the 5th–3rd centuries BCE, there were seven major powerful states left. The Warring States period ended in 221 BCE after the state of Qin conquered the other six states, reunited China and established the dominant order of autocracy. Qin Shi Huang proclaimed himself the Emperor of the Qin dynasty, becoming the first emperor of a unified China. He enacted legalist reforms, notably the standardization of Chinese characters, measurements, road widths, and currency. His dynasty also conquered the Yue tribes in Guangxi, Guangdong, and Northern Vietnam. The Qin dynasty lasted only fifteen years, falling soon after the Qin Shi Huang's death. Following widespread revolts during which the imperial library was burned,[q] the Han dynasty emerged to rule China between 206 BCE and 220 CE, creating a cultural identity among its populace still remembered in the ethnonym of the modern Han Chinese. The Han expanded the empire's territory considerably, with military campaigns reaching Central Asia, Mongolia, Korea, and Yunnan, and the recovery of Guangdong and northern Vietnam from Nanyue. Han involvement in Central Asia and Sogdia helped establish the land route of the Silk Road, replacing the earlier path over the Himalayas to India. Han China gradually became the largest economy of the ancient world. Despite the Han's initial decentralization and the official abandonment of the Qin philosophy of Legalism in favor of Confucianism, Qin's legalist institutions and policies continued to be employed by the Han government and its successors. After the end of the Han dynasty, a period of strife known as Three Kingdoms followed, at the end of which Wei was swiftly overthrown by the Jin dynasty. The Jin fell to civil war upon the ascension of the developmentally disabled Emperor Hui; the Five Barbarians then rebelled and ruled northern China as the Sixteen States. The Xianbei unified them as the Northern Wei, whose Emperor Xiaowen reversed his predecessors' apartheid policies and enforced a drastic sinification on his subjects. In the south, the general Liu Yu secured the abdication of the Jin in favor of the Liu Song. The various successors of these states became known as the Northern and Southern dynasties, with the two areas finally reunited by the Sui in 589. The Sui restored the Han to power through China, reformed its agriculture, economy and imperial examination system, constructed the Grand Canal, and patronized Buddhism. However, they fell quickly when their conscription for public works and a failed war in northern Korea provoked widespread unrest. Under the succeeding Tang and Song dynasties, Chinese economy, technology, and culture entered a golden age. The Tang dynasty retained control of the Western Regions and the Silk Road, which brought traders to as far as Mesopotamia and the Horn of Africa, and made the capital Chang'an a cosmopolitan urban center. However, it was devastated and weakened by the An Lushan rebellion in the 8th century. In 907, the Tang disintegrated completely when the local military governors became ungovernable. The Song dynasty ended the separatist situation in 960, leading to a balance of power between the Song and the Liao dynasty. The Song was the first government in world history to issue paper money and the first Chinese polity to establish a permanent navy which was supported by the developed shipbuilding industry along with the sea trade. Between the 10th and 11th century CE, the population of China doubled to around 100 million people, mostly because of the expansion of rice cultivation in central and southern China, and the production of abundant food surpluses. The Song dynasty also saw a revival of Confucianism, in response to the growth of Buddhism during the Tang, and a flourishing of philosophy and the arts, as landscape art and porcelain were brought to new levels of complexity. However, the military weakness of the Song army was observed by the Jin dynasty. In 1127, Emperor Emeritus Huizong, Emperor Qinzong and the capital Bianjing were captured during the Jin–Song wars. The remnants of the Song retreated to southern China and reestablished the Song at Jiankang. The Mongol conquest of China began in 1205 with the campaigns against Western Xia by Genghis Khan, who also invaded Jin territories. In 1271, the Mongol leader Kublai Khan established the Yuan dynasty, which conquered the last remnant of the Song dynasty in 1279. Before the Mongol invasion, the population of Song China was 120 million citizens; this was reduced to 60 million by the time of the census in 1300. A peasant named Zhu Yuanzhang overthrew the Yuan in 1368 and founded the Ming dynasty as the Hongwu Emperor. Under the Ming dynasty, China enjoyed another golden age, developing one of the strongest navies in the world and a rich and prosperous economy amid a flourishing of art and culture. It was during this period that admiral Zheng He led the Ming treasure voyages throughout the Indian Ocean, reaching as far as East Africa. In the early Ming dynasty, China's capital was moved from Nanjing to Beijing. With the budding of capitalism, philosophers such as Wang Yangming critiqued and expanded Neo-Confucianism with concepts of individualism and equality of four occupations. The scholar-official stratum became a supporting force of industry and commerce in the tax boycott movements, which, together with the famines and defense against Japanese invasions of Korea (1592–1598) and Later Jin incursions led to an exhausted treasury. In 1644, Beijing was captured by a coalition of peasant rebel forces led by Li Zicheng. The Chongzhen Emperor committed suicide when the city fell. The Manchu Qing dynasty, then allied with Ming dynasty general Wu Sangui, overthrew Li's short-lived Shun dynasty and subsequently seized control of Beijing, which became the new capital of the Qing dynasty. The Qing dynasty, which lasted from 1644 until 1912, was the last imperial dynasty of China. The transition from Ming to Qing (1618–1683) cost 25 million lives, but the Qing appeared to have restored China's imperial power and inaugurated another flowering of the arts. After the Southern Ming ended, the further conquest of the Dzungar Khanate added Mongolia, Tibet and Xinjiang to the empire. Meanwhile, China's population growth resumed and shortly began to accelerate. It is commonly agreed that pre-modern China's population experienced two growth spurts, one during the Northern Song period (960–1127), and other during the Qing period (around 1700–1830). By the High Qing era China was possibly the most commercialized country in the world, and imperial China experienced a second commercial revolution by the end of the 18th century. On the other hand, the centralized autocracy was strengthened in part to suppress anti-Qing sentiment with the policy of valuing agriculture and restraining commerce, like the Haijin during the early Qing period and ideological control as represented by the literary inquisition, causing some social and technological stagnation. In the mid-19th century, the Opium Wars with Britain and France forced China to pay compensation, open treaty ports, allow extraterritoriality for foreign nationals, and cede Hong Kong to the British under the 1842 Treaty of Nanking, the first of what have been termed the unequal treaties. The First Sino-Japanese War (1894–1895) resulted in Qing China's loss of influence in the Korean Peninsula, as well as the cession of Taiwan to Japan. The Qing dynasty also began experiencing internal unrest in which tens of millions of people died, especially in the White Lotus Rebellion, the failed Taiping Rebellion that ravaged southern China in the 1850s and 1860s and the Dungan Revolt (1862–1877) in the northwest. The initial success of the Self-Strengthening Movement of the 1860s was frustrated by a series of military defeats in the 1880s and 1890s. In the 19th century, the great Chinese diaspora began. Losses due to emigration were added to by conflicts and catastrophes such as the Northern Chinese Famine of 1876–1879, in which between 9 and 13 million people died. The Guangxu Emperor drafted a reform plan in 1898 to establish a modern constitutional monarchy, but these plans were thwarted by the Empress Dowager Cixi. The ill-fated anti-foreign Boxer Rebellion of 1899–1901 further weakened the dynasty. Although Cixi sponsored a program of reforms known as the late Qing reforms, the Xinhai Revolution of 1911 ended the Qing dynasty. Puyi, the last Emperor, abdicated in 1912. On 1 January 1912, the Republic of China (ROC) was established, and Sun Yat-sen of the Kuomintang was proclaimed provisional president. In 1912, the presidency was given to Yuan Shikai, a former Qing general who in 1915 proclaimed himself Emperor of China. In the face of popular condemnation and opposition from his own Beiyang Army, he was forced to re-establish the republic in 1916. After Yuan's death in 1916, China was politically fragmented. Its Beijing-based government was internationally recognized but virtually powerless; regional warlords controlled most of its territory. During this period, China participated in World War I and saw a far-reaching popular uprising called the May Fourth Movement. In the late 1920s, the Kuomintang under Chiang Kai-shek reunified most the country through the Northern Expedition. The Kuomintang moved the nation's capital to Nanjing and implemented "political tutelage", an intermediate stage of political development outlined in Sun Yat-sen's Three Principles of the People program for transforming China into a modern democratic state. The Kuomintang briefly allied with the Chinese Communist Party (CCP) during the Northern Expedition, though the alliance broke down in 1927 after Chiang violently suppressed the CCP and other leftists in Shanghai, marking the beginning of the Chinese Civil War. CCP forces in Jiangxi were wiped out by the Nationalist government in 1934, leading the CCP to initiate the Long March and relocate to Yan'an in Shaanxi. It would be the base of the communists before major combat in the Chinese Civil War ended in 1949. In 1931, Japan invaded and occupied Manchuria. Japan invaded other parts of China in 1937, precipitating the Second Sino-Japanese War (1937–1945), a theater of World War II. The war forced an uneasy alliance between the Kuomintang and the CCP. Japanese forces committed numerous war atrocities against the civilian population; as many as 20 million Chinese civilians died. An estimated 40,000 to over 300,000 Chinese were massacred in Nanjing alone during the Japanese occupation. The Republic of China, along with the UK, the United States, and the Soviet Union, were recognized as the Allied "Big Four" in the Declaration by United Nations. Along with the other three great powers, China was one of the four major Allies of World War II, and was later considered one of the primary victors in the war. After the surrender of Japan in 1945, China emerged victorious but war-ravaged and financially drained. Taiwan, along with the Penghu, were handed over to ROC control; however, the validity of this handover is controversial. In 1946, fighting between CCP and KMT forces broke out and the country resumed a state of civil war that lasted more than three years. Constitutional rule was established in 1947, but because of the ongoing war, many provisions of the ROC constitution were never implemented in mainland China. By 1949, the CCP took control of most of mainland China, and the ROC government retreated to Taiwan. On 1 October 1949, CCP Chairman Mao Zedong formally proclaimed the People's Republic of China. In 1950, the PRC captured Hainan from the ROC and annexed Tibet. The CCP consolidated its popularity among the peasants through the Land Reform Movement, which included the state-tolerated executions of between 1 and 2 million landlords by peasants and former tenants. Though the PRC initially allied closely with the Soviet Union, the relations between the two communist nations gradually deteriorated, leading China to develop an independent industrial system and its own nuclear weapons. The Chinese population increased from 550 million in 1950 to 900 million in 1974. However, the Great Leap Forward, a massive industrialization project, resulted in an estimated 15 to 55 million deaths between 1959 and 1961, mostly from starvation. In 1964, China detonated its first atomic bomb. In 1966, Mao and his allies launched the Cultural Revolution, sparking a decade of political recrimination and social upheaval that lasted until Mao's death in 1976. After Mao's death, the Gang of Four were arrested by Hua Guofeng. The Cultural Revolution was rebuked, with millions rehabilitated. Deng Xiaoping took power in 1978, and started the reform and opening up, instituting large-scale political and economic reforms to transition away from planned economy. China adopted its current constitution on 4 December 1982. In 1989, there were protests such those in Tiananmen Square, and then throughout the entire nation. Jiang Zemin was elevated to become the CCP general secretary, becoming the paramount leader. China's economy grew sevenfold during Jiang's tenure. British Hong Kong and Portuguese Macau returned to China in 1997 and 1999, respectively, as special administrative regions under the principle of one country, two systems. In 2002, Hu Jintao succeeded Jiang as the general secretary. Under Hu, China maintained its high rate of economic growth, overtaking the United Kingdom, France, Germany and Japan to become the world's second-largest economy. However, the growth also severely impacted the country's resources and environment, and caused major social displacement. Xi Jinping succeeded Hu as paramount leader in 2012. Shortly after his ascension to power, Xi launched a vast anti-corruption crackdown, that prosecuted more than 2 million officials by 2022. During his tenure, Xi has consolidated power unseen since the initiation of economic and political reforms. Geography China's landscape is vast and diverse, ranging from the Gobi and Taklamakan Deserts in the arid north to the subtropical forests in the wetter south. The Himalaya, Karakoram, Pamir and Tian Shan mountain ranges separate China from much of South and Central Asia. The Yangtze and Yellow Rivers, the third- and sixth-longest in the world, respectively, run from the Tibetan Plateau to the densely populated eastern seaboard. China's coastline along the Pacific Ocean is 14,500 km (9,000 mi) long and is bounded by the Bohai, Yellow, East China and South China seas. China connects through the Kazakh border to the Eurasian Steppe. The territory of China lies between latitudes 18° and 54° N, and longitudes 73° and 135° E. The geographical center of China is marked by the Center of the Country Monument at 35°50′40.9″N 103°27′7.5″E / 35.844694°N 103.452083°E / 35.844694; 103.452083 (Geographical center of China). China's landscapes vary significantly across its vast territory. In the east, along the shores of the Yellow Sea and the East China Sea, there are extensive and densely populated alluvial plains, while on the edges of the Inner Mongolian plateau in the north, broad grasslands predominate. Southern China is dominated by hills and low mountain ranges, while the central-east hosts the deltas of China's two major rivers, the Yellow River and the Yangtze River. Other major rivers include the Xi, Mekong, Brahmaputra and Amur. To the west sit major mountain ranges, most notably the Himalayas. High plateaus feature among the more arid landscapes of the north, such as the Taklamakan and the Gobi Desert. The world's highest point, Mount Everest (8,848 m), lies on the Sino-Nepalese border. The country's lowest point, and the world's third-lowest, is the dried lake bed of Ayding Lake (−154 m) in the Turpan Depression. Despite spanning the equivalent of five geographical time zones (from UTC+5 to UTC+9), China uses a single national time zone, China Standard Time (UTC+8). This uniform time policy was adopted in 1949. China's climate is mainly dominated by dry seasons and wet monsoons, which lead to pronounced temperature differences between winter and summer. In the winter, northern winds coming from high-latitude areas are cold and dry; in summer, southern winds from coastal areas at lower latitudes are warm and moist. A major environmental issue in China is the continued expansion of its deserts, particularly the Gobi Desert. Although barrier tree lines planted since the 1970s have reduced the frequency of sandstorms, prolonged drought and poor agricultural practices have resulted in dust storms plaguing northern China each spring, which then spread to other parts of East Asia, including Japan and Korea. Water quality, erosion, and pollution control have become important issues in China's relations with other countries. Melting glaciers in the Himalayas could potentially lead to water shortages for hundreds of millions of people. According to academics, in order to limit climate change in China to 1.5 °C (2.7 °F) electricity generation from coal in China without carbon capture must be phased out by 2045. Official government statistics about Chinese agricultural productivity are considered unreliable, due to exaggeration of production at subsidiary government levels. Much of China has a climate very suitable for agriculture and the country has been the world's largest producer of rice, wheat, tomatoes, eggplant, grapes, watermelon, spinach, and many other crops. In 2021, 12 percent of global permanent meadows and pastures belonged to China, as well as 8% of global cropland. China is one of 17 megadiverse countries, lying in two of the world's major biogeographic realms: the Palearctic and the Indomalayan. By one measure, China has over 34,687 species of animals and vascular plants, making it the third-most biodiverse country in the world, after Brazil and Colombia. The country is a party to the Convention on Biological Diversity; its National Biodiversity Strategy and Action Plan was received by the convention in 2010. China is home to at least 551 species of mammals (the third-highest in the world), 1,221 species of birds (eighth), 424 species of reptiles (seventh) and 333 species of amphibians (seventh). Wildlife in China shares habitat with, and bears acute pressure from, one of the world's largest population of humans. At least 840 animal species are threatened, vulnerable or in danger of local extinction, due mainly to human activity such as habitat destruction, pollution and poaching for food, fur and traditional Chinese medicine. Endangered wildlife is protected by law, and as of 2019[update], the country has over 2,750 nature reserves, covering a total area of 1,470,000 km2 (570,000 sq mi), 15 percent of China's total land area. Most wild animals have been eliminated from the core agricultural regions of east and central China, but they have fared better in the mountainous south and west. The Baiji was confirmed extinct on 12 December 2006. China has over 32,000 species of vascular plants, and is home to a variety of forest types. Cold coniferous forests predominate in the north of the country, supporting animal species such as moose and Asian black bear, along with over 120 bird species. The understory of moist conifer forests may contain thickets of bamboo. In higher montane stands of juniper and yew, the bamboo is replaced by rhododendrons. Subtropical forests, which are predominate in central and southern China, support a high density of plant species including numerous rare endemics. Tropical and seasonal rainforests, though confined to Yunnan and Hainan, contain a quarter of all the animal and plant species found in China. China has over 10,000 recorded species of fungi. In the early 2000s, China has suffered from environmental deterioration and pollution due to its rapid pace of industrialization. Environmental regulations fairly stringent, though they are poorly enforced, frequently disregarded in favor of rapid economic development. China has the second-highest death toll because of air pollution, after India, with approximately 1 million deaths. Although China ranks as the highest CO2 emitting country, it only emits 8 tons of CO2 per capita, significantly lower than developed countries such as the United States (16.1), Australia (16.8) and South Korea (13.6). Greenhouse gas emissions by China are the world's largest. 90.4% of China's national surface water was graded suitable for human consumption by the Ministry of Ecology and Environment in 2024. China has prioritized clamping down on pollution, bringing a significant decrease in air pollution in the 2010s. In 2020, the Chinese government announced its aims for the country to reach its peak emissions levels before 2030, and achieve carbon neutrality by 2060 in line with the Paris Agreement, which, according to Climate Action Tracker, would lower the expected rise in global temperature by 0.2–0.3 degrees – "the biggest single reduction ever estimated by the Climate Action Tracker". According to China's government, the forest coverage of the country grew from 10% of the overall territory in 1949 to 25% in 2024. China is the world's leading investor in renewable energy and its commercialization, with $546 billion invested in 2022; it the world's leading manufacturer and innovator of renewable energy technologies and invests heavily in local-scale renewable energy projects. Long heavily relying on non-renewable energy sources such as coal, China's adaptation of renewable energy has increased significantly in recent years. In 2024, 58.2% of China's electricity came from coal (largest producer in the world), 13.5% from hydroelectric power (largest), 9.8% from wind (largest), 8.3% from solar energy (largest), 4.4% from nuclear energy (second-largest), 3% from natural gas (fifth-largest), and 2.1% from bioenergy (largest); in total, 38% of China's energy came from clean energy sources. Despite its emphasis on renewables, China remains deeply connected to global oil markets and next to India, has been the largest importer of Russian crude oil in 2022. China is the second-largest country by land area after Russia, and the third- or fourth-largest country by total area.[r] China's total area is generally stated as being approximately 9,600,000 km2 (3,700,000 sq mi). Specific area figures range from 9,572,900 km2 (3,696,100 sq mi) according to the Encyclopædia Britannica, to 9,596,961 km2 (3,705,407 sq mi) according to the UN Demographic Yearbook, and The World Factbook. China has the longest combined land border in the world, measuring 22,117 km (13,743 mi) and its coastline covers approximately 14,500 km (9,000 mi) from the mouth of the Yalu River (Amnok River) to the Gulf of Tonkin. China borders 14 nations and covers the bulk of East Asia, bordering Vietnam, Laos, and Myanmar in Southeast Asia; India, Bhutan, Nepal, Pakistan[s] and Afghanistan in South Asia; Tajikistan, Kyrgyzstan and Kazakhstan in Central Asia; and Russia, Mongolia, and North Korea in Inner Asia and Northeast Asia. It is narrowly separated from Bangladesh and Thailand to the southwest and south, and has several maritime neighbors such as Japan, Philippines, Malaysia, and Indonesia. China has resolved its land borders with 12 out of 14 neighboring countries, having pursued substantial compromises in most of them. China currently has a disputed land border with India and Bhutan. China is additionally involved in maritime disputes with multiple countries over territory in the East and South China Seas, such as the Senkaku Islands, which it refers as the Diaoyu Islands, and the entirety of South China Sea Islands. Government and politics The People's Republic of China is a communist state under the absolute leadership of the Chinese Communist Party (CCP). The CCP is officially guided by socialism with Chinese characteristics, which it describes as Marxism adapted to Chinese circumstances. The Chinese constitution states that the PRC "is a socialist state governed by a people's democratic dictatorship that is led by the working class and based on an alliance of workers and peasants", and that "the defining feature of socialism with Chinese characteristics is the leadership of the Chinese Communist Party." The PRC officially characterizes itself as a democracy—more specifically, a whole-process people's democracy—that is organized around the Leninist principle of democratic centralism. However, the country is commonly described as an authoritarian one-party state and a dictatorship, with some of the world's heaviest restrictions in many civil areas, most notably against freedom of the press, freedom of assembly, free formation of social organizations, freedom of religion and freedom of the Internet. China has consistently been ranked amongst the lowest as an "authoritarian regime" by the Economist Intelligence Unit's Democracy Index, ranking at 145th out of 167 countries in 2024. Other sources suggest that terming China as "authoritarian" does not sufficiently account for the multiple consultation mechanisms that exist in the Chinese governmental system. The CCP is the founding and sole ruling party of the PRC. According to the CCP constitution, the Party's highest body is the National Congress held every five years. The National Congress elects the Central Committee, which convenes at least once a year. The Central Committee then elects the party's Politburo, Politburo Standing Committee and the general secretary (party leader), the top leadership of the country. The general secretary holds ultimate power and authority over party and state and serves as the paramount leader of China. The current general secretary is Xi Jinping, who took office on 15 November 2012. The National Congress also elects the Central Commission for Discipline Inspection, the CCP's supreme disciplinary organ. The government in China is under the sole control of the CCP. The CCP controls appointments in government bodies, with most senior government officials being CCP members. The CCP maintains committees in the each level of government. At the local level, the CCP committee of a subdivision and its secretary outranks the local government and its head; CCP committee of a provincial division and its secretary outranks the provincial people's government and the governor while the CCP committee of a city and its secretary outranks the municipal people's government the mayor. The National People's Congress (NPC), with nearly 3,000-members, as the supreme organ of state power holds the unified powers of the state, creating a system where all state organs including the presidency, the State Council, the State Central Military Commission, the Supreme People's Court, the Supreme People's Procuratorate, and the National Supervisory Commission are subject to its oversight through democratic centralism. However, observers often describe it as a "rubber stamp" body. The NPC meets annually, while the NPC Standing Committee, around 175 members elected from NPC delegates, meets every couple of months. Elections are indirect and not pluralistic, with nominations at all levels being controlled by the CCP by law. The NPC is dominated by the CCP, with another eight minor parties having nominal representation under the condition of upholding CCP leadership. The NPC elects the president, who is the ceremonial state representative. The incumbent president is Xi Jinping, who is also the general secretary of the CCP and the chairman of the Central Military Commission, making him China's paramount leader and supreme commander of the armed forces. The premier is the head of government, with Li Qiang being the incumbent. The premier is officially nominated by the president and then elected by the NPC, and has generally been either the second- or third-ranking member of the Politburo Standing Committee (PSC). The premier presides over the State Council, China's cabinet, composed of four vice premiers, state councillors, and the heads of ministries and commissions. The Chinese People's Political Consultative Conference (CPPCC) is a political advisory body that is critical in China's "united front" system, which aims to gather non-CCP voices to support the CCP. Similar to the people's congresses, CPPCCs have subdivisions; the National Committee of the CPPCC is chaired by Wang Huning, the fourth-ranking member of the PSC. The governance of China is characterized by a high degree of political centralization but significant economic decentralization.: 7 Policy instruments or processes are often tested locally before being applied more widely, resulting in a policy that involves experimentation and feedback.: 14 Generally, central government leadership refrains from drafting specific policies, instead using the informal networks and site visits to affirm or suggest changes to the direction of local policy experiments or pilot programs.: 71 The typical approach is that central government leadership begins drafting formal policies, law, or regulations after policy has been developed at local levels.: 71 The PRC is constitutionally a unitary state divided into 23 provinces,[t] five autonomous regions (each with a designated minority group), four direct-administered municipalities—collectively referred to as "mainland China"—as well as the special administrative regions (SARs) of Hong Kong and Macau. The PRC regards the island of Taiwan as its Taiwan Province, Kinmen and Matsu as a part of Fujian Province, and islands the ROC controls in the South China Sea as a part of Hainan Province and Guangdong Province, though all these territories are governed by the Republic of China (ROC). Geographically, all 31 provincial divisions of mainland China can be grouped into six regions: North China, East China, Southwestern China, South Central China, Northwestern China, and Northeast China. Taiwan (台湾省), governed by the Republic of China The PRC has diplomatic relations with 179 United Nations member-states and maintains embassies in 174. As of 2024[update], China has the largest diplomatic networks of any country in the world. China is of the five permanent members of the United Nations Security Council. It is a member of intergovernmental organizations including the G20, the Shanghai Cooperation Organisation, the BRICS, the East Asia Summit, and the APEC. China is also a former member and leader of the Non-Aligned Movement and still considers itself an advocate for developing countries. China is widely described as either a potential or established superpower, due to its influence in the fields of geopolitics, technology, manufacturing, economics and culture. Much of current Chinese foreign policy is officially based on Premier Zhou Enlai's Five Principles of Peaceful Coexistence, as well as by the concept of "harmony without uniformity", which encourages diplomatic relations between states despite ideological differences. Per its policy of non-alignment, China maintains no military alliances except its defense treaty with North Korea. Most countries have switched recognition from the ROC to the PRC since the latter replaced the former in the UN in 1971. The PRC officially maintains the one China principle: the view that there is only one sovereign state with the name "China"—represented by the PRC—and that Taiwan is an integral part of China. The unique status of Taiwan has led to countries formally recognizing the PRC to maintain unique "one China policies" that differ from each other; some countries explicitly recognize the PRC's claim over Taiwan, while others, including the U.S. and Japan, only acknowledge the claim. China has a close political, economic and military relationship with Russia, and the two states often vote in unison in the UN Security Council. China has provided Russia with economic, technological, and diplomatic support during the Russo-Ukrainian war. China's relationship with the United States is complex, and includes deep trade ties but significant political differences. Since the early 2000s, China has followed a policy of engaging with African nations for trade and bilateral co-operation. It maintains extensive and highly diversified trade links with the European Union, and became its largest trading partner for goods. China is increasing its influence in Central Asia and South Pacific. The country has strong trade ties with ASEAN countries and major South American economies, and is the largest trading partner of Brazil, Chile, Peru, Uruguay, Argentina, and several others. In 2013, China initiated the Belt and Road Initiative (BRI), a large global infrastructure building initiative with funding on the order of $50–100 billion per year. BRI could be one of the largest development plans in modern history. It expanded significantly over the next six years and, as of April 2020[update], included 138 countries and 30 international organizations. In addition to intensifying foreign policy relations, the focus is particularly on building efficient transport routes, especially the maritime Silk Road with its connections to East Africa and Europe. However many loans made under the program are unsustainable and China has faced a number of calls for debt relief from debtor nations. The People's Liberation Army (PLA) is considered one of the world's most powerful militaries and has rapidly modernized in the recent decades. Per the principle of "the Party commands the gun," the CCP maintains absolute control of the PLA. It consists of four services: the Ground Force (PLAGF), the Navy (PLAN), the Air Force (PLAAF) and the Rocket Force (PLARF). It also has four independent arms: the Aerospace Force, the Cyberspace Force, the Information Support Force, and the Joint Logistics Support Force, the first three of which were split from the disbanded Strategic Support Force (PLASSF). Its 2 million active duty personnel is the largest in the world. The PLA holds the world's third-largest stockpile of nuclear weapons, and the world's second-largest navy by tonnage. China's official military budget for 2024 totalled US$229 billion (1.67 trillion Yuan), the second-largest in the world, though the Stockholm International Peace Research Institute estimates that its real expenditure that year was US$314 billion, making up 12% of global military spending and accounting for 1.7% of the country's GDP. But on a Purchasing Power Parity basis, China's 2024 military budget was the equivalent of US$567 billion. The PLA is commanded by the Central Military Commission (CMC) of the party and the state; though officially two separate organizations, the two CMCs have identical membership except during leadership transition periods and effectively function as one organization. The chairman of the CMC is the commander-in-chief of the PLA, who maintains absolute control over the military per the chairman responsibility system. The situation of human rights in China has attracted significant criticism from foreign governments, foreign press agencies, and non-governmental organizations, alleging widespread civil rights violations such as detention without trial, forced confessions, torture, restrictions of fundamental rights, and excessive use of the death penalty. Since its inception, Freedom House has ranked China as "not free" in its Freedom in the World survey, while Amnesty International has documented significant human rights abuses. The Chinese constitution nevertheless states that the "fundamental rights" of citizens include freedom of speech, freedom of the press, the right to a fair trial, freedom of religion, universal suffrage, and property rights. However, in practice, these provisions do not afford significant protection against criminal prosecution by the state. Although some criticisms of government policies and the ruling CCP are tolerated, censorship of political speech and information is amongst the harshest in the world and is routinely used to prevent collective action. The government suppresses popular protests and demonstrations that it considers a potential threat to "social stability". China additionally uses a massive surveillance network of cameras, facial recognition software, sensors, and surveillance of personal technology as a means of social control of persons living in the country. China is regularly accused of large-scale repression and human rights abuses in Tibet and Xinjiang, where significant numbers of ethnic minorities reside, including violent police crackdowns and religious suppression. Since 2017, the Chinese government has been engaged in a harsh crackdown in Xinjiang, with around one million Uyghurs and other ethnic and religion minorities being detained in internment camps aimed at changing the political thinking of detainees, their identities, and their religious beliefs, in what some described as a genocide or crimes against humanity. According to reports, political indoctrination, torture, physical and psychological abuse, forced sterilization, sexual abuse, and forced labor are common in these facilities. The Chinese authorities have also cracked down on dissent in Hong Kong, especially after the passage of a national security law in 2020. In 2017 and 2020, the Pew Research Center ranked the severity of Chinese government restrictions on religion as being among the world's highest, despite ranking religious-related social hostilities in China as low in severity. China has limited protections regarding LGBT rights. The Global Slavery Index estimated that in 2016 more than 3.8 million people (0.25% of the population) were living in "conditions of modern slavery", including victims of human trafficking, forced labor, forced marriage, child labor, and state-imposed forced labor. The state-imposed re-education through labor (laojiao) system was formally abolished in 2013, but it is not clear to what extent its practices have stopped. The much larger reform through labor (laogai) system includes labor prison factories, detention centers, and re-education camps; the Laogai Research Foundation has estimated in June 2008 that there were nearly 1,422 of these facilities, though it cautioned that this number was likely an underestimate. Political concerns in China include the growing gap between rich and poor and government corruption. Nonetheless, international surveys show the Chinese public have a high level of satisfaction with their government.: 137 These views are generally attributed to the material comforts and security available to large segments of the Chinese populace as well as the government's attentiveness and responsiveness. : 136 According to the World Values Survey (2022), 91% of Chinese respondents have significant confidence in their government.: 13 A Harvard University survey published in July 2020 found that citizen satisfaction with the government had increased since 2003, also rating China's government as more effective and capable than ever in the survey's history. A 2020 study by University of Southern California researchers affiliated with the Hoover Institution found that more anonymous surveys show 50 to 70 percent support for the CCP, much lower than what direct surveys show at above 90 percent. Economy China has the world's second-largest economy in terms of nominal GDP, and the world's largest in terms of purchasing power parity (PPP). As of 2022[update], China accounts for around 18% of the global economy by nominal GDP. China is one of the world's fastest-growing major economies, with its economic growth having been almost consistently above 5 percent since the introduction of the reform and opening up policy in 1978. According to the World Bank, China's GDP grew from $150 billion in 1978 to $18.74 trillion by 2024. It ranks 78th by nominal GDP per capita, making it an upper-middle income country. Of the world's 500 largest companies, 135 are headquartered in China. China was one of the world's foremost economic powers throughout the arc of East Asian and global history. The country had one of the largest economies in the world for most of the past two millennia, during which it has seen cycles of prosperity and decline. Since economic reforms began in 1978, China has developed into a highly diversified economy and one of the most consequential players in international trade. China officially calls its economic system as the socialist market economy. Modern-day China is often described as an example of state capitalism or party-state capitalism, with both market forces and the state playing a major role in the economy. China has numerous state-owned enterprises; the state dominates in strategic "pillar" sectors such as infrastructure, telecommunications, finance, energy production and heavy industries.: 20 The Chinese government issues five-year plans to guide the direction of the economy.: 8 Private enterprise has expanded enormously, with around 57 million private businesses recorded in 2025. According to official statistics, privately owned companies constitute more than 60% of China's GDP. China accounted for 18.6% of the world's total wealth in 2022, second highest in the world after the U.S. China brought more people out of extreme poverty than any other country in history—between 1978 and 2018, China reduced extreme poverty by 800 million,: 23 with the average standard of living multiplying by a factor of twenty-six. From 1990 to 2018, the proportion of the Chinese population living with an income of less than $1.90 per day (2011 PPP) decreased from 66.3% to 0.3%, the share living with an income of less than $3.20 per day from 90.0% to 2.9%, and the share living with an income of less than $5.50 per day decreased from 98.3% to 17.0%. Per capita incomes have risen significantly – when the PRC was founded in 1949, per capita income in China was one-fifth of the world average; per capita incomes now equal the world average itself. China's development is highly uneven; its major cities and coastal areas are far more prosperous than its rural and interior regions. It has a high level of economic inequality, which has increased quickly since the economic reforms. Income inequality decreased in the 2010s, and China's Gini coefficient was 0.37 in 2023. In March 2025, Forbes estimated China ranked second in the world, after the U.S., in total number of billionaires and total number of millionaires, with 516 Chinese billionaires, while Hurun Global Rich List estimated it ranked first, with 1,021 billionaires. China also has 6.3 million millionaires as of 2025, second highest after the U.S. In 2019, China overtook the U.S. as the home to the highest number of people who have a net personal wealth of at least $110,000, according to the global wealth report by Credit Suisse. China had 85 female billionaires as of January 2021[update], two-thirds of the global total. China has had the world's largest middle-class population since 2015; the middle-class grew to 500 million by 2024. China is the world's leading manufacturing power, accounting for 30% of global manufacturing. It has been the world's largest manufacturing nation since 2010, after overtaking the U.S., which had been the largest for the previous hundred years. China is the world's leading producer of steel and rare earths, the world's leading electronics industry manufacturer, and the world's dominant shipbuilding manufacturer. China has the world's largest market for automobiles, having surpassed the United States in both auto sales and production. The country is the world's largest exporter of cars by number as of 2024. The Chinese automotive industry is regarded as one of the most competitive and innovative in the world. China is the world's leader in electric vehicle consumption, production and innovation, as well as the leading producer of batteries for electric vehicles. China is the second-largest retail market after the United States. China leads the world in e-commerce, accounting for over 37% of the global market share in 2021. China has three out of the ten largest stock exchanges in the world—Shanghai, Hong Kong and Shenzhen—that together have a market capitalization of over $15.9 trillion, as of October 2020[update]. China has three out of the world's ten most competitive financial centers according to the 2024 Global Financial Centres Index—Shanghai, Hong Kong, and Shenzhen. As of at least 2024, China has the world's second-largest equity markets and futures markets, as well as the third-largest bond market.: 153 China has the world's largest banking sector. Its finance sector is dominated by state-owned institutions. China has been a member of the World Trade Organization since 2001 and is the world's largest trading power. By 2016, China was the largest trading partner of 124 countries. China became the world's largest trading nation in 2013 by the sum of imports and exports, as well as the world's largest commodity importer, accounting for roughly 45% of maritime's dry-bulk market. China's foreign exchange reserves reached US$3.246 trillion as of March 2024[update], making its reserves by far the world's largest. In 2022, China was amongst the world's largest recipient of inward foreign direct investment (FDI), attracting $180 billion, though most of these were speculated to be from Hong Kong. China also invests abroad, with a total outward FDI of $147.9 billion in 2023. The Chinese government has promoted the internationalization of the renminbi in order to wean itself off its dependence on the U.S. dollar. The renminbi is the world's fourth-most traded currency as of 2023[update]. However, partly due to capital controls that make the renminbi fall short of being a fully convertible currency, it remains far behind the Euro and the U.S. Dollar in international trade volumes. The Chinese government has also been cited for failing to crack down on the manufacturing and export of counterfeit goods. In 2023, Harvard University's Economic Complexity Index ranked complexity of China's exports 16th in the world, up from 24th in 2010. China received 65.7 million international visitors in 2019, and in 2018 was the fourth-most-visited country in the world. It also experiences an enormous volume of domestic tourism; Chinese tourists made an estimated 6 billion travels within the country in 2019. China hosts the world's second-largest number of World Heritage Sites (60) after Italy, and is one of the most popular tourist destinations (first in the Asia-Pacific). China was a world leader in science and technology until the Ming dynasty. Ancient and medieval Chinese discoveries and inventions, such as papermaking, printing, the compass, and gunpowder (the Four Great Inventions), became widespread across East Asia, the Middle East and later Europe. Chinese mathematicians were the first to use negative numbers. By the 17th century, the Western World surpassed China in scientific and technological advancement. The causes of this early modern Great Divergence continue to be debated by scholars. After repeated military defeats by the European colonial powers and Imperial Japan in the 19th century, Chinese reformers began promoting modern science and technology as part of the Self-Strengthening Movement. After the Communists came to power in 1949, efforts were made to organize science and technology based on the model of the Soviet Union, in which scientific research was part of central planning. After Mao's death in 1976, science and technology were promoted as one of the Four Modernizations, and the Soviet-inspired academic system was gradually reformed. Since the end of the Cultural Revolution, China has made significant investments in scientific research and is quickly catching up with the U.S. in R&D spending. China officially spent around 2.7% of its GDP on R&D in 2024, totaling to around $496 billion. China was ranked 10th in the Global Innovation Index in 2025, a considerable improvement from its rank of 35th in 2013. Chinese supercomputers are ranked among the fastest in the world.[u] China is the world's largest industrial robotics producer and user in the world, accounting for 51% of the world's 2024 total demand, and 43% of global production. Its efforts to develop the most advanced semiconductors and jet engines have seen delays and setbacks. China is also considered a world leader in artificial intelligence. China is developing its education system with an emphasis on science, technology, engineering, and mathematics (STEM). Its academic publication apparatus became the world's largest publisher of scientific papers in 2016. According to the World Intellectual Property Indicators, China received more applications than the U.S. did in 2018 and 2019 and ranked first globally in patents, utility models, trademarks, industrial designs, and creative goods exports in 2021. In 2022, China overtook the US in the Nature Index, which measures the share of published articles in leading scientific journals. The Chinese space program started in 1958 with some technology transfers from the Soviet Union. However, it did not launch the nation's first satellite until 1970 with the Dong Fang Hong I, which made China the fifth country to do so independently. In 2003, China became the third country in the world to independently send humans into space with Yang Liwei's spaceflight aboard Shenzhou 5. As of 2023, eighteen Chinese nationals have journeyed into space, including two women. In 2011, China launched its first space station testbed, Tiangong-1. In 2013, a Chinese robotic rover Yutu successfully touched down on the lunar surface as part of the Chang'e 3 mission. In 2019, China became the first country to land a probe—Chang'e 4—on the far side of the Moon. In 2020, Chang'e 5 successfully returned Moon samples to the Earth, making China the third country to do so independently. In 2021, China became the third country to land a spacecraft on Mars and the second one to deploy a rover (Zhurong) on Mars. China completed its own modular space station, the Tiangong, in low Earth orbit on 3 November 2022. On 29 November 2022, China performed its first in-orbit crew handover aboard the Tiangong. In May 2023, China announced a plan to land humans on the Moon by 2030. To that end, China has been developing a lunar-capable super-heavy launcher, the Long March 10, a new crewed spacecraft, and a crewed lunar lander. China sent Chang'e 6 on 3 May 2024, which conducted the first lunar sample return from Apollo Basin on the far side of the Moon. This is China's second lunar sample return mission, the first was achieved by Chang'e 5 from the lunar near side 4 years ago. It also carried a Chinese rover called Jinchan to conduct infrared spectroscopy of lunar surface and imaged Chang'e 6 lander on lunar surface. Infrastructure After a decades-long infrastructural boom, China has produced numerous world-leading infrastructural projects: it has the largest high-speed rail network, the most supertall skyscrapers, the largest power plant (the Three Gorges Dam), the most extensive ultra-high-voltage transmission network and innovation infrastructure, and a global satellite navigation system with the largest number of satellites. China is the largest telecom market in the world and currently has the largest number of active cellphones of any country, with over 1.7 billion subscribers, as of February 2023[update]. It has the largest number of internet and broadband users, with over 1.125 billion Internet users as of December 2025[update]—equivalent to around 80.1% of its population. By 2018, China had more than 1 billion 4G users, accounting for 40% of world's total. As of December 2023[update], China had over 810 million 5G users and 3.38 million base stations installed. China Mobile, China Unicom and China Telecom, are the three large providers of mobile and internet in China. Combined, the three operators had over 3.4 million 4G base-stations in China. China has developed its own satellite navigation system, dubbed BeiDou, which began offering commercial navigation services across Asia in 2012 as well as global services by the end of 2018. BeiDou followed GPS and GLONASS as the third completed global navigation satellite. Since the late 1990s, China's national road network has been significantly expanded through the creation of a network of national highways and expressways. In 2022, China's highways had reached a total length of 177,000 km (110,000 mi), making it the longest highway system in the world. In urban areas, bicycles remain a common mode of transport, despite the increasing prevalence of automobiles – as of 2023[update], there are approximately 200 million bicycles in China. China's railways, which are operated by the state-owned China Railway, are among the busiest in the world. As of 2025[update], the country had 165,000 km (102,526 mi) of railways, the second-longest network in the world. The railways strain to meet enormous demand particularly during the Chinese New Year holiday, when the world's largest annual human migration called Chunyun takes place. China's high-speed rail (HSR) system started construction in the early 2000s. By the end of 2025, high speed rail in China had reached 50,400 kilometers (31,317 miles) of dedicated lines alone, making it the longest HSR network in the world. Services on the Beijing–Shanghai, Beijing–Tianjin, and Chengdu–Chongqing lines reach up to 350 km/h (217 mph), making them the fastest conventional high speed railway services in the world. With an annual ridership of over 3.3 billion passengers in 2024, it is the world's busiest. The network includes the Beijing–Guangzhou high-speed railway, the single longest HSR line in the world, and the Beijing–Shanghai high-speed railway, which has three of longest railroad bridges in the world. The Shanghai maglev train, which reaches 431 km/h (268 mph), is the fastest commercial train service in the world. Since 2000, the growth of rapid transit systems in Chinese cities has accelerated. As of December 2023[update], 55 Chinese cities have urban mass transit systems in operation. As of 2020[update], China boasts the five longest metro systems in the world with the networks in Shanghai, Beijing, Guangzhou, Chengdu and Shenzhen being the largest. The civil aviation industry in China is mostly state-dominated, with the Chinese government retaining a majority stake in the majority of Chinese airlines. The top three airlines in China are Air China, China Southern Airlines, and China Eastern Airlines, which collectively made up 71% of the market in 2018, are all state-owned. Air travel has expanded rapidly in the last decades, with the number of passengers increasing from 16.6 million in 1990 to 551.2 million in 2017. China had approximately 259 airports in 2024. China has over 2,000 river and seaports, about 130 of which are open to foreign shipping. Of the fifty busiest container ports, 18 are located in China, of which the busiest is the Port of Shanghai, also the busiest port in the world. The country's inland waterways are the world's sixth-longest, and total 27,700 km (17,212 mi). Water supply and sanitation infrastructure in China is facing challenges such as rapid urbanization, as well as water scarcity, contamination, and pollution. According to the Joint Monitoring Program for Water Supply and Sanitation, 93% of rural households had access to basic sanitation in 2022 (up from 77% in 2015). The ongoing South–North Water Transfer Project intends to abate water shortage in the north. Demographics The 2020 Chinese census recorded the population as approximately 1,411,778,724. About 17.95% were 14 years old or younger, 63.35% were between 15 and 59 years old, and 18.7% were over 60 years old. Between 2010 and 2020, the average population growth rate was 0.53%. Since 2022, deaths have outpaced births in the country. In 2023, the total fertility rate was reported to be 1.09, ranking among the lowest in the world. In 2023, National Bureau of Statistics estimated that the population fell 850,000 from 2021 to 2022, the first decline since 1961. In 2025, China's population officially stood at 1.404 billion with births at 7.92 million, the lowest recorded birthrate since at least 1949. Given concerns about population growth, China implemented a two-child limit during the 1970s, and, in 1979, began to advocate for an even stricter limit of one child per family. Beginning in the mid-1980s, however, given the unpopularity of the strict limits, China began to allow some major exemptions, particularly in rural areas, resulting in what was actually a "1.5"-child policy from the mid-1980s to 2015; ethnic minorities were also exempt from one-child limits. The next major loosening of the policy was enacted in December 2013, allowing families to have two children if one parent is an only child. In 2016, the one-child policy was replaced in favor of a two-child policy. A three-child policy was announced in May 2021, due to population aging, and in July 2021, all family size limits as well as penalties for exceeding them were removed. According to one group of scholars, one-child limits had little effect on population growth or total population size. However, these scholars have been challenged. The policy, along with traditional preference for boys, may have contributed to an imbalance in the sex ratio at birth. The 2020 census found that males accounted for 51.2% of the total population. However, China's sex ratio is more balanced than it was in 1953, when males accounted for 51.8% of the population. China maintains a restrictive immigration policy, with permanent residence granted to only around 12,000 foreigners as of 2023. China has urbanized significantly in recent decades. The percent of the country's population living in urban areas increased from 20% in 1980 to over 68% in 2025, according to Chinese government figures. According to the United Nations, the country's urbanization rate is 83.7 percent, having peaked in absolute numbers in 2021. China has over 160 cities with a population of over one million, including the 18 megacities as of 2024[update] (cities with a population of over 10 million) of Chongqing, Shanghai, Beijing, Chengdu, Guangzhou, Shenzhen, Tianjin, Xi'an, Suzhou, Zhengzhou, Wuhan, Hangzhou, Linyi, Shijiazhuang, Dongguan, Qingdao, Changsha and Hefei. The total permanent population of Chongqing, Shanghai, Beijing and Chengdu is above 20 million. Shanghai is China's most populous urban area while Chongqing is its largest city proper, the only city in China with a permanent population of over 30 million. The figures in the table below are from the 2020 census, and are only estimates of the urban populations within administrative city limits; a different ranking exists for total municipal populations. The large "floating populations" of migrant workers make conducting censuses in urban areas difficult; the figures below include only long-term residents. China legally recognizes 56 distinct ethnic groups, who comprise the Zhonghua minzu. The largest of these nationalities are the Han Chinese, who constitute more than 91% of the total population. The Han Chinese – the world's largest single ethnic group – outnumber other ethnic groups in every place excluding Tibet, Xinjiang, Linxia, and autonomous prefectures like Xishuangbanna. Ethnic minorities account for less than 10% of the population of China, according to the 2020 census. Compared with the 2010 population census, the Han population increased by 60,378,693 persons, or 4.93%, while the population of the 55 national minorities combined increased by 11,675,179 persons, or 10.26%. The 2020 census recorded a total of 845,697 foreign nationals living in mainland China. There are as many as 284 living languages in China. The languages most commonly spoken belong to the Sinitic branch of the Sino-Tibetan language family, which contains Mandarin, spoken by 80% of the population, and other varieties of Chinese language: Jin, Wu, Min, Hakka, Yue, Xiang, Gan, Hui, Ping and unclassified Tuhua (Shaozhou Tuhua and Xiangnan Tuhua). Languages of the Tibeto-Burman branch, including Tibetan, Qiang, Naxi and Yi, are spoken across the Tibetan and Yunnan–Guizhou Plateau. Other ethnic minority languages in southwestern China include Zhuang, Thai, Dong and Sui of the Tai-Kadai family, Miao and Yao of the Hmong–Mien family, and Wa of the Austroasiatic family. Across northeastern and northwestern China, local ethnic groups speak Altaic languages including Manchu, Mongolian and several Turkic languages: Uyghur, Kazakh, Kyrgyz, Salar and Western Yugur. Korean is spoken natively along the border with North Korea. Sarikoli, the language of Tajiks in China, is an Indo-European language. Taiwanese indigenous peoples, including a small population on the mainland, speak Austronesian languages. Standard Chinese, a variety based on the Beijing dialect of Mandarin, is the national language of China, having de facto official status. It is used as a lingua franca between people of different linguistic backgrounds. In the autonomous regions of China, other languages may also serve as a lingua franca, such as Uyghur in Xinjiang, where governmental services in Uyghur are constitutionally guaranteed. Freedom of religion is guaranteed by China's constitution, although religious organizations that lack official approval can be subject to state persecution. The government of the country is officially atheist, and the Chinese Communist Party requires its members to be atheist. Religious affairs and issues in the country are overseen by the National Religious Affairs Administration, under the CCP's United Front Work Department. Over the millennia, the Chinese civilization has been influenced by various religious movements. The "three doctrines" of Confucianism, Taoism, and Buddhism have historically shaped Chinese culture, enriching a theological and spiritual framework of traditional religion which harks back to the early Shang and Zhou dynasty. Chinese folk religion, which is framed by the three doctrines and by other traditions, consists in allegiance to the shen, who can be deities of the surrounding nature or ancestral principles of human groups, concepts of civility, culture heroes, many of whom feature in Chinese mythology and history. Amongst the most popular cults of folk religion are those of the Yellow Emperor, embodiment of the God of Heaven and one of the two divine patriarchs of the Chinese people, of Mazu (goddess of the seas), Guandi (god of war and business), Caishen (god of prosperity and richness), Pangu and many others. In the early decades of the 21st century, the Chinese government has been engaged in a rehabilitation of folk cults—formally recognizing them as "folk beliefs" as distinguished from doctrinal religions, and often reconstructing them into forms of "highly curated" civil religion—as well as in a national and international promotion of Buddhism. China is home to many of the world's tallest religious statues, representing either deities of Chinese folk religion or enlightened beings of Buddhism; the tallest of all is the Spring Temple Buddha in Henan. Statistics on religious affiliation in China are difficult to gather due to complex and varying definitions of religion and the diffusive nature of Chinese religious traditions. Scholars note that in China there is no clear boundary between the three doctrines and local folk religious practices. Chinese religions or some of their currents are also definable as non-theistic and humanistic, since they do not hold that divine creativity is completely transcendent, but that it is inherent in the world and in particular in the human being. In 2023, according to surveys done by Pew Research, 93% of respondents were formally unaffiliated with any religion. However, in terms of practices, 75% visit family graveyards each year, 47% believe in feng shui, 33% believe in buddha, 26% burn incense to deities each year and 18% believe in taoist deities. These are not exclusive beliefs and often these will overlap as the respondents will have multiple beliefs at the same time. For example, of those 33% who believe in buddha, a significant portion also believe in figures such as Taoist immortals, Jesus Christ, Catholic God and Allah. Chinese folk religion also comprises a variety of salvationist doctrinal organized movements which emerged since the Song dynasty. There are also ethnic minorities in China who maintain their own indigenous religions, while major religions characteristic of specific ethnic groups include Tibetan Buddhism among Tibetans, Mongols and Yugurs, and Islam among the Hui, Uyghur, Kazakh, and Kyrgyz peoples, and other ethnicities in the northern and northwestern regions of the country. Compulsory education in China comprises primary and junior secondary school, which together last for nine years from the age of 6 and 15. The Gaokao, China's national university entrance exam, is a prerequisite for entrance into most higher education institutions. Vocational education is available to students at the secondary and tertiary level. More than 10 million Chinese students graduated from vocational colleges every year. In 2024, about 92.0 percent of students continued their education at a three-year senior secondary school, while 60.8 percent of secondary school graduates were enrolled in higher education. China has the largest education system in the world, with about 287 million students and 18.85 million full-time teachers in over 470,300 schools in 2024. Annual education investment went from less than US$50 billion in 2003 to more than US$817 billion in 2020. However, there remains an inequality in education spending. In 2010, the annual education expenditure per secondary school student in Beijing totalled ¥20,023, while in Guizhou, one of the poorest provinces, it only totalled ¥3,204.[needs update] China's literacy rate has grown dramatically, from only 20% in 1949 and 65.5% in 1979, to 97% of the population over age 15 in 2020. As of 2024[update], China has over 3,167 universities, with over 47.6 million students enrolled in mainland China, giving China the largest higher education system in the world. As of 2025[update], China had the world's highest number of top universities. As of 2025, there were 2 Chinese universities in the global top 20, 5 in the top 50, and 19 in the top 200, behind only the United States and the United Kingdom in terms of the overall representation in the Aggregate Ranking of Top Universities, a composite ranking system combining three of the world's most influential university rankings (ARWU+QS+THE). China had five universities listed among the world's top 50, placing it third after the United States and the United Kingdom based on aggregate performance from four widely observed university rankings (THE+ARWU+QS+US News). China is home to two of the highest-ranking universities (Tsinghua University and Peking University) in Asia and emerging economies, according to the Times Higher Education World University Rankings and the Academic Ranking of World Universities. These universities are members of the C9 League, an alliance of elite Chinese universities offering comprehensive and leading education. The National Health Commission, together with its counterparts in the local commissions, oversees the health needs of the population. An emphasis on public health and preventive medicine has characterized Chinese health policy since the early 1950s. The Communist Party started the Patriotic Health Campaign, which was aimed at improving sanitation and hygiene, as well as treating and preventing several diseases. Diseases such as cholera, typhoid and scarlet fever, which were previously rife in China, were nearly eradicated by the campaign. After Deng Xiaoping began instituting economic reforms in 1978, the health of the Chinese public improved rapidly because of better nutrition, although many of the free public health services provided in the countryside disappeared. Healthcare in China became mostly privatized, and experienced a significant rise in quality. In 2009, the government began a three-year large-scale healthcare provision initiative worth US$124 billion. By 2011, the campaign resulted in 95% of China's population having basic health insurance coverage. By 2022, China had established itself as a key producer and exporter of pharmaceuticals, producing around 40 percent of active pharmaceutical ingredients in 2017. As of 2024[update], the life expectancy at birth exceeds 79 years. As of 2023[update], the infant mortality rate is 5 per thousand. Both have improved significantly since the 1950s.[v] Rates of stunting, a condition caused by malnutrition, have declined from 33.1% in 1990 to 4.5% in 2024. Despite significant improvements in health and the construction of advanced medical facilities, China has several emerging public health problems, such as respiratory illnesses caused by widespread air pollution, hundreds of millions of cigarette smokers, and an increase in obesity among urban youths. Chinese mental health services are inadequate. China's large population and densely populated cities have led to serious disease outbreaks, such as SARS in 2003, although this has since been largely contained. The COVID-19 pandemic was first identified in Wuhan in December 2019; pandemic led the government to enforce strict public health measures intended to completely eradicate the virus, a goal that was abandoned in December 2022 following protests. Culture and society Since ancient times, Chinese culture has been heavily influenced by Confucianism. Chinese culture, in turn, has heavily influenced East Asia and Southeast Asia. For much of the country's dynastic era, opportunities for social advancement could be provided by high performance in the prestigious imperial examinations, which have their origins in the Han dynasty. The literary emphasis of the exams affected the general perception of cultural refinement in China, such as the belief that calligraphy, poetry and painting were higher forms of art than dancing or drama. Chinese culture has long emphasized a sense of deep history and a largely inward-looking national perspective. Examinations and a culture of merit remain greatly valued in China today. Today, the Chinese government has accepted numerous elements of traditional Chinese culture as being integral to Chinese society. With the rise of Chinese nationalism and the end of the Cultural Revolution, various forms of traditional Chinese art, literature, music, film, fashion and architecture have seen a vigorous revival, and folk and variety art in particular have sparked interest nationally and even worldwide. Chinese architecture has developed over millennia in China and has remained a vestigial source of perennial influence on the development of East Asian architecture, including in Japan, Korea, and Mongolia. and minor influences on the architecture of Southeast and South Asia including the countries of Malaysia, Singapore, Indonesia, Sri Lanka, Thailand, Laos, Cambodia, Vietnam and the Philippines. Chinese architecture is characterized by bilateral symmetry, use of enclosed open spaces, feng shui (e.g. directional hierarchies), a horizontal emphasis, and an allusion to various cosmological, mythological or in general symbolic elements. Chinese architecture traditionally classifies structures according to type, ranging from pagodas to palaces. Chinese architecture varies widely based on status or affiliation, such as whether the structures were constructed for emperors, commoners, or for religious purposes. Other variations in Chinese architecture are shown in vernacular styles associated with different geographic regions and different ethnic heritages, such as the stilt houses in the south, the Yaodong buildings in the northwest, the yurt buildings of nomadic people, and the Siheyuan buildings in the north. Chinese literature has its roots in the Zhou dynasty's literary tradition. The classical texts of China encompass a wide range of thoughts and subjects, such as the calendar, military, astrology, herbology, and geography, as well as many others. Among the most significant early works are the I Ching and the Shujing, which are part of the Four Books and Five Classics. These texts were the cornerstone of the Confucian curriculum sponsored by the state throughout the dynastic periods. Inherited from the Classic of Poetry, classical Chinese poetry developed to its floruit during the Tang dynasty. Li Bai and Du Fu opened the forking ways for the poetic circles through romanticism and realism respectively. Chinese historiography began with the Shiji, the overall scope of the historiographical tradition in China is termed the Twenty-Four Histories, which set a vast stage for Chinese fictions along with Chinese mythology and folklore. Pushed by a burgeoning citizen class in the Ming dynasty, Chinese classical fiction rose to a boom of the historical, town and gods and demons fictions as represented by the Four Great Classical Novels which include Water Margin, Romance of the Three Kingdoms, Journey to the West and Dream of the Red Chamber. Along with the wuxia fictions of Jin Yong and Liang Yusheng, it remains an enduring source of popular culture in the Chinese sphere of influence. In the wake of the New Culture Movement after the end of the Qing dynasty, Chinese literature embarked on a new era with written vernacular Chinese for ordinary citizens. Hu Shih and Lu Xun were pioneers in modern literature. Various literary genres, such as misty poetry, scar literature, young adult fiction and the xungen literature, which is influenced by magic realism, emerged following the Cultural Revolution. Mo Yan, a xungen literature author, was awarded the Nobel Prize in Literature in 2012. Chinese music covers a highly diverse range of music from traditional music to modern music. Chinese music dates back before the pre-imperial times. Traditional Chinese musical instruments were traditionally grouped into eight categories known as bayin (八音). Traditional Chinese opera is a form of musical theatre in China originating thousands of years and has regional style forms such as Beijing and Cantonese opera. Chinese pop (C-Pop) includes mandopop and cantopop. Chinese hip hop and Hong Kong hip hop have become popular. Hanfu is the historical clothing of the Han people in China. The qipao or cheongsam is a popular Chinese female dress. The hanfu movement has been popular in contemporary times and seeks to revitalize Hanfu clothing. China Fashion Week is the country's only national-level fashion festival. The mass media of China primarily consists of television, newspapers, radio, and magazines. State media outlets operate under the control of the CCP. The largest media organizations are the People's Daily, Xinhua News Agency, and the China Media Group consisting of China Central Television, China Global Television Network, China National Radio and China Radio International. Access to foreign media remains heavily restricted. Cinema was first introduced to China in 1896 and the first Chinese film, Dingjun Mountain, was released in 1905. China has had the largest number of movie screens in the world since 2016; China became the largest cinema market in 2020, and domestic movies dominate the market. The top three highest-grossing films in China as of 2025[update] were Ne Zha 2 (2025), The Battle at Lake Changjin (2021), and Wolf Warrior 2 (2017). In 2025, the video game market of China was the world's largest by revenue. China has the most comprehensive and sophisticated Internet censorship regime in the world called the Great Firewall, with numerous websites being blocked. The Great Firewall has allowed China to develop its own major internet services and companies, such as Tencent, Alibaba, Baidu, Douyin, Xiaohongshu, Bilibili and Weibo.: 8 The Cyberspace Administration of China acts as the national internet regulator and censor. China requires a real-name system for Internet services and online platforms. Chinese cuisine is highly diverse, drawing on several millennia of culinary history and geographical variety, in which the most influential are known as the "Eight Major Cuisines", including Sichuan, Cantonese, Jiangsu, Shandong, Fujian, Hunan, Anhui, and Zhejiang cuisines. Chinese cuisine is known for its breadth of cooking methods and ingredients. China's staple food is rice in the northeast and south, and wheat-based breads and noodles in the north. Bean products such as tofu and soy milk remain a popular source of protein. Pork is now the most popular meat in China, accounting for about 60% of the country's total meat consumption. Pork-free Chinese Islamic cuisine is served at halal-certified restaurants in various regions while vegetarian Buddhist cuisine is commonly found at restaurants near shrines and temples. China has one of the oldest sporting cultures. There is evidence that archery (shèjiàn) was practiced during the Western Zhou dynasty. Swordplay (jiànshù) and cuju, a sport loosely related to association football date back to China's early dynasties as well. Physical fitness is widely emphasized in Chinese culture, with morning exercises such as qigong and tai chi widely practiced, and commercial gyms and private fitness clubs are gaining popularity. Basketball is the most popular spectator sport in China. The Chinese Basketball Association and the American National Basketball Association also have a huge national following amongst the Chinese populace, with native-born and NBA-bound Chinese players and well-known national household names such as Yao Ming and Yi Jianlian being held in high esteem. China's professional football league, known as Chinese Super League, is the largest football market in East Asia. Other popular sports include martial arts, table tennis, badminton, swimming and snooker. China is home to a huge number of cyclists, with an estimated 470 million bicycles as of 2012[update]. China has the world's largest esports market. Many more traditional sports, such as dragon boat racing, Mongolian-style wrestling and horse racing are also popular. China has participated in the Olympic Games since 1932, although it has only participated as the PRC since 1952. China hosted the 2008 Summer Olympics in Beijing, where its athletes received 48 gold medals – the highest number of any participating nation that year. China also won the most medals at the 2012 Summer Paralympics, with 231 overall, including 95 gold. In 2011, Shenzhen hosted the 2011 Summer Universiade. China hosted the 2013 East Asian Games in Tianjin and the 2014 Summer Youth Olympics in Nanjing, the first country to host both regular and Youth Olympics. Beijing and its nearby city Zhangjiakou collaboratively hosted the 2022 Winter Olympics, making Beijing the first dual Olympic city by holding both the Summer Olympics and the Winter Olympics. China hosted the Asian Games in 1990 (Beijing), 2010 (Guangzhou), and 2023 (Hangzhou). See also Notes References Further reading External links World portal 35°N 103°E / 35°N 103°E / 35; 103 |
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[SOURCE: https://en.wikipedia.org/wiki/Python_(programming_language)#cite_note-166] | [TOKENS: 4314] |
Contents Python (programming language) Python is a high-level, general-purpose programming language. Its design philosophy emphasizes code readability with the use of significant indentation. Python is dynamically type-checked and garbage-collected. It supports multiple programming paradigms, including structured (particularly procedural), object-oriented and functional programming. Guido van Rossum began working on Python in the late 1980s as a successor to the ABC programming language. Python 3.0, released in 2008, was a major revision and not completely backward-compatible with earlier versions. Beginning with Python 3.5, capabilities and keywords for typing were added to the language, allowing optional static typing. As of 2026[update], the Python Software Foundation supports Python 3.10, 3.11, 3.12, 3.13, and 3.14, following the project's annual release cycle and five-year support policy. Python 3.15 is currently in the alpha development phase, and the stable release is expected to come out in October 2026. Earlier versions in the 3.x series have reached end-of-life and no longer receive security updates. Python has gained widespread use in the machine learning community. It is widely taught as an introductory programming language. Since 2003, Python has consistently ranked in the top ten of the most popular programming languages in the TIOBE Programming Community Index, which ranks based on searches in 24 platforms. History Python was conceived in the late 1980s by Guido van Rossum at Centrum Wiskunde & Informatica (CWI) in the Netherlands. It was designed as a successor to the ABC programming language, which was inspired by SETL, capable of exception handling and interfacing with the Amoeba operating system. Python implementation began in December 1989. Van Rossum first released it in 1991 as Python 0.9.0. Van Rossum assumed sole responsibility for the project, as the lead developer, until 12 July 2018, when he announced his "permanent vacation" from responsibilities as Python's "benevolent dictator for life" (BDFL); this title was bestowed on him by the Python community to reflect his long-term commitment as the project's chief decision-maker. (He has since come out of retirement and is self-titled "BDFL-emeritus".) In January 2019, active Python core developers elected a five-member Steering Council to lead the project. The name Python derives from the British comedy series Monty Python's Flying Circus. (See § Naming.) Python 2.0 was released on 16 October 2000, featuring many new features such as list comprehensions, cycle-detecting garbage collection, reference counting, and Unicode support. Python 2.7's end-of-life was initially set for 2015, and then postponed to 2020 out of concern that a large body of existing code could not easily be forward-ported to Python 3. It no longer receives security patches or updates. While Python 2.7 and older versions are officially unsupported, a different unofficial Python implementation, PyPy, continues to support Python 2, i.e., "2.7.18+" (plus 3.11), with the plus signifying (at least some) "backported security updates". Python 3.0 was released on 3 December 2008, and was a major revision and not completely backward-compatible with earlier versions, with some new semantics and changed syntax. Python 2.7.18, released in 2020, was the last release of Python 2. Several releases in the Python 3.x series have added new syntax to the language, and made a few (considered very minor) backward-incompatible changes. As of January 2026[update], Python 3.14.3 is the latest stable release. All older 3.x versions had a security update down to Python 3.9.24 then again with 3.9.25, the final version in 3.9 series. Python 3.10 is, since November 2025, the oldest supported branch. Python 3.15 has an alpha released, and Android has an official downloadable executable available for Python 3.14. Releases receive two years of full support followed by three years of security support. Design philosophy and features Python is a multi-paradigm programming language. Object-oriented programming and structured programming are fully supported, and many of their features support functional programming and aspect-oriented programming – including metaprogramming and metaobjects. Many other paradigms are supported via extensions, including design by contract and logic programming. Python is often referred to as a 'glue language' because it is purposely designed to be able to integrate components written in other languages. Python uses dynamic typing and a combination of reference counting and a cycle-detecting garbage collector for memory management. It uses dynamic name resolution (late binding), which binds method and variable names during program execution. Python's design offers some support for functional programming in the "Lisp tradition". It has filter, map, and reduce functions; list comprehensions, dictionaries, sets, and generator expressions. The standard library has two modules (itertools and functools) that implement functional tools borrowed from Haskell and Standard ML. Python's core philosophy is summarized in the Zen of Python (PEP 20) written by Tim Peters, which includes aphorisms such as these: However, Python has received criticism for violating these principles and adding unnecessary language bloat. Responses to these criticisms note that the Zen of Python is a guideline rather than a rule. The addition of some new features had been controversial: Guido van Rossum resigned as Benevolent Dictator for Life after conflict about adding the assignment expression operator in Python 3.8. Nevertheless, rather than building all functionality into its core, Python was designed to be highly extensible via modules. This compact modularity has made it particularly popular as a means of adding programmable interfaces to existing applications. Van Rossum's vision of a small core language with a large standard library and easily extensible interpreter stemmed from his frustrations with ABC, which represented the opposite approach. Python claims to strive for a simpler, less-cluttered syntax and grammar, while giving developers a choice in their coding methodology. Python lacks do .. while loops, which Rossum considered harmful. In contrast to Perl's motto "there is more than one way to do it", Python advocates an approach where "there should be one – and preferably only one – obvious way to do it". In practice, however, Python provides many ways to achieve a given goal. There are at least three ways to format a string literal, with no certainty as to which one a programmer should use. Alex Martelli is a Fellow at the Python Software Foundation and Python book author; he wrote that "To describe something as 'clever' is not considered a compliment in the Python culture." Python's developers typically prioritize readability over performance. For example, they reject patches to non-critical parts of the CPython reference implementation that would offer increases in speed that do not justify the cost of clarity and readability.[failed verification] Execution speed can be improved by moving speed-critical functions to extension modules written in languages such as C, or by using a just-in-time compiler like PyPy. Also, it is possible to transpile to other languages. However, this approach either fails to achieve the expected speed-up, since Python is a very dynamic language, or only a restricted subset of Python is compiled (with potential minor semantic changes). Python is meant to be a fun language to use. This goal is reflected in the name – a tribute to the British comedy group Monty Python – and in playful approaches to some tutorials and reference materials. For instance, some code examples use the terms "spam" and "eggs" (in reference to a Monty Python sketch), rather than the typical terms "foo" and "bar". A common neologism in the Python community is pythonic, which has a broad range of meanings related to program style: Pythonic code may use Python idioms well; be natural or show fluency in the language; or conform with Python's minimalist philosophy and emphasis on readability. Syntax and semantics Python is meant to be an easily readable language. Its formatting is visually uncluttered and often uses English keywords where other languages use punctuation. Unlike many other languages, it does not use curly brackets to delimit blocks, and semicolons after statements are allowed but rarely used. It has fewer syntactic exceptions and special cases than C or Pascal. Python uses whitespace indentation, rather than curly brackets or keywords, to delimit blocks. An increase in indentation comes after certain statements; a decrease in indentation signifies the end of the current block. Thus, the program's visual structure accurately represents its semantic structure. This feature is sometimes termed the off-side rule. Some other languages use indentation this way; but in most, indentation has no semantic meaning. The recommended indent size is four spaces. Python's statements include the following: The assignment statement (=) binds a name as a reference to a separate, dynamically allocated object. Variables may subsequently be rebound at any time to any object. In Python, a variable name is a generic reference holder without a fixed data type; however, it always refers to some object with a type. This is called dynamic typing—in contrast to statically-typed languages, where each variable may contain only a value of a certain type. Python does not support tail call optimization or first-class continuations; according to Van Rossum, the language never will. However, better support for coroutine-like functionality is provided by extending Python's generators. Before 2.5, generators were lazy iterators; data was passed unidirectionally out of the generator. From Python 2.5 on, it is possible to pass data back into a generator function; and from version 3.3, data can be passed through multiple stack levels. Python's expressions include the following: In Python, a distinction between expressions and statements is rigidly enforced, in contrast to languages such as Common Lisp, Scheme, or Ruby. This distinction leads to duplicating some functionality, for example: A statement cannot be part of an expression; because of this restriction, expressions such as list and dict comprehensions (and lambda expressions) cannot contain statements. As a particular case, an assignment statement such as a = 1 cannot be part of the conditional expression of a conditional statement. Python uses duck typing, and it has typed objects but untyped variable names. Type constraints are not checked at definition time; rather, operations on an object may fail at usage time, indicating that the object is not of an appropriate type. Despite being dynamically typed, Python is strongly typed, forbidding operations that are poorly defined (e.g., adding a number and a string) rather than quietly attempting to interpret them. Python allows programmers to define their own types using classes, most often for object-oriented programming. New instances of classes are constructed by calling the class, for example, SpamClass() or EggsClass()); the classes are instances of the metaclass type (which is an instance of itself), thereby allowing metaprogramming and reflection. Before version 3.0, Python had two kinds of classes, both using the same syntax: old-style and new-style. Current Python versions support the semantics of only the new style. Python supports optional type annotations. These annotations are not enforced by the language, but may be used by external tools such as mypy to catch errors. Python includes a module typing including several type names for type annotations. Also, mypy supports a Python compiler called mypyc, which leverages type annotations for optimization. 1.33333 frozenset() Python includes conventional symbols for arithmetic operators (+, -, *, /), the floor-division operator //, and the modulo operator %. (With the modulo operator, a remainder can be negative, e.g., 4 % -3 == -2.) Also, Python offers the ** symbol for exponentiation, e.g. 5**3 == 125 and 9**0.5 == 3.0. Also, it offers the matrix‑multiplication operator @ . These operators work as in traditional mathematics; with the same precedence rules, the infix operators + and - can also be unary, to represent positive and negative numbers respectively. Division between integers produces floating-point results. The behavior of division has changed significantly over time: In Python terms, the / operator represents true division (or simply division), while the // operator represents floor division. Before version 3.0, the / operator represents classic division. Rounding towards negative infinity, though a different method than in most languages, adds consistency to Python. For instance, this rounding implies that the equation (a + b)//b == a//b + 1 is always true. Also, the rounding implies that the equation b*(a//b) + a%b == a is valid for both positive and negative values of a. As expected, the result of a%b lies in the half-open interval [0, b), where b is a positive integer; however, maintaining the validity of the equation requires that the result must lie in the interval (b, 0] when b is negative. Python provides a round function for rounding a float to the nearest integer. For tie-breaking, Python 3 uses the round to even method: round(1.5) and round(2.5) both produce 2. Python versions before 3 used the round-away-from-zero method: round(0.5) is 1.0, and round(-0.5) is −1.0. Python allows Boolean expressions that contain multiple equality relations to be consistent with general usage in mathematics. For example, the expression a < b < c tests whether a is less than b and b is less than c. C-derived languages interpret this expression differently: in C, the expression would first evaluate a < b, resulting in 0 or 1, and that result would then be compared with c. Python uses arbitrary-precision arithmetic for all integer operations. The Decimal type/class in the decimal module provides decimal floating-point numbers to a pre-defined arbitrary precision with several rounding modes. The Fraction class in the fractions module provides arbitrary precision for rational numbers. Due to Python's extensive mathematics library and the third-party library NumPy, the language is frequently used for scientific scripting in tasks such as numerical data processing and manipulation. Functions are created in Python by using the def keyword. A function is defined similarly to how it is called, by first providing the function name and then the required parameters. Here is an example of a function that prints its inputs: To assign a default value to a function parameter in case no actual value is provided at run time, variable-definition syntax can be used inside the function header. Code examples "Hello, World!" program: Program to calculate the factorial of a non-negative integer: Libraries Python's large standard library is commonly cited as one of its greatest strengths. For Internet-facing applications, many standard formats and protocols such as MIME and HTTP are supported. The language includes modules for creating graphical user interfaces, connecting to relational databases, generating pseudorandom numbers, arithmetic with arbitrary-precision decimals, manipulating regular expressions, and unit testing. Some parts of the standard library are covered by specifications—for example, the Web Server Gateway Interface (WSGI) implementation wsgiref follows PEP 333—but most parts are specified by their code, internal documentation, and test suites. However, because most of the standard library is cross-platform Python code, only a few modules must be altered or rewritten for variant implementations. As of 13 March 2025,[update] the Python Package Index (PyPI), the official repository for third-party Python software, contains over 614,339 packages. Development environments Most[which?] Python implementations (including CPython) include a read–eval–print loop (REPL); this permits the environment to function as a command line interpreter, with which users enter statements sequentially and receive results immediately. Also, CPython is bundled with an integrated development environment (IDE) called IDLE, which is oriented toward beginners.[citation needed] Other shells, including IDLE and IPython, add additional capabilities such as improved auto-completion, session-state retention, and syntax highlighting. Standard desktop IDEs include PyCharm, Spyder, and Visual Studio Code; there are web browser-based IDEs, such as the following environments: Implementations CPython is the reference implementation of Python. This implementation is written in C, meeting the C11 standard since version 3.11. Older versions use the C89 standard with several select C99 features, but third-party extensions are not limited to older C versions—e.g., they can be implemented using C11 or C++. CPython compiles Python programs into an intermediate bytecode, which is then executed by a virtual machine. CPython is distributed with a large standard library written in a combination of C and native Python. CPython is available for many platforms, including Windows and most modern Unix-like systems, including macOS (and Apple M1 Macs, since Python 3.9.1, using an experimental installer). Starting with Python 3.9, the Python installer intentionally fails to install on Windows 7 and 8; Windows XP was supported until Python 3.5, with unofficial support for VMS. Platform portability was one of Python's earliest priorities. During development of Python 1 and 2, even OS/2 and Solaris were supported; since that time, support has been dropped for many platforms. All current Python versions (since 3.7) support only operating systems that feature multithreading, by now supporting not nearly as many operating systems (dropping many outdated) than in the past. All alternative implementations have at least slightly different semantics. For example, an alternative may include unordered dictionaries, in contrast to other current Python versions. As another example in the larger Python ecosystem, PyPy does not support the full C Python API. Creating an executable with Python often is done by bundling an entire Python interpreter into the executable, which causes binary sizes to be massive for small programs, yet there exist implementations that are capable of truly compiling Python. Alternative implementations include the following: Stackless Python is a significant fork of CPython that implements microthreads. This implementation uses the call stack differently, thus allowing massively concurrent programs. PyPy also offers a stackless version. Just-in-time Python compilers have been developed, but are now unsupported: There are several compilers/transpilers to high-level object languages; the source language is unrestricted Python, a subset of Python, or a language similar to Python: There are also specialized compilers: Some older projects existed, as well as compilers not designed for use with Python 3.x and related syntax: A performance comparison among various Python implementations, using a non-numerical (combinatorial) workload, was presented at EuroSciPy '13. In addition, Python's performance relative to other programming languages is benchmarked by The Computer Language Benchmarks Game. There are several approaches to optimizing Python performance, despite the inherent slowness of an interpreted language. These approaches include the following strategies or tools: Language Development Python's development is conducted mostly through the Python Enhancement Proposal (PEP) process; this process is the primary mechanism for proposing major new features, collecting community input on issues, and documenting Python design decisions. Python coding style is covered in PEP 8. Outstanding PEPs are reviewed and commented on by the Python community and the steering council. Enhancement of the language corresponds with development of the CPython reference implementation. The mailing list python-dev is the primary forum for the language's development. Specific issues were originally discussed in the Roundup bug tracker hosted by the foundation. In 2022, all issues and discussions were migrated to GitHub. Development originally took place on a self-hosted source-code repository running Mercurial, until Python moved to GitHub in January 2017. CPython's public releases have three types, distinguished by which part of the version number is incremented: Many alpha, beta, and release-candidates are also released as previews and for testing before final releases. Although there is a rough schedule for releases, they are often delayed if the code is not ready yet. Python's development team monitors the state of the code by running a large unit test suite during development. The major academic conference on Python is PyCon. Also, there are special Python mentoring programs, such as PyLadies. Naming Python's name is inspired by the British comedy group Monty Python, whom Python creator Guido van Rossum enjoyed while developing the language. Monty Python references appear frequently in Python code and culture; for example, the metasyntactic variables often used in Python literature are spam and eggs, rather than the traditional foo and bar. Also, the official Python documentation contains various references to Monty Python routines. Python users are sometimes referred to as "Pythonistas". Languages influenced by Python See also Notes References Further reading External links |
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[SOURCE: https://en.wikipedia.org/wiki/General_theory_of_relativity] | [TOKENS: 12364] |
Contents General relativity General relativity, also known as the general theory of relativity, and as Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in May 1916 and is the accepted description of the gravitation of macroscopic objects in modern physics. General relativity generalizes special relativity and refines Isaac Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time, or four-dimensional spacetime. In particular, the curvature of spacetime is directly related to the energy, momentum and stress of whatever is present, including matter and radiation. The relation is specified by the Einstein field equations, a system of second-order partial differential equations. John Archibald Wheeler summarized it: "Space-time tells matter how to move; matter tells space-time how to curve." Newton's law of universal gravitation, which describes gravity in classical mechanics, can be seen as a prediction of general relativity for the almost flat spacetime geometry around stationary mass distributions. Some predictions of general relativity, however, are beyond Newton's law of universal gravitation in classical physics. These predictions concern the passage of time, the geometry of space, the motion of bodies in free fall, and the propagation of light, and include gravitational time dilation, gravitational lensing, the gravitational redshift of light, the Shapiro time delay and singularities/black holes. So far, all tests of general relativity have been in agreement with the theory. The time-dependent solutions of general relativity enable us to extrapolate the history of the universe into the past and future, and have provided the modern framework for cosmology, thus leading to the discovery of the Big Bang and cosmic microwave background radiation. Despite the introduction of a number of alternative theories, general relativity continues to be the simplest theory consistent with experimental data. Reconciliation of general relativity with the laws of quantum physics remains a problem, however, as no self-consistent theory of quantum gravity has been found. It is not yet known how gravity can be unified with the three non-gravitational interactions: strong, weak and electromagnetic. Einstein's theory has astrophysical implications, including the prediction of black holes—regions of space in which space and time are distorted in such a way that nothing, not even light, can escape from them. Black holes are the end-state for massive stars. Microquasars and active galactic nuclei are believed to be stellar black holes and supermassive black holes. It also predicts gravitational lensing, where the bending of light results in distorted and multiple images of the same distant astronomical phenomenon. Other predictions include the existence of gravitational waves, which have been observed directly by the physics collaboration LIGO and other observatories. In addition, general relativity has provided the basis for cosmological models of an expanding universe. Widely acknowledged as a theory of extraordinary beauty, general relativity has often been described as the most beautiful of all existing physical theories. History Henri Poincaré's 1905 theory of the dynamics of the electron was a relativistic theory which he applied to all forces, including gravity. While others thought that gravity was instantaneous or of electromagnetic origin, he suggested that relativity was "something due to our methods of measurement". In his theory, he showed that gravitational waves propagate at the speed of light. Soon afterwards, Einstein started thinking about how to incorporate gravity into his relativistic framework. In 1907, beginning with a simple thought experiment involving an observer in free fall (FFO), he embarked on what would be an eight-year search for a relativistic theory of gravity. After numerous detours and false starts, his work culminated in the presentation to the Prussian Academy of Science in November 1915 of what are known as the Einstein field equations, which form the core of Einstein's general theory of relativity. These equations specify how the geometry of space and time is influenced by whatever matter and radiation are present. A version of non-Euclidean geometry, called Riemannian geometry, enabled Einstein to develop general relativity by providing the key mathematical framework on which he fit his physical ideas of gravity. This idea was pointed out by mathematician Marcel Grossmann and published by Grossmann and Einstein in 1913. The Einstein field equations are nonlinear and are considered difficult to solve. Einstein used approximation methods in working out initial predictions of the theory. But in 1916, the astrophysicist Karl Schwarzschild found the first non-trivial exact solution to the Einstein field equations, the Schwarzschild metric. This solution laid the groundwork for the description of the final stages of gravitational collapse, and the objects known today as black holes. In the same year, the first steps towards generalizing Schwarzschild's solution to electrically charged objects were taken, eventually resulting in the Reissner–Nordström solution, which is associated with electrically charged black holes. In 1917, Einstein applied his theory to the universe as a whole, initiating the field of relativistic cosmology. In line with contemporary thinking, he assumed a static universe, adding a new parameter to his original field equations—the cosmological constant—to match that observational presumption. By 1929, however, the work of Hubble and others had shown that the universe is expanding. This is readily described by the expanding cosmological solutions found by Friedmann in 1922, which do not require a cosmological constant. Lemaître used these solutions to formulate the earliest version of the Big Bang models, in which the universe has evolved from an extremely hot and dense earlier state. Einstein later declared the cosmological constant the biggest blunder of his life. During that period, general relativity remained something of a curiosity among physical theories. It was clearly superior to Newtonian gravity, being consistent with special relativity and accounting for several effects unexplained by the Newtonian theory. Einstein showed in 1915 how his theory explained the anomalous perihelion advance of the planet Mercury without any arbitrary parameters ("fudge factors"), and in 1919 an expedition led by Eddington confirmed general relativity's prediction for the deflection of starlight by the Sun during the total solar eclipse of 29 May 1919, instantly making Einstein famous. Yet the theory remained outside the mainstream of theoretical physics and astrophysics until developments between approximately 1960 and 1975 known as the golden age of general relativity. Physicists began to understand the concept of a black hole, and to identify quasars as one of these objects' astrophysical manifestations. Ever more precise solar system tests confirmed the theory's predictive power, and relativistic cosmology also became amenable to direct observational tests. General relativity has acquired a reputation as a theory of extraordinary beauty. Subrahmanyan Chandrasekhar has noted that at multiple levels, general relativity exhibits what Francis Bacon has termed a "strangeness in the proportion" (i.e. elements that excite wonderment and surprise). It juxtaposes fundamental concepts (space and time versus matter and motion) which had previously been considered as entirely independent. Chandrasekhar also noted that Einstein's only guides in his search for an exact theory were the principle of equivalence and his sense that a proper description of gravity should be geometrical at its basis, so that there was an "element of revelation" in the manner in which Einstein arrived at his theory. Other elements of beauty associated with the general theory of relativity are its simplicity and symmetry, the manner in which it incorporates invariance and unification, and its perfect logical consistency. In the preface to Relativity: The Special and the General Theory, Einstein said "The present book is intended, as far as possible, to give an exact insight into the theory of Relativity to those readers who, from a general scientific and philosophical point of view, are interested in the theory, but who are not conversant with the mathematical apparatus of theoretical physics. The work presumes a standard of education corresponding to that of a university matriculation examination, and, despite the shortness of the book, a fair amount of patience and force of will on the part of the reader. The author has spared himself no pains in his endeavour to present the main ideas in the simplest and most intelligible form, and on the whole, in the sequence and connection in which they actually originated." From classical mechanics to general relativity General relativity can be understood by examining its similarities with and departures from classical physics. The first step is the realization that classical mechanics and Newton's law of gravity admit a geometric description. The combination of this description with the laws of special relativity results in a heuristic derivation of general relativity. At the base of classical mechanics is the notion that a body's motion can be described as a combination of free (or inertial) motion, and deviations from this free motion. Such deviations are caused by external forces acting on a body in accordance with Newton's second law of motion, which states that the net force acting on a body is equal to that body's (inertial) mass multiplied by its acceleration. The preferred inertial motions are related to the geometry of space and time: in the standard reference frames of classical mechanics, objects in free motion move along straight lines at constant speed. In modern parlance, their paths are geodesics, straight world lines in curved spacetime. Conversely, one might expect that inertial motions, once identified by observing the actual motions of bodies and making allowances for the external forces (such as electromagnetism or friction), can be used to define the geometry of space, as well as a time coordinate. However, there is an ambiguity once gravity comes into play. According to Newton's law of gravity, and independently verified by experiments such as that of Eötvös and its successors (see Eötvös experiment), there is a universality of free fall (also known as the weak equivalence principle, or the universal equality of inertial and passive-gravitational mass): the trajectory of a test body in free fall depends only on its position and initial speed, but not on any of its material properties. A simplified version of this is embodied in Einstein's elevator experiment, illustrated in the figure on the right: for an observer in an enclosed room, it is impossible to decide, by mapping the trajectory of bodies such as a dropped ball, whether the room is stationary in a gravitational field and the ball accelerating, or in free space aboard a rocket that is accelerating at a rate equal to that of the gravitational field versus the ball which upon release has nil acceleration. Given the universality of free fall, there is no observable distinction between inertial motion and motion under the influence of the gravitational force. This suggests the definition of a new class of inertial motion, namely that of objects in free fall under the influence of gravity. This new class of preferred motions, too, defines a geometry of space and time—in mathematical terms, it is the geodesic motion associated with a specific connection which depends on the gradient of the gravitational potential. Space, in this construction, still has the ordinary Euclidean geometry. However, spacetime as a whole is more complicated. As can be shown using simple thought experiments following the free-fall trajectories of different test particles, the result of transporting spacetime vectors that can denote a particle's velocity (time-like vectors) will vary with the particle's trajectory; mathematically speaking, the Newtonian connection is not integrable. From this, one can deduce that spacetime is curved. The resulting Newton–Cartan theory is a geometric formulation of Newtonian gravity using only covariant concepts, i.e. a description which is valid in any desired coordinate system. In this geometric description, tidal effects—the relative acceleration of bodies in free fall—are related to the derivative of the connection, showing how the modified geometry is caused by the presence of mass. As intriguing as geometric Newtonian gravity may be, its basis, classical mechanics, is merely a limiting case of (special) relativistic mechanics. In the language of symmetry: where gravity can be neglected, physics is Lorentz invariant as in special relativity rather than Galilei invariant as in classical mechanics. (The defining symmetry of special relativity is the Poincaré group, which includes translations, rotations, boosts and reflections.) The differences between the two become significant when dealing with speeds approaching the speed of light, and with high-energy phenomena. With Lorentz symmetry, additional structures come into play. They are defined by the set of light cones (see image). The light-cones define a causal structure: for each event A, there is a set of events that can, in principle, either influence or be influenced by A via signals or interactions that do not need to travel faster than light (such as event B in the image), and a set of events for which such an influence is impossible (such as event C in the image). These sets are observer-independent. In conjunction with the world-lines of freely falling particles, the light-cones can be used to reconstruct the spacetime's semi-Riemannian metric, at least up to a positive scalar factor. In mathematical terms, this defines a conformal structure or conformal geometry. Special relativity is defined in the absence of gravity. For practical applications, it is a suitable model whenever gravity can be neglected. Bringing gravity into play, and assuming the universality of free fall motion, an analogous reasoning as in the previous section applies: there are no global inertial frames. Instead there are approximate inertial frames moving alongside freely falling particles. Translated into the language of spacetime: the straight time-like lines that define a gravity-free inertial frame are deformed to lines that are curved relative to each other, suggesting that the inclusion of gravity necessitates a change in spacetime geometry. A priori, it is not clear whether the new local frames in free fall coincide with the reference frames in which the laws of special relativity hold—that theory is based on the propagation of light, and thus on electromagnetism, which could have a different set of preferred frames. But using different assumptions about the special-relativistic frames (such as their being earth-fixed, or in free fall), one can derive different predictions for the gravitational redshift, that is, the way in which the frequency of light shifts as the light propagates through a gravitational field (cf. below). The actual measurements show that free-falling frames are the ones in which light propagates as it does in special relativity. The generalization of this statement, namely that the laws of special relativity hold to good approximation in freely falling (and non-rotating) reference frames, is known as the Einstein equivalence principle, a crucial guiding principle for generalizing special-relativistic physics to include gravity. The same experimental data shows that time as measured by clocks in a gravitational field—proper time, to give the technical term—does not follow the rules of special relativity. In the language of spacetime geometry, it is not measured by the Minkowski metric. As in the Newtonian case, this is suggestive of a more general geometry. At small scales, all reference frames that are in free fall are equivalent, and approximately Minkowskian. Consequently, we are dealing with a curved generalization of Minkowski space. The metric tensor that defines the geometry—in particular, how lengths and angles are measured—is not the Minkowski metric of special relativity, it is a generalization known as a semi- or pseudo-Riemannian metric. Furthermore, each Riemannian metric is naturally associated with one particular kind of connection, the Levi-Civita connection, and this is, in fact, the connection that satisfies the equivalence principle and makes space locally Minkowskian (that is, in suitable locally inertial coordinates, the metric is Minkowskian, and its first partial derivatives and the connection coefficients vanish). Having formulated the relativistic, geometric version of the effects of gravity, the question of gravity's source remains. In Newtonian gravity, the source is mass. In special relativity, mass turns out to be part of a more general quantity called the stress–energy tensor, which includes both energy and momentum densities as well as stress: pressure and shear. Using the equivalence principle, this tensor is readily generalized to curved spacetime. Drawing further upon the analogy with geometric Newtonian gravity, it is natural to assume that the field equation for gravity relates this tensor and the Ricci tensor, which describes a particular class of tidal effects: the change in volume for a small cloud of test particles that are initially at rest, and then fall freely. In special relativity, conservation of energy–momentum corresponds to the statement that the stress–energy tensor is divergence-free. This formula, too, is readily generalized to curved spacetime by replacing partial derivatives with their curved-manifold counterparts, covariant derivatives studied in differential geometry. With this additional condition—the covariant divergence of the stress–energy tensor, and hence of whatever is on the other side of the equation, is zero—the simplest nontrivial set of equations are what are called Einstein's (field) equations: G μ ν ≡ R μ ν − 1 2 R g μ ν = κ T μ ν {\displaystyle G_{\mu \nu }\equiv R_{\mu \nu }-{\tfrac {1}{2}}R\,g_{\mu \nu }=\kappa T_{\mu \nu }\,} On the left-hand side is the Einstein tensor, G μ ν {\displaystyle G_{\mu \nu }} , which is symmetric and a specific divergence-free combination of the Ricci tensor R μ ν {\displaystyle R_{\mu \nu }} and the metric. In particular, R = g μ ν R μ ν {\displaystyle R=g^{\mu \nu }R_{\mu \nu }} is the curvature scalar. The Ricci tensor itself is related to the more general Riemann curvature tensor as R μ ν = R α μ α ν . {\displaystyle R_{\mu \nu }={R^{\alpha }}_{\mu \alpha \nu }.} On the right-hand side, κ {\displaystyle \kappa } is a constant and T μ ν {\displaystyle T_{\mu \nu }} is the stress–energy tensor. All tensors are written in abstract index notation. Matching the theory's prediction to observational results for planetary orbits or, equivalently, assuring that the weak-gravity, low-speed limit is Newtonian mechanics, the proportionality constant κ {\displaystyle \kappa } is found to be κ = 8 π G / c 4 {\textstyle \kappa ={8\pi G}/{c^{4}}} , where G {\displaystyle G} is the Newtonian constant of gravitation and c {\displaystyle c} the speed of light in vacuum. When there is no matter present, so that the stress–energy tensor vanishes, the results are the vacuum Einstein equations, R μ ν = 0. {\displaystyle R_{\mu \nu }=0.} In general relativity, the world line of a particle free from all external, non-gravitational force is a particular type of geodesic in curved spacetime. In other words, a freely moving or falling particle always moves along a geodesic. The geodesic equation is: d 2 x μ d s 2 + Γ μ α β d x α d s d x β d s = 0 , {\displaystyle {d^{2}x^{\mu } \over ds^{2}}+\Gamma ^{\mu }{}_{\alpha \beta }{dx^{\alpha } \over ds}{dx^{\beta } \over ds}=0,} where s {\displaystyle s} is a scalar parameter of motion (e.g. the proper time), and Γ μ α β {\displaystyle \Gamma ^{\mu }{}_{\alpha \beta }} are Christoffel symbols (sometimes called the affine connection coefficients or Levi-Civita connection coefficients) which is symmetric in the two lower indices. Greek indices may take the values: 0, 1, 2, 3 and the summation convention is used for repeated indices α {\displaystyle \alpha } and β {\displaystyle \beta } . The quantity on the left-hand-side of this equation is the acceleration of a particle, and so this equation is analogous to Newton's laws of motion which likewise provide formulae for the acceleration of a particle. This equation of motion employs the Einstein notation, meaning that repeated indices are summed (i.e. from zero to three). The Christoffel symbols are functions of the four spacetime coordinates, and so are independent of the velocity or acceleration or other characteristics of a test particle whose motion is described by the geodesic equation. In general relativity, the effective gravitational potential energy of an object of mass m revolving around a massive central body M is given by U f ( r ) = − G M m r + L 2 2 m r 2 − G M L 2 m c 2 r 3 {\displaystyle U_{f}(r)=-{\frac {GMm}{r}}+{\frac {L^{2}}{2mr^{2}}}-{\frac {GML^{2}}{mc^{2}r^{3}}}} A conservative total force can then be obtained as its negative gradient F f ( r ) = − G M m r 2 + L 2 m r 3 − 3 G M L 2 m c 2 r 4 {\displaystyle F_{f}(r)=-{\frac {GMm}{r^{2}}}+{\frac {L^{2}}{mr^{3}}}-{\frac {3GML^{2}}{mc^{2}r^{4}}}} where L is the angular momentum. The first term represents the force of Newtonian gravity, which is described by the inverse-square law. The second term represents the centrifugal force in the circular motion. The third term represents the relativistic effect. There are alternatives to general relativity built upon the same premises, which include additional rules and/or constraints, leading to different field equations. Examples are Whitehead's theory, Brans–Dicke theory, teleparallelism, f(R) gravity and Einstein–Cartan theory. Definition and basic applications The derivation outlined in the previous section contains all the information needed to define general relativity, describe its key properties, and address a question of crucial importance in physics, namely how the theory can be used for model-building. General relativity is a metric theory of gravitation. At its core are Einstein's equations, which describe the relation between the geometry of a four-dimensional pseudo-Riemannian manifold representing spacetime, and the distribution of energy, momentum and stress contained in that spacetime. Phenomena that in classical mechanics are ascribed to the action of the force of gravity (such as free-fall, orbital motion, and spacecraft trajectories), correspond to inertial motion within a curved geometry of spacetime in general relativity; there is no gravitational force deflecting objects from their natural, straight paths. Instead, gravity corresponds to changes in the properties of space and time, which in turn changes the straightest-possible paths that objects will naturally follow. The curvature is, in turn, caused by the stress–energy of matter. Paraphrasing the relativist John Archibald Wheeler, spacetime tells matter how to move; matter tells spacetime how to curve. While general relativity replaces the scalar gravitational potential of classical physics by a symmetric rank-two tensor, the latter reduces to the former in certain limiting cases. For weak gravitational fields and low speed relative to the speed of light, the theory's predictions converge on those of Newton's law of universal gravitation. As it is constructed using tensors, general relativity exhibits general covariance: its laws—and further laws formulated within the general relativistic framework—take on the same form in all coordinate systems. Furthermore, the theory does not contain any invariant geometric background structures, i.e. it is background-independent. It thus satisfies a more stringent general principle of relativity, namely that the laws of physics are the same for all observers. Locally, as expressed in the equivalence principle, spacetime is Minkowskian, and the laws of physics exhibit local Lorentz invariance. The core concept of general-relativistic model-building is that of a solution of Einstein's equations. Given both Einstein's equations and suitable equations for the properties of matter, such a solution consists of a specific semi-Riemannian manifold (usually defined by giving the metric in specific coordinates), and specific matter fields defined on that manifold. Matter and geometry must satisfy Einstein's equations, so in particular, the matter's stress–energy tensor must be divergence-free. The matter must, of course, also satisfy whatever additional equations were imposed on its properties. In short, such a solution is a model universe that satisfies the laws of general relativity, and possibly additional laws governing whatever matter might be present. Einstein's equations are nonlinear partial differential equations and, as such, difficult to solve exactly. Nevertheless, a number of exact solutions are known, although only a few have direct physical applications. The best-known exact solutions, and also those most interesting from a physics point of view, are the Schwarzschild solution, the Reissner–Nordström solution and the Kerr metric, each corresponding to a certain type of black hole in an otherwise empty universe, and the Friedmann–Lemaître–Robertson–Walker and de Sitter universes, each describing an expanding cosmos. Exact solutions of great theoretical interest include the Gödel universe (which opens up the intriguing possibility of time travel in curved spacetimes), the Taub–NUT solution (a model universe that is homogeneous, but anisotropic), and anti-de Sitter space (which has recently come to prominence in the context of what is called the Maldacena conjecture). Given the difficulty of finding exact solutions, Einstein's field equations are also solved frequently by numerical integration on a computer, or by considering small perturbations of exact solutions. In the field of numerical relativity, powerful computers are employed to simulate the geometry of spacetime and to solve Einstein's equations for interesting situations such as two colliding black holes. In principle, such methods may be applied to any system, given sufficient computer resources, and may address fundamental questions such as naked singularities. Approximate solutions may also be found by perturbation theories such as linearized gravity and its generalization, the post-Newtonian expansion, both of which were developed by Einstein. The latter provides a systematic approach to solving for the geometry of a spacetime that contains a distribution of matter that moves slowly compared with the speed of light. The expansion involves a series of terms; the first terms represent Newtonian gravity, whereas the later terms represent ever smaller corrections to Newton's theory due to general relativity. An extension of this expansion is the parametrized post-Newtonian (PPN) formalism, which allows quantitative comparisons between the predictions of general relativity and alternative theories. Consequences of Einstein's theory General relativity has a number of physical consequences. Some follow directly from the theory's axioms, whereas others have become clear only in the course of many years of research that followed Einstein's initial publication. Assuming that the equivalence principle holds, gravity influences the passage of time. Light sent down into a gravity well is blueshifted, whereas light sent in the opposite direction (i.e., climbing out of the gravity well) is redshifted; collectively, these two effects are known as the gravitational frequency shift. More generally, processes close to a massive body run more slowly when compared with processes taking place farther away; this effect is known as gravitational time dilation. Gravitational redshift has been measured in the laboratory and using astronomical observations. Gravitational time dilation in the Earth's gravitational field has been measured numerous times using atomic clocks, while ongoing validation is provided as a side effect of the operation of the Global Positioning System (GPS). Tests in stronger gravitational fields are provided by the observation of binary pulsars. All results are in agreement with general relativity. However, at the existing level of accuracy, these observations cannot distinguish between general relativity and other theories in which the equivalence principle is valid. In the vicinity of a non-rotating sphere, the time dilation due to gravity, derived from the Schwarzschild metric, is t 0 = t f 1 − 2 G M r c 2 {\displaystyle t_{0}=t_{f}{\sqrt {1-{\frac {2GM}{rc^{2}}}}}} where General relativity predicts that the path of light will follow the curvature of spacetime as it passes near a massive object. This effect was initially confirmed by observing the light of stars or distant quasars being deflected as it passes the Sun. This and related predictions follow from the fact that light follows what is called a light-like or null geodesic—a generalization of the straight lines along which light travels in classical physics. Such geodesics are the generalization of the invariance of lightspeed in special relativity. As one examines suitable model spacetimes (either the exterior Schwarzschild solution or, for more than a single mass, the post-Newtonian expansion), several effects of gravity on light propagation emerge. Although the bending of light can also be derived by extending the universality of free fall to light, the angle of deflection resulting from such calculations is only half the value given by general relativity. Closely related to light deflection is the Shapiro time delay, the phenomenon that light signals take longer to move through a gravitational field than they would in the absence of that field. There have been numerous successful tests of this prediction. In the parameterized post-Newtonian formalism (PPN), measurements of both the deflection of light and the gravitational time delay determine a parameter called γ, which encodes the influence of gravity on the geometry of space. Predicted in 1916 by Albert Einstein, there are gravitational waves: ripples in the metric of spacetime that propagate at the speed of light. These are one of several analogies between weak-field gravity and electromagnetism in that, they are analogous to electromagnetic waves. On 11 February 2016, the Advanced LIGO team announced that they had directly detected gravitational waves from a pair of black holes merging. The simplest type of such a wave can be visualized by its action on a ring of freely floating particles. A sine wave propagating through such a ring towards the reader distorts the ring in a characteristic, rhythmic fashion (animated image to the right). Since Einstein's equations are non-linear, arbitrarily strong gravitational waves do not obey linear superposition, making their description difficult. However, linear approximations of gravitational waves are sufficiently accurate to describe the exceedingly weak waves that are expected to arrive here on Earth from far-off cosmic events, which typically result in relative distances increasing and decreasing by 10−21 or less. Data analysis methods routinely make use of the fact that these linearized waves can be Fourier decomposed. Some exact solutions describe gravitational waves without any approximation, e.g., a wave train traveling through empty space or Gowdy universes, varieties of an expanding cosmos filled with gravitational waves. But for gravitational waves produced in astrophysically relevant situations, such as the merger of two black holes, numerical methods are the only way to construct appropriate models. General relativity differs from classical mechanics in a number of predictions concerning orbiting bodies. It predicts an overall rotation (precession) of planetary orbits, as well as orbital decay caused by the emission of gravitational waves and effects related to the relativity of direction. In general relativity, the apsides of any orbit (the point of the orbiting body's closest approach to the system's center of mass) will precess; the orbit is not an ellipse, but akin to an ellipse that rotates on its focus, resulting in a rose curve-like shape (see image). Einstein first derived this result by using an approximate metric representing the Newtonian limit and treating the orbiting body as a test particle. For him, the fact that his theory gave a straightforward explanation of Mercury's anomalous perihelion shift, discovered earlier by Urbain Le Verrier in 1859, was important evidence that he had at last identified the correct form of the gravitational field equations. The effect can also be derived by using either the exact Schwarzschild metric (describing spacetime around a spherical mass) or the much more general post-Newtonian formalism. It is due to the influence of gravity on the geometry of space and to the contribution of self-energy to a body's gravity (encoded in the nonlinearity of Einstein's equations). Relativistic precession has been observed for all planets that allow for accurate precession measurements (Mercury, Venus, and Earth), as well as in binary pulsar systems, where it is larger by five orders of magnitude. In general relativity the perihelion shift σ {\displaystyle \sigma } , expressed in radians per revolution, is approximately given by: σ = 24 π 3 L 2 T 2 c 2 ( 1 − e 2 ) , {\displaystyle \sigma ={\frac {24\pi ^{3}L^{2}}{T^{2}c^{2}(1-e^{2})}}\ ,} where: According to general relativity, a binary system will emit gravitational waves, thereby losing energy. Due to this loss, the distance between the two orbiting bodies decreases, and so does their orbital period. Within the Solar System or for ordinary double stars, the effect is too small to be observable. This is not the case for a close binary pulsar, a system of two orbiting neutron stars, one of which is a pulsar: from the pulsar, observers on Earth receive a regular series of radio pulses that can serve as a highly accurate clock, which allows precise measurements of the orbital period. Because neutron stars are immensely compact, significant amounts of energy are emitted in the form of gravitational radiation. The first observation of a decrease in orbital period due to the emission of gravitational waves was made by Hulse and Taylor, using the binary pulsar PSR1913+16 they had discovered in 1974. This was the first detection of gravitational waves, albeit indirect, for which they were awarded the 1993 Nobel Prize in physics. Since then, several other binary pulsars have been found, in particular the double pulsar PSR J0737−3039, where both stars are pulsars and which was last reported to also be in agreement with general relativity in 2021 after 16 years of observations. Several relativistic effects are directly related to the relativity of direction. One is geodetic precession: the axis direction of a gyroscope in free fall in curved spacetime will change when compared, for instance, with the direction of light received from distant stars—even though such a gyroscope represents the way of keeping a direction as stable as possible ("parallel transport"). For the Moon–Earth system, this effect has been measured with the help of lunar laser ranging. More recently, it has been measured for test masses aboard the satellite Gravity Probe B to a precision of better than 0.3%. Near a rotating mass, there are gravitomagnetic or frame-dragging effects. A distant observer will determine that objects close to the mass get "dragged around". This is most extreme for rotating black holes where, for any object entering a zone known as the ergosphere, rotation is inevitable. Such effects can again be tested through their influence on the orientation of gyroscopes in free fall. Somewhat controversial tests have been performed using the LAGEOS satellites, confirming the relativistic prediction. Also the Mars Global Surveyor probe around Mars has been used. Astrophysical applications The deflection of light by gravity is responsible for a new class of astronomical phenomena. If a massive object is situated between the astronomer and a distant target object with appropriate mass and relative distances, the astronomer will see multiple distorted images of the target. Such effects are known as gravitational lensing. Depending on the configuration, scale, and mass distribution, there can be two or more images, a bright ring known as an Einstein ring, or partial rings called arcs. The earliest example was discovered in 1979; since then, more than a hundred gravitational lenses have been observed. Even if the multiple images are too close to each other to be resolved, the effect can still be measured, e.g., as an overall brightening of the target object; a number of such "microlensing events" have been observed. Gravitational lensing has developed into a tool of observational astronomy. It is used to detect the presence and distribution of dark matter, provide a "natural telescope" for observing distant galaxies, and to obtain an independent estimate of the Hubble constant. Statistical evaluations of lensing data provide valuable insight into the structural evolution of galaxies. Observations of binary pulsars provide strong indirect evidence for the existence of gravitational waves (see Orbital decay, above). Detection of these waves is a major goal of contemporary relativity-related research. Several land-based gravitational wave detectors are in operation, for example the interferometric detectors GEO 600, LIGO (two detectors), TAMA 300 and VIRGO. Various pulsar timing arrays are using millisecond pulsars to detect gravitational waves in the 10−9 to 10−6 hertz frequency range, which originate from binary supermassive blackholes. A European space-based detector, eLISA / NGO, is under development, with a precursor mission (LISA Pathfinder) having launched in December 2015. Observations of gravitational waves promise to complement observations in the electromagnetic spectrum. They are expected to yield information about black holes and other dense objects such as neutron stars and white dwarfs, about certain kinds of supernova implosions, and about processes in the very early universe, including the signature of certain types of hypothetical cosmic string. In February 2016, the Advanced LIGO team announced that they had detected gravitational waves from a black hole merger. Whenever the ratio of an object's mass to its radius becomes sufficiently large, general relativity predicts the formation of a black hole, a region of space from which nothing, not even light, can escape. In the accepted models of stellar evolution, neutron stars of around 1.4 solar masses, and stellar black holes with a few to a few dozen solar masses, are thought to be the final state for the evolution of massive stars. Usually a galaxy has one supermassive black hole with a few million to a few billion solar masses in its center, and its presence is thought to have played an important role in the formation of the galaxy and larger cosmic structures. Astronomically, the most important property of compact objects is that they provide a supremely efficient mechanism for converting gravitational energy into electromagnetic radiation. Accretion, the falling of dust or gaseous matter onto stellar or supermassive black holes, is thought to be responsible for some spectacularly luminous astronomical objects, especially diverse kinds of active galactic nuclei on galactic scales and stellar-size objects such as microquasars. In particular, accretion can lead to relativistic jets, focused beams of highly energetic particles that are being flung into space at almost light speed. General relativity plays a central role in modelling all these phenomena, and observations provide strong evidence for the existence of black holes with the properties predicted by the theory. Black holes are also sought-after targets in the search for gravitational waves (cf. section § Gravitational waves, above). Merging black hole binaries should lead to some of the strongest gravitational wave signals reaching detectors on Earth, and the phase directly before the merger ("chirp") could be used as a "standard candle" to deduce the distance to the merger events–and hence serve as a probe of cosmic expansion at large distances. The gravitational waves produced as a stellar black hole plunges into a supermassive one should provide direct information about the supermassive black hole's geometry. The existing models of cosmology are based on Einstein's field equations, which include the cosmological constant Λ {\displaystyle \Lambda } since it has important influence on the large-scale dynamics of the cosmos, R μ ν − 1 2 R g μ ν + Λ g μ ν = 8 π G c 4 T μ ν {\displaystyle R_{\mu \nu }-{\textstyle 1 \over 2}R\,g_{\mu \nu }+\Lambda \ g_{\mu \nu }={\frac {8\pi G}{c^{4}}}\,T_{\mu \nu }} where g μ ν {\displaystyle g_{\mu \nu }} is the spacetime metric. Isotropic and homogeneous solutions of these enhanced equations, the Friedmann–Lemaître–Robertson–Walker solutions, allow physicists to model a universe that has evolved over the past 14 billion years from a hot, early Big Bang phase. Once a small number of parameters (for example the universe's mean matter density) have been fixed by astronomical observation, further observational data can be used to put the models to the test. Predictions, all successful, include the initial abundance of chemical elements formed in a period of primordial nucleosynthesis, the large-scale structure of the universe, and the existence and properties of a "thermal echo" from the early cosmos, the cosmic background radiation. Astronomical observations of the cosmological expansion rate allow the total amount of matter in the universe to be estimated, although the nature of that matter remains mysterious in part. About 90% of all matter appears to be dark matter, which has mass (or, equivalently, gravitational influence), but does not interact electromagnetically and, hence, cannot be observed directly. There is no generally accepted description of this new kind of matter, within the framework of known particle physics or otherwise. Observational evidence from redshift surveys of distant supernovae and measurements of the cosmic background radiation also show that the evolution of the universe is significantly influenced by a cosmological constant resulting in an acceleration of cosmic expansion or, equivalently, by a form of energy with an unusual equation of state, known as dark energy, the nature of which remains unclear. An inflationary phase, an additional phase of strongly accelerated expansion at cosmic times of around 10−33 seconds, was hypothesized in 1980 to account for several puzzling observations that were unexplained by classical cosmological models, such as the nearly perfect homogeneity of the cosmic background radiation. Recent measurements of the cosmic background radiation have resulted in the first evidence for this scenario. However, there are a bewildering variety of possible inflationary scenarios, which cannot be restricted by existing observations. An even larger question is the physics of the earliest universe, prior to the inflationary phase and close to where the classical models predict the big bang singularity. An authoritative answer would require a complete theory of quantum gravity, which has not yet been developed (cf. the section on quantum gravity, below). Kurt Gödel showed that solutions to Einstein's equations exist that contain closed timelike curves (CTCs), which allow for loops in time. The solutions require extreme physical conditions unlikely ever to occur in practice, and it remains an open question whether further laws of physics will eliminate them completely. Since then, other—similarly impractical—GR solutions containing CTCs have been found, such as the Tipler cylinder and traversable wormholes. Stephen Hawking introduced chronology protection conjecture, which is an assumption beyond those of standard general relativity to prevent time travel. Some exact solutions in general relativity such as Alcubierre drive offer examples of warp drive but these solutions require exotic matter distribution, and generally suffer from semiclassical instability. Advanced concepts The spacetime symmetry group for special relativity is the Poincaré group, which is a ten-dimensional group of three Lorentz boosts, three rotations, and four spacetime translations. It is logical to ask what symmetries, if any, might apply in General Relativity. A tractable case might be to consider the symmetries of spacetime as seen by observers located far away from all sources of the gravitational field. The naive expectation for asymptotically flat spacetime symmetries might be simply to extend and reproduce the symmetries of flat spacetime of special relativity, viz., the Poincaré group. In 1962 Hermann Bondi, M. G. van der Burg, A. W. Metzner and Rainer K. Sachs addressed this asymptotic symmetry problem in order to investigate the flow of energy at infinity due to propagating gravitational waves. Their first step was to decide on some physically sensible boundary conditions to place on the gravitational field at light-like infinity to characterize what it means to say a metric is asymptotically flat, making no a priori assumptions about the nature of the asymptotic symmetry group—not even the assumption that such a group exists. Then after designing what they considered to be the most sensible boundary conditions, they investigated the nature of the resulting asymptotic symmetry transformations that leave invariant the form of the boundary conditions appropriate for asymptotically flat gravitational fields. What they found was that the asymptotic symmetry transformations actually do form a group and the structure of this group does not depend on the particular gravitational field that happens to be present. This means that, as expected, one can separate the kinematics of spacetime from the dynamics of the gravitational field at least at spatial infinity. The puzzling surprise in 1962 was their discovery of a rich infinite-dimensional group (the so-called BMS group) as the asymptotic symmetry group, instead of the finite-dimensional Poincaré group, which is a subgroup of the BMS group. Not only are the Lorentz transformations asymptotic symmetry transformations, there are also additional transformations that are not Lorentz transformations but are asymptotic symmetry transformations. In fact, they found an additional infinity of transformation generators known as supertranslations. This implies the conclusion that General Relativity (GR) does not reduce to special relativity in the case of weak fields at long distances. It turns out that the BMS symmetry, suitably modified, could be seen as a restatement of the universal soft graviton theorem in quantum field theory (QFT), which relates universal infrared (soft) QFT with GR asymptotic spacetime symmetries. In general relativity, no material body can catch up with or overtake a light pulse. No influence from an event A can reach any other location X before light sent out at A to X. In consequence, an exploration of all light worldlines (null geodesics) yields key information about the spacetime's causal structure. This structure can be displayed using Penrose–Carter diagrams in which infinitely large regions of space and infinite time intervals are shrunk ("compactified") so as to fit onto a finite map, while light still travels along diagonals as in standard spacetime diagrams. Aware of the importance of causal structure, Roger Penrose and others developed what is known as global geometry. In global geometry, the object of study is not one particular solution (or family of solutions) to Einstein's equations. Rather, relations that hold true for all geodesics, such as the Raychaudhuri equation, and additional non-specific assumptions about the nature of matter (usually in the form of energy conditions) are used to derive general results. Using global geometry, some spacetimes can be shown to contain boundaries called horizons, which demarcate one region from the rest of spacetime. The best-known examples are black holes: if mass is compressed into a sufficiently compact region of space (as specified in the hoop conjecture, the relevant length scale is the Schwarzschild radius, given by the equation r s = 2 G M c 2 , {\displaystyle r_{\text{s}}={\frac {2GM}{c^{2}}},} ), no light from inside can escape to the outside. Since no object can overtake a light pulse, all interior matter is imprisoned as well. Passage from the exterior to the interior is still possible, showing that the boundary, the black hole's horizon, is not a physical barrier. Early studies of black holes relied on explicit solutions of Einstein's equations, notably the spherically symmetric Schwarzschild solution (used to describe a static black hole) and the axisymmetric Kerr solution (used to describe a rotating, stationary black hole, and introducing interesting features such as the ergosphere). Using global geometry, later studies have revealed more general properties of black holes. With time they become rather simple objects characterized by eleven parameters specifying: electric charge, mass–energy, linear momentum, angular momentum, and location at a specified time. This is stated by the black hole uniqueness theorem: "black holes have no hair", that is, no distinguishing marks like the hairstyles of humans. Irrespective of the complexity of a gravitating object collapsing to form a black hole, the object that results (having emitted gravitational waves) is very simple. Even more remarkably, there is a general set of laws known as black hole mechanics, which is analogous to the laws of thermodynamics. For instance, by the second law of black hole mechanics, the area of the event horizon of a general black hole will never decrease with time, analogous to the entropy of a thermodynamic system. This limits the energy that can be extracted by classical means from a rotating black hole (e.g. by the Penrose process). There is strong evidence that the laws of black hole mechanics are, in fact, a subset of the laws of thermodynamics, and that the black hole area is proportional to its entropy. This leads to a modification of the original laws of black hole mechanics: for instance, as the second law of black hole mechanics becomes part of the second law of thermodynamics, it is possible for the black hole area to decrease as long as other processes ensure that entropy increases overall. As thermodynamical objects with nonzero temperature, black holes should emit thermal radiation. Semiclassical calculations indicate that indeed they do, with the surface gravity playing the role of temperature in Planck's law. This radiation is known as Hawking radiation (cf. the quantum theory section, below). There are many other types of horizons. In an expanding universe, an observer may find that some regions of the past cannot be observed ("particle horizon"), and some regions of the future cannot be influenced (event horizon). Even in flat Minkowski space, when described by an accelerated observer (Rindler space), there will be horizons associated with a semiclassical radiation known as Unruh radiation. Another general feature of general relativity is the appearance of spacetime boundaries known as singularities. Spacetime can be explored by following up on timelike and lightlike geodesics—all possible ways that light and particles in free fall can travel. But some solutions of Einstein's equations have "ragged edges"—regions known as spacetime singularities, where the paths of light and falling particles come to an abrupt end, and geometry becomes ill-defined. In the more interesting cases, these are "curvature singularities", where geometrical quantities characterizing spacetime curvature, such as the Ricci scalar, take on infinite values. Well-known examples of spacetimes with future singularities—where worldlines end—are the Schwarzschild solution, which describes a singularity inside an eternal static black hole, or the Kerr solution with its ring-shaped singularity inside an eternal rotating black hole. The Friedmann–Lemaître–Robertson–Walker solutions and other spacetimes describing universes have past singularities on which worldlines begin, namely Big Bang singularities, and some have future singularities (Big Crunch) as well. Given that these examples are all highly symmetric—and thus simplified—it is tempting to conclude that the occurrence of singularities is an artifact of idealization. The famous singularity theorems, proved using the methods of global geometry, say otherwise: singularities are a generic feature of general relativity, and unavoidable once the collapse of an object with realistic matter properties has proceeded beyond a certain stage and also at the beginning of a wide class of expanding universes. However, the theorems say little about the properties of singularities, and much of current research is devoted to characterizing these entities' generic structure (hypothesized e.g. by the BKL conjecture). The cosmic censorship hypothesis states that all realistic future singularities (no perfect symmetries, matter with realistic properties) are safely hidden away behind a horizon, and thus invisible to all distant observers. While no formal proof yet exists, numerical simulations offer supporting evidence of its validity. Each solution of Einstein's equation encompasses the whole history of a universe—it is not just some snapshot of how things are, but a whole, possibly matter-filled, spacetime. It describes the state of matter and geometry everywhere and at every moment in that particular universe. Due to its general covariance, Einstein's theory is not sufficient by itself to determine the time evolution of the metric tensor. It must be combined with a coordinate condition, which is analogous to gauge fixing in other field theories. To understand Einstein's equations as partial differential equations, it is helpful to formulate them in a way that describes the evolution of the universe over time. This is done in "3+1" formulations, where spacetime is split into three space dimensions and one time dimension. The best-known example is the ADM formalism. These decompositions show that the spacetime evolution equations of general relativity are well-behaved: solutions always exist, and are uniquely defined, once suitable initial conditions have been specified. Such formulations of Einstein's field equations are the basis of numerical relativity. The notion of evolution equations is intimately tied in with another aspect of general relativistic physics. In Einstein's theory, it turns out to be impossible to find a general definition for a seemingly simple property such as a system's total mass (or energy). The main reason is that the gravitational field—like any physical field—must be ascribed a certain energy, but that it proves to be fundamentally impossible to localize that energy. Nevertheless, there are possibilities to define a system's total mass, either using a hypothetical "infinitely distant observer" (ADM mass) or suitable symmetries (Komar mass). If one excludes from the system's total mass the energy being carried away to infinity by gravitational waves, the result is the Bondi mass at null infinity. Just as in classical physics, it can be shown that these masses are positive. Corresponding global definitions exist for momentum and angular momentum. There have also been a number of attempts to define quasi-local quantities, such as the mass of an isolated system formulated using only quantities defined within a finite region of space containing that system. The hope is to obtain a quantity useful for general statements about isolated systems, such as a more precise formulation of the hoop conjecture. Relationship with quantum theory If general relativity were considered to be one of the two pillars of modern physics, then quantum theory, the basis of understanding matter from elementary particles to solid-state physics, would be the other. However, how to reconcile quantum theory with general relativity is still an open question. Ordinary quantum field theories, which form the basis of modern elementary particle physics, are defined in flat Minkowski space, which is an excellent approximation when it comes to describing the behavior of microscopic particles in weak gravitational fields like those found on Earth. In order to describe situations in which gravity is strong enough to influence (quantum) matter, yet not strong enough to require quantization itself, physicists have formulated quantum field theories in curved spacetime. These theories rely on general relativity to describe a curved background spacetime, and define a generalized quantum field theory to describe the behavior of quantum matter within that spacetime. Using this formalism, it can be shown that black holes emit a blackbody spectrum of particles known as Hawking radiation leading to the possibility that they evaporate over time. As briefly mentioned above, this radiation plays an important role for the thermodynamics of black holes. The demand for consistency between a quantum description of matter and a geometric description of spacetime, as well as the appearance of singularities (where curvature length scales become microscopic), indicate the need for a full theory of quantum gravity: for an adequate description of the interior of black holes, and of the very early universe, a theory is required in which gravity and the associated geometry of spacetime are described in the language of quantum physics. Despite major efforts, no complete and consistent theory of quantum gravity is currently known, even though a number of candidates exist. Attempts to generalize ordinary quantum field theories, used in elementary particle physics to describe fundamental interactions, so as to include gravity have led to serious problems. Some have argued that at low energies, this approach proves successful, in that it results in an acceptable effective (quantum) field theory of gravity. At very high energies, however, the perturbative results are badly divergent and lead to models devoid of predictive power ("perturbative non-renormalizability"). One attempt to overcome these limitations is string theory, a quantum theory not of point particles, but of minute one-dimensional extended objects. The theory promises to be a unified description of all particles and interactions, including gravity; the price to pay is unusual features such as six extra dimensions of space in addition to the usual three. In what is called the second superstring revolution, it was conjectured that both string theory and a unification of general relativity and supersymmetry known as supergravity form part of a hypothesized eleven-dimensional model known as M-theory, which would constitute a uniquely defined and consistent theory of quantum gravity. Another approach starts with the canonical quantization procedures of quantum theory. Using the initial-value-formulation of general relativity (cf. evolution equations above), the result is the Wheeler–deWitt equation (an analogue of the Schrödinger equation) which turns out to be ill-defined without a proper ultraviolet (lattice) cutoff. However, with the introduction of what are now known as Ashtekar variables, this leads to a model known as loop quantum gravity. Space is represented by a web-like structure called a spin network, evolving over time in discrete steps. Depending on which features of general relativity and quantum theory are accepted unchanged, and on what level changes are introduced, there are numerous other attempts to arrive at a viable theory of quantum gravity, some examples being the lattice theory of gravity based on the Feynman Path Integral approach and Regge calculus, dynamical triangulations, causal sets, twistor models or the path integral based models of quantum cosmology. All candidate theories still have major formal and conceptual problems to overcome. They also face the common problem that, as yet, there is no way to put quantum gravity predictions to experimental tests (and thus to decide between the candidates where their predictions vary), although there is hope for this to change as future data from cosmological observations and particle physics experiments becomes available. Current status General relativity has emerged as a highly successful model of gravitation and cosmology, which has so far unambiguously fitted observational and experimental data. However, there are strong theoretical reasons to consider the theory to be incomplete. The problem of quantum gravity and the question of the reality of spacetime singularities remain open. Observational data that is taken as evidence for dark energy and dark matter could also indicate the need to consider alternatives or modifications of general relativity. Even taken as is, general relativity provides many possibilities for further exploration. Mathematical relativists seek to understand the nature of singularities and the fundamental properties of Einstein's equations, while numerical relativists run increasingly powerful computer simulations, such as those describing merging black holes. In February 2016, it was announced that gravitational waves were directly detected by the Advanced LIGO team on 14 September 2015. A century after its introduction, general relativity remains a highly active area of research. See also References Bibliography Further reading External links |
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Contents Internet The Internet (or internet)[a] is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP)[b] to communicate between networks and devices. It is a network of networks that comprises private, public, academic, business, and government networks of local to global scope, linked by electronic, wireless, and optical networking technologies. The Internet carries a vast range of information services and resources, such as the interlinked hypertext documents and applications of the World Wide Web (WWW), electronic mail, discussion groups, internet telephony, streaming media and file sharing. Most traditional communication media, including telephone, radio, television, paper mail, newspapers, and print publishing, have been transformed by the Internet, giving rise to new media such as email, online music, digital newspapers, news aggregators, and audio and video streaming websites. The Internet has enabled and accelerated new forms of personal interaction through instant messaging, Internet forums, and social networking services. Online shopping has also grown to occupy a significant market across industries, enabling firms to extend brick and mortar presences to serve larger markets. Business-to-business and financial services on the Internet affect supply chains across entire industries. The origins of the Internet date back to research that enabled the time-sharing of computer resources, the development of packet switching, and the design of computer networks for data communication. The set of communication protocols to enable internetworking on the Internet arose from research and development commissioned in the 1970s by the Defense Advanced Research Projects Agency (DARPA) of the United States Department of Defense in collaboration with universities and researchers across the United States and in the United Kingdom and France. The Internet has no single centralized governance in either technological implementation or policies for access and usage. Each constituent network sets its own policies. The overarching definitions of the two principal name spaces on the Internet, the Internet Protocol address (IP address) space and the Domain Name System (DNS), are directed by a maintainer organization, the Internet Corporation for Assigned Names and Numbers (ICANN). The technical underpinning and standardization of the core protocols is an activity of the non-profit Internet Engineering Task Force (IETF). Terminology The word internetted was used as early as 1849, meaning interconnected or interwoven. The word Internet was used in 1945 by the United States War Department in a radio operator's manual, and in 1974 as the shorthand form of Internetwork. Today, the term Internet most commonly refers to the global system of interconnected computer networks, though it may also refer to any group of smaller networks. The word Internet may be capitalized as a proper noun, although this is becoming less common. This reflects the tendency in English to capitalize new terms and move them to lowercase as they become familiar. The word is sometimes still capitalized to distinguish the global internet from smaller networks, though many publications, including the AP Stylebook since 2016, recommend the lowercase form in every case. In 2016, the Oxford English Dictionary found that, based on a study of around 2.5 billion printed and online sources, "Internet" was capitalized in 54% of cases. The terms Internet and World Wide Web are often used interchangeably; it is common to speak of "going on the Internet" when using a web browser to view web pages. However, the World Wide Web, or the Web, is only one of a large number of Internet services. It is the global collection of web pages, documents and other web resources linked by hyperlinks and URLs. History In the 1960s, computer scientists began developing systems for time-sharing of computer resources. J. C. R. Licklider proposed the idea of a universal network while working at Bolt Beranek & Newman and, later, leading the Information Processing Techniques Office at the Advanced Research Projects Agency (ARPA) of the United States Department of Defense. Research into packet switching,[c] one of the fundamental Internet technologies, started in the work of Paul Baran at RAND in the early 1960s and, independently, Donald Davies at the United Kingdom's National Physical Laboratory in 1965. After the Symposium on Operating Systems Principles in 1967, packet switching from the proposed NPL network was incorporated into the design of the ARPANET, an experimental resource sharing network proposed by ARPA. ARPANET development began with two network nodes which were interconnected between the University of California, Los Angeles and the Stanford Research Institute on 29 October 1969. The third site was at the University of California, Santa Barbara, followed by the University of Utah. By the end of 1971, 15 sites were connected to the young ARPANET. Thereafter, the ARPANET gradually developed into a decentralized communications network, connecting remote centers and military bases in the United States. Other user networks and research networks, such as the Merit Network and CYCLADES, were developed in the late 1960s and early 1970s. Early international collaborations for the ARPANET were rare. Connections were made in 1973 to Norway (NORSAR and, later, NDRE) and to Peter Kirstein's research group at University College London, which provided a gateway to British academic networks, the first internetwork for resource sharing. ARPA projects, the International Network Working Group and commercial initiatives led to the development of various protocols and standards by which multiple separate networks could become a single network, or a network of networks. In 1974, Vint Cerf at Stanford University and Bob Kahn at DARPA published a proposal for "A Protocol for Packet Network Intercommunication". Cerf and his graduate students used the term internet as a shorthand for internetwork in RFC 675. The Internet Experiment Notes and later RFCs repeated this use. The work of Louis Pouzin and Robert Metcalfe had important influences on the resulting TCP/IP design. National PTTs and commercial providers developed the X.25 standard and deployed it on public data networks. The ARPANET initially served as a backbone for the interconnection of regional academic and military networks in the United States to enable resource sharing. Access to the ARPANET was expanded in 1981 when the National Science Foundation (NSF) funded the Computer Science Network (CSNET). In 1982, the Internet Protocol Suite (TCP/IP) was standardized, which facilitated worldwide proliferation of interconnected networks. TCP/IP network access expanded again in 1986 when the National Science Foundation Network (NSFNet) provided access to supercomputer sites in the United States for researchers, first at speeds of 56 kbit/s and later at 1.5 Mbit/s and 45 Mbit/s. The NSFNet expanded into academic and research organizations in Europe, Australia, New Zealand and Japan in 1988–89. Although other network protocols such as UUCP and PTT public data networks had global reach well before this time, this marked the beginning of the Internet as an intercontinental network. Commercial Internet service providers emerged in 1989 in the United States and Australia. The ARPANET was decommissioned in 1990. The linking of commercial networks and enterprises by the early 1990s, as well as the advent of the World Wide Web, marked the beginning of the transition to the modern Internet. Steady advances in semiconductor technology and optical networking created new economic opportunities for commercial involvement in the expansion of the network in its core and for delivering services to the public. In mid-1989, MCI Mail and Compuserve established connections to the Internet, delivering email and public access products to the half million users of the Internet. Just months later, on 1 January 1990, PSInet launched an alternate Internet backbone for commercial use; one of the networks that added to the core of the commercial Internet of later years. In March 1990, the first high-speed T1 (1.5 Mbit/s) link between the NSFNET and Europe was installed between Cornell University and CERN, allowing much more robust communications than were capable with satellites. Later in 1990, Tim Berners-Lee began writing WorldWideWeb, the first web browser, after two years of lobbying CERN management. By Christmas 1990, Berners-Lee had built all the tools necessary for a working Web: the HyperText Transfer Protocol (HTTP) 0.9, the HyperText Markup Language (HTML), the first Web browser (which was also an HTML editor and could access Usenet newsgroups and FTP files), the first HTTP server software (later known as CERN httpd), the first web server, and the first Web pages that described the project itself. In 1991 the Commercial Internet eXchange was founded, allowing PSInet to communicate with the other commercial networks CERFnet and Alternet. Stanford Federal Credit Union was the first financial institution to offer online Internet banking services to all of its members in October 1994. In 1996, OP Financial Group, also a cooperative bank, became the second online bank in the world and the first in Europe. By 1995, the Internet was fully commercialized in the U.S. when the NSFNet was decommissioned, removing the last restrictions on use of the Internet to carry commercial traffic. As technology advanced and commercial opportunities fueled reciprocal growth, the volume of Internet traffic started experiencing similar characteristics as that of the scaling of MOS transistors, exemplified by Moore's law, doubling every 18 months. This growth, formalized as Edholm's law, was catalyzed by advances in MOS technology, laser light wave systems, and noise performance. Since 1995, the Internet has tremendously impacted culture and commerce, including the rise of near-instant communication by email, instant messaging, telephony (Voice over Internet Protocol or VoIP), two-way interactive video calls, and the World Wide Web. Increasing amounts of data are transmitted at higher and higher speeds over fiber optic networks operating at 1 Gbit/s, 10 Gbit/s, or more. The Internet continues to grow, driven by ever-greater amounts of online information and knowledge, commerce, entertainment and social networking services. During the late 1990s, it was estimated that traffic on the public Internet grew by 100 percent per year, while the mean annual growth in the number of Internet users was thought to be between 20% and 50%. This growth is often attributed to the lack of central administration, which allows organic growth of the network, as well as the non-proprietary nature of the Internet protocols, which encourages vendor interoperability and prevents any one company from exerting too much control over the network. In November 2006, the Internet was included on USA Today's list of the New Seven Wonders. As of 31 March 2011[update], the estimated total number of Internet users was 2.095 billion (30% of world population). It is estimated that in 1993 the Internet carried only 1% of the information flowing through two-way telecommunication. By 2000 this figure had grown to 51%, and by 2007 more than 97% of all telecommunicated information was carried over the Internet. Modern smartphones can access the Internet through cellular carrier networks, and internet usage by mobile and tablet devices exceeded desktop worldwide for the first time in October 2016. As of 2018[update], 80% of the world's population were covered by a 4G network. The International Telecommunication Union (ITU) estimated that, by the end of 2017, 48% of individual users regularly connect to the Internet, up from 34% in 2012. Mobile Internet connectivity has played an important role in expanding access in recent years, especially in Asia and the Pacific and in Africa. The number of unique mobile cellular subscriptions increased from 3.9 billion in 2012 to 4.8 billion in 2016, two-thirds of the world's population, with more than half of subscriptions located in Asia and the Pacific. The limits that users face on accessing information via mobile applications coincide with a broader process of fragmentation of the Internet. Fragmentation restricts access to media content and tends to affect the poorest users the most. One solution, zero-rating, is the practice of Internet service providers allowing users free connectivity to access specific content or applications without cost. Social impact The Internet has enabled new forms of social interaction, activities, and social associations, giving rise to the scholarly study of the sociology of the Internet. Between 2000 and 2009, the number of Internet users globally rose from 390 million to 1.9 billion. By 2010, 22% of the world's population had access to computers with 1 billion Google searches every day, 300 million Internet users reading blogs, and 2 billion videos viewed daily on YouTube. In 2014 the world's Internet users surpassed 3 billion or 44 percent of world population, but two-thirds came from the richest countries, with 78 percent of Europeans using the Internet, followed by 57 percent of the Americas. However, by 2018, Asia alone accounted for 51% of all Internet users, with 2.2 billion out of the 4.3 billion Internet users in the world. China's Internet users surpassed a major milestone in 2018, when the country's Internet regulatory authority, China Internet Network Information Centre, announced that China had 802 million users. China was followed by India, with some 700 million users, with the United States third with 275 million users. However, in terms of penetration, in 2022, China had a 70% penetration rate compared to India's 60% and the United States's 90%. In 2022, 54% of the world's Internet users were based in Asia, 14% in Europe, 7% in North America, 10% in Latin America and the Caribbean, 11% in Africa, 4% in the Middle East and 1% in Oceania. In 2019, Kuwait, Qatar, the Falkland Islands, Bermuda and Iceland had the highest Internet penetration by the number of users, with 93% or more of the population with access. As of 2022, it was estimated that 5.4 billion people use the Internet, more than two-thirds of the world's population. Early computer systems were limited to the characters in the American Standard Code for Information Interchange (ASCII), a subset of the Latin alphabet. After English (27%), the most requested languages on the World Wide Web are Chinese (25%), Spanish (8%), Japanese (5%), Portuguese and German (4% each), Arabic, French and Russian (3% each), and Korean (2%). Modern character encoding standards, such as Unicode, allow for development and communication in the world's widely used languages. However, some glitches such as mojibake (incorrect display of some languages' characters) still remain. Several neologisms exist that refer to Internet users: Netizen (as in "citizen of the net") refers to those actively involved in improving online communities, the Internet in general or surrounding political affairs and rights such as free speech, Internaut refers to operators or technically highly capable users of the Internet, digital citizen refers to a person using the Internet in order to engage in society, politics, and government participation. The Internet allows greater flexibility in working hours and location, especially with the spread of unmetered high-speed connections. The Internet can be accessed almost anywhere by numerous means, including through mobile Internet devices. Mobile phones, datacards, handheld game consoles and cellular routers allow users to connect to the Internet wirelessly.[citation needed] Educational material at all levels from pre-school (e.g. CBeebies) to post-doctoral (e.g. scholarly literature through Google Scholar) is available on websites. The internet has facilitated the development of virtual universities and distance education, enabling both formal and informal education. The Internet allows researchers to conduct research remotely via virtual laboratories, with profound changes in reach and generalizability of findings as well as in communication between scientists and in the publication of results. By the late 2010s the Internet had been described as "the main source of scientific information "for the majority of the global North population".: 111 Wikis have also been used in the academic community for sharing and dissemination of information across institutional and international boundaries. In those settings, they have been found useful for collaboration on grant writing, strategic planning, departmental documentation, and committee work. The United States Patent and Trademark Office uses a wiki to allow the public to collaborate on finding prior art relevant to examination of pending patent applications. Queens, New York has used a wiki to allow citizens to collaborate on the design and planning of a local park. The English Wikipedia has the largest user base among wikis on the World Wide Web and ranks in the top 10 among all sites in terms of traffic. The Internet has been a major outlet for leisure activity since its inception, with entertaining social experiments such as MUDs and MOOs being conducted on university servers, and humor-related Usenet groups receiving much traffic. Many Internet forums have sections devoted to games and funny videos. Another area of leisure activity on the Internet is multiplayer gaming. This form of recreation creates communities, where people of all ages and origins enjoy the fast-paced world of multiplayer games. These range from MMORPG to first-person shooters, from role-playing video games to online gambling. While online gaming has been around since the 1970s, modern modes of online gaming began with subscription services such as GameSpy and MPlayer. Streaming media is the real-time delivery of digital media for immediate consumption or enjoyment by end users. Streaming companies (such as Netflix, Disney+, Amazon's Prime Video, Mubi, Hulu, and Apple TV+) now dominate the entertainment industry, eclipsing traditional broadcasters. Audio streamers such as Spotify and Apple Music also have significant market share in the audio entertainment market. Video sharing websites are also a major factor in the entertainment ecosystem. YouTube was founded on 15 February 2005 and is now the leading website for free streaming video with more than two billion users. It uses a web player to stream and show video files. YouTube users watch hundreds of millions, and upload hundreds of thousands, of videos daily. Other video sharing websites include Vimeo, Instagram and TikTok.[citation needed] Although many governments have attempted to restrict both Internet pornography and online gambling, this has generally failed to stop their widespread popularity. A number of advertising-funded ostensible video sharing websites known as "tube sites" have been created to host shared pornographic video content. Due to laws requiring the documentation of the origin of pornography, these websites now largely operate in conjunction with pornographic movie studios and their own independent creator networks, acting as de-facto video streaming services. Major players in this field include the market leader Aylo, the operator of PornHub and numerous other branded sites, as well as other independent operators such as xHamster and Xvideos. As of 2023[update], Internet traffic to pornographic video sites rivalled that of mainstream video streaming and sharing services. Remote work is facilitated by tools such as groupware, virtual private networks, conference calling, videotelephony, and VoIP so that work may be performed from any location, such as the worker's home.[citation needed] The spread of low-cost Internet access in developing countries has opened up new possibilities for peer-to-peer charities, which allow individuals to contribute small amounts to charitable projects for other individuals. Websites, such as DonorsChoose and GlobalGiving, allow small-scale donors to direct funds to individual projects of their choice. A popular twist on Internet-based philanthropy is the use of peer-to-peer lending for charitable purposes. Kiva pioneered this concept in 2005, offering the first web-based service to publish individual loan profiles for funding. The low cost and nearly instantaneous sharing of ideas, knowledge, and skills have made collaborative work dramatically easier, with the help of collaborative software, which allow groups to easily form, cheaply communicate, and share ideas. An example of collaborative software is the free software movement, which has produced, among other things, Linux, Mozilla Firefox, and OpenOffice.org (later forked into LibreOffice).[citation needed] Content management systems allow collaborating teams to work on shared sets of documents simultaneously without accidentally destroying each other's work.[citation needed] The internet also allows for cloud computing, virtual private networks, remote desktops, and remote work.[citation needed] The online disinhibition effect describes the tendency of many individuals to behave more stridently or offensively online than they would in person. A significant number of feminist women have been the target of various forms of harassment, including insults and hate speech, to, in extreme cases, rape and death threats, in response to posts they have made on social media. Social media companies have been criticized in the past for not doing enough to aid victims of online abuse. Children also face dangers online such as cyberbullying and approaches by sexual predators, who sometimes pose as children themselves. Due to naivety, they may also post personal information about themselves online, which could put them or their families at risk unless warned not to do so. Many parents choose to enable Internet filtering or supervise their children's online activities in an attempt to protect their children from pornography or violent content on the Internet. The most popular social networking services commonly forbid users under the age of 13. However, these policies can be circumvented by registering an account with a false birth date, and a significant number of children aged under 13 join such sites.[citation needed] Social networking services for younger children, which claim to provide better levels of protection for children, also exist. Internet usage has been correlated to users' loneliness. Lonely people tend to use the Internet as an outlet for their feelings and to share their stories with others, such as in the "I am lonely will anyone speak to me" thread.[citation needed] Cyberslacking can become a drain on corporate resources; employees spend a significant amount of time surfing the Web while at work. Internet addiction disorder is excessive computer use that interferes with daily life. Nicholas G. Carr believes that Internet use has other effects on individuals, for instance improving skills of scan-reading and interfering with the deep thinking that leads to true creativity. Electronic business encompasses business processes spanning the entire value chain: purchasing, supply chain management, marketing, sales, customer service, and business relationship. E-commerce seeks to add revenue streams using the Internet to build and enhance relationships with clients and partners. According to International Data Corporation, the size of worldwide e-commerce, when global business-to-business and -consumer transactions are combined, equate to $16 trillion in 2013. A report by Oxford Economics added those two together to estimate the total size of the digital economy at $20.4 trillion, equivalent to roughly 13.8% of global sales. While much has been written of the economic advantages of Internet-enabled commerce, there is also evidence that some aspects of the Internet such as maps and location-aware services may serve to reinforce economic inequality and the digital divide. Electronic commerce may be responsible for consolidation and the decline of mom-and-pop, brick and mortar businesses resulting in increases in income inequality. A 2013 Institute for Local Self-Reliance report states that brick-and-mortar retailers employ 47 people for every $10 million in sales, while Amazon employs only 14. Similarly, the 700-employee room rental start-up Airbnb was valued at $10 billion in 2014, about half as much as Hilton Worldwide, which employs 152,000 people. At that time, Uber employed 1,000 full-time employees and was valued at $18.2 billion, about the same valuation as Avis Rent a Car and The Hertz Corporation combined, which together employed almost 60,000 people. Advertising on popular web pages can be lucrative, and e-commerce. Online advertising is a form of marketing and advertising which uses the Internet to deliver promotional marketing messages to consumers. It includes email marketing, search engine marketing (SEM), social media marketing, many types of display advertising (including web banner advertising), and mobile advertising. In 2011, Internet advertising revenues in the United States surpassed those of cable television and nearly exceeded those of broadcast television.: 19 Many common online advertising practices are controversial and increasingly subject to regulation. The Internet has achieved new relevance as a political tool. The presidential campaign of Howard Dean in 2004 in the United States was notable for its success in soliciting donation via the Internet. Many political groups use the Internet to achieve a new method of organizing for carrying out their mission, having given rise to Internet activism. Social media websites, such as Facebook and Twitter, helped people organize the Arab Spring, by helping activists organize protests, communicate grievances, and disseminate information. Many have understood the Internet as an extension of the Habermasian notion of the public sphere, observing how network communication technologies provide something like a global civic forum. However, incidents of politically motivated Internet censorship have now been recorded in many countries, including western democracies. E-government is the use of technological communications devices, such as the Internet, to provide public services to citizens and other persons in a country or region. E-government offers opportunities for more direct and convenient citizen access to government and for government provision of services directly to citizens. Cybersectarianism is a new organizational form that involves: highly dispersed small groups of practitioners that may remain largely anonymous within the larger social context and operate in relative secrecy, while still linked remotely to a larger network of believers who share a set of practices and texts, and often a common devotion to a particular leader. Overseas supporters provide funding and support; domestic practitioners distribute tracts, participate in acts of resistance, and share information on the internal situation with outsiders. Collectively, members and practitioners of such sects construct viable virtual communities of faith, exchanging personal testimonies and engaging in the collective study via email, online chat rooms, and web-based message boards. In particular, the British government has raised concerns about the prospect of young British Muslims being indoctrinated into Islamic extremism by material on the Internet, being persuaded to join terrorist groups such as the so-called "Islamic State", and then potentially committing acts of terrorism on returning to Britain after fighting in Syria or Iraq.[citation needed] Applications and services The Internet carries many applications and services, most prominently the World Wide Web, including social media, electronic mail, mobile applications, multiplayer online games, Internet telephony, file sharing, and streaming media services. The World Wide Web is a global collection of documents, images, multimedia, applications, and other resources, logically interrelated by hyperlinks and referenced with Uniform Resource Identifiers (URIs), which provide a global system of named references. URIs symbolically identify services, web servers, databases, and the documents and resources that they can provide. HyperText Transfer Protocol (HTTP) is the main access protocol of the World Wide Web. Web services also use HTTP for communication between software systems for information transfer, sharing and exchanging business data and logistics and is one of many languages or protocols that can be used for communication on the Internet. World Wide Web browser software, such as Microsoft Edge, Mozilla Firefox, Opera, Apple's Safari, and Google Chrome, enable users to navigate from one web page to another via the hyperlinks embedded in the documents. These documents may also contain computer data, including graphics, sounds, text, video, multimedia and interactive content. Client-side scripts can include animations, games, office applications and scientific demonstrations. Email is an important communications service available via the Internet. The concept of sending electronic text messages between parties, analogous to mailing letters or memos, predates the creation of the Internet. Internet telephony is a common communications service realized with the Internet. The name of the principal internetworking protocol, the Internet Protocol, lends its name to voice over Internet Protocol (VoIP).[citation needed] VoIP systems now dominate many markets, being as easy and convenient as a traditional telephone, while having substantial cost savings, especially over long distances. File sharing is the practice of transferring large amounts of data in the form of computer files across the Internet, for example via file servers. The load of bulk downloads to many users can be eased by the use of "mirror" servers or peer-to-peer networks. Access to the file may be controlled by user authentication, the transit of the file over the Internet may be obscured by encryption, and money may change hands for access to the file. The price can be paid by the remote charging of funds from, for example, a credit card whose details are also passed—usually fully encrypted—across the Internet. The origin and authenticity of the file received may be checked by a digital signature. Governance The Internet is a global network that comprises many voluntarily interconnected autonomous networks. It operates without a central governing body. The technical underpinning and standardization of the core protocols (IPv4 and IPv6) is an activity of the Internet Engineering Task Force (IETF), a non-profit organization of loosely affiliated international participants that anyone may associate with by contributing technical expertise. While the hardware components in the Internet infrastructure can often be used to support other software systems, it is the design and the standardization process of the software that characterizes the Internet and provides the foundation for its scalability and success. The responsibility for the architectural design of the Internet software systems has been assumed by the IETF. The IETF conducts standard-setting work groups, open to any individual, about the various aspects of Internet architecture. The resulting contributions and standards are published as Request for Comments (RFC) documents on the IETF web site. The principal methods of networking that enable the Internet are contained in specially designated RFCs that constitute the Internet Standards. Other less rigorous documents are simply informative, experimental, or historical, or document the best current practices when implementing Internet technologies. To maintain interoperability, the principal name spaces of the Internet are administered by the Internet Corporation for Assigned Names and Numbers (ICANN). ICANN is governed by an international board of directors drawn from across the Internet technical, business, academic, and other non-commercial communities. The organization coordinates the assignment of unique identifiers for use on the Internet, including domain names, IP addresses, application port numbers in the transport protocols, and many other parameters. Globally unified name spaces are essential for maintaining the global reach of the Internet. This role of ICANN distinguishes it as perhaps the only central coordinating body for the global Internet. The National Telecommunications and Information Administration, an agency of the United States Department of Commerce, had final approval over changes to the DNS root zone until the IANA stewardship transition on 1 October 2016. Regional Internet registries (RIRs) were established for five regions of the world to assign IP address blocks and other Internet parameters to local registries, such as Internet service providers, from a designated pool of addresses set aside for each region:[citation needed] The Internet Society (ISOC) was founded in 1992 with a mission to "assure the open development, evolution and use of the Internet for the benefit of all people throughout the world". Its members include individuals as well as corporations, organizations, governments, and universities. Among other activities ISOC provides an administrative home for a number of less formally organized groups that are involved in developing and managing the Internet, including: the Internet Engineering Task Force (IETF), Internet Architecture Board (IAB), Internet Engineering Steering Group (IESG), Internet Research Task Force (IRTF), and Internet Research Steering Group (IRSG). On 16 November 2005, the United Nations-sponsored World Summit on the Information Society in Tunis established the Internet Governance Forum (IGF) to discuss Internet-related issues.[citation needed] Infrastructure The communications infrastructure of the Internet consists of its hardware components and a system of software layers that control various aspects of the architecture. As with any computer network, the Internet physically consists of routers, media (such as cabling and radio links), repeaters, and modems. However, as an example of internetworking, many of the network nodes are not necessarily Internet equipment per se. Internet packets are carried by other full-fledged networking protocols, with the Internet acting as a homogeneous networking standard, running across heterogeneous hardware, with the packets guided to their destinations by IP routers.[citation needed] Internet service providers (ISPs) establish worldwide connectivity between individual networks at various levels of scope. At the top of the routing hierarchy are the tier 1 networks, large telecommunication companies that exchange traffic directly with each other via very high speed fiber-optic cables and governed by peering agreements. Tier 2 and lower-level networks buy Internet transit from other providers to reach at least some parties on the global Internet, though they may also engage in peering. End-users who only access the Internet when needed to perform a function or obtain information, represent the bottom of the routing hierarchy.[citation needed] An ISP may use a single upstream provider for connectivity, or implement multihoming to achieve redundancy and load balancing. Internet exchange points are major traffic exchanges with physical connections to multiple ISPs. Large organizations, such as academic institutions, large enterprises, and governments, may perform the same function as ISPs, engaging in peering and purchasing transit on behalf of their internal networks. Research networks tend to interconnect with large subnetworks such as GEANT, GLORIAD, Internet2, and the UK's national research and education network, JANET.[citation needed] Common methods of Internet access by users include broadband over coaxial cable, fiber optics or copper wires, Wi-Fi, satellite, and cellular telephone technology.[citation needed] Grassroots efforts have led to wireless community networks. Commercial Wi-Fi services that cover large areas are available in many cities, such as New York, London, Vienna, Toronto, San Francisco, Philadelphia, Chicago and Pittsburgh. Most servers that provide internet services are today hosted in data centers, and content is often accessed through high-performance content delivery networks. Colocation centers often host private peering connections between their customers, internet transit providers, cloud providers, meet-me rooms for connecting customers together, Internet exchange points, and landing points and terminal equipment for fiber optic submarine communication cables, connecting the internet. Internet Protocol Suite The Internet standards describe a framework known as the Internet protocol suite (also called TCP/IP, based on the first two components.) This is a suite of protocols that are ordered into a set of four conceptional layers by the scope of their operation, originally documented in RFC 1122 and RFC 1123:[citation needed] The most prominent component of the Internet model is the Internet Protocol. IP enables internetworking, essentially establishing the Internet itself. Two versions of the Internet Protocol exist, IPv4 and IPv6.[citation needed] Aside from the complex array of physical connections that make up its infrastructure, the Internet is facilitated by bi- or multi-lateral commercial contracts (e.g., peering agreements), and by technical specifications or protocols that describe the exchange of data over the network.[citation needed] For locating individual computers on the network, the Internet provides IP addresses. IP addresses are used by the Internet infrastructure to direct internet packets to their destinations. They consist of fixed-length numbers, which are found within the packet. IP addresses are generally assigned to equipment either automatically via Dynamic Host Configuration Protocol, or are configured.[citation needed] Domain Name Systems convert user-inputted domain names (e.g. "en.wikipedia.org") into IP addresses.[citation needed] Internet Protocol version 4 (IPv4) defines an IP address as a 32-bit number. IPv4 is the initial version used on the first generation of the Internet and is still in dominant use. It was designed in 1981 to address up to ≈4.3 billion (109) hosts. However, the explosive growth of the Internet has led to IPv4 address exhaustion, which entered its final stage in 2011, when the global IPv4 address allocation pool was exhausted. Because of the growth of the Internet and the depletion of available IPv4 addresses, a new version of IP IPv6, was developed in the mid-1990s, which provides vastly larger addressing capabilities and more efficient routing of Internet traffic. IPv6 uses 128 bits for the IP address and was standardized in 1998. IPv6 deployment has been ongoing since the mid-2000s and is currently in growing deployment around the world, since Internet address registries began to urge all resource managers to plan rapid adoption and conversion. By design, IPv6 is not directly interoperable with IPv4. Instead, it establishes a parallel version of the Internet not directly accessible with IPv4 software. Thus, translation facilities exist for internetworking, and some nodes have duplicate networking software for both networks. Essentially all modern computer operating systems support both versions of the Internet Protocol.[citation needed] Network infrastructure, however, has been lagging in this development.[citation needed] A subnet or subnetwork is a logical subdivision of an IP network.: 1, 16 Computers that belong to a subnet are addressed with an identical most-significant bit-group in their IP addresses. This results in the logical division of an IP address into two fields, the network number or routing prefix and the rest field or host identifier. The rest field is an identifier for a specific host or network interface.[citation needed] The routing prefix may be expressed in Classless Inter-Domain Routing (CIDR) notation written as the first address of a network, followed by a slash character (/), and ending with the bit-length of the prefix. For example, 198.51.100.0/24 is the prefix of the Internet Protocol version 4 network starting at the given address, having 24 bits allocated for the network prefix, and the remaining 8 bits reserved for host addressing. Addresses in the range 198.51.100.0 to 198.51.100.255 belong to this network. The IPv6 address specification 2001:db8::/32 is a large address block with 296 addresses, having a 32-bit routing prefix.[citation needed] For IPv4, a network may also be characterized by its subnet mask or netmask, which is the bitmask that when applied by a bitwise AND operation to any IP address in the network, yields the routing prefix. Subnet masks are also expressed in dot-decimal notation like an address. For example, 255.255.255.0 is the subnet mask for the prefix 198.51.100.0/24.[citation needed] Computers and routers use routing tables in their operating system to forward IP packets to reach a node on a different subnetwork. Routing tables are maintained by manual configuration or automatically by routing protocols. End-nodes typically use a default route that points toward an ISP providing transit, while ISP routers use the Border Gateway Protocol to establish the most efficient routing across the complex connections of the global Internet.[citation needed] The default gateway is the node that serves as the forwarding host (router) to other networks when no other route specification matches the destination IP address of a packet. Security Internet resources, hardware, and software components are the target of criminal or malicious attempts to gain unauthorized control to cause interruptions, commit fraud, engage in blackmail or access private information. Malware is malicious software used and distributed via the Internet. It includes computer viruses which are copied with the help of humans, computer worms which copy themselves automatically, software for denial of service attacks, ransomware, botnets, and spyware that reports on the activity and typing of users.[citation needed] Usually, these activities constitute cybercrime. Defense theorists have also speculated about the possibilities of hackers using cyber warfare using similar methods on a large scale. Malware poses serious problems to individuals and businesses on the Internet. According to Symantec's 2018 Internet Security Threat Report (ISTR), malware variants number has increased to 669,947,865 in 2017, which is twice as many malware variants as in 2016. Cybercrime, which includes malware attacks as well as other crimes committed by computer, was predicted to cost the world economy US$6 trillion in 2021, and is increasing at a rate of 15% per year. Since 2021, malware has been designed to target computer systems that run critical infrastructure such as the electricity distribution network. Malware can be designed to evade antivirus software detection algorithms. The vast majority of computer surveillance involves the monitoring of data and traffic on the Internet. In the United States for example, under the Communications Assistance For Law Enforcement Act, all phone calls and broadband Internet traffic (emails, web traffic, instant messaging, etc.) are required to be available for unimpeded real-time monitoring by Federal law enforcement agencies. Under the Act, all U.S. telecommunications providers are required to install packet sniffing technology to allow Federal law enforcement and intelligence agencies to intercept all of their customers' broadband Internet and VoIP traffic.[d] The large amount of data gathered from packet capture requires surveillance software that filters and reports relevant information, such as the use of certain words or phrases, the access to certain types of web sites, or communicating via email or chat with certain parties. Agencies, such as the Information Awareness Office, NSA, GCHQ and the FBI, spend billions of dollars per year to develop, purchase, implement, and operate systems for interception and analysis of data. Similar systems are operated by Iranian secret police to identify and suppress dissidents. The required hardware and software were allegedly installed by German Siemens AG and Finnish Nokia. Some governments, such as those of Myanmar, Iran, North Korea, Mainland China, Saudi Arabia and the United Arab Emirates, restrict access to content on the Internet within their territories, especially to political and religious content, with domain name and keyword filters. In Norway, Denmark, Finland, and Sweden, major Internet service providers have voluntarily agreed to restrict access to sites listed by authorities. While this list of forbidden resources is supposed to contain only known child pornography sites, the content of the list is secret. Many countries, including the United States, have enacted laws against the possession or distribution of certain material, such as child pornography, via the Internet but do not mandate filter software. Many free or commercially available software programs, called content-control software are available to users to block offensive specific on individual computers or networks in order to limit access by children to pornographic material or depiction of violence.[citation needed] Performance As the Internet is a heterogeneous network, its physical characteristics, including, for example the data transfer rates of connections, vary widely. It exhibits emergent phenomena that depend on its large-scale organization. PB per monthYear020,00040,00060,00080,000100,000120,000140,000199019952000200520102015Petabytes per monthGlobal Internet Traffic Volume The volume of Internet traffic is difficult to measure because no single point of measurement exists in the multi-tiered, non-hierarchical topology. Traffic data may be estimated from the aggregate volume through the peering points of the Tier 1 network providers, but traffic that stays local in large provider networks may not be accounted for.[citation needed] An Internet blackout or outage can be caused by local signaling interruptions. Disruptions of submarine communications cables may cause blackouts or slowdowns to large areas, such as in the 2008 submarine cable disruption. Less-developed countries are more vulnerable due to the small number of high-capacity links. Land cables are also vulnerable, as in 2011 when a woman digging for scrap metal severed most connectivity for the nation of Armenia. Internet blackouts affecting almost entire countries can be achieved by governments as a form of Internet censorship, as in the blockage of the Internet in Egypt, whereby approximately 93% of networks were without access in 2011 in an attempt to stop mobilization for anti-government protests. Estimates of the Internet's electricity usage have been the subject of controversy, according to a 2014 peer-reviewed research paper that found claims differing by a factor of 20,000 published in the literature during the preceding decade, ranging from 0.0064 kilowatt hours per gigabyte transferred (kWh/GB) to 136 kWh/GB. The researchers attributed these discrepancies mainly to the year of reference (i.e. whether efficiency gains over time had been taken into account) and to whether "end devices such as personal computers and servers are included" in the analysis. In 2011, academic researchers estimated the overall energy used by the Internet to be between 170 and 307 GW, less than two percent of the energy used by humanity. This estimate included the energy needed to build, operate, and periodically replace the estimated 750 million laptops, a billion smart phones and 100 million servers worldwide as well as the energy that routers, cell towers, optical switches, Wi-Fi transmitters and cloud storage devices use when transmitting Internet traffic. According to a non-peer-reviewed study published in 2018 by The Shift Project (a French think tank funded by corporate sponsors), nearly 4% of global CO2 emissions could be attributed to global data transfer and the necessary infrastructure. The study also said that online video streaming alone accounted for 60% of this data transfer and therefore contributed to over 300 million tons of CO2 emission per year, and argued for new "digital sobriety" regulations restricting the use and size of video files. See also Notes References Sources Further reading External links |
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[SOURCE: https://en.wikipedia.org/wiki/Sundown_town] | [TOKENS: 2557] |
Contents Sundown town Sundown towns, also known as sunset towns, gray towns, or sundowner towns, were all-White municipalities or neighborhoods in the United States that practiced a form of racial segregation by excluding non-whites via some combination of discriminatory local laws, intimidation or violence. They were most prevalent before the 1950s. The term came into use because of signs that directed "colored people" to leave town by sundown. Sundown counties and sundown suburbs were created as well. While sundown laws became illegal following the passage of the Civil Rights Act of 1968, some commentators hold that certain 21st-century practices perpetuate a modified version of the sundown town. Some of these modern practices include racial profiling by local police and sheriff's departments, vandalism of public art, harassment by private citizens, and gentrification. Specific examples of exclusion of Native Americans, Asians, Latinos, Jews, and Catholics alongside many other communities include towns such as Minden and Gardnerville, Nevada, in which sirens were used from 1917 until 1974 to signal Native Americans to leave town by 6:30 p.m. each evening, a practice that symbolically persisted into the 21st century. In Antioch, California, Chinese residents faced curfews as early as 1851, and in 1876, a mob destroyed the Chinatown district, prompting a mass exodus that left only a small number of Chinese residents by the mid-20th century. Mexican Americans were excluded from Midwestern sundown towns through racially restrictive housing covenants, signs (often posted within the same infamous "No Blacks, No Dogs" signs), and police harassment. Additionally, Jews and Catholics were unwelcome in certain communities, with some towns explicitly prohibiting them from owning property or joining local clubs. Black Americans were also affected through widespread and often well-documented exclusionary policies. These discriminatory policies and actions distinguish sundown towns from towns that have no Black residents for demographic reasons. Historically, towns have been confirmed as sundown towns by newspaper articles, county histories, and Works Progress Administration files; this information has been corroborated by tax or U.S. census records showing an absence of Black people or a sharp drop in the Black population between two censuses. History The earliest legal restrictions on the nighttime activities and movements of African Americans and other racial minorities date back to the colonial era. The general court and legislative assembly of the Province of New Hampshire passed "An Act to Prevent Disorders in the Night" in 1714: Whereas great disorders, insolencies and burglaries are oft times raised and committed in the night time by Indian, Negro, and Molatto Servants and Slaves to the Disquiet and hurt of her Majesty's subjects, No Indian, Negro, or Molatto is to be from Home after 9 o'clock. Notices emphasizing and re-affirming the curfew were published in The New Hampshire Gazette in 1764 and 1771. Following the American Revolutionary War, Virginia was the first U.S. state to prohibit the entry of all Free Negros. In the Northwest Territory, which existed from 1787 to 1803, local authorities across the region imposed special regulations on free Black Americans migrating to the territory, known as "black laws"; these included requiring them to register themselves with county officials and post bonds "designed to ensure that they would not become dependent on public relief." As noted by the historian Kate Masur, "many Americans–in free states and slave states alike–viewed laws that imposed special regulations on free people of African or Native American descent as just another appropriate use of the police power." Following the end of the Reconstruction era, thousands of towns and counties across the United States became sundown localities, as part of the imposition of Jim Crow laws and other segregationist practices. In most cases, the exclusion was official town policy or was promulgated by the community's real estate agents via exclusionary covenants governing who could buy or rent property. In others, the policy was enforced through intimidation. This intimidation could occur in several ways, including harassment by law enforcement officers. Though no sundown towns exist today in the sense of publicly or legally excluding non-white residents, some commentators have applied the term to towns practicing other forms of racial exclusion. In 1844, Oregon, which had banned slavery, banned African Americans from the territory altogether. Those who failed to leave were liable to receive lashings under a law known as the "Peter Burnett Lash Law", named for Provisional Supreme Judge Peter Burnett. No persons were ever lashed under the law; it was quickly amended to replace lashing with forced labor, and eventually repealed the following year after a change in the makeup of the legislature. However, additional laws aimed at African Americans entering Oregon were ratified in 1849 and 1857, the last of which was not repealed until 1926. Outside Oregon, other places looked to laws and legislation to restrict Black people from residing within cities, towns and states. In 1853, new black residents were banned from moving to the state of Illinois. Those new residents who remained more than ten days and were unable to pay the fine were to be punished by forced labor. Although this law faced significant resistance, especially in Illinois' small black community, it was not repealed until the end of the Civil War in 1865. Similar bans on all black migration were passed in Michigan, Ohio and Iowa. New laws were enacted in the 20th century. One example is Louisville, Kentucky, whose mayor proposed a law in 1911 that would restrict Black people from owning property in certain parts of the city. This city ordinance reached public attention when it was challenged in the U.S. Supreme Court in the case of Buchanan v. Warley in 1917. Ultimately, the court decided that the laws passed in Louisville were unconstitutional, thus setting the legal precedent that similar laws could not exist or be passed in the future. However, this outcome did not stop towns from excluding black residents. Some city planners and real estate companies exercised their private authority to uphold racial segregation at the community level. In addition to discriminatory housing rules, violence and harassment were sometimes used by locals to discourage Black people from remaining in their cities after sundown. Whites in the North were threatened by the increased minority populations moving into their neighborhoods, and racial tensions started to build. Interracial violence became more common, sometimes escalating to race riots. After the civil rights movement of the 1950s and 1960s, and especially since the Fair Housing Act of 1968 prohibition of racial discrimination in the sale, rental and financing of housing, sundown towns gradually disappeared, with de facto sundown towns existing into the 1980s. However, as sociologist James W. Loewen wrote in his 2005 book, Sundown Towns: A Hidden Dimension of American Racism, it is impossible to count precisely the number of sundown towns at any given time because most towns have not kept records of the ordinances or signs that marked the town's sundown status. He further noted that hundreds of cities across America have been sundown towns at some point in their history. Additionally, Loewen wrote that sundown status meant more than just African Americans being unable to live in those towns. Any Black people who entered or were found in sundown towns after sunset were subject to harassment, threats and violence, including lynching. The U.S. Supreme Court case of Brown v. Board of Education declared segregation of schools unconstitutional in 1954. Loewen speculates that the case caused some municipalities in the South to become sundown towns: Missouri, Tennessee and Kentucky saw drastic drops in African American populations living in those states following the decision. In 2019, sociologist Heather O'Connell wrote that sundown towns are "(primarily) a thing of the past". However, historian James W. Loewen notes persisting effects of sundown towns' violently enforced segregation even after they may have been integrated to a small degree, a phenomenon he called "second-generation sundown towns." Function African Americans were not the only minority group not allowed to live in white towns. One example, according to Loewen, is that, in 1870, Chinese people made up one-third of Idaho's population. Following a wave of violence and an 1886 anti-Chinese convention in Boise, almost none remained by 1910.: 51 The towns of Minden and Gardnerville in Nevada had an ordinance from 1917 to 1974 that required Native Americans to leave the towns by 6:30 p.m. each day. A whistle, later a siren, was sounded at 6 p.m. daily, alerting Native Americans to leave by sundown.: 23 In 2021, the state of Nevada passed a law prohibiting the appropriation of Native American imagery by the mascots of schools, and the sounding of sirens that were once associated with sundown ordinances. Despite this law, Minden continued to play its siren for two more years, claiming that it was a nightly tribute to first responders. An additional state law in 2023 led Minden to end the siren. Two examples of the road signs documented during the first half of the 20th century include: In her 2011 article "Preemption, Patchwork Immigration Laws, and the Potential for Brown Sundown Towns" in the Fordham Law Review, Maria Marulanda outlines the possibility for non-blacks to be excluded from towns in the United States. She argues that immigration laws and ordinances in certain municipalities could create situations similar to those experienced by African Americans in sundown towns. Hispanic Americans are likely to suffer, despite the purported target being undocumented immigrants, in these cases of racial exclusion. From 1851 to at least 1876, Antioch, California, had a sundown ordinance that barred Chinese residents from being out in public after dark. In 1876, white residents drove the Chinese out of town and then burned down the Chinatown section of the city. Chinese Americans were also excluded from most of San Francisco, leading to the establishment of Chinatown. Described by former NAACP President Julian Bond as "one of the survival tools of segregated life", The Negro Motorist Green Book (at times titled The Negro Traveler's Green Book or The Negro Motorist Green-Book, and commonly referred to simply as the "Green Book") was an annual segregation-era guidebook for African American motorists, published by New York travel agent and former Hackensack, New Jersey, letter carrier Victor H. Green. It was published in the United States from 1936 to 1966, during the Jim Crow era, when discrimination against non-whites was widespread. Road trips for African Americans were inconvenient and in some cases dangerous because of racial segregation, racial profiling by police, the high rate of murder of African American travelers[citation needed], and the existence of numerous sundown towns. According to author Kate Kelly, "there were at least 10,000 'sundown towns' in the United States as late as the 1960s; in a 'sundown town' nonwhites had to leave the city limits by dusk, or they could be picked up by the police or worse. These towns were not limited to the South—they ranged from Levittown, New York, to Glendale, California, and included the majority of municipalities in Illinois." The Green Book also advised drivers to wear, or have ready, a chauffeur's cap and, if stopped, relate that "they were delivering a car for a white person." On June 7, 2017, the NAACP issued a warning to prospective African American travelers to Missouri. This is the first NAACP warning ever covering an entire state. The NAACP conference president suggested that, if prospective African American travelers must go to Missouri, they travel with bail money in hand. Many suburban areas in the United States were incorporated following the establishment of Jim Crow laws. The majority of suburbs were made up of all white residents from the time they were first created. Most sundown suburbs were created between 1906 and 1968. By 1970, at the peak of the Civil Rights era, some sundown suburbs had already begun to desegregate. Harassment and inducements contributed to keeping African Americans out of new suburban areas. List of sundown towns Sundown towns in popular culture See also References Further reading External links |
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[SOURCE: https://en.wikipedia.org/wiki/URL#Syntax] | [TOKENS: 957] |
Contents URL A uniform resource locator (URL), colloquially known as web address, is a reference to a resource on the World Wide Web. A URL specifies the location of a resource on a computer network and a mechanism for retrieving it. A URL is a specific type of Uniform Resource Identifier (URI), although many people use the two terms interchangeably.[a] A URL is most commonly used to reference a web page (HTTP/HTTPS) but is also used for file transfer (FTP), email (mailto), database access (JDBC), and many other applications. Most web browsers display the URL of a web page above the page in an address bar. As an example of a web page URL, https://www.example.com/index.html indicates protocol https, hostname www.example.com, and file name index.html. History The Uniform Resource Locator was defined in RFC 1738 in 1994 by Tim Berners-Lee, the inventor of the World Wide Web, and the URI working group of the Internet Engineering Task Force (IETF), as an outcome of collaboration started at the IETF Living Documents birds of a feather session in 1992. The format combines the pre-existing system of domain names (created in 1985) with file path syntax, where slashes are used to separate directory and filenames. Conventions already existed where server names could be prefixed to complete file paths, preceded by a double slash (//). Berners-Lee later expressed regret at the use of dots to separate the parts of the domain name within URIs, wishing he had used slashes throughout, and also said that, given the colon following the first component of a URI, the two slashes before the domain name were unnecessary. Early WorldWideWeb collaborators, including Berners-Lee, originally proposed the use of UDIs: Universal Document Identifiers. An early (1993) draft of the HTML Specification referred to "Universal" Resource Locators. This was dropped some time between June 1994 and October 1994. In his book Weaving the Web, Berners-Lee emphasizes his preference for the original inclusion of "universal" in the expansion rather than the word "uniform", to which it was later changed, and he gives a brief account of the contention that led to the change. Syntax Every HTTP URL conforms to the syntax of a generic URI. The URI generic syntax consists of five components organized hierarchically in order of decreasing significance from left to right:: §3 A component is undefined if it has an associated delimiter and the delimiter does not appear in the URI; the scheme and path components are always defined.: §5.2.1 A component is empty if it has no characters; the scheme component is always non-empty.: §3 The authority component consists of subcomponents: This is represented in a syntax diagram as: The URI comprises: A web browser will usually dereference a URL by performing an HTTP request to the specified host, by default on port number 80. URLs using the https scheme require that requests and responses be made over a secure connection to the website. Internationalized URL Internet users are distributed throughout the world using a wide variety of languages and alphabets, and expect to be able to create URLs in their own local alphabets. An Internationalized Resource Identifier (IRI) is a form of URL that includes Unicode characters. All modern browsers support IRIs. The parts of the URL requiring special treatment for different alphabets are the domain name and path. The domain name in the IRI is known as an Internationalized Domain Name (IDN). Web and Internet software automatically convert the domain name into punycode usable by the Domain Name System; for example, the Chinese URL http://例子.卷筒纸 becomes http://xn--fsqu00a.xn--3lr804guic/. The xn-- indicates that the character was not originally ASCII. The URL path name can also be specified by the user in the local writing system. If not already encoded, it is converted to UTF-8, and any characters not part of the basic URL character set are escaped as hexadecimal using percent-encoding; for example, the Japanese URL http://example.com/引き割り.html becomes http://example.com/%E5%BC%95%E3%81%8D%E5%89%B2%E3%82%8A.html. The target computer decodes the address and displays the page. Protocol-relative URLs Protocol-relative links (PRL), also known as protocol-relative URLs (PRURL), are URLs that have no protocol specified. For example, //example.com will use the protocol of the current page, typically HTTP or HTTPS. See also Notes Citations References External links |
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[SOURCE: https://en.wikipedia.org/wiki/Ferranti_Pegasus] | [TOKENS: 1227] |
Contents Ferranti Pegasus Pegasus was an early British vacuum-tube (valve) computer built by Ferranti Ltd that pioneered design features to improve usability for both engineers and programmers. It was originally named the Ferranti Package Computer as its hardware design followed that of the Elliott 401 with modular plug-in packages. Much of the development was the product of three men: W. S. (Bill) Elliott (hardware), Christopher Strachey (software) and Bernard Swann (marketing and customer support). It was Ferranti's most popular valve computer with 38 units being sold. The first Pegasus was delivered in 1956 and the last was delivered in 1959. Ferranti received funding for the development from the National Research Development Corporation (NRDC). At least two Pegasus machines survive today: one in The Science Museum, London and one which was displayed in the Science and Industry Museum, Manchester but which has now been moved to the storage in the Science Museum archives at Wroughton. The Pegasus in The Science Museum, London ran its first program in December 1959 and was regularly demonstrated until 2009 when it developed a severe electrical fault. In early 2014, the Science Museum decided to retire it permanently, effectively ending the life of one of the world's oldest working computers. The Pegasus officially held the title of the world's oldest computer until 2012, when the restoration of the Harwell computer was completed at the National Museum of Computing. Design In those days it was common for it to be unclear whether a failure was due to the hardware or the program. As a consequence, Christopher Strachey of NRDC, who was himself a brilliant programmer, recommended the following design objectives: The first objective was only partially met, because both program code and the data on which it was to operate had to be in the 128 words of primary storage contained in 8-word nickel delay lines. The rest of the memory was held on a 7936-word magnetic drum, which rotated at 3750 rpm, so it was often necessary to use ingenuity to reduce the number of transfers between the fast store and the drum. Pegasus had eight accumulators, seven of which could also be used as index registers, the first computer to allow this dual use. Accumulators 6 and 7 were known as p and q and were involved in multiplication and division and some double-length shift instructions. Each word contained 39 bits plus 1 bit for parity checking. Two 19-bit instructions were packed into one word, with the extra bit that could be used to indicate a breakpoint (optional stop), to assist in debugging. In line with Strachey's second objective, it had a relatively generous instruction set for a computer of its time, but there was no explicit hardware provision for handling either characters or floating-point numbers. The speed of arithmetic operations was about the same as in the Elliott 402 computer, which could add in 204 microseconds and multiply in 3366 microseconds. The Pegasus basic instruction cycle time for add/subtract/move and logical instructions was 128 microseconds. Multiply, divide, justify and shift instructions took a variable time to complete. Transfers to and from the drum were synchronous. The layout of blocks on the drum was interleaved to allow some processing between transfers to/from consecutive blocks. The computer was advertised as weighing 2,560 lb (1.2 t). The extent to which Strachey's third objective was reached depends on how one views a price of £50,000 for Pegasus 1, which did not have magnetic tape drives, line printer or punched card input and output. The modular design with plug-in units of hardware did, however, make it very reliable by the standards of the day, and maintenance was "a doddle of a job". In its second year of use in 1958–59, the Pegasus at King's College (part of Durham University) in Newcastle upon Tyne had a typical reliability in excess of 98%, and 95.4% overall. Applications The initial version of Pegasus, Pegasus 1 was intended for scientific and engineering applications. Its input was via 5-hole paper tape with output on tape. The variant for business data processing was called Pegasus 2 and could be equipped with punched cards, magnetic tape and line printer. In 1956 the first Pegasus was used to calculate the stresses and strains in the tail plane of the Saunders-Roe SR.53;[citation needed] the results were used to check the manufacturer's figures; the programmer was Anne Robson. Because of the importance of a computer, it was housed in the drawing room, complete with an Adam's ceiling, of Ferranti's London office in Portland Place. A Pegasus 1 was installed at Cybor House, Sheffield by Stafford Beer for the use of United Steel. It was the first computer installed for management cybernetics. The Pegasus at Southampton University was used for analysis of ground resonance data for the Saro P.531 helicopter, which eventually entered production as the Westland Scout and Westland Wasp. In 1957 a Pegasus computer was used to calculate 7480 digits of π, a record at the time. In 1959 Handley Page Ltd were advertising for experienced Pegasus programmers to join their aviation design team at Cricklewood, London The Computing Laboratory at Newcastle University (then "King's College, Durham University") was established in 1957, and a Ferranti Pegasus was installed as the first computer – reputed at the time to be the first computer of any kind in the North East of England. The University of Leeds had a Pegasus computer, run by Sandy Douglas. This was used, among other things, for a project to process the University's matriculation records and by the British Market Research Bureau to analyse National Readership Survey data. Other people who worked on the Pegasus included Hugh McGregor Ross and Donald B. Gillies. See also References Bibliography External links |
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[SOURCE: https://en.wikipedia.org/wiki/Special:BookSources/9781138207929] | [TOKENS: 380] |
Contents Book sources This page allows users to search multiple sources for a book given a 10- or 13-digit International Standard Book Number. Spaces and dashes in the ISBN do not matter. This page links to catalogs of libraries, booksellers, and other book sources where you will be able to search for the book by its International Standard Book Number (ISBN). Online text Google Books and other retail sources below may be helpful if you want to verify citations in Wikipedia articles, because they often let you search an online version of the book for specific words or phrases, or you can browse through the book (although for copyright reasons the entire book is usually not available). At the Open Library (part of the Internet Archive) you can borrow and read entire books online. Online databases Subscription eBook databases Libraries Alabama Alaska California Colorado Connecticut Delaware Florida Georgia Illinois Indiana Iowa Kansas Kentucky Massachusetts Michigan Minnesota Missouri Nebraska New Jersey New Mexico New York North Carolina Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Washington state Wisconsin Bookselling and swapping Find your book on a site that compiles results from other online sites: These sites allow you to search the catalogs of many individual booksellers: Non-English book sources If the book you are looking for is in a language other than English, you might find it helpful to look at the equivalent pages on other Wikipedias, linked below – they are more likely to have sources appropriate for that language. Find other editions The WorldCat xISBN tool for finding other editions is no longer available. However, there is often a "view all editions" link on the results page from an ISBN search. Google books often lists other editions of a book and related books under the "about this book" link. You can convert between 10 and 13 digit ISBNs with these tools: Find on Wikipedia See also Get free access to research! Research tools and services Outreach Get involved |
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