text stringlengths 0 473k |
|---|
[SOURCE: https://en.wikipedia.org/wiki/Superhabitable_world] | [TOKENS: 2639] |
Contents Superhabitable world A superhabitable world is a hypothetical type of planet or moon that is better suited than Earth for the emergence and evolution of life. The concept was introduced in a 2014 paper by René Heller and John Armstrong, in which they criticized the language used in the search for habitable exoplanets and proposed clarifications. The authors argued that knowing whether a world is located within the star's habitable zone is insufficient to determine its habitability, and that the prevailing model of characterization was geocentric or anthropocentric in nature. Instead, they proposed a biocentric model that prioritized characteristics affecting the abundance of life and biodiversity on a world's surface. If a world possesses more diverse flora and fauna than there are on Earth, then it would empirically show that its natural environment is more hospitable to life. To identify such a world, one should consider its geological processes, formation age, atmospheric composition, ocean coverage, and the type of star that it orbits. In other words, a superhabitable world would likely be larger, warmer, and older than Earth, with an evenly-distributed ocean, and orbiting a K-type main-sequence star. In 2020, astronomers, building on Heller and Armstrong's hypothesis, identified 24 potentially superhabitable exoplanets based on measured characteristics that fit these criteria. Stellar characteristics A star's characteristics is a key consideration for planetary habitability. The types of stars generally considered to be potential hosts for habitable worlds include F, G, K, and M-type main-sequence stars. The most massive stars—O, B, and A-type, respectively—have average lifespans on the main sequence that are considered too short for complex life to develop, ranging from a few hundred million years for A-type stars to only a few million years for O-type stars. Thus, F-type stars are described as the "hot limit" for stars that can potentially support life, as their lifespan of 2 to 4 billion years would be sufficient for habitability. However, F-type stars emit large amounts of ultraviolet radiation, and without the presence of a protective ozone layer, could disrupt nucleic acid-based life on a planet's surface. On the opposite end, the less massive red dwarfs, which generally includes M-type stars, are by far the most common and long-lived stars in the universe, but ongoing research points to serious challenges to their ability to support life. Due to the low luminosity of red dwarfs, the circumstellar habitable zone (HZ)[a] is in very close proximity to the star, which causes any planet to become tidally locked. The primary concern for researchers, however, is the star's propensity for frequent outbreaks of high-energy radiation, especially early in its life, that could strip away a planet's atmosphere. At the same time, red dwarfs do not emit enough quiescent UV radiation (i.e., UV radiation emitted during inactive periods) to support biological processes like photosynthesis. Dismissing both ends, astronomers are led to conclude that G and K-type stars—yellow and orange dwarfs, respectively—provide the best life-supporting characteristics. However, a limiting factor to the habitability of yellow dwarfs is their higher emissions of ionizing radiation and shorter lifespans compared to cooler orange dwarfs. Therefore, researchers conclude that orange dwarfs offer the best conditions for a superhabitable world. Also nicknamed "Goldilocks stars", orange dwarfs emit low enough levels of ultraviolet radiation to eliminate the need for a protective ozone layer, but just enough to contribute to necessary biological processes. Additionally, the long average lifespan of an orange dwarf (18 to 34 billion years, compared to 10 billion for the Sun) provides a more stable habitable zone throughout the star's lifetime, providing more time for life to develop. Planetary characteristics It is necessary for the age of any superhabitable world to be greater than Earth's age (~4.5 billion years). This necessity is based on the belief that as a planet or moon ages, it experiences increasing levels of biodiversity, since native species have had more time to evolve, adapt, and stabilize the environmental conditions suitable for life. However, the eventual exhaustion of a world's internally generated heat means that there is also an upper limit to the age of any habitable world; internal cooling would lead to changes to the average global temperature and atmospheric composition. Therefore, the optimal age range for a superhabitable world would be roughly 5–8 billion years. During the main sequence phase, a star burns hydrogen in its core, producing energy through nuclear fusion. Over time, as the hydrogen fuel is consumed, the star's core contracts and heats up, leading to an increase in the rate of fusion. This causes the star to gradually become more luminous, and as its luminosity increases, the amount of energy it emits grows, pushing the habitable zone (HZ) outward. Studies suggest that Earth's orbit lies near the inner edge of the Solar System's HZ, which could harm its long-term livability as it nears the end of its HZ lifetime. Ideally, the orbit of a superhabitable world should be further out and closer to the center of the HZ relative to Earth's orbit, but knowing whether a world is in this region is insufficient on its own to determine habitability. Not all rocky planets in the HZ may be habitable, while tidal heating can render planets or moons habitable beyond this region. For example, Jupiter's moon Europa is well beyond the outer limits of the Solar System's HZ, yet as a result of its orbital interactions with the other Galilean moons, it is believed to have a subsurface ocean of liquid water beneath its icy surface. According to a 2023 paper by Jonathan Jernigan and colleagues, marine biological activity increases on planets with increasing obliquity and eccentricity. The authors suggest that planets with a high obliquity or eccentricity (or both) may be superhabitable, and that scientists should be keen to look for biosignatures on exoplanets with these orbital characteristics. Assuming that a greater surface area would provide greater biodiversity, the size of a superhabitable world should generally be greater than 1 R🜨, with the condition that its mass is not arbitrarily large. Studies of the mass-radius relationship indicate that there is a transition point between rocky planets and gaseous planets (i.e., mini-Neptunes) that occurs around 2 M🜨 or 1.7 R🜨. Another study argues that there is a natural radius limit, set at 1.6 R🜨, below which nearly all planets are terrestrial, composed primarily of rock-iron-water mixtures. Heller and Armstrong argue that the optimal mass and radius of a superhabitable world can be determined by geological activity; the more massive a planetary body, the longer time it will continuously generate internal heat—a major contributing factor to plate tectonics. Too much mass, however, can slow plate tectonics by increasing the pressure of the mantle. It is believed that plate tectonics peak in bodies between 1 and 5 M🜨, and from this perspective, a planet can be considered superhabitable up to around 2 M🜨. Assuming this planet has a density similar to Earth's, its radius should be between 1.2 and 1.3 R🜨. An important geological process is plate tectonics, which appears to be common in terrestrial planets with a significant rotation speed and an internal heat source. If large bodies of water are present on a planet, plate tectonics can maintain high levels of carbon dioxide (CO2) in its atmosphere and increase the global surface temperature through the greenhouse effect. However, if tectonic activity is not significant enough to increase temperatures above the freezing point of water, the planet could experience a permanent ice age, unless the process is offset by another energy source like tidal heating or stellar irradiation. On the other hand, if the effects of any of these processes are too strong, the amount of greenhouse gases in the atmosphere could cause a runaway greenhouse effect by trapping heat and preventing adequate cooling. The presence of a magnetic field is important for the long-term survivability of life on the surface of a planet or moon. A sufficiently strong magnetic field effectively shields a world's surface and atmosphere against ionizing radiation emanating from the interstellar medium and its host star. A planet can generate an intrinsic magnetic field through a dynamo that involves an internal heat source, an electrically conductive fluid like molten iron, and a significant rotation speed, while a moon could be extrinsically protected by its host planet's magnetic field. Less massive bodies and those that are tidally locked are likely to have a weak to non-existent magnetic field, which over time can result in the loss of a significant portion of its atmosphere by hydrodynamic escape and become a desert planet. If a planet's rotation is too slow, such as with Venus, then it cannot generate an Earth-like magnetic field. A more massive planet could overcome this problem by hosting multiple moons, which, through their combined gravitational effects, can boost the planet's magnetic field. The appearance of a superhabitable world should be similar to the conditions found in the tropical climates of Earth. Due to the denser atmosphere and less temperature variation across its surface, such a world would lack any major ice sheets and have a higher concentration of clouds, while plant life would potentially cover more of the planet's surface and be visible from space. When considering the differences in the peak wavelength of visible light for K-type stars and the lower stellar flux of the planet, surface vegetation may exhibit colors different than the typical green color found on Earth. Instead, vegetation on these worlds could have a red, orange, or even purple appearance. An ocean that covers a large portion of a world's surface with fractionate continents and archipelagos could provide a stable environment across its surface. In addition, the greater surface gravity of a superhabitable world could reduce the average ocean depth and create shallow ocean basins, providing the optimal environment for marine life to thrive. For example, marine ecosystems found in the shallow areas of Earth's oceans and seas, given the amount of light and heat they receive, are observed to have greater biodiversity and are generally seen as being more comfortable for aquatic species. This has led researchers to speculate that shallow water environments on exoplanets should be similarly suitable for life. In general, the climate of a superhabitable planet would be warm, moist, and homogeneous, allowing life to extend across the surface without presenting large population differences. These characteristics are in contrast to those found on Earth, which has more variable and inhospitable regions that include frigid tundra and dry deserts. Deserts on superhabitable planets would be more limited in area and would likely support habitat-rich coastal environments. The optimum surface temperature for Earth-like life is unknown, although it appears that on Earth, organism diversity has been greater in warmer periods. It is therefore possible that exoplanets with slightly higher average temperatures than that of Earth are more suitable for life. The denser atmosphere of a superhabitable planet would naturally provide a greater average temperature and less variability of the global climate. Ideally, the temperature should reach the optimal levels for plant life, which is 25 °C (77 °F). In addition, a large distributed ocean would have the ability to regulate a planet's surface temperature similar to Earth's ocean currents, and could allow it to maintain a moderate temperature within the habitable zone. There are no solid arguments to explain if Earth's atmosphere has the optimal composition, but relative atmospheric oxygen levels is required to meet the high-energy demands of complex life (O2). Therefore, it is hypothesized that oxygen abundance in the atmosphere is essential for complex life on other worlds. List of potentially superhabitable exoplanets In September 2020, Dirk Schulze-Makuch and colleagues identified 24 contenders for superhabitable planets out of more than 4000 confirmed exoplanets and exoplanet candidates. The criteria included measurable factors like type of star, and the planet's age, mass, radius, and surface temperature. The authors also considered more hypothetical factors like the presence of abundant water, a large moon, and a geological recycling mechanism like plate tectonics. Kepler-1126b (KOI-2162.01) and Kepler-69c (KOI-172.02) are the only objects in the list that have been confirmed as exoplanets. However, earlier research on Kepler-69c suggests that because its orbit lies near the inner edge of the HZ, its atmosphere could likely be in a runaway greenhouse state, which could heavily impact its prospects for habitability. The full list can be found below. See also Notes References External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Irreligion_in_the_Middle_East] | [TOKENS: 1419] |
Contents Irreligion in the Middle East Irreligion in the Middle East is the lack of religion in the Middle East. Though atheists in the Middle East are rarely public about their lack of belief, as they are persecuted in many countries where they are classified as terrorists, there are some atheist organizations in the Middle East. Islam dominates public and private life in most Middle Eastern countries. Nonetheless, there reside small numbers of irreligious individuals within those countries who often face serious formal and, in some cases, informal legal and social consequences. In terms of atheism and apostasy, while the Quran condemns the practice, it does not explicitly criminalize or pronounce a hadd (a specific criminal punishment) for apostasy. Muslim scholars have traditionally believed that it should be penalized with execution as per the hadiths on the matter but many scholars today argue that this punishment should not be implemented as it related to treason in the past and does not anymore. Middle Eastern nations with some form of Sharia law in court punish non-believers in varying ways, however, many non-Muslims and even some Muslims argue that these punishments are barbaric and inhumane. Background In the World Values Survey conducted from 2010 to 2014, results show that in Yemen, Jordan, and Iraq, fewer than 0.5% of those surveyed self-defined themselves as atheists; meanwhile, the highest percentage of self-defined atheists within the Middle East was in Kuwait, at 0.8%. Despite the relatively low number of publicly atheist individuals in the Middle East, some media platforms have claimed that the Middle East is witnessing a new rise of outspoken secular and irreligious citizens. In a BBC News article that highlights a recent Arab Barometer survey on Middle East and North African citizens, Egypt was shown to have a comparatively significant increase in the proportion of people who say they are not actively religious from 2013 to 2019. Some of these citizens who come from a state with severe punishments for atheists, like the death penalty, have reported living in fear. Regardless, transparent data on how many citizens in the Middle East are atheists, apostates, or of other form of irreligious identity have been challenging for researchers to discover. In one report by the Immigration and Refugee Board of Canada, atheists residing in Kurdish region of Iraq also have difficulties expressing their disbelief publicly—despite the Kurdish government generally considered to be secular. Rise of the "New Atheists" One of the rising form of non-religious sectors within the Middle East have been labeled as the new atheists. This organization essentially retaliates against religious institutions by claiming they are violent and unnecessary, though some argue that they are mostly criticizing the Islamic faith and community. The new atheism popularly rose from the U.S. following the 9/11 attacks and widespread coverage on Islamic extremists, and it found a number of followers within the Middle East. Ismail Mohammed, from Egypt, is a new atheist who utilizes social media platforms to vocalize atheism. An Egyptian newspaper Al-Sabah claimed 3 million of Egypt's 84 million population have no religion, citing an unnamed US survey but no such survey exists. However, the exact number of apostates or atheists in Egypt has not been accurately measured, and the validity of this estimate has not been proven. Persecution of non-believers Like other non-Muslims, atheists suffer persecution in the Middle East. 88 percent of Muslims in Egypt reportedly approve of the death penalty for those who leave Islam. In one report by the International Humanists, in Article 121 of Iranian law, homosexuality is punishable up to death for a non-Muslim subject, while the Muslim active party is punished through 100 lashes. Though persecution of blasphemous atheists are often carried out by law in the Middle East, some states like Turkey and Lebanon do allow atheists to live rather safely though withstanding any promise of legal form of safety. Meanwhile, some scholars have been opposing the death penalty for apostasy in the Islamic realm. Writers Abdullah Saeed and Hassan Saeed published a book claiming the history and fundamentals of Islam support freedom of religion, and that since the Quran does not explicitly state to punish apostasy with death it is unethical to support capital punishment for non-religious individuals. And although the Quran does not state exactly how apostasy should be punished, it has historically been debated among the Islamic communities. Scholars Rudolph Peters and Gret J.J. De Vries document that some, like the Hanafite lawyers, did argue that under the penal law an Imam should execute the apostate by a sword; meanwhile women and children have been seen as uniformly by the community as the exceptions to execution. Prevalence Though still uncommon, public acknowledgement of atheism is widely considered to be growing in the Middle East. Though data on how prevalent atheism is can be difficult to measure where social desirability bias may obscure survey answers, there have been attempts to record potential trends. Youth in the Persian Gulf countries have increasingly been expressing their atheism on the Internet in recent years, despite residing in heavily religious societies. The Web and the Internet have been a popular tool where more than 50 atheist Facebook groups and pages, some with more than 8,000 followers, have formed especially since the Arab spring. Relevant data In a 2012 Global Religious based survey conducted by Gallup showed the percentage of people who identify as religious, with the highest being 96, Iraq came in at 88 and Saudi Arabia at 75. Meanwhile, the Global Atheism Index for the same year shows the percent of self-identified atheist in Iraq at 0 and in Saudi Arabia at 5. In comparison, the Global Distribution of self-identified atheist was at 13 percent. In another aspect of BBC News' survey conducted by Arab Barometer in 2013, which was shortly after the Arab Spring, Lebanese citizens have significantly declined in religious beliefs. According to a summary by Arab Weekly, the survey indicates that less than 25 percent of Lebanese identify as religious, but it is not clear how many are atheists. A 2020 Online Survey by Gamaan found a much larger percentage of Iranians identifying as atheist (8.8%), Zoroastrian (8%), a large fraction (22.2%) identifying as not following an organized religion and only 40% self-identifying as Muslims. In 2010, a Pew Research study found that in Jordan and Egypt, where 58 percent and 74 percent respectively believe that Sharia law should be imposed on both Muslim and non-Muslim citizens of their nation, had a high number of people who believe in the death penalty for those who abandon their Islamic faith. The study found 86 percent of Egyptians, 82 percent of Jordanians, as well as 66 percent from Palestinian Territory surveyed citizens who support sharia law also support capital punishment for apostates; also 46 percent Lebanese and 42 percent Iraqis agreed to the capital punishment. List of notable non-religious Middle Eastern people See also References |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Internet#cite_ref-30] | [TOKENS: 9291] |
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 |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Katie_Hafner] | [TOKENS: 866] |
Contents Katie Hafner Katie Hafner (born December 5, 1957) is an American journalist and author. She is a former staff member of The New York Times, and has written articles and books on subjects including technology and history. She co-produces and hosts the podcast series Lost Women of Science. Her first novel, The Boys, was published in 2022. Early life and education Hafner was born in Rochester, New York, and raised in Amherst, Massachusetts. She earned a bachelor's degree in German literature from the University of California at San Diego in 1979 and a master's degree from the Columbia University Graduate School of Journalism in 1981. Career Beginning in 1983, Hafner worked as a reporter at Computerworld and then at The San Diego Union. She became a staff editor at Business Week in 1986, leaving in 1989. From 1990 to 1994, she worked freelance, writing articles and books, before becoming technology correspondent at Newsweek. In February 1998 she became a writer for the weekly Circuits section of The New York Times, where she remained on staff for a decade. She has also written for Esquire, Wired, The Golfer’s Journal, The New Republic, and The New York Times Magazine. Hafner's first book was Cyberpunk: Outlaws and Hackers on the Computer Frontier (1991), an exploration of youth computer-hacking in three parts, co-written with John Markoff. In 1996, with her then husband, Matthew Lyon, she published Where Wizards Stay Up Late: The Origins of the Internet. This was one of the earliest in-depth and comprehensive histories of the ARPANET and how it led to the Internet. It explored the "human dimension" of the development of the ARPANET covering the "theorists, computer programmers, electronic engineers, and computer gurus who had the foresight and determination to pursue their ideas and affect the future of technology and society". Her 2001 book on the online community The WELL, an expansion of a 1997 article for Wired, was praised there for "flashes of genuine insight". Her sixth book, Mother Daughter Me (2013), a memoir about trying to live with her mother and her teenage daughter in a house in San Francisco, was named one of "Ten Titles to Pick Up Now" in the August 2013 issue of O Magazine and was on other lists of recommendations including Parade magazine's 2013 "Summer Reading List". Her first novel, The Boys, was published in July 2022, the first novel to be published by the relaunched Spiegel & Grau. Hafner's 2006 New York Times article "Growing Wikipedia Refines its 'Anyone Can Edit' Policy" is included in the second edition of The McGraw-Hill Guide Writing for College, Writing for Life, an English composition textbook. She is on the advisory board of the Internet Hall of Fame. She is interviewed in the John Korty documentary Miracle in a Box, about the rebuilding of a Steinway piano.[citation needed] Hafner is co-executive producer and host of the podcast series Lost Women of Science. The first season tells the story of Dr. Dorothy Andersen, the first person to identify and describe cystic fibrosis. The second season is the story of Klára Dán von Neumann, one of the first women to work as a computer programmer. The third season is about Yvonne Young Clark, the first woman to earn a degree in mechanical engineering from Howard University and the first Black member of the Society of Women Engineers. Personal life Hafner's first husband was John Markoff. They divorced and she married Matthew Lyon, a university administrator, in 1992; they had a daughter. He died in February 2002. In 2012 she remarried to Robert M. Wachter, who is chairman of the Department of Medicine at the University of California, San Francisco. In June 2022, he announced that she probably had long COVID. In March 2023 she participated in an hour-long vodcast with Roy Wood Jr. on the Matilda effect. Books References External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Khirbat_Al-Manara] | [TOKENS: 137] |
Contents Khirbat Al-Manara Khirbat Al-Manara was a Palestinian Arab village in the Haifa Subdistrict. It was depopulated during the 1948 Arab-Israeli War on May 21, 1948. It was located 19 km south of Haifa. History In the 1931 census Khirbat Al-Manara was counted together with Ijzim, Al-Mazar and Qumbaza. The total population was 2160, 88 Christians, 2082 Muslims, in a total of 442 houses. References Bibliography External links This geography of Palestine article is a stub. You can help Wikipedia by adding missing information. |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Permanent_members_of_the_United_Nations_Security_Council] | [TOKENS: 1075] |
Contents Permanent members of the United Nations Security Council The permanent members of the United Nations Security Council (also known as the Permanent Five, Big Five, or P5) are the five sovereign states to whom the UN Charter of 1945 grants a permanent seat on the UN Security Council: China, France, Russia, United Kingdom, and United States. The permanent members were all Allies in World War II (and the victors of that war), and are the five states with the first and most nuclear weapons. All have the power of veto, which enables any one of them to block any non-"procedural" Council decision, regardless of its level of international support. The remaining 10 members of the UN Security Council are elected by the General Assembly, giving a total of 15 UN member states on the Security Council, which convenes meetings at the headquarters of the United Nations in New York City. There have been various proposals to reform the UNSC, including the introduction of new permanent members for the G4 nations of Brazil, Germany, India, and Japan. The Uniting for Consensus movement, under the leadership of Italy, opposes these bids. Permanent members The following is a table of the current permanent members of the United Nations Security Council. History Based on the consensus concerning the Security Council's structure agreed upon at the 1944 Dumbarton Oaks Conference and subsequently at UN's founding in 1945, the five permanent members of the Security Council were the French Republic, the Republic of China, the Soviet Union, the United Kingdom, and the United States. There have been two seat changes since then, although these have not been reflected in Article 23 of the UN Charter, as it has not been accordingly amended: Additionally, between the founding of the United Nations and the end of the 20th century, many of the overseas territories of the United Kingdom and France became independent with the breakup of the British Empire and French colonial empire, and France had a reduction in de jure territory with the independence of Algeria in 1962.[d] France maintained its seat as there was no change in its international status or recognition. (During this time, France also reformed its provisional government into the French Fourth Republic in 1946 and into the French Fifth Republic in 1958, both under the leadership of Charles de Gaulle.) The five permanent members of the Security Council were the victorious powers in World War II and have maintained the world's most powerful military forces ever since. They annually top the list of countries with the highest military expenditures along with India and Germany; in 2011, they spent over US$1 trillion combined on defence, accounting for over 60% of global military expenditures (the US alone accounting for over 40%). They are also among the world's top 10 largest arms exporters and are the only nations officially recognised as "nuclear-weapon states" under the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), though there are other states known or believed to be in possession of nuclear weapons. Veto power The "power of veto" refers to the veto power wielded solely by the permanent members, enabling them to prevent the adoption of any "substantive" draft Council resolution, regardless of the level of international support for the draft. The veto does not apply to procedural votes, which is significant in that the Security Council's permanent membership can vote against a "procedural" draft resolution, without necessarily blocking its adoption by the council. The veto is exercised when any permanent member — the so-called "P5" — casts a "negative" vote on a "substantive" draft resolution. Abstention or absence from the vote by a permanent member does not prevent a draft resolution from being adopted. Expansion There have been proposals for the introduction of new permanent members. The candidates usually mentioned are Brazil, Germany, India, and Japan. They compose the group of four countries known as the G4 nations, which mutually support one another's bids for permanent seats. This sort of reform has historically been opposed by Uniting for Consensus, which is composed primarily of nations that are regional rivals and economic competitors of the G4. The group is composed of: Since 1992, Italy and other council members have instead proposed semi-permanent seats or expanding the number of temporary seats. In 2024, the United States proposed the creation of two permanent seats on the Security Council for African countries, in the event of an expansion of the Security Council. Most of the leading candidates for permanent membership are regularly elected onto the Security Council by their respective groups. Japan was elected for eleven two-year terms, Brazil for ten terms, and Germany for three terms. India has been elected to the council eight times in total, with the most recent successful bid being in 2020. In 2013, the P5 and G4 members of the UN Security Council accounted for eight of the world's ten largest defence budgets, according to the Stockholm International Peace Research Institute (SIPRI). Leaders of the permanent members The following are the heads of state or heads of government that represent the permanent members of the UN Security Council as of 2025[update]: Comparison 3rd 4th 1st 5th 2nd See also Notes References Further reading |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Military_history] | [TOKENS: 10888] |
Contents Military history Military history is the study of armed conflict in the history of humanity, and its impact on the societies, cultures and economies thereof, as well as the resulting changes to local and international relationships. Professional historians normally focus on military affairs that had a major impact on the societies involved as well as the aftermath of conflicts, while amateur historians and hobbyists often take a larger interest in the details of battles, equipment, and uniforms in use. The essential subjects of military history study are the causes of war, the social and cultural foundations, military doctrine on each side, the logistics, leadership, technology, strategy, and tactics used, and how these changed over time. On the other hand, just war theory explores the moral dimensions of warfare, and to better limit the destructive reality caused by war, seeks to establish a doctrine of military ethics. As an applied field, military history has been studied at academies and service schools because the military command seeks to not repeat past mistakes, and improve upon its current performance by instilling an ability in commanders to perceive historical parallels during a battle, so as to capitalize on the lessons learned from the past. When certifying military history instructors the Combat Studies Institute deemphasizes rote detail memorization and focuses on themes and context in relation to current and future conflict, using the motto "Past is Prologue." The discipline of military history is dynamic, changing with development as much of the subject area as the societies and organisations that make use of it. The dynamic nature of the discipline of military history is largely due to the rapid change of military forces, and the art and science of managing them, as well as the frenetic pace of technological development that had taken place during the period known as the Industrial Revolution, and more recently in the nuclear and information ages. An important recent concept is the Revolution in Military Affairs (RMA) which attempts to explain how warfare has been shaped by emerging technologies, such as gunpowder. It highlights the short outbursts of rapid change followed by periods of relative stability. Popular versus academic military history In terms of the history profession in major countries, military history is an orphan, despite its enormous popularity with the general public. William H. McNeill points out: In recent decades University level courses in military history remain popular; often they use films to humanize the combat experience. For example, Eugene P. A. Scleh, history professor at the University of Maine, has explored the advantages and problems of teaching a course of "Modern War and Its Images" entirely through films. Students said they found the documentaries more valuable than the dramas. However, military historians are frustrated by their marginal status in major history departments. Academic historians concerned with military topics have their own scholarly organization, Society for Military History. Since 1937 it has published The Journal of Military History. Its four issues a year include scholarly articles reviews of new books, and a bibliography of new publications and dissertations. The Society has 2300 members, holds an annual convention, and gives out prizes for the best scholarship. Historiography of military history Historiography is the study of the history and method of the discipline of history or the study of a specialised topic. In this case, military history with an eye to gaining an accurate assessment of conflicts using all available sources. For this reason military history is periodised, creating overlaying boundaries of study and analysis in which descriptions of battles by leaders may be unreliable due to the inclination to minimize mention of failure and exaggerate success. Military historians use Historiographical analysis in an effort to allow an unbiased, contemporary view of records. One military historian, Jeremy Black, outlined problems 21st-century military historians face as an inheritance of their predecessors: Eurocentricity, a technological bias, a focus on leading military powers and dominant military systems, the separation of land from sea and recently air conflicts, the focus on state-to-state conflict, a lack of focus on political "tasking" in how forces are used. If these challenges were not sufficient for military historians, the limits of method are complicated by the lack of records, either destroyed or never recorded due to their value as a military secret. Scholars still do not know the exact nature of Greek fire, for instance. Researching Operation Enduring Freedom and Operation Iraqi Freedom, for example, have presented unique challenges to historians due to records that were destroyed to protect classified military information, among other reasons. Historians use their knowledge of government regulation and military organization, and employing a targeted and systematic research strategy to piece together war histories. Despite these limits, wars are some of the most studied and detailed periods of human history. Military historians have often compared organization, tactical and strategic ideas, leadership, and national support of the militaries of different nations. In the early 1980s, historian Jeffrey Kimball studied the influence of a historian's political position on current events on interpretive disagreement regarding the causes of 20th century wars. He surveyed the ideological preferences of 109 active diplomatic historians in the United States as well as 54 active military historians. He finds that their current political views are moderately correlated with their historiographical interpretations. A clear position on the left-right continuum regarding capitalism was apparent in most cases. All groups agreed with the proposition, "historically, Americans have tended to view questions of their national security in terms of such extremes as good vs. evil." Though the Socialists were split, the other groups agreed that "miscalculation and/or misunderstanding of the situation" had caused U.S. interventionism." Kimball reports that: People interested in military history from all periods of time, and all subtopics, are increasingly turning to the Internet for many more resources than are typically available in nearby libraries. Since 1993, one of the most popular sites, with over 4000 members (subscriptions are free) has been H-WAR, sponsored by the H-Net network based at Michigan State University. H-War has six coeditors, and an academic advisory board that sets policy. It sponsors daily moderated discussions of current topics, announcements of new publications and conferences, and reports on developments at conferences. The H-Net family of lists has sponsored and published over 46,000 scholarly book reviews, thousands of which deal with books in military history broadly conceived. Wikipedia itself has a very wide coverage of military history, with over 180,000 articles. Its editors sponsor Wikipedia:WikiProject Military history and encourage readers to join. Military museums specialize in military histories; they are often organized from a national point of view, where a museum in a particular country will have displays organized around conflicts in which that country has taken part. They typically take a broad view of warfare's role in the nation's history. They typically include displays of weapons and other military equipment, uniforms, wartime propaganda, and exhibits on civilian life during wartime, and decorations, among others. A military museum may be dedicated to a particular or area, such as the Imperial War Museum Duxford for military aircraft, Deutsches Panzermuseum for tanks, the Lange Max Museum for the Western Front (World War I), the International Spy Museum for espionage, The National World War I Museum for World War I, the "D-Day Paratroopers Historical Center" (Normandy) for WWII airborne, or more generalist, such as the Canadian War Museum or the Musée de l'Armée. For the Italian alpine wall one can find the most popular museum of bunkers in the small museum n8bunker at Olang / Kronplatz in the heard of the dolomites of South Tyrol. The U.S. Army and the state National Guards operate 98 military history museums across the United States and three abroad. Curators debate how or whether the goal of providing diverse representations of war, in terms of positive and negative aspects of warfare. War is seldom presented as a good thing, but soldiers are heavily praised. David Lowenthal has observed that in today's museums, "nothing seems too horrendous to commemorate". Yet as Andrew Whitmarsh notes, "museums frequently portray a sanitised version of warfare." The actual bomber that dropped the atomic bomb on Japan became the focus of an angry national controversy with veterans attacking curators and historians when the Smithsonian Institution planned to put its fuselage on public display in 1995. The uproar led to cancellation of the exhibit. Early historians The documentation of military history begins with the confrontation between Upper and Lower Egypt c. 3150 BC and Sumer (current Iraq) and Elam (current Iran) c. 2700 BC near the modern Basra. The Egyptian military scribe Tjaneni recorded the Battle of Megiddo (15th century BC) which is accepted as the first battle in relatively reliable detail. Military details are abundant in heroic epics, such as the Epic of Gilgamesh, Fall of Jericho and Conquest of Canaan, Trojan War in Homer's Iliad, and Mahabharata (though their historicity has been challenged). More credible records of the Israelite military history from the conquest of Canaan to the defeats by the Assyrian and Babylonian Empires are in the Biblical historical books following the Book of Joshua. Next were The Histories by Herodotus (484–425 BC) who is often called the "father of history", and the History of the Peloponnesian War by Thucydides. Despite being an Athenian, Thucydides' impartiality allowed him to take advantage of his exile to research the war from different perspectives by carefully examining documents and interviewing eyewitnesses. An approach centered on the analysis of a leader was taken by Xenophon (430–355 BC) in Anabasis, recording the expedition of Cyrus the Younger into Anatolia. And Anabasis of Alexander described the expedition in the reverse direction. Greek historians of the 2nd century BC, such as Polybius, and later Roman historians, such as Sallust, Livy, Appian and Cassius Dio, wrote about wars of the rise of Rome to the primacy over the Mediterranean. The memoirs of the Roman Julius Caesar (100–44 BC) enable a comparative approach for campaigns such as Commentarii de Bello Gallico and Commentarii de Bello Civili. East of the Mediterranean world, Arthashastra in India and The Art of War, The Book of Lord Shang, and less known but not less rich in military records Guanzi in China present strategic doctrines during the Axial Age. Records of the Grand Historian by Sima Qian and Han Fei Zi describe the Warring States of China and the former also its culmination in the Qin wars of unification. Technological evolution The nature of warfare never changes, only its superficial manifestations. Joshua and David, Hector and Achilles would recognize the combat that our soldiers and Marines have waged in the alleys of Somalia and Iraq. The uniforms evolve, bronze gives way to titanium, arrows may be replaced by laser-guided bombs, but the heart of the matter is still killing your enemies until any survivors surrender and do your will. — Ralph Peters New weapons development can dramatically alter the face of war, the cost of warfare, the preparations, and the training of soldiers and leaders. A rule of thumb is that if your enemy has a potentially war winning weapon, you have to either match it or neutralize it. Chariots originated around 2000 BC. The chariot was an effective, fast weapon; while one man controlled the maneuvering of the chariot, a second bowman could shoot arrows at enemy soldiers. These became crucial to the maintenance of several governments, including the New Egyptian Kingdom and the Shang dynasty and the nation states of the early to middle Zhou dynasty. Some of the military unit types and technologies which were developed in the ancient world are: For settled agrarian civilizations, the infantry became the core of military action. The infantry started as opposing armed groups of soldiers underneath commanders. The Greeks and early Romans used rigid, heavily armed phalanxes. The Macedonians and Hellenistic states would adopt phalanx formations with sarissa pikemen. The Romans would later adopt more flexible maniples from their neighbors which made them extremely successful in the field of battle. The kingdoms of the Warring States in East Asia also adopted infantry combat, a transition from chariot warfare from centuries earlier. Archers were a major component of many ancient armies, notably those of the Persians, Scythians, Egyptians, Nubians, Indians, Chinese, Koreans and Japanese. Cavalry became an important tool. In the Sicilian Expedition, led by Athens in an attempt to subdue Syracuse, the well-trained Syracusan cavalry became crucial to the success of the Syracusans. Macedonian Alexander the Great effectively deployed his cavalry forces to secure victories. In battles such as the Battle of Cannae of the Second Punic War, and the Battle of Carrhae of the Roman-Persian Wars, the importance of the cavalry would be repeated. There were also horse archers, who had the ability to shoot on horseback—the Parthians, Scythians, Mongols, and other various steppe people were especially fearsome with this tactic. By the 3rd–4th century AD, heavily armored cavalry became widely adopted by the Parthians, Sasanians, Byzantines, Eastern Han dynasty and Three Kingdoms, etc. The early Indo-Iranians developed the use of chariots in warfare. The scythed chariot was later invented in India and soon adopted by the Persians. War elephants were sometimes deployed for fighting in ancient warfare. They were first used in India and later adopted by the Persians. War elephants were also used in the Battle of the Hydaspes River, and by Hannibal in the Second Punic War against the Romans. One of the most important military transactions of the ancient world was Chandragupta Maurya's gift of 500 elephants to Seleucus I Nicator. Naval warfare was often crucial to military success. Early navies used sailing ships without cannons; often the goal was to ram the enemy ships and cause them to sink. There was human oar power, often using slaves, built up to ramming speed. Galleys were used in the 3rd millennium BC by the Cretans. The Greeks later advanced these ships. In 1210 BC, the first recorded naval battle was fought between Suppiluliuma II, king of the Hittites, and Cyprus, which was defeated. In the Greco-Persian Wars, the navy became of increasing importance. Triremes were involved in more complicated sea-land operations. Themistocles helped to build up a stronger Greek navy, composed of 310 ships, and defeated the Persians at the Battle of Salamis, ending the Persian invasion of Greece. In the First Punic War, the war between Carthage and Rome started with an advantage to Carthage because of their naval experience. A Roman fleet was built in 261 BC, with the addition of the corvus that allowed Roman soldiers to board enemy ships. The bridge would prove effective at the Battle of Mylae, resulting in a Roman victory. The Vikings, in the 8th century AD, invented a ship propelled by oars with a dragon decorating the prow, hence called the Drakkar. The 12th century AD Song dynasty invented ships with watertight bulkhead compartments while the 2nd century BC Han dynasty invented rudders and sculled oars for their warships. Fortifications are important in warfare. Early hill-forts were used to protect inhabitants in the Iron Age. They were primitive forts surrounded by ditches filled with water. Forts were then built out of mud bricks, stones, wood, and other available materials. Romans used rectangular fortresses built out of wood and stone. As long as there have been fortifications, there have been contraptions to break in, dating back to the times of Romans and earlier. Siege warfare is often necessary to capture forts. Some of the military unit types and technologies which were used in the medieval period are: Bows and arrows were often used by combatants. Egyptians shot arrows from chariots effectively. The crossbow was developed around 500 BC in China, and was used heavily in the Middle Ages. The English/Welsh longbow from the 12th century also became important in the Middle Ages. It helped to give the English a large early advantage in the Hundred Years' War, even though the English were eventually defeated. The Battle of Crécy and the Battle of Agincourt are excellent examples of how to destroy an enemy using a longbow. It dominated battlefields for over a century. There is evidence for gunpowder evolving slowly from formulations by Chinese alchemists as early as the 4th century, at first as experiments for life force and metal transmutation, and later experiments as pyrotechnics and incendiaries. By the 10th century, the developments in gunpowder led to many new weapons that were improved over time. The Chinese used incendiary devices based on this in siege warfare against the Mongols starting in the mid 13th century. "Pots with wicks of flax or cotton were used, containing a combination of sulfur, saltpeter (potassium nitrate), aconitine, oil, resin, ground charcoal and wax." Joseph Needham argued the Chinese were able to destroy buildings and walls using such devices. Such experimentation was not present in Western Europe, where the combination of saltpeter, sulfur and charcoal were used exclusively for explosives and as a propellant in firearms. What the Chinese often referred to as the "fire drug" arrived in Europe, fully fleshed out, as gunpowder. Cannons were first used in Europe in the early 14th century, and played a vital role in the Hundred Years' War. The first cannons were simply welded metal bars in the form of a cylinder, and the first cannonballs were made of stone. By 1346, at the Battle of Crécy, the cannon had been used; at the Battle of Agincourt they would be used again. The first infantry firearms, from fire lances to hand cannons, were held in one hand, while the explosive charge was ignited by a lit match or hot coal held in the other hand. In the mid-15th century came the matchlock, allowing the gun to be aimed and fired while held steady with both hands, as used in the arquebus. Starting about 1500, clever but complicated firing mechanisms were invented to generate sparks to ignite the powder instead of a lit match, starting with the wheel lock, snaplock, snaphance, and finally the flintlock mechanism, which was simple and reliable, becoming standard with the musket by the early 17th century. At the beginning of the 16th century, the first European fire ships were used. Ships were filled with flammable materials, set on fire, and sent to enemy lines. This tactic was successfully used by Francis Drake to scatter the Spanish Armada at the Battle of Gravelines, and would later be used by the Chinese, Russians, Greeks, and several other countries in naval battles. Naval mines were invented in the 17th century, though they were not used in great numbers until the American Civil War. They were used heavily in the First and Second World Wars. Air-deployed naval mines were used to mine the North Vietnamese port of Haiphong during the Vietnam War. The Iraqi Navy of Saddam Hussein used naval mines extensively during the Tanker War, as part of the Iran–Iraq War. The first navigable submarine was built in 1624 by Cornelius Drebbel, it could cruise at a depth of 15 feet (5 m). However, the first military submarine was constructed in 1885 by Isaac Peral. The Turtle was developed by David Bushnell during the American Revolution. Robert Fulton then improved the submarine design by creating the Nautilus. The Howitzer, a type of field artillery, was developed in the 17th century to fire high trajectory explosive shells at targets that could not be reached by flat trajectory projectiles. Organizational changes resulting in better training and intercommunication, made the concept combined arms possible, allowing the use of infantry, cavalry, and artillery in a coordinated way.[citation needed] Bayonets also became of wide usage to infantry soldiers. Bayonet is named after Bayonne, France where it was first manufactured in the 16th century. It is used often in infantry charges to fight in hand-to-hand combat. General Jean Martinet introduced the bayonet to the French army. They were used heavily in the American Civil War, and continued to be used in modern wars like the Invasion of Iraq. Balloons were first used in warfare at the end of the 18th century. It was first introduced in Paris of 1783; the first balloon traveled over 5 miles (8 km). Previously military scouts could only see from high points on the ground, or from the mast of a ship. Now they could be high in the sky, signalling to troops on the ground. This made it much more difficult for troop movements to go unobserved. At the end of the 18th century, iron-cased artillery rockets were successfully used militarily in India against the British by Tipu Sultan of the Kingdom of Mysore during the Anglo-Mysore Wars. Rockets were generally inaccurate at that time, though William Hale, in 1844, was able to develop a better rocket. The new rocket no longer needed the rocket stick, and had a higher accuracy. In the 1860s there were a series of advancements in rifles. The first repeating rifle was designed in 1860 by a company bought out by Winchester, which made new and improved versions. Springfield rifles arrived in the mid-19th century also. Machine guns arrived in the late 19th century. Automatic rifles and light machine guns first arrived at the beginning of the 20th century. In the later part of the 19th century, the self-propelled torpedo was developed. The HNoMS Rap was the world's first torpedo boat. The fire lance, the predecessor of the gun, was invented in China between the tenth and eleventh centuries. The barrel was originally designed out of bamboo shoots, later with metal. Joseph Needham notes "all the long preparations and tentative experiments were made in China, and everything came to Islam and the West fully fledged, whether it was the fire lance or the explosive bomb, the rocket or the metal-barrel handgun and bombard." By the 1320s, Europe had guns, but scholars state that the exact time and method of migration from China remains a mystery. Evidence of firearms is found in Iran and Central Asia in the late fourteenth century. It was not until roughly 1442 that guns were referenced in India. Reliable references to guns in Russia begin around 1382. An illustration of a "pot-shaped gun" found in the Holkham Hall Milemete manuscript dated to 1326 shows earliest advent of firearms in European history. The illustration shows an arrow, set in the pot-shaped gun pointed directly at a structure. Archaeological evidence of such "gun arrows" were discovered in Eltz Castle, "dated by relation to a historical event (a feud with the Archbishop of Trier in 1331–36 leading to a siege), seem to confirm again that this was at least one of the types of guns like the Milemete used in these very early examples." According to Peter Fraser Purton, the best evidence of the earliest gun in Europe is the Loshult gun, dated to the fourteenth century. Discovered in 1861, the Loshult was made of bronze measured 11.8 inches in length. A replica of the Loshult was created, using similar gunpowder compounds with present-day materials, to determine the effectiveness of the weapon. The Gunpowder Research Group, who designed the recreation, found that at high elevations, the Loshult could fire as far as 1300 meters. Though inaccurate, missing targets further than 200 meters, the Loshult could fire a range of projectiles such as arrows and shot. It was determined that the Loshult could be effectively fired at ranks of soldiers and structures. Written works from the Cabinet des Titres of the Imperial Library of Paris has found evidence of canons in France in 1338. The works illustrate canons being used on-board ships at the Rouen during that time. "...an iron Fire-arm, which was provided with forty-eight bolts, made of iron and freather; also one pound of saltpetre and half a pound of sulphur to make the powder propel arrows." Researchers have been unable to determine the sizes of these cannons and others, outside the artifacts recovered. Sir Henry Brackenbury was able to surmise the approximate size of these cannons by comparing receipts for both the firearms and the corresponding amounts of gunpowder purchased. The receipts show a transaction for "25 Livres for 5 canons." Brackenbury was able to deduce, when comparing the costs of the cannons and the gunpowder apportioned, that they each iron cannon weighed approximately 25 lbs, while the brass cannons weighed roughly 22 lbs. Philip the Bold (1363–1404) is credited[by whom?] with creating the most effective artillery power in Europe in the late fourteenth century, effectively creating the Burgundian estate. Philip's development of a large artillery army made the small country a reputable force against larger empires such as England and France.[original research?][failed verification] Philip had achieved this by establishing a large scale artillery manufacturing economy in Burgundy. Philip used his new cache of artillery to help the French capture an English-held fortress of Odruik. The artillery used to take Odruik used cannonballs measuring to about 450 pounds. Large artillery was a major contributing factor to the fall of Constantinople at the hands of Mehmed the Conqueror (1432–1481). Having resigned his position as ruler due to youth and inexperience in 1446, Mehmed moved to the Ottoman capital of Manisa. After his father, Murad II died in 1451, Mehmed once again became Sultan. He turned his attention to claiming the Byzantine capital, Constantinople. Mehmed, like Philip, started mass-producing cannons by enticing craftsmen to his cause with money and freedom. For 55 days, Constantinople was bombarded with artillery fire, throwing cannonballs as large as 800 lbs at its walls. On 29 May 1453, Constantinople fell into Ottoman control. As guns and artillery became more advanced and prevalent, so too did the tactics by which they were implemented. According to Historian Michael Roberts "...a military revolution began with the broad adoption of firearms and artillery by late sixteenth-century European armies." Infantry with firearms replaced cavalry. Empires adapted their strongholds to withstand artillery fire. Eventually drilling strategies and battlefield tactics were adapted for the evolution in firearms use. In Japan, at the same time during the sixteenth-century, this military evolution was also taking hold. These changes included a universal adoption of firearms, tactical developments for effective use, logistical restructuring within the military itself, and "the emergence of centralized and political and institutional relationships indicative of the early modern order." Tactically, beginning with Oda Nobunaga, the technique known as "volleying" or countermarch drills were implemented. Volley fire is an organized implementation of firearms, where infantry are structured in ranks. The ranks will alternate between loading and firing positions, allowing more consistent rates of fire and preventing enemies from taking over a position while members reload. Historical evidence shows that Oda Nobunaga implemented his volley technique successfully in 1575, twenty years before evidence of such a technique is shown in Europe. The first indications of the countermarch technique in Europe was by Lord William Louis of Nassau (1538–1574) in the mid-1590s. Korea also seemed to be adapting the volley technique, earlier than even the Japanese. "Koreans seem to have employed some kind of volley principle with guns by 1447, when the Korean King Sejong the Great instructed his gunners to shoot their 'fire barrels' in squads of five, taking turns firing and loading." This was on display during what Kenneth Swope called the First Great East Asian War, when Japan was trying to take control and subjugate Korea. Toyotomi Hideyoshi (1537–1598) made a failed invasion of Korea, which lasted six years, eventually pushed back by the Koreans with the aid of Ming China. Japan, using overwhelming firepower, had many early victories on the Korean peninsulas. Though the Koreans had similar manpower, "the curtain of arrows thrown up by defenders was wiped out by [Japanese] gunfire." After the Japanese were finally pushed back in 1598, sweeping military reforms took place in Korea, largely based on updating and implementing the volley technique with firearms. It was Qi Jiguang, a Ming Chinese General that provided the original treatise, disseminated to Koreans, that aided in this venture. In these manuals, Qi "...gave detailed instructions in the use of small group tactics, psychological warfare, and other 'modern' techniques." Qi emphasized repetitive drilling, dividing men into smaller groups, separating the strong from weak. Qi's ethos was one of synthesizing smaller groups, trained in various tactical formations, into larger companies, battalions and armies. By doing this they could "operate as eyes, hands, and feet..." aiding to overall unit cohesion. At the start of the World Wars, various nations had developed weapons that were a surprise to their adversaries, leading to a need to learn from this, and alter how to combat them. Flame throwers were first used in the First World War. The French were the first to introduce the armored car in 1902. Then in 1918, the British produced the first armored troop carrier. Many early tanks were proof of concept but impractical until further development. In World War I, the British and French held a crucial advantage due to their superiority in tanks; the Germans had only a few dozen A7V tanks, as well as 170 captured tanks. The British and French both had several hundred each. The French tanks included the 13 ton Schneider CA1, with a 75 mm gun, and the British had the Mark IV and Mark V tanks. On 17 December 1903, the Wright Brothers performed the first controlled, powered, heavier-than-air flight; it went 39 meters (120 ft). In 1907, the first helicopter flew, but it was not practical for usage. Aviation became important in World War I, in which several aces gained fame. In 1911 an aircraft took off from a warship for the first time. Landings on a cruiser were another matter. This led to the development of an aircraft carrier with a decent unobstructed flight deck. Chemical warfare exploded into the public consciousness in World War I but may have been used in earlier wars without as much human attention. The Germans used gas-filled shells at the Battle of Bolimov in January 1915. These were not lethal, however. In April 1915, the Germans developed a chlorine gas that was highly lethal, and used it to moderate effect at the Second Battle of Ypres. Gas masks were invented in matter of weeks, and poison gas proved ineffective at winning battles. It was made illegal by all nations in the 1920s. World War II gave rise to even more technology. The worth of aircraft grew from mostly reconnaissance to strategic bombing and more. The worth of the aircraft carrier was proved in the battles between the United States and Japan like the Battle of Midway. Radar was independently invented by the Allies and Axis powers. It used radio waves to detect objects. Molotov cocktails were invented by General Franco in the Spanish Civil War, directing the Nationalists to use them against Soviet tanks in the assault on Toledo. The atomic bomb was developed by the Manhattan Project and dropped on Hiroshima and Nagasaki in 1945, quickly and controversially ending World War II. During the Cold War, the main powers engaged in a Nuclear arms race which comprised the making of atomic bombs, hydrogen bombs, and more advanced nuclear bombs. In the space race, both nations attempted to launch human beings into space, to the moon and send satellites. Other technological advances were centered on intelligence (like the spy satellite) and missiles (ballistic missiles, cruise missiles). The nuclear submarine was invented in 1955. This meant submarines no longer needed to surface as often, and could run more quietly. They evolved into underwater missile platforms and completed what became called nuclear triad. Periods of military history Prehistoric warfare refers to war that occurred between societies without recorded history. The Tollense valley battlefield is the oldest evidence of a large scale battle in Europe. More than 4,000 warriors fought in a battle on the site in the 13th century BC. Much of what we know of ancient history is the history of militaries: their conquests, their movements, and their technological innovations. There are many reasons for this. Kingdoms and empires, the central units of control in the ancient world, could only be maintained through military force. Due to limited agricultural ability, there were relatively few areas that could support large communities, therefore fighting was common. The Umma–Lagash war was one of the first wars in recorded history, fought between the Sumerian city-states of Lagash and Umma. The border conflict over the fertile Guedena region lasted for several generations. Weapons and armor, designed to be sturdy, tended to last longer than other artifacts, and thus a great deal of surviving artifacts recovered tend to fall in this category as they are more likely to survive. Weapons and armor were also mass-produced to a scale that makes them quite plentiful throughout history, and thus more likely to be found in archaeological digs. Such items were also considered signs of prosperity or virtue, and thus were likely to be placed in tombs and monuments to prominent warriors. And writing, when it existed, was often used for kings to boast of military conquests or victories. Writing, when used by the common man, also tended to record such events, as major battles and conquests constituted major events that many would have considered worthy of recording either in an epic such as the Homeric writings pertaining to the Trojan War, or even personal writings. Indeed, the earliest stories center on warfare, as war was both a common and dramatic aspect of life; the witnessing of a major battle involving many thousands of soldiers would be quite a spectacle, even today, and thus considered worthy both of being recorded in song and art, but also in realistic histories, as well as being a central element in a fictional work. Lastly, as nation states evolved and empires grew, the increased need for order and efficiency lead to an increase in the number of records and writings. Officials and armies would have good reason for keeping detailed records and accounts involving any and all things concerning a matter such as warfare that, in the words of Sun Tzu, was "a matter of vital importance to the state". For all these reasons, military history comprises a large part of ancient history. Notable militaries in the ancient world included the Egyptians, Assyrians, Babylonians, Persians, Ancient Greeks (notably the Spartans and Macedonians), Kushites, Indians (notably the Magadhas, Gangaridais, Gandharas and Cholas), Early Imperial Chinese (notably the Qin and Han dynasties), Xiongnu Confederation, Ancient Romans, and Carthaginians. The Fertile Crescent of Mesopotamia was the center of several prehistoric conquests. Mesopotamia was conquered by the Sumerians, Akkadians, Babylonians, Assyrians and Persians. Iranians were the first nation to introduce cavalry into their army. Egypt began growing as an ancient power, but eventually fell to the Libyans, Nubians, Assyrians, Persians, Greeks, Romans, Byzantines and Arabs. The earliest recorded battle in India was the Battle of the Ten Kings. The Indian epics Mahabharata and Ramayana are centered on conflicts and refer to military formations, theories of warfare and esoteric weaponry. Chanakya's Arthashastra contains a detailed study on ancient warfare, including topics on espionage and war elephants. Alexander the Great invaded Northwestern India and defeated King Porus in the Battle of the Hydaspes River. The same region was soon re conquered by Chandragupta Maurya after defeating the Macedonians and Seleucids. He also went on to conquer the Nanda Empire and unify Northern India. Most of Southern Asia was unified under his grandson Ashoka the Great after the Kalinga War, though the empire collapsed not long after his reign. In China, the Shang dynasty and Zhou dynasty had risen and collapsed. This led to a Warring States period, in which several states continued to fight with each other over territory. Philosopher-strategists such as Confucius and Sun Tzu wrote various manuscripts on ancient warfare (as well as international diplomacy). The Warring States era philosopher Mozi (Micius) and his Mohist followers invented various siege weapons and siegecraft, including the Cloud Ladder (a four-wheeled, extendable ramp) to scale fortified walls during a siege of an enemy city. The warring states were first unified by Qin Shi Huang after a series of military conquests, creating the first empire in China. His empire was succeeded by the Han dynasty, which expanded into Central Asia, Northern China/Manchuria, Southern China, and present day Korea and Vietnam. The Han came into conflict with settled people such as the Wiman Joseon, and proto-Vietnamese Nanyue. They also came into conflict with the Xiongnu (Huns), Yuezhi, and other steppe civilizations. The Han defeated and drove the Xiongnus west, securing the city-states along the silk route that continued into the Parthian Empire. After the decline of central imperial authority, the Han dynasty collapsed into an era of civil war and continuous warfare during the Three Kingdoms period in the 3rd century AD. The Achaemenid Persian Empire was founded by Cyrus the Great after conquering the Median Empire, Neo-Babylonian Empire, Lydia and Asia Minor. His successor Cambyses went on to conquer the Egyptian Empire, much of Central Asia, and parts of Greece, India and Libya. The empire later fell to Alexander the Great after defeating Darius III. After being ruled by the Seleucid dynasty, the Persian Empire was subsequently ruled by the Parthian and Sassanid dynasties, which were the Roman Empire's greatest rivals during the Roman-Persian Wars. In Greece, several city-states rose to power, including Athens and Sparta. The Greeks successfully stopped two Persian invasions, the first at the Battle of Marathon, where the Persians were led by Darius the Great, and the second at the Battle of Salamis, a naval battle where the Greek ships were deployed by orders of Themistocles and the Persians were under Xerxes I, and the land engagement of the Battle of Plataea. The Peloponnesian War then erupted between the two Greek powers Athens and Sparta. Athens built a long wall to protect its inhabitants, but the wall helped to facilitate the spread of a plague that killed about 30,000 Athenians, including Pericles. After a disastrous campaign against Syracuse, the Athenian navy was decisively defeated by Lysander at the Battle of Aegospotami. The Macedonians, underneath Philip II of Macedon and Alexander the Great, invaded Persia and won several major victories, establishing Macedonia as a major power. However, following Alexander's death at an early age, the empire quickly fell apart. Meanwhile, Rome was gaining power, following a rebellion against the Etruscans. During the three Punic Wars, the Romans defeated the neighboring power of Carthage. The First Punic War centered on naval warfare. The Second Punic War started with Hannibal's invasion of Italy by crossing the Alps. He famously won the encirclement at the Battle of Cannae. However, after Scipio invaded Carthage, Hannibal was forced to follow and was defeated at the Battle of Zama, ending the role of Carthage as a power. After defeating Carthage the Romans went on to become the Mediterranean's dominant power, successfully campaigning in Greece, (Aemilius Paulus decisive victory over Macedonia at the Battle of Pydna), in the Middle East (Lucius Licinius Lucullus, Gnaeus Pompeius Magnus), in Gaul (Gaius Julius Caesar) and defeating several Germanic tribes (Gaius Marius, Germanicus). While Roman armies suffered several major losses, their large population and ability (and will) to replace battlefield casualties, their training, organization, tactical and technical superiority enabled Rome to stay a predominant military force for several centuries, utilizing well trained and maneuverable armies to routinely overcome the much larger "tribal" armies of their foes (see Battles of Aquae Sextiae, Vercellae, Tigranocerta, Alesia). In 54 BC, the Roman triumvir Marcus Licinius Crassus took the offensive against the Parthian Empire in the east. In a decisive battle at Carrhae Romans were defeated and the golden Aquilae (legionary battle standards) were taken as trophies to Ctesiphon. The battle was one of the worst defeats suffered by the Roman Republic in its entire history. While successfully dealing with foreign opponents, Rome experienced numerous civil wars, notably the power struggles of Roman generals such as Marius and Sulla during the end of the Republic. Caesar was also notable for his role in the civil war against the other member of the Triumvirate (Pompey) and against the Roman Senate. The successors of Caesar—Octavian and Mark Anthony—also fought a civil war with Caesar's assassins (Senators Brutus, Cassius, etc.). Octavian and Mark Anthony eventually fought another civil war between themselves to determine the sole ruler of Rome. Octavian emerged victorious and Rome was turned into an empire with a huge standing army of professional soldiers. By the time of Marcus Aurelius, the Romans had expanded to the Atlantic Ocean in the west and to Mesopotamia in the east and controlled Northern Africa and Central Europe up to the Black Sea. However, Aurelius marked the end of the Five Good Emperors, and Rome quickly fell into decline. The Huns, Goths, and other barbaric groups invaded Rome, which continued to suffer from inflation and other internal strifes. Despite the attempts of Diocletian, Constantine I, and Theodosius I, western Rome collapsed and was eventually conquered in 476. The Byzantine empire continued to prosper, however. When stirrups came into use some time during the Dark Ages militaries were forever changed. This invention coupled with technological, cultural, and social developments had forced a dramatic transformation in the character of warfare from antiquity, changing military tactics and the role of cavalry and artillery. Similar patterns of warfare existed in other parts of the world. In China around the 5th century armies moved from massed infantry to cavalry based forces, copying the steppe nomads. The Middle East and North Africa used similar, if often more advanced, technologies than Europe. In Japan, the Medieval warfare period is considered by many to have stretched into the 19th century. In Africa along the Sahel and Sudan states like the Kingdom of Sennar and Fulani Empire employed Medieval tactics and weapons well after they had been supplanted in Europe. In the Medieval period, feudalism was firmly implanted, and there existed many landlords in Europe. Landlords often owned castles to protect their territory. The Islamic Arab Empire began rapidly expanding throughout the Middle East, North Africa, and Central Asia, initially led by Rashidun Caliphate, and later under the Umayyads. While their attempts to invade Europe by way of the Balkans were defeated by Byzantium and Bulgaria, the Arabs expanded to the Iberian Peninsula in the west and the Indus Valley in the east. The Abassids then took over the Arab Empire, though the Umayyads remained in control of Islamic Spain. At the Battle of Tours, the Franks under Charles Martel stopped short a Muslim invasion. The Abassids defeated the Tang Chinese army at the Battle of Talas, but were later defeated by the Seljuk Turks and the Mongols centuries later, until the Arab Empire eventually came to an end after the Battle of Baghdad in 1258. In China, the Sui dynasty had risen and conquered the Chen dynasty of the south. They invaded Vietnam (northern Vietnam had been in Chinese control since the Han dynasty), fighting the troops of Champa, who had cavalry mounted on elephants. After decades of economic turmoil and a failed invasion of Korea, the Sui collapsed and was followed by the Tang dynasty, who fought with various Turkic groups, the Tibetans of Lhasa, the Tanguts, the Khitans, and collapsed due to political fragmentation of powerful regional military governors (jiedushi). The innovative Song dynasty followed next, inventing new weapons of war that employed the use of Greek Fire and gunpowder (see section below) against enemies such as the Jurchens. The Mongols under Genghis Khan, Ögedei Khan, Möngke Khan, and Kublai Khan conquered most of Eurasia. They took over China, Persia, Turkestan, and Russia. After Kublai Khan took power and created the Yuan dynasty, the divisions of the empire ceased to cooperate with each other, and the Mongol Empire was only nominally united. In New Zealand, prior to European discovery, oral histories, legends and whakapapa include many stories of battles and wars. Māori warriors were held in high esteem. One group of Polynesians migrated to the Chatham Islands, where they developed the largely pacifist Moriori culture. Their pacifism left the Moriori unable to defend themselves when the islands were invaded by mainland Māori in the 1830s. They proceeded to massacre the Moriori and enslave the survivors. Warrior culture also developed in the isolated Hawaiian Islands. During the 1780s and 1790s the chiefs and alii were constantly fighting for power. After a series of battles the Hawaiian Islands were united for the first time under a single ruler who would become known as Kamehameha I. After gunpowder weapons were first developed in Song dynasty China (see also: Technology of the Song dynasty), the technology later spread west to the Ottoman Empire, from where it spread to the Safavid Empire of Persia and the Mughal Empire of India. The arquebus was later adopted by European armies during the Italian Wars of the early 16th century. This all brought an end to the dominance of armored cavalry on the battlefield. The simultaneous decline of the feudal system—and the absorption of the medieval city-states into larger states—allowed the creation of professional standing armies to replace the feudal levies and mercenaries that had been the standard military component of the Middle Ages. In Africa, Ahmad ibn Ibrihim al-Ghazi, was the first African commander to use gunpowder on the continent in the Ethiopian–Adal War, that lasted for fourteen years (1529–1543). The period spanning between the 1648 Peace of Westphalia and the 1789 French Revolution is also known as Kabinettskriege (Princes' warfare) as wars were mainly carried out by imperial or monarchics states, decided by cabinets and limited in scope and in their aims. They also involved quickly shifting alliances, and mainly used mercenaries. Over the course of the 18th–19th centuries all military arms and services underwent significant developments that included a more mobile field artillery, the transition from use of battalion infantry drill in close order to open order formations and the transfer of emphasis from the use of bayonets to the rifle that replaced the musket, and virtual replacement of all types of cavalry with the universal dragoons, or mounted infantry. The Military Revolution is a conceptual schema for explaining the transformation of European military strategy, tactics and technology in the early modern period. The argument is that dramatic advances in technology, government finance, and public administration transformed and modernized European armies, tactics, and logistics. Since warfare was so central to the European state, the transformation had a major impact on modernizing government bureaucracies, taxation, and the national economy. The concept was introduced by Michael Roberts in the 1950s as he focused on Sweden 1560–1660. Roberts emphasized the introduction of muskets that could not be aimed at small targets, but could be very effective when fired in volleys by three ranks of infantry soldiers, with one firing while the other two ranks reloaded. All three ranks march forward to demolish the enemy. The infantry now had the firepower that had been reserved to the artillery, and had mobility that could rapidly advance in the battlefield, which the artillery lacked. The infantry thereby surpassed the artillery in tactical maneuvering on the battlefield. Roberts linked these advances with larger historical consequences, arguing that innovations in tactics, drill and doctrine by the Dutch and Swedes 1560–1660 led to a need for more and better trained troops and thus for permanent forces (standing armies). Armies grew much larger and more expensive. These changes in turn had major political consequences in the level of administrative support and the supply of money, men and provisions, producing new financial demands and the creation of new governmental institutions. "Thus, argued Roberts, the modern art of war made possible—and necessary—the creation of the modern state". In the 1990s the concept was modified and extended by Geoffrey Parker, who argued that developments in fortification and siege warfare caused the revolution. The concept of a military revolution based upon technology has given way to models based more on a slow evolution in which technology plays a minor role to organization, command and control, logistics and in general non-material improvements. The revolutionary nature of these changes was only visible after a long evolution that handed Europe a predominant place in warfare, a place that the industrial revolution would confirm. The concept of a military revolution in the sixteenth and seventeenth centuries has received a mixed reception among historians. Noted military historians Michael Duffy and Jeremy Black have strongly criticised it as misleading, exaggerated and simplistic. As weapons—particularly small arms—became easier to use, countries began to abandon a complete reliance on professional soldiers in favor of conscription. Technological advances became increasingly important; while the armies of the previous period had usually had similar weapons, the industrial age saw encounters such as the Battle of Sadowa, in which possession of a more advanced technology played a decisive role in the outcome. Conscription was employed in industrial warfare to increase the number of military personnel that were available for combat. Conscription was notably used by Napoleon Bonaparte and the major parties during the two World Wars. Total war was used in industrial warfare, the objective being to prevent the opposing nation to engage in war. Napoleon was the innovator. William Tecumseh Sherman's "March to the Sea" and Philip Sheridan's burning of the Shenandoah Valley during the American Civil War were examples. On the largest scale the strategic bombing of enemy cities and industrial factories during World War II was total warfare. Since the 1940s, preparation for a major war has been based on technological arms races involving all sorts of new weapons systems, such as nuclear and biological, as well as computerized control systems, and the opening of new venues, such as seen in the Space race involving the United States, the Soviet Union, and more recently, China. Modern war also saw the improvement of armored tank technology. While tanks were present in the First World War, and the Second World War, armored warfare technology came to a head with the start of the Cold War. Many of the technologies commonly seen on main battle tanks today, such as composite armor, high caliber cannons, and advanced targeting systems, would be developed during this time.[citation needed] A distinctive feature since 1945 is the decline in number and casualties of interstate wars. Instead actual fighting has largely been a matter of civil wars and insurgencies. The major exceptions were the Indo-Pakistani War of 1971, the Iran–Iraq War 1980–1988, the Gulf War of 1990–91, and the Russo-Ukrainian War. See also Notes and references Further reading External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/United_States#cite_note-290] | [TOKENS: 17273] |
Contents United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguous states border Canada to the north and Mexico to the south, with the semi-exclave of Alaska in the northwest and the archipelago of Hawaii in the Pacific Ocean. The United States also asserts sovereignty over five major island territories and various uninhabited islands in Oceania and the Caribbean.[j] It is a megadiverse country, with the world's third-largest land area[c] and third-largest population, exceeding 341 million.[k] Paleo-Indians first migrated from North Asia to North America at least 15,000 years ago, and formed various civilizations. Spanish colonization established Spanish Florida in 1513, the first European colony in what is now the continental United States. British colonization followed with the 1607 settlement of Virginia, the first of the Thirteen Colonies. Enslavement of Africans was practiced in all colonies by 1770 and supplied most of the labor for the Southern Colonies' plantation economy. Clashes with the British Crown began as a civil protest over the illegality of taxation without representation in Parliament and the denial of other English rights. They evolved into the American Revolution, which led to the Declaration of Independence and a society based on universal rights. Victory in the 1775–1783 Revolutionary War brought international recognition of U.S. sovereignty and fueled westward expansion, further dispossessing native inhabitants. As more states were admitted, a North–South division over slavery led the Confederate States of America to declare secession and fight the Union in the 1861–1865 American Civil War. With the United States' victory and reunification, slavery was abolished nationally. By the late 19th century, the U.S. economy outpaced the French, German and British economies combined. As of 1900, the country had established itself as a great power, a status solidified after its involvement in World War I. Following Japan's attack on Pearl Harbor in 1941, the U.S. entered World War II. Its aftermath left the U.S. and the Soviet Union as rival superpowers, competing for ideological dominance and international influence during the Cold War. The Soviet Union's collapse in 1991 ended the Cold War, leaving the U.S. as the world's sole superpower. The U.S. federal government is a representative democracy with a president and a constitution that grants separation of powers under three branches: legislative, executive, and judicial. The United States Congress is a bicameral national legislature composed of the House of Representatives (a lower house based on population) and the Senate (an upper house based on equal representation for each state). Federalism grants substantial autonomy to the 50 states. In addition, 574 Native American tribes have sovereignty rights, and there are 326 Native American reservations. Since the 1850s, the Democratic and Republican parties have dominated American politics. American ideals and values are based on a democratic tradition inspired by the American Enlightenment movement. A developed country, the U.S. ranks high in economic competitiveness, innovation, and higher education. Accounting for over a quarter of nominal global GDP, its economy has been the world's largest since about 1890. It is the wealthiest country, with the highest disposable household income per capita among OECD members, though its wealth inequality is highly pronounced. Shaped by centuries of immigration, the culture of the U.S. is diverse and globally influential. Making up more than a third of global military spending, the country has one of the strongest armed forces and is a designated nuclear state. A member of numerous international organizations, the U.S. plays a major role in global political, cultural, economic, and military affairs. Etymology Documented use of the phrase "United States of America" dates back to January 2, 1776. On that day, Stephen Moylan, a Continental Army aide to General George Washington, wrote a letter to Joseph Reed, Washington's aide-de-camp, seeking to go "with full and ample powers from the United States of America to Spain" to seek assistance in the Revolutionary War effort. The first known public usage is an anonymous essay published in the Williamsburg newspaper The Virginia Gazette on April 6, 1776. Sometime on or after June 11, 1776, Thomas Jefferson wrote "United States of America" in a rough draft of the Declaration of Independence, which was adopted by the Second Continental Congress on July 4, 1776. The term "United States" and its initialism "U.S.", used as nouns or as adjectives in English, are common short names for the country. The initialism "USA", a noun, is also common. "United States" and "U.S." are the established terms throughout the U.S. federal government, with prescribed rules.[l] "The States" is an established colloquial shortening of the name, used particularly from abroad; "stateside" is the corresponding adjective or adverb. "America" is the feminine form of the first word of Americus Vesputius, the Latinized name of Italian explorer Amerigo Vespucci (1454–1512);[m] it was first used as a place name by the German cartographers Martin Waldseemüller and Matthias Ringmann in 1507.[n] Vespucci first proposed that the West Indies discovered by Christopher Columbus in 1492 were part of a previously unknown landmass and not among the Indies at the eastern limit of Asia. In English, the term "America" usually does not refer to topics unrelated to the United States, despite the usage of "the Americas" to describe the totality of the continents of North and South America. History The first inhabitants of North America migrated from Siberia approximately 15,000 years ago, either across the Bering land bridge or along the now-submerged Ice Age coastline. Small isolated groups of hunter-gatherers are said to have migrated alongside herds of large herbivores far into Alaska, with ice-free corridors developing along the Pacific coast and valleys of North America in c. 16,500 – c. 13,500 BCE (c. 18,500 – c. 15,500 BP). The Clovis culture, which appeared around 11,000 BCE, is believed to be the first widespread culture in the Americas. Over time, Indigenous North American cultures grew increasingly sophisticated, and some, such as the Mississippian culture, developed agriculture, architecture, and complex societies. In the post-archaic period, the Mississippian cultures were located in the midwestern, eastern, and southern regions, and the Algonquian in the Great Lakes region and along the Eastern Seaboard, while the Hohokam culture and Ancestral Puebloans inhabited the Southwest. Native population estimates of what is now the United States before the arrival of European colonizers range from around 500,000 to nearly 10 million. Christopher Columbus began exploring the Caribbean for Spain in 1492, leading to Spanish-speaking settlements and missions from what are now Puerto Rico and Florida to New Mexico and California. The first Spanish colony in the present-day continental United States was Spanish Florida, chartered in 1513. After several settlements failed there due to starvation and disease, Spain's first permanent town, Saint Augustine, was founded in 1565. France established its own settlements in French Florida in 1562, but they were either abandoned (Charlesfort, 1578) or destroyed by Spanish raids (Fort Caroline, 1565). Permanent French settlements were founded much later along the Great Lakes (Fort Detroit, 1701), the Mississippi River (Saint Louis, 1764) and especially the Gulf of Mexico (New Orleans, 1718). Early European colonies also included the thriving Dutch colony of New Nederland (settled 1626, present-day New York) and the small Swedish colony of New Sweden (settled 1638 in what became Delaware). British colonization of the East Coast began with the Virginia Colony (1607) and the Plymouth Colony (Massachusetts, 1620). The Mayflower Compact in Massachusetts and the Fundamental Orders of Connecticut established precedents for local representative self-governance and constitutionalism that would develop throughout the American colonies. While European settlers in what is now the United States experienced conflicts with Native Americans, they also engaged in trade, exchanging European tools for food and animal pelts.[o] Relations ranged from close cooperation to warfare and massacres. The colonial authorities often pursued policies that forced Native Americans to adopt European lifestyles, including conversion to Christianity. Along the eastern seaboard, settlers trafficked Africans through the Atlantic slave trade, largely to provide manual labor on plantations. The original Thirteen Colonies[p] that would later found the United States were administered as possessions of the British Empire by Crown-appointed governors, though local governments held elections open to most white male property owners. The colonial population grew rapidly from Maine to Georgia, eclipsing Native American populations; by the 1770s, the natural increase of the population was such that only a small minority of Americans had been born overseas. The colonies' distance from Britain facilitated the entrenchment of self-governance, and the First Great Awakening, a series of Christian revivals, fueled colonial interest in guaranteed religious liberty. Following its victory in the French and Indian War, Britain began to assert greater control over local affairs in the Thirteen Colonies, resulting in growing political resistance. One of the primary grievances of the colonists was the denial of their rights as Englishmen, particularly the right to representation in the British government that taxed them. To demonstrate their dissatisfaction and resolve, the First Continental Congress met in 1774 and passed the Continental Association, a colonial boycott of British goods enforced by local "committees of safety" that proved effective. The British attempt to then disarm the colonists resulted in the 1775 Battles of Lexington and Concord, igniting the American Revolutionary War. At the Second Continental Congress, the colonies appointed George Washington commander-in-chief of the Continental Army, and created a committee that named Thomas Jefferson to draft the Declaration of Independence. Two days after the Second Continental Congress passed the Lee Resolution to create an independent, sovereign nation, the Declaration was adopted on July 4, 1776. The political values of the American Revolution evolved from an armed rebellion demanding reform within an empire to a revolution that created a new social and governing system founded on the defense of liberty and the protection of inalienable natural rights; sovereignty of the people; republicanism over monarchy, aristocracy, and other hereditary political power; civic virtue; and an intolerance of political corruption. The Founding Fathers of the United States, who included Washington, Jefferson, John Adams, Benjamin Franklin, Alexander Hamilton, John Jay, James Madison, Thomas Paine, and many others, were inspired by Classical, Renaissance, and Enlightenment philosophies and ideas. Though in practical effect since its drafting in 1777, the Articles of Confederation was ratified in 1781 and formally established a decentralized government that operated until 1789. After the British surrender at the siege of Yorktown in 1781, American sovereignty was internationally recognized by the Treaty of Paris (1783), through which the U.S. gained territory stretching west to the Mississippi River, north to present-day Canada, and south to Spanish Florida. The Northwest Ordinance (1787) established the precedent by which the country's territory would expand with the admission of new states, rather than the expansion of existing states. The U.S. Constitution was drafted at the 1787 Constitutional Convention to overcome the limitations of the Articles. It went into effect in 1789, creating a federal republic governed by three separate branches that together formed a system of checks and balances. George Washington was elected the country's first president under the Constitution, and the Bill of Rights was adopted in 1791 to allay skeptics' concerns about the power of the more centralized government. His resignation as commander-in-chief after the Revolutionary War and his later refusal to run for a third term as the country's first president established a precedent for the supremacy of civil authority in the United States and the peaceful transfer of power. In the late 18th century, American settlers began to expand westward in larger numbers, many with a sense of manifest destiny. The Louisiana Purchase of 1803 from France nearly doubled the territory of the United States. Lingering issues with Britain remained, leading to the War of 1812, which was fought to a draw. Spain ceded Florida and its Gulf Coast territory in 1819. The Missouri Compromise of 1820, which admitted Missouri as a slave state and Maine as a free state, attempted to balance the desire of northern states to prevent the expansion of slavery into new territories with that of southern states to extend it there. Primarily, the compromise prohibited slavery in all other lands of the Louisiana Purchase north of the 36°30′ parallel. As Americans expanded further into territory inhabited by Native Americans, the federal government implemented policies of Indian removal or assimilation. The most significant such legislation was the Indian Removal Act of 1830, a key policy of President Andrew Jackson. It resulted in the Trail of Tears (1830–1850), in which an estimated 60,000 Native Americans living east of the Mississippi River were forcibly removed and displaced to lands far to the west, causing 13,200 to 16,700 deaths along the forced march. Settler expansion as well as this influx of Indigenous peoples from the East resulted in the American Indian Wars west of the Mississippi. During the colonial period, slavery became legal in all the Thirteen colonies, but by 1770 it provided the main labor force in the large-scale, agriculture-dependent economies of the Southern Colonies from Maryland to Georgia. The practice began to be significantly questioned during the American Revolution, and spurred by an active abolitionist movement that had reemerged in the 1830s, states in the North enacted laws to prohibit slavery within their boundaries. At the same time, support for slavery had strengthened in Southern states, with widespread use of inventions such as the cotton gin (1793) having made slavery immensely profitable for Southern elites. The United States annexed the Republic of Texas in 1845, and the 1846 Oregon Treaty led to U.S. control of the present-day American Northwest. Dispute with Mexico over Texas led to the Mexican–American War (1846–1848). After the victory of the U.S., Mexico recognized U.S. sovereignty over Texas, New Mexico, and California in the 1848 Mexican Cession; the cession's lands also included the future states of Nevada, Colorado and Utah. The California gold rush of 1848–1849 spurred a huge migration of white settlers to the Pacific coast, leading to even more confrontations with Native populations. One of the most violent, the California genocide of thousands of Native inhabitants, lasted into the mid-1870s. Additional western territories and states were created. Throughout the 1850s, the sectional conflict regarding slavery was further inflamed by national legislation in the U.S. Congress and decisions of the Supreme Court. In Congress, the Fugitive Slave Act of 1850 mandated the forcible return to their owners in the South of slaves taking refuge in non-slave states, while the Kansas–Nebraska Act of 1854 effectively gutted the anti-slavery requirements of the Missouri Compromise. In its Dred Scott decision of 1857, the Supreme Court ruled against a slave brought into non-slave territory, simultaneously declaring the entire Missouri Compromise to be unconstitutional. These and other events exacerbated tensions between North and South that would culminate in the American Civil War (1861–1865). Beginning with South Carolina, 11 slave-state governments voted to secede from the United States in 1861, joining to create the Confederate States of America. All other state governments remained loyal to the Union.[q] War broke out in April 1861 after the Confederacy bombarded Fort Sumter. Following the Emancipation Proclamation on January 1, 1863, many freed slaves joined the Union army. The war began to turn in the Union's favor following the 1863 Siege of Vicksburg and Battle of Gettysburg, and the Confederates surrendered in 1865 after the Union's victory in the Battle of Appomattox Court House. Efforts toward reconstruction in the secessionist South had begun as early as 1862, but it was only after President Lincoln's assassination that the three Reconstruction Amendments to the Constitution were ratified to protect civil rights. The amendments codified nationally the abolition of slavery and involuntary servitude except as punishment for crimes, promised equal protection under the law for all persons, and prohibited discrimination on the basis of race or previous enslavement. As a result, African Americans took an active political role in ex-Confederate states in the decade following the Civil War. The former Confederate states were readmitted to the Union, beginning with Tennessee in 1866 and ending with Georgia in 1870. National infrastructure, including transcontinental telegraph and railroads, spurred growth in the American frontier. This was accelerated by the Homestead Acts, through which nearly 10 percent of the total land area of the United States was given away free to some 1.6 million homesteaders. From 1865 through 1917, an unprecedented stream of immigrants arrived in the United States, including 24.4 million from Europe. Most came through the Port of New York, as New York City and other large cities on the East Coast became home to large Jewish, Irish, and Italian populations. Many Northern Europeans as well as significant numbers of Germans and other Central Europeans moved to the Midwest. At the same time, about one million French Canadians migrated from Quebec to New England. During the Great Migration, millions of African Americans left the rural South for urban areas in the North. Alaska was purchased from Russia in 1867. The Compromise of 1877 is generally considered the end of the Reconstruction era, as it resolved the electoral crisis following the 1876 presidential election and led President Rutherford B. Hayes to reduce the role of federal troops in the South. Immediately, the Redeemers began evicting the Carpetbaggers and quickly regained local control of Southern politics in the name of white supremacy. African Americans endured a period of heightened, overt racism following Reconstruction, a time often considered the nadir of American race relations. A series of Supreme Court decisions, including Plessy v. Ferguson, emptied the Fourteenth and Fifteenth Amendments of their force, allowing Jim Crow laws in the South to remain unchecked, sundown towns in the Midwest, and segregation in communities across the country, which would be reinforced in part by the policy of redlining later adopted by the federal Home Owners' Loan Corporation. An explosion of technological advancement, accompanied by the exploitation of cheap immigrant labor, led to rapid economic expansion during the Gilded Age of the late 19th century. It continued into the early 20th, when the United States already outpaced the economies of Britain, France, and Germany combined. This fostered the amassing of power by a few prominent industrialists, largely by their formation of trusts and monopolies to prevent competition. Tycoons led the nation's expansion in the railroad, petroleum, and steel industries. The United States emerged as a pioneer of the automotive industry. These changes resulted in significant increases in economic inequality, slum conditions, and social unrest, creating the environment for labor unions and socialist movements to begin to flourish. This period eventually ended with the advent of the Progressive Era, which was characterized by significant economic and social reforms. Pro-American elements in Hawaii overthrew the Hawaiian monarchy; the islands were annexed in 1898. That same year, Puerto Rico, the Philippines, and Guam were ceded to the U.S. by Spain after the latter's defeat in the Spanish–American War. (The Philippines was granted full independence from the U.S. on July 4, 1946, following World War II. Puerto Rico and Guam have remained U.S. territories.) American Samoa was acquired by the United States in 1900 after the Second Samoan Civil War. The U.S. Virgin Islands were purchased from Denmark in 1917. The United States entered World War I alongside the Allies in 1917 helping to turn the tide against the Central Powers. In 1920, a constitutional amendment granted nationwide women's suffrage. During the 1920s and 1930s, radio for mass communication and early television transformed communications nationwide. The Wall Street Crash of 1929 triggered the Great Depression, to which President Franklin D. Roosevelt responded with the New Deal plan of "reform, recovery and relief", a series of unprecedented and sweeping recovery programs and employment relief projects combined with financial reforms and regulations. Initially neutral during World War II, the U.S. began supplying war materiel to the Allies of World War II in March 1941 and entered the war in December after Japan's attack on Pearl Harbor. Agreeing to a "Europe first" policy, the U.S. concentrated its wartime efforts on Japan's allies Italy and Germany until their final defeat in May 1945. The U.S. developed the first nuclear weapons and used them against the Japanese cities of Hiroshima and Nagasaki in August 1945, ending the war. The United States was one of the "Four Policemen" who met to plan the post-war world, alongside the United Kingdom, the Soviet Union, and China. The U.S. emerged relatively unscathed from the war, with even greater economic power and international political influence. The end of World War II in 1945 left the U.S. and the Soviet Union as superpowers, each with its own political, military, and economic sphere of influence. Geopolitical tensions between the two superpowers soon led to the Cold War. The U.S. implemented a policy of containment intended to limit the Soviet Union's sphere of influence; engaged in regime change against governments perceived to be aligned with the Soviets; and prevailed in the Space Race, which culminated with the first crewed Moon landing in 1969. Domestically, the U.S. experienced economic growth, urbanization, and population growth following World War II. The civil rights movement emerged, with Martin Luther King Jr. becoming a prominent leader in the early 1960s. The Great Society plan of President Lyndon B. Johnson's administration resulted in groundbreaking and broad-reaching laws, policies and a constitutional amendment to counteract some of the worst effects of lingering institutional racism. The counterculture movement in the U.S. brought significant social changes, including the liberalization of attitudes toward recreational drug use and sexuality. It also encouraged open defiance of the military draft (leading to the end of conscription in 1973) and wide opposition to U.S. intervention in Vietnam, with the U.S. totally withdrawing in 1975. A societal shift in the roles of women was significantly responsible for the large increase in female paid labor participation starting in the 1970s, and by 1985 the majority of American women aged 16 and older were employed. The Fall of Communism and the dissolution of the Soviet Union from 1989 to 1991 marked the end of the Cold War and left the United States as the world's sole superpower. This cemented the United States' global influence, reinforcing the concept of the "American Century" as the U.S. dominated international political, cultural, economic, and military affairs. The 1990s saw the longest recorded economic expansion in American history, a dramatic decline in U.S. crime rates, and advances in technology. Throughout this decade, technological innovations such as the World Wide Web, the evolution of the Pentium microprocessor in accordance with Moore's law, rechargeable lithium-ion batteries, the first gene therapy trial, and cloning either emerged in the U.S. or were improved upon there. The Human Genome Project was formally launched in 1990, while Nasdaq became the first stock market in the United States to trade online in 1998. In the Gulf War of 1991, an American-led international coalition of states expelled an Iraqi invasion force that had occupied neighboring Kuwait. The September 11 attacks on the United States in 2001 by the pan-Islamist militant organization al-Qaeda led to the war on terror and subsequent military interventions in Afghanistan and in Iraq. The U.S. housing bubble culminated in 2007 with the Great Recession, the largest economic contraction since the Great Depression. In the 2010s and early 2020s, the United States has experienced increased political polarization and democratic backsliding. The country's polarization was violently reflected in the January 2021 Capitol attack, when a mob of insurrectionists entered the U.S. Capitol and sought to prevent the peaceful transfer of power in an attempted self-coup d'état. Geography The United States is the world's third-largest country by total area behind Russia and Canada.[c] The 48 contiguous states and the District of Columbia have a combined area of 3,119,885 square miles (8,080,470 km2). In 2021, the United States had 8% of the Earth's permanent meadows and pastures and 10% of its cropland. Starting in the east, the coastal plain of the Atlantic seaboard gives way to inland forests and rolling hills in the Piedmont plateau region. The Appalachian Mountains and the Adirondack Massif separate the East Coast from the Great Lakes and the grasslands of the Midwest. The Mississippi River System, the world's fourth-longest river system, runs predominantly north–south through the center of the country. The flat and fertile prairie of the Great Plains stretches to the west, interrupted by a highland region in the southeast. The Rocky Mountains, west of the Great Plains, extend north to south across the country, peaking at over 14,000 feet (4,300 m) in Colorado. The supervolcano underlying Yellowstone National Park in the Rocky Mountains, the Yellowstone Caldera, is the continent's largest volcanic feature. Farther west are the rocky Great Basin and the Chihuahuan, Sonoran, and Mojave deserts. In the northwest corner of Arizona, carved by the Colorado River, is the Grand Canyon, a steep-sided canyon and popular tourist destination known for its overwhelming visual size and intricate, colorful landscape. The Cascade and Sierra Nevada mountain ranges run close to the Pacific coast. The lowest and highest points in the contiguous United States are in the State of California, about 84 miles (135 km) apart. At an elevation of 20,310 feet (6,190.5 m), Alaska's Denali (also called Mount McKinley) is the highest peak in the country and on the continent. Active volcanoes in the U.S. are common throughout Alaska's Alexander and Aleutian Islands. Located entirely outside North America, the archipelago of Hawaii consists of volcanic islands, physiographically and ethnologically part of the Polynesian subregion of Oceania. In addition to its total land area, the United States has one of the world's largest marine exclusive economic zones spanning approximately 4.5 million square miles (11.7 million km2) of ocean. With its large size and geographic variety, the United States includes most climate types. East of the 100th meridian, the climate ranges from humid continental in the north to humid subtropical in the south. The western Great Plains are semi-arid. Many mountainous areas of the American West have an alpine climate. The climate is arid in the Southwest, Mediterranean in coastal California, and oceanic in coastal Oregon, Washington, and southern Alaska. Most of Alaska is subarctic or polar. Hawaii, the southern tip of Florida and U.S. territories in the Caribbean and Pacific are tropical. The United States receives more high-impact extreme weather incidents than any other country. States bordering the Gulf of Mexico are prone to hurricanes, and most of the world's tornadoes occur in the country, mainly in Tornado Alley. Due to climate change in the country, extreme weather has become more frequent in the U.S. in the 21st century, with three times the number of reported heat waves compared to the 1960s. Since the 1990s, droughts in the American Southwest have become more persistent and more severe. The regions considered as the most attractive to the population are the most vulnerable. The U.S. is one of 17 megadiverse countries containing large numbers of endemic species: about 17,000 species of vascular plants occur in the contiguous United States and Alaska, and over 1,800 species of flowering plants are found in Hawaii, few of which occur on the mainland. The United States is home to 428 mammal species, 784 birds, 311 reptiles, 295 amphibians, and around 91,000 insect species. There are 63 national parks, and hundreds of other federally managed monuments, forests, and wilderness areas, administered by the National Park Service and other agencies. About 28% of the country's land is publicly owned and federally managed, primarily in the Western States. Most of this land is protected, though some is leased for commercial use, and less than one percent is used for military purposes. Environmental issues in the United States include debates on non-renewable resources and nuclear energy, air and water pollution, biodiversity, logging and deforestation, and climate change. The U.S. Environmental Protection Agency (EPA) is the federal agency charged with addressing most environmental-related issues. The idea of wilderness has shaped the management of public lands since 1964, with the Wilderness Act. The Endangered Species Act of 1973 provides a way to protect threatened and endangered species and their habitats. The United States Fish and Wildlife Service implements and enforces the Act. In 2024, the U.S. ranked 35th among 180 countries in the Environmental Performance Index. Government and politics The United States is a federal republic of 50 states and a federal capital district, Washington, D.C. The U.S. asserts sovereignty over five unincorporated territories and several uninhabited island possessions. It is the world's oldest surviving federation, and its presidential system of federal government has been adopted, in whole or in part, by many newly independent states worldwide following their decolonization. The Constitution of the United States serves as the country's supreme legal document. Most scholars describe the United States as a liberal democracy.[r] Composed of three branches, all headquartered in Washington, D.C., the federal government is the national government of the United States. The U.S. Constitution establishes a separation of powers intended to provide a system of checks and balances to prevent any of the three branches from becoming supreme. The three-branch system is known as the presidential system, in contrast to the parliamentary system where the executive is part of the legislative body. Many countries around the world adopted this aspect of the 1789 Constitution of the United States, especially in the postcolonial Americas. In the U.S. federal system, sovereign powers are shared between three levels of government specified in the Constitution: the federal government, the states, and Indian tribes. The U.S. also asserts sovereignty over five permanently inhabited territories: American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the U.S. Virgin Islands. Residents of the 50 states are governed by their elected state government, under state constitutions compatible with the national constitution, and by elected local governments that are administrative divisions of a state. States are subdivided into counties or county equivalents, and (except for Hawaii) further divided into municipalities, each administered by elected representatives. The District of Columbia is a federal district containing the U.S. capital, Washington, D.C. The federal district is an administrative division of the federal government. Indian country is made up of 574 federally recognized tribes and 326 Indian reservations. They hold a government-to-government relationship with the U.S. federal government in Washington and are legally defined as domestic dependent nations with inherent tribal sovereignty rights. In addition to the five major territories, the U.S. also asserts sovereignty over the United States Minor Outlying Islands in the Pacific Ocean and the Caribbean. The seven undisputed islands without permanent populations are Baker Island, Howland Island, Jarvis Island, Johnston Atoll, Kingman Reef, Midway Atoll, and Palmyra Atoll. U.S. sovereignty over the unpopulated Bajo Nuevo Bank, Navassa Island, Serranilla Bank, and Wake Island is disputed. The Constitution is silent on political parties. However, they developed independently in the 18th century with the Federalist and Anti-Federalist parties. Since then, the United States has operated as a de facto two-party system, though the parties have changed over time. Since the mid-19th century, the two main national parties have been the Democratic Party and the Republican Party. The former is perceived as relatively liberal in its political platform while the latter is perceived as relatively conservative in its platform. The United States has an established structure of foreign relations, with the world's second-largest diplomatic corps as of 2024[update]. It is a permanent member of the United Nations Security Council and home to the United Nations headquarters. The United States is a member of the G7, G20, and OECD intergovernmental organizations. Almost all countries have embassies and many have consulates (official representatives) in the country. Likewise, nearly all countries host formal diplomatic missions with the United States, except Iran, North Korea, and Bhutan. Though Taiwan does not have formal diplomatic relations with the U.S., it maintains close unofficial relations. The United States regularly supplies Taiwan with military equipment to deter potential Chinese aggression. Its geopolitical attention also turned to the Indo-Pacific when the United States joined the Quadrilateral Security Dialogue with Australia, India, and Japan. The United States has a "Special Relationship" with the United Kingdom and strong ties with Canada, Australia, New Zealand, the Philippines, Japan, South Korea, Israel, and several European Union countries such as France, Italy, Germany, Spain, and Poland. The U.S. works closely with its NATO allies on military and national security issues, and with countries in the Americas through the Organization of American States and the United States–Mexico–Canada Free Trade Agreement. The U.S. exercises full international defense authority and responsibility for Micronesia, the Marshall Islands, and Palau through the Compact of Free Association. It has increasingly conducted strategic cooperation with India, while its ties with China have steadily deteriorated. Beginning in 2014, the U.S. had become a key ally of Ukraine. After Donald Trump was elected U.S. president in 2024, he sought to negotiate an end to the Russo-Ukrainian War. He paused all military aid to Ukraine in March 2025, although the aid resumed later. Trump also ended U.S. intelligence sharing with the country, but this too was eventually restored. The president is the commander-in-chief of the United States Armed Forces and appoints its leaders, the secretary of defense and the Joint Chiefs of Staff. The Department of Defense, headquartered at the Pentagon near Washington, D.C., administers five of the six service branches, which are made up of the U.S. Army, Marine Corps, Navy, Air Force, and Space Force. The Coast Guard is administered by the Department of Homeland Security in peacetime and can be transferred to the Department of the Navy in wartime. Total strength of the entire military is about 1.3 million active duty with an additional 400,000 in reserve. The United States spent $997 billion on its military in 2024, which is by far the largest amount of any country, making up 37% of global military spending and accounting for 3.4% of the country's GDP. The U.S. possesses 42% of the world's nuclear weapons—the second-largest stockpile after that of Russia. The U.S. military is widely regarded as the most powerful and advanced in the world. The United States has the third-largest combined armed forces in the world, behind the Chinese People's Liberation Army and Indian Armed Forces. The U.S. military operates about 800 bases and facilities abroad, and maintains deployments greater than 100 active duty personnel in 25 foreign countries. The United States has engaged in over 400 military interventions since its founding in 1776, with over half of these occurring between 1950 and 2019 and 25% occurring in the post-Cold War era. State defense forces (SDFs) are military units that operate under the sole authority of a state government. SDFs are authorized by state and federal law but are under the command of the state's governor. By contrast, the 54 U.S. National Guard organizations[t] fall under the dual control of state or territorial governments and the federal government; their units can also become federalized entities, but SDFs cannot be federalized. The National Guard personnel of a state or territory can be federalized by the president under the National Defense Act Amendments of 1933; this legislation created the Guard and provides for the integration of Army National Guard and Air National Guard units and personnel into the U.S. Army and (since 1947) the U.S. Air Force. The total number of National Guard members is about 430,000, while the estimated combined strength of SDFs is less than 10,000. There are about 18,000 U.S. police agencies from local to national level in the United States. Law in the United States is mainly enforced by local police departments and sheriff departments in their municipal or county jurisdictions. The state police departments have authority in their respective state, and federal agencies such as the Federal Bureau of Investigation (FBI) and the U.S. Marshals Service have national jurisdiction and specialized duties, such as protecting civil rights, national security, enforcing U.S. federal courts' rulings and federal laws, and interstate criminal activity. State courts conduct almost all civil and criminal trials, while federal courts adjudicate the much smaller number of civil and criminal cases that relate to federal law. There is no unified "criminal justice system" in the United States. The American prison system is largely heterogenous, with thousands of relatively independent systems operating across federal, state, local, and tribal levels. In 2025, "these systems hold nearly 2 million people in 1,566 state prisons, 98 federal prisons, 3,116 local jails, 1,277 juvenile correctional facilities, 133 immigration detention facilities, and 80 Indian country jails, as well as in military prisons, civil commitment centers, state psychiatric hospitals, and prisons in the U.S. territories." Despite disparate systems of confinement, four main institutions dominate: federal prisons, state prisons, local jails, and juvenile correctional facilities. Federal prisons are run by the Federal Bureau of Prisons and hold pretrial detainees as well as people who have been convicted of federal crimes. State prisons, run by the department of corrections of each state, hold people sentenced and serving prison time (usually longer than one year) for felony offenses. Local jails are county or municipal facilities that incarcerate defendants prior to trial; they also hold those serving short sentences (typically under a year). Juvenile correctional facilities are operated by local or state governments and serve as longer-term placements for any minor adjudicated as delinquent and ordered by a judge to be confined. In January 2023, the United States had the sixth-highest per capita incarceration rate in the world—531 people per 100,000 inhabitants—and the largest prison and jail population in the world, with more than 1.9 million people incarcerated. An analysis of the World Health Organization Mortality Database from 2010 showed U.S. homicide rates "were 7 times higher than in other high-income countries, driven by a gun homicide rate that was 25 times higher". Economy The U.S. has a highly developed mixed economy that has been the world's largest nominally since about 1890. Its 2024 gross domestic product (GDP)[e] of more than $29 trillion constituted over 25% of nominal global economic output, or 15% at purchasing power parity (PPP). From 1983 to 2008, U.S. real compounded annual GDP growth was 3.3%, compared to a 2.3% weighted average for the rest of the G7. The country ranks first in the world by nominal GDP, second when adjusted for purchasing power parities (PPP), and ninth by PPP-adjusted GDP per capita. In February 2024, the total U.S. federal government debt was $34.4 trillion. Of the world's 500 largest companies by revenue, 138 were headquartered in the U.S. in 2025, the highest number of any country. The U.S. dollar is the currency most used in international transactions and the world's foremost reserve currency, backed by the country's dominant economy, its military, the petrodollar system, its large U.S. treasuries market, and its linked eurodollar. Several countries use it as their official currency, and in others it is the de facto currency. The U.S. has free trade agreements with several countries, including the USMCA. Although the United States has reached a post-industrial level of economic development and is often described as having a service economy, it remains a major industrial power; in 2024, the U.S. manufacturing sector was the world's second-largest by value output after China's. New York City is the world's principal financial center, and its metropolitan area is the world's largest metropolitan economy. The New York Stock Exchange and Nasdaq, both located in New York City, are the world's two largest stock exchanges by market capitalization and trade volume. The United States is at the forefront of technological advancement and innovation in many economic fields, especially in artificial intelligence; electronics and computers; pharmaceuticals; and medical, aerospace and military equipment. The country's economy is fueled by abundant natural resources, a well-developed infrastructure, and high productivity. The largest trading partners of the United States are the European Union, Mexico, Canada, China, Japan, South Korea, the United Kingdom, Vietnam, India, and Taiwan. The United States is the world's largest importer and second-largest exporter.[u] It is by far the world's largest exporter of services. Americans have the highest average household and employee income among OECD member states, and the fourth-highest median household income in 2023, up from sixth-highest in 2013. With personal consumption expenditures of over $18.5 trillion in 2023, the U.S. has a heavily consumer-driven economy and is the world's largest consumer market. The U.S. ranked first in the number of dollar billionaires and millionaires in 2023, with 735 billionaires and nearly 22 million millionaires. Wealth in the United States is highly concentrated; in 2011, the richest 10% of the adult population owned 72% of the country's household wealth, while the bottom 50% owned just 2%. U.S. wealth inequality increased substantially since the late 1980s, and income inequality in the U.S. reached a record high in 2019. In 2024, the country had some of the highest wealth and income inequality levels among OECD countries. Since the 1970s, there has been a decoupling of U.S. wage gains from worker productivity. In 2016, the top fifth of earners took home more than half of all income, giving the U.S. one of the widest income distributions among OECD countries. There were about 771,480 homeless persons in the U.S. in 2024. In 2022, 6.4 million children experienced food insecurity. Feeding America estimates that around one in five, or approximately 13 million, children experience hunger in the U.S. and do not know where or when they will get their next meal. Also in 2022, about 37.9 million people, or 11.5% of the U.S. population, were living in poverty. The United States has a smaller welfare state and redistributes less income through government action than most other high-income countries. It is the only advanced economy that does not guarantee its workers paid vacation nationally and one of a few countries in the world without federal paid family leave as a legal right. The United States has a higher percentage of low-income workers than almost any other developed country, largely because of a weak collective bargaining system and lack of government support for at-risk workers. The United States has been a leader in technological innovation since the late 19th century and scientific research since the mid-20th century. Methods for producing interchangeable parts and the establishment of a machine tool industry enabled the large-scale manufacturing of U.S. consumer products in the late 19th century. By the early 20th century, factory electrification, the introduction of the assembly line, and other labor-saving techniques created the system of mass production. In the 21st century, the United States continues to be one of the world's foremost scientific powers, though China has emerged as a major competitor in many fields. The U.S. has the highest research and development expenditures of any country and ranks ninth as a percentage of GDP. In 2022, the United States was (after China) the country with the second-highest number of published scientific papers. In 2021, the U.S. ranked second (also after China) by the number of patent applications, and third by trademark and industrial design applications (after China and Germany), according to World Intellectual Property Indicators. In 2025 the United States ranked third (after Switzerland and Sweden) in the Global Innovation Index. The United States is considered to be a world leader in the development of artificial intelligence technology. In 2023, the United States was ranked the second most technologically advanced country in the world (after South Korea) by Global Finance magazine. The United States has maintained a space program since the late 1950s, beginning with the establishment of the National Aeronautics and Space Administration (NASA) in 1958. NASA's Apollo program (1961–1972) achieved the first crewed Moon landing with the 1969 Apollo 11 mission; it remains one of the agency's most significant milestones. Other major endeavors by NASA include the Space Shuttle program (1981–2011), the Voyager program (1972–present), the Hubble and James Webb space telescopes (launched in 1990 and 2021, respectively), and the multi-mission Mars Exploration Program (Spirit and Opportunity, Curiosity, and Perseverance). NASA is one of five agencies collaborating on the International Space Station (ISS); U.S. contributions to the ISS include several modules, including Destiny (2001), Harmony (2007), and Tranquility (2010), as well as ongoing logistical and operational support. The United States private sector dominates the global commercial spaceflight industry. Prominent American spaceflight contractors include Blue Origin, Boeing, Lockheed Martin, Northrop Grumman, and SpaceX. NASA programs such as the Commercial Crew Program, Commercial Resupply Services, Commercial Lunar Payload Services, and NextSTEP have facilitated growing private-sector involvement in American spaceflight. In 2023, the United States received approximately 84% of its energy from fossil fuel, and its largest source of energy was petroleum (38%), followed by natural gas (36%), renewable sources (9%), coal (9%), and nuclear power (9%). In 2022, the United States constituted about 4% of the world's population, but consumed around 16% of the world's energy. The U.S. ranks as the second-highest emitter of greenhouse gases behind China. The U.S. is the world's largest producer of nuclear power, generating around 30% of the world's nuclear electricity. It also has the highest number of nuclear power reactors of any country. From 2024, the U.S. plans to triple its nuclear power capacity by 2050. The United States' 4 million miles (6.4 million kilometers) of road network, owned almost entirely by state and local governments, is the longest in the world. The extensive Interstate Highway System that connects all major U.S. cities is funded mostly by the federal government but maintained by state departments of transportation. The system is further extended by state highways and some private toll roads. The U.S. is among the top ten countries with the highest vehicle ownership per capita (850 vehicles per 1,000 people) in 2022. A 2022 study found that 76% of U.S. commuters drive alone and 14% ride a bicycle, including bike owners and users of bike-sharing networks. About 11% use some form of public transportation. Public transportation in the United States is well developed in the largest urban areas, notably New York City, Washington, D.C., Boston, Philadelphia, Chicago, and San Francisco; otherwise, coverage is generally less extensive than in most other developed countries. The U.S. also has many relatively car-dependent localities. Long-distance intercity travel is provided primarily by airlines, but travel by rail is more common along the Northeast Corridor, the only high-speed rail in the U.S. that meets international standards. Amtrak, the country's government-sponsored national passenger rail company, has a relatively sparse network compared to that of Western European countries. Service is concentrated in the Northeast, California, the Midwest, the Pacific Northwest, and Virginia/Southeast. The United States has an extensive air transportation network. U.S. civilian airlines are all privately owned. The three largest airlines in the world, by total number of passengers carried, are U.S.-based; American Airlines became the global leader after its 2013 merger with US Airways. Of the 50 busiest airports in the world, 16 are in the United States, as well as five of the top 10. The world's busiest airport by passenger volume is Hartsfield–Jackson Atlanta International in Atlanta, Georgia. In 2022, most of the 19,969 U.S. airports were owned and operated by local government authorities, and there are also some private airports. Some 5,193 are designated as "public use", including for general aviation. The Transportation Security Administration (TSA) has provided security at most major airports since 2001. The country's rail transport network, the longest in the world at 182,412.3 mi (293,564.2 km), handles mostly freight (in contrast to more passenger-centered rail in Europe). Because they are often privately owned operations, U.S. railroads lag behind those of the rest of the world in terms of electrification. The country's inland waterways are the world's fifth-longest, totaling 25,482 mi (41,009 km). They are used extensively for freight, recreation, and a small amount of passenger traffic. Of the world's 50 busiest container ports, four are located in the United States, with the busiest in the country being the Port of Los Angeles. Demographics The U.S. Census Bureau reported 331,449,281 residents on April 1, 2020,[v] making the United States the third-most-populous country in the world, after India and China. The Census Bureau's official 2025 population estimate was 341,784,857, an increase of 3.1% since the 2020 census. According to the Bureau's U.S. Population Clock, on July 1, 2024, the U.S. population had a net gain of one person every 16 seconds, or about 5400 people per day. In 2023, 51% of Americans age 15 and over were married, 6% were widowed, 10% were divorced, and 34% had never been married. In 2023, the total fertility rate for the U.S. stood at 1.6 children per woman, and, at 23%, it had the world's highest rate of children living in single-parent households in 2019. Most Americans live in the suburbs of major metropolitan areas. The United States has a diverse population; 37 ancestry groups have more than one million members. White Americans with ancestry from Europe, the Middle East, or North Africa form the largest racial and ethnic group at 57.8% of the United States population. Hispanic and Latino Americans form the second-largest group and are 18.7% of the United States population. African Americans constitute the country's third-largest ancestry group and are 12.1% of the total U.S. population. Asian Americans are the country's fourth-largest group, composing 5.9% of the United States population. The country's 3.7 million Native Americans account for about 1%, and some 574 native tribes are recognized by the federal government. In 2024, the median age of the United States population was 39.1 years. While many languages and dialects are spoken in the United States, English is by far the most commonly spoken and written. De facto, English is the official language of the United States, and in 2025, Executive Order 14224 declared English official. However, the U.S. has never had a de jure official language, as Congress has never passed a law to designate English as official for all three federal branches. Some laws, such as U.S. naturalization requirements, nonetheless standardize English. Twenty-eight states and the United States Virgin Islands have laws that designate English as the sole official language; 19 states and the District of Columbia have no official language. Three states and four U.S. territories have recognized local or indigenous languages in addition to English: Hawaii (Hawaiian), Alaska (twenty Native languages),[w] South Dakota (Sioux), American Samoa (Samoan), Puerto Rico (Spanish), Guam (Chamorro), and the Northern Mariana Islands (Carolinian and Chamorro). In total, 169 Native American languages are spoken in the United States. In Puerto Rico, Spanish is more widely spoken than English. According to the American Community Survey (2020), some 245.4 million people in the U.S. age five and older spoke only English at home. About 41.2 million spoke Spanish at home, making it the second most commonly used language. Other languages spoken at home by one million people or more include Chinese (3.40 million), Tagalog (1.71 million), Vietnamese (1.52 million), Arabic (1.39 million), French (1.18 million), Korean (1.07 million), and Russian (1.04 million). German, spoken by 1 million people at home in 2010, fell to 857,000 total speakers in 2020. America's immigrant population is by far the world's largest in absolute terms. In 2022, there were 87.7 million immigrants and U.S.-born children of immigrants in the United States, accounting for nearly 27% of the overall U.S. population. In 2017, out of the U.S. foreign-born population, some 45% (20.7 million) were naturalized citizens, 27% (12.3 million) were lawful permanent residents, 6% (2.2 million) were temporary lawful residents, and 23% (10.5 million) were unauthorized immigrants. In 2019, the top countries of origin for immigrants were Mexico (24% of immigrants), India (6%), China (5%), the Philippines (4.5%), and El Salvador (3%). In fiscal year 2022, over one million immigrants (most of whom entered through family reunification) were granted legal residence. The undocumented immigrant population in the U.S. reached a record high of 14 million in 2023. The First Amendment guarantees the free exercise of religion in the country and forbids Congress from passing laws respecting its establishment. Religious practice is widespread, among the most diverse in the world, and profoundly vibrant. The country has the world's largest Christian population, which includes the fourth-largest population of Catholics. Other notable faiths include Judaism, Buddhism, Hinduism, Islam, New Age, and Native American religions. Religious practice varies significantly by region. "Ceremonial deism" is common in American culture. The overwhelming majority of Americans believe in a higher power or spiritual force, engage in spiritual practices such as prayer, and consider themselves religious or spiritual. In the Southern United States' "Bible Belt", evangelical Protestantism plays a significant role culturally; New England and the Western United States tend to be more secular. Mormonism, a Restorationist movement founded in the U.S. in 1847, is the predominant religion in Utah and a major religion in Idaho. About 82% of Americans live in metropolitan areas, particularly in suburbs; about half of those reside in cities with populations over 50,000. In 2022, 333 incorporated municipalities had populations over 100,000, nine cities had more than one million residents, and four cities—New York City, Los Angeles, Chicago, and Houston—had populations exceeding two million. Many U.S. metropolitan populations are growing rapidly, particularly in the South and West. According to the Centers for Disease Control and Prevention (CDC), average U.S. life expectancy at birth reached 79.0 years in 2024, its highest recorded level. This was an increase of 0.6 years over 2023. The CDC attributed the improvement to a significant fall in the number of fatal drug overdoses in the country, noting that "heart disease continues to be the leading cause of death in the United States, followed by cancer and unintentional injuries." In 2024, life expectancy at birth for American men rose to 76.5 years (+0.7 years compared to 2023), while life expectancy for women was 81.4 years (+0.3 years). Starting in 1998, life expectancy in the U.S. fell behind that of other wealthy industrialized countries, and Americans' "health disadvantage" gap has been increasing ever since. The Commonwealth Fund reported in 2020 that the U.S. had the highest suicide rate among high-income countries. Approximately one-third of the U.S. adult population is obese and another third is overweight. The U.S. healthcare system far outspends that of any other country, measured both in per capita spending and as a percentage of GDP, but attains worse healthcare outcomes when compared to peer countries for reasons that are debated. The United States is the only developed country without a system of universal healthcare, and a significant proportion of the population that does not carry health insurance. Government-funded healthcare coverage for the poor (Medicaid) and for those age 65 and older (Medicare) is available to Americans who meet the programs' income or age qualifications. In 2010, then-President Obama passed the Patient Protection and Affordable Care Act.[x] Abortion in the United States is not federally protected, and is illegal or restricted in 17 states. American primary and secondary education, known in the U.S. as K–12 ("kindergarten through 12th grade"), is decentralized. School systems are operated by state, territorial, and sometimes municipal governments and regulated by the U.S. Department of Education. In general, children are required to attend school or an approved homeschool from the age of five or six (kindergarten or first grade) until they are 18 years old. This often brings students through the 12th grade, the final year of a U.S. high school, but some states and territories allow them to leave school earlier, at age 16 or 17. The U.S. spends more on education per student than any other country, an average of $18,614 per year per public elementary and secondary school student in 2020–2021. Among Americans age 25 and older, 92.2% graduated from high school, 62.7% attended some college, 37.7% earned a bachelor's degree, and 14.2% earned a graduate degree. The U.S. literacy rate is near-universal. The U.S. has produced the most Nobel Prize winners of any country, with 411 (having won 413 awards). U.S. tertiary or higher education has earned a global reputation. Many of the world's top universities, as listed by various ranking organizations, are in the United States, including 19 of the top 25. American higher education is dominated by state university systems, although the country's many private universities and colleges enroll about 20% of all American students. Local community colleges generally offer open admissions, lower tuition, and coursework leading to a two-year associate degree or a non-degree certificate. As for public expenditures on higher education, the U.S. spends more per student than the OECD average, and Americans spend more than all nations in combined public and private spending. Colleges and universities directly funded by the federal government do not charge tuition and are limited to military personnel and government employees, including: the U.S. service academies, the Naval Postgraduate School, and military staff colleges. Despite some student loan forgiveness programs in place, student loan debt increased by 102% between 2010 and 2020, and exceeded $1.7 trillion in 2022. Culture and society The United States is home to a wide variety of ethnic groups, traditions, and customs. The country has been described as having the values of individualism and personal autonomy, as well as a strong work ethic and competitiveness. Voluntary altruism towards others also plays a major role; according to a 2016 study by the Charities Aid Foundation, Americans donated 1.44% of total GDP to charity—the highest rate in the world by a large margin. Americans have traditionally been characterized by a unifying political belief in an "American Creed" emphasizing consent of the governed, liberty, equality under the law, democracy, social equality, property rights, and a preference for limited government. The U.S. has acquired significant hard and soft power through its diplomatic influence, economic power, military alliances, and cultural exports such as American movies, music, video games, sports, and food. The influence that the United States exerts on other countries through soft power is referred to as Americanization. Nearly all present Americans or their ancestors came from Europe, Africa, or Asia (the "Old World") within the past five centuries. Mainstream American culture is a Western culture largely derived from the traditions of European immigrants with influences from many other sources, such as traditions brought by slaves from Africa. More recent immigration from Asia and especially Latin America has added to a cultural mix that has been described as a homogenizing melting pot, and a heterogeneous salad bowl, with immigrants contributing to, and often assimilating into, mainstream American culture. Under the First Amendment to the Constitution, the United States is considered to have the strongest protections of free speech of any country. Flag desecration, hate speech, blasphemy, and lese majesty are all forms of protected expression. A 2016 Pew Research Center poll found that Americans were the most supportive of free expression of any polity measured. Additionally, they are the "most supportive of freedom of the press and the right to use the Internet without government censorship". The U.S. is a socially progressive country with permissive attitudes surrounding human sexuality. LGBTQ rights in the United States are among the most advanced by global standards. The American Dream, or the perception that Americans enjoy high levels of social mobility, plays a key role in attracting immigrants. Whether this perception is accurate has been a topic of debate. While mainstream culture holds that the United States is a classless society, scholars identify significant differences between the country's social classes, affecting socialization, language, and values. Americans tend to greatly value socioeconomic achievement, but being ordinary or average is promoted by some as a noble condition as well. The National Foundation on the Arts and the Humanities is an agency of the United States federal government that was established in 1965 with the purpose to "develop and promote a broadly conceived national policy of support for the humanities and the arts in the United States, and for institutions which preserve the cultural heritage of the United States." It is composed of four sub-agencies: Colonial American authors were influenced by John Locke and other Enlightenment philosophers. The American Revolutionary Period (1765–1783) is notable for the political writings of Benjamin Franklin, Alexander Hamilton, Thomas Paine, and Thomas Jefferson. Shortly before and after the Revolutionary War, the newspaper rose to prominence, filling a demand for anti-British national literature. An early novel is William Hill Brown's The Power of Sympathy, published in 1791. Writer and critic John Neal in the early- to mid-19th century helped advance America toward a unique literature and culture by criticizing predecessors such as Washington Irving for imitating their British counterparts, and by influencing writers such as Edgar Allan Poe, who took American poetry and short fiction in new directions. Ralph Waldo Emerson and Margaret Fuller pioneered the influential Transcendentalism movement; Henry David Thoreau, author of Walden, was influenced by this movement. The conflict surrounding abolitionism inspired writers, like Harriet Beecher Stowe, and authors of slave narratives, such as Frederick Douglass. Nathaniel Hawthorne's The Scarlet Letter (1850) explored the dark side of American history, as did Herman Melville's Moby-Dick (1851). Major American poets of the 19th century American Renaissance include Walt Whitman, Melville, and Emily Dickinson. Mark Twain was the first major American writer to be born in the West. Henry James achieved international recognition with novels like The Portrait of a Lady (1881). As literacy rates rose, periodicals published more stories centered around industrial workers, women, and the rural poor. Naturalism, regionalism, and realism were the major literary movements of the period. While modernism generally took on an international character, modernist authors working within the United States more often rooted their work in specific regions, peoples, and cultures. Following the Great Migration to northern cities, African-American and black West Indian authors of the Harlem Renaissance developed an independent tradition of literature that rebuked a history of inequality and celebrated black culture. An important cultural export during the Jazz Age, these writings were a key influence on Négritude, a philosophy emerging in the 1930s among francophone writers of the African diaspora. In the 1950s, an ideal of homogeneity led many authors to attempt to write the Great American Novel, while the Beat Generation rejected this conformity, using styles that elevated the impact of the spoken word over mechanics to describe drug use, sexuality, and the failings of society. Contemporary literature is more pluralistic than in previous eras, with the closest thing to a unifying feature being a trend toward self-conscious experiments with language. Twelve American laureates have won the Nobel Prize in Literature. Media in the United States is broadly uncensored, with the First Amendment providing significant protections, as reiterated in New York Times Co. v. United States. The four major broadcasters in the U.S. are the National Broadcasting Company (NBC), Columbia Broadcasting System (CBS), American Broadcasting Company (ABC), and Fox Broadcasting Company (Fox). The four major broadcast television networks are all commercial entities. The U.S. cable television system offers hundreds of channels catering to a variety of niches. In 2021, about 83% of Americans over age 12 listened to broadcast radio, while about 40% listened to podcasts. In the prior year, there were 15,460 licensed full-power radio stations in the U.S. according to the Federal Communications Commission (FCC). Much of the public radio broadcasting is supplied by National Public Radio (NPR), incorporated in February 1970 under the Public Broadcasting Act of 1967. U.S. newspapers with a global reach and reputation include The Wall Street Journal, The New York Times, The Washington Post, and USA Today. About 800 publications are produced in Spanish. With few exceptions, newspapers are privately owned, either by large chains such as Gannett or McClatchy, which own dozens or even hundreds of newspapers; by small chains that own a handful of papers; or, in an increasingly rare situation, by individuals or families. Major cities often have alternative newspapers to complement the mainstream daily papers, such as The Village Voice in New York City and LA Weekly in Los Angeles. The five most-visited websites in the world are Google, YouTube, Facebook, Instagram, and ChatGPT—all of them American-owned. Other popular platforms used include X (formerly Twitter) and Amazon. In 2025, the U.S. was the world's second-largest video game market by revenue (after China). In 2015, the U.S. video game industry consisted of 2,457 companies that employed around 220,000 jobs and generated $30.4 billion in revenue. There are 444 game publishers, developers, and hardware companies in California alone. According to the Game Developers Conference (GDC), the U.S. is the top location for video game development, with 58% of the world's game developers based there in 2025. The United States is well known for its theater. Mainstream theater in the United States derives from the old European theatrical tradition and has been heavily influenced by the British theater. By the middle of the 19th century, America had created new distinct dramatic forms in the Tom Shows, the showboat theater and the minstrel show. The central hub of the American theater scene is the Theater District in Manhattan, with its divisions of Broadway, off-Broadway, and off-off-Broadway. Many movie and television celebrities have gotten their big break working in New York productions. Outside New York City, many cities have professional regional or resident theater companies that produce their own seasons. The biggest-budget theatrical productions are musicals. U.S. theater has an active community theater culture. The Tony Awards recognizes excellence in live Broadway theater and are presented at an annual ceremony in Manhattan. The awards are given for Broadway productions and performances. One is also given for regional theater. Several discretionary non-competitive awards are given as well, including a Special Tony Award, the Tony Honors for Excellence in Theatre, and the Isabelle Stevenson Award. Folk art in colonial America grew out of artisanal craftsmanship in communities that allowed commonly trained people to individually express themselves. It was distinct from Europe's tradition of high art, which was less accessible and generally less relevant to early American settlers. Cultural movements in art and craftsmanship in colonial America generally lagged behind those of Western Europe. For example, the prevailing medieval style of woodworking and primitive sculpture became integral to early American folk art, despite the emergence of Renaissance styles in England in the late 16th and early 17th centuries. The new English styles would have been early enough to make a considerable impact on American folk art, but American styles and forms had already been firmly adopted. Not only did styles change slowly in early America, but there was a tendency for rural artisans there to continue their traditional forms longer than their urban counterparts did—and far longer than those in Western Europe. The Hudson River School was a mid-19th-century movement in the visual arts tradition of European naturalism. The 1913 Armory Show in New York City, an exhibition of European modernist art, shocked the public and transformed the U.S. art scene. American Realism and American Regionalism sought to reflect and give America new ways of looking at itself. Georgia O'Keeffe, Marsden Hartley, and others experimented with new and individualistic styles, which would become known as American modernism. Major artistic movements such as the abstract expressionism of Jackson Pollock and Willem de Kooning and the pop art of Andy Warhol and Roy Lichtenstein developed largely in the United States. Major photographers include Alfred Stieglitz, Edward Steichen, Dorothea Lange, Edward Weston, James Van Der Zee, Ansel Adams, and Gordon Parks. The tide of modernism and then postmodernism has brought global fame to American architects, including Frank Lloyd Wright, Philip Johnson, and Frank Gehry. The Metropolitan Museum of Art in Manhattan is the largest art museum in the United States and the fourth-largest in the world. American folk music encompasses numerous music genres, variously known as traditional music, traditional folk music, contemporary folk music, or roots music. Many traditional songs have been sung within the same family or folk group for generations, and sometimes trace back to such origins as the British Isles, mainland Europe, or Africa. The rhythmic and lyrical styles of African-American music in particular have influenced American music. Banjos were brought to America through the slave trade. Minstrel shows incorporating the instrument into their acts led to its increased popularity and widespread production in the 19th century. The electric guitar, first invented in the 1930s, and mass-produced by the 1940s, had an enormous influence on popular music, in particular due to the development of rock and roll. The synthesizer, turntablism, and electronic music were also largely developed in the U.S. Elements from folk idioms such as the blues and old-time music were adopted and transformed into popular genres with global audiences. Jazz grew from blues and ragtime in the early 20th century, developing from the innovations and recordings of composers such as W.C. Handy and Jelly Roll Morton. Louis Armstrong and Duke Ellington increased its popularity early in the 20th century. Country music developed in the 1920s, bluegrass and rhythm and blues in the 1940s, and rock and roll in the 1950s. In the 1960s, Bob Dylan emerged from the folk revival to become one of the country's most celebrated songwriters. The musical forms of punk and hip hop both originated in the United States in the 1970s. The United States has the world's largest music market, with a total retail value of $15.9 billion in 2022. Most of the world's major record companies are based in the U.S.; they are represented by the Recording Industry Association of America (RIAA). Mid-20th-century American pop stars, such as Frank Sinatra and Elvis Presley, became global celebrities and best-selling music artists, as have artists of the late 20th century, such as Michael Jackson, Madonna, Whitney Houston, and Mariah Carey, and of the early 21st century, such as Eminem, Britney Spears, Lady Gaga, Katy Perry, Taylor Swift and Beyoncé. The United States has the world's largest apparel market by revenue. Apart from professional business attire, American fashion is eclectic and predominantly informal. Americans' diverse cultural roots are reflected in their clothing; however, sneakers, jeans, T-shirts, and baseball caps are emblematic of American styles. New York, with its Fashion Week, is considered to be one of the "Big Four" global fashion capitals, along with Paris, Milan, and London. A study demonstrated that general proximity to Manhattan's Garment District has been synonymous with American fashion since its inception in the early 20th century. A number of well-known designer labels, among them Tommy Hilfiger, Ralph Lauren, Tom Ford and Calvin Klein, are headquartered in Manhattan. Labels cater to niche markets, such as preteens. New York Fashion Week is one of the most influential fashion shows in the world, and is held twice each year in Manhattan; the annual Met Gala, also in Manhattan, has been called the fashion world's "biggest night". The U.S. film industry has a worldwide influence and following. Hollywood, a district in central Los Angeles, the nation's second-most populous city, is also metonymous for the American filmmaking industry. The major film studios of the United States are the primary source of the most commercially successful movies selling the most tickets in the world. Largely centered in the New York City region from its beginnings in the late 19th century through the first decades of the 20th century, the U.S. film industry has since been primarily based in and around Hollywood. Nonetheless, American film companies have been subject to the forces of globalization in the 21st century, and an increasing number of films are made elsewhere. The Academy Awards, popularly known as "the Oscars", have been held annually by the Academy of Motion Picture Arts and Sciences since 1929, and the Golden Globe Awards have been held annually since January 1944. The industry peaked in what is commonly referred to as the "Golden Age of Hollywood", from the early sound period until the early 1960s, with screen actors such as John Wayne and Marilyn Monroe becoming iconic figures. In the 1970s, "New Hollywood", or the "Hollywood Renaissance", was defined by grittier films influenced by French and Italian realist pictures of the post-war period. The 21st century has been marked by the rise of American streaming platforms, which came to rival traditional cinema. Early settlers were introduced by Native Americans to foods such as turkey, sweet potatoes, corn, squash, and maple syrup. Of the most enduring and pervasive examples are variations of the native dish called succotash. Early settlers and later immigrants combined these with foods they were familiar with, such as wheat flour, beef, and milk, to create a distinctive American cuisine. New World crops, especially pumpkin, corn, potatoes, and turkey as the main course are part of a shared national menu on Thanksgiving, when many Americans prepare or purchase traditional dishes to celebrate the occasion. Characteristic American dishes such as apple pie, fried chicken, doughnuts, french fries, macaroni and cheese, ice cream, hamburgers, hot dogs, and American pizza derive from the recipes of various immigrant groups. Mexican dishes such as burritos and tacos preexisted the United States in areas later annexed from Mexico, and adaptations of Chinese cuisine as well as pasta dishes freely adapted from Italian sources are all widely consumed. American chefs have had a significant impact on society both domestically and internationally. In 1946, the Culinary Institute of America was founded by Katharine Angell and Frances Roth. This would become the United States' most prestigious culinary school, where many of the most talented American chefs would study prior to successful careers. The United States restaurant industry was projected at $899 billion in sales for 2020, and employed more than 15 million people, representing 10% of the nation's workforce directly. It is the country's second-largest private employer and the third-largest employer overall. The United States is home to over 220 Michelin star-rated restaurants, 70 of which are in New York City. Wine has been produced in what is now the United States since the 1500s, with the first widespread production beginning in what is now New Mexico in 1628. In the modern U.S., wine production is undertaken in all fifty states, with California producing 84 percent of all U.S. wine. With more than 1,100,000 acres (4,500 km2) under vine, the United States is the fourth-largest wine-producing country in the world, after Italy, Spain, and France. The classic American diner, a casual restaurant type originally intended for the working class, emerged during the 19th century from converted railroad dining cars made stationary. The diner soon evolved into purpose-built structures whose number expanded greatly in the 20th century. The American fast-food industry developed alongside the nation's car culture. American restaurants developed the drive-in format in the 1920s, which they began to replace with the drive-through format by the 1940s. American fast-food restaurant chains, such as McDonald's, Burger King, Chick-fil-A, Kentucky Fried Chicken, Dunkin' Donuts and many others, have numerous outlets around the world. The most popular spectator sports in the U.S. are American football, basketball, baseball, soccer, and ice hockey. Their premier leagues are, respectively, the National Football League, the National Basketball Association, Major League Baseball, Major League Soccer, and the National Hockey League, All these leagues enjoy wide-ranging domestic media coverage and, except for the MLS, all are considered the preeminent leagues in their respective sports in the world. While most major U.S. sports such as baseball and American football have evolved out of European practices, basketball, volleyball, skateboarding, and snowboarding are American inventions, many of which have become popular worldwide. Lacrosse and surfing arose from Native American and Native Hawaiian activities that predate European contact. The market for professional sports in the United States was approximately $69 billion in July 2013, roughly 50% larger than that of Europe, the Middle East, and Africa combined. American football is by several measures the most popular spectator sport in the United States. Although American football does not have a substantial following in other nations, the NFL does have the highest average attendance (67,254) of any professional sports league in the world. In the year 2024, the NFL generated over $23 billion, making them the most valued professional sports league in the United States and the world. Baseball has been regarded as the U.S. "national sport" since the late 19th century. The most-watched individual sports in the U.S. are golf and auto racing, particularly NASCAR and IndyCar. On the collegiate level, earnings for the member institutions exceed $1 billion annually, and college football and basketball attract large audiences, as the NCAA March Madness tournament and the College Football Playoff are some of the most watched national sporting events. In the U.S., the intercollegiate sports level serves as the main feeder system for professional and Olympic sports, with significant exceptions such as Minor League Baseball. This differs greatly from practices in nearly all other countries, where publicly and privately funded sports organizations serve this function. Eight Olympic Games have taken place in the United States. The 1904 Summer Olympics in St. Louis, Missouri, were the first-ever Olympic Games held outside of Europe. The Olympic Games will be held in the U.S. for a ninth time when Los Angeles hosts the 2028 Summer Olympics. U.S. athletes have won a total of 2,968 medals (1,179 gold) at the Olympic Games, the most of any country. In other international competition, the United States is the home of a number of prestigious events, including the America's Cup, World Baseball Classic, the U.S. Open, and the Masters Tournament. The U.S. men's national soccer team has qualified for eleven World Cups, while the women's national team has won the FIFA Women's World Cup and Olympic soccer tournament four and five times, respectively. The 1999 FIFA Women's World Cup was hosted by the United States. Its final match was attended by 90,185, setting the world record for largest women's sporting event crowd at the time. The United States hosted the 1994 FIFA World Cup and will co-host, along with Canada and Mexico, the 2026 FIFA World Cup. See also Notes References This article incorporates text from a free content work. Licensed under CC BY-SA IGO 3.0 (license statement/permission). Text taken from World Food and Agriculture – Statistical Yearbook 2023, FAO, FAO. External links 40°N 100°W / 40°N 100°W / 40; -100 (United States of America) |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Near_Eastern_archaeology] | [TOKENS: 1048] |
Contents Near Eastern archaeology Near Eastern archaeology is a regional branch of the wider, global discipline of archaeology. It refers generally to the excavation and study of artifacts and material culture of the Near East from antiquity to the recent past. Definition The definition of the Near East is usually based around West Asia, the Balkans, and North Africa, including the historical Fertile Crescent, the Levant, Anatolia, East Thrace and Egypt. The history of archaeological investigation in this region grew out of the 19th century discipline of biblical archaeology, efforts mostly by Europeans to uncover evidence for Christian biblical narratives. Much archaeological work in this region is still influenced by that discipline, although within the last three decades there has been a marked tendency by some archaeologists to dissociate their work from biblical frameworks. The most common fields of study are biblical archaeology dealing with the region and history of the Bible; Assyriology dealing with Mesopotamia; Egyptology dealing with the history of Ancient Egypt; and prehistoric archaeology which is not tied to a region but instead deals with the origins of culture before the invention of writing. Geographic subdivisions Egyptology is one example of a specialized branch that deals with the Nile Valley cultures of Egypt and associated regions in sub-Saharan Africa, the Sinai Peninsula to the east, and parts of North Africa. It includes language studies, history and archaeology and other related disciplines. The name Levant (or Syria-Palestine) is used to refer to the area adjacent to the east coast of the Mediterranean. The southern region included in this term encompasses Israel, the West Bank, Gaza Strip, and part of Jordan. Palestine was its ancient Roman and Byzantine name and was also in use during the Crusades (1095–1291), the period of Ottoman rule (1517-1917) and the British Mandate (1918–1948). The same region is also called the Holy Land, the Land of Israel, and Canaan. The foregoing names can be perceived as having political overtones, meaning that the more neutral, geographically based term the southern Levant has become popular with archaeologists who wish to refer to this area without prejudice or political orientation. In many contexts the Sinai Peninsula is also considered to be part of the southern Levant, although it is part of the modern state of Egypt. Archaeologically, it is distinguished from the heartland of Egypt, the Nile Valley and Delta. The term northern Levant can be used to refer to Lebanon, the Syrian littoral and portions of the Mediterranean coast of Turkey in the province of Hatay. These regions are often included in Greater Syria, a name used to refer to the whole area between Anatolia, Mesopotamia, and Arabia. The Mediterranean coast of Lebanon, the Syrian Arab Republic, and parts of northern Israel are also known as Phoenicia, after the ancient kingdom. However, this term suffers from the same problems as Canaan and equivalents and so is generally now only used in a strict historical sense. The peninsula of Anatolia, most of modern Turkey, is bordered by several seas and includes parts of Northern Mesopotamia. The Tigris and Euphrates rise in Turkey and flow south into Iraq. Cyprus (ancient Alashiya), a large island in the eastern Mediterranean was a separate cultural entity during most periods of human occupation. However, its proximity to both Anatolia and the northern and southern Levant was responsible for influences from and to both these regions. This was especially the case as Cyprus was an important source of copper for much of the region. Mesopotamia ("The Land of Two Rivers") is considered to begin more or less near the modern border with Iraq and refers to the flat valley of the southern Tigris and Euphrates and their tributaries. These rivers empty into the Shatt al-Arab waterway that separates Iraq from Iran. Sumerology is a very specialized discipline that deals with the history, language and archaeology of ancient Sumer (southern Mesopotamia), mostly during the 4th and 3rd millennium BCE. Assyriology deals with the Assyrians who succeeded the Sumerians and covers much of the region while that language was still in use. Iran, sometimes known as Persia, includes a large plateau and its periphery, including the Zagros Mountains. Sub-disciplines of this region deal mostly with the languages, history and archaeology of regions within this large area. The Arabian Peninsula and its offshore islands is a separate geographical zone that has contacts with Sinai, the well-watered regions to the north, and by sea with the far-east. Organisations Due to the historic interest in the archaeology of the Near East, especially due to the biblical links of the area, there are a large number of organisations dedicated to the archaeological investigation of the region. These include the American Society of Overseas Research which publishes the journal Near Eastern Archaeology Magazine, the Council for British Research in the Levant which publishes the journal Levant, and the Netherlands Institute for the Near East which publishes the journal Bibliotheca Orientalis. See also References External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Order_of_Defence_Merit] | [TOKENS: 142] |
Contents Order of Defence Merit The Order of Defence Merit is an award of the Brazilian Military, established on 10 June 2002 by decree No. 4263. The order is presented in five grades and recognizes distinguished service and exceptional contributions to Brazil by members of the Brazilian Military and the armies of friendly nations as well as civilians, and, less common, to organizations and institutions. Grades The five grades are Grand Cross, Grand Officer, Commander, Officer, and Knight. Notable recipients Notes References This Brazilian military article is a stub. You can help Wikipedia by adding missing information. This article related to orders, decorations, and medals is a stub. You can help Wikipedia by adding missing information. |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/List_of_computer_system_manufacturers] | [TOKENS: 125] |
Contents List of computer system manufacturers A computer system is a nominally complete computer that includes the hardware, operating system (main software), and the means to use peripheral equipment needed and used for full or mostly full operation. Such systems may constitute personal computers (including desktop computers, portable computers, laptops, all-in-ones, and more), mainframe computers, minicomputers, servers, and workstations, among other classes of computing. The following is a list of notable manufacturers and sellers of computer systems, both present and past. There are currently 432 companies in this incomplete list. Current Inactive See also Notes References |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/List_of_fictional_computers] | [TOKENS: 249] |
Contents List of fictional computers Computers have often been used as fictional objects in literature, films, and in other forms of media. Fictional computers may be depicted as considerably more sophisticated than anything yet devised in the real world. Fictional computers may be referred to with a made-up manufacturer's brand name and model number or a nickname. This is a list of computers or fictional artificial intelligences that have appeared in notable works of fiction. The work may be about the computer, or the computer may be an important element of the story. Only static computers are included. Robots and other fictional computers that are described as existing in a mobile or humanlike form are discussed in a separate list of fictional robots and androids. Literature Film Radio The Brain was described as, "a mass of electronic equipment", with a voice "produced by electrical impulses". It had the power to think and give orders. The Brain was a "Receiver, transmitter, computer", and we're told "it can do everything a man can do but a million times quicker, even answer questions", and made current computer technology seem like an abacus. Television Comics/graphic novels Computer and video games Board games and role-playing games Unsorted works See also Further reading References External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Meta_Platforms#cite_ref-44] | [TOKENS: 8626] |
Contents Meta Platforms Meta Platforms, Inc. (doing business as Meta) is an American multinational technology company headquartered in Menlo Park, California. Meta owns and operates several prominent social media platforms and communication services, including Facebook, Instagram, WhatsApp, Messenger, Threads and Manus. The company also operates an advertising network for its own sites and third parties; as of 2023[update], advertising accounted for 97.8 percent of its total revenue. Meta has been described as a part of Big Tech, which refers to the largest six tech companies in the United States, Alphabet (Google), Amazon, Apple, Meta (Facebook), Microsoft, and Nvidia, which are also the largest companies in the world by market capitalization. The company was originally established in 2004 as TheFacebook, Inc., and was renamed Facebook, Inc. in 2005. In 2021, it rebranded as Meta Platforms, Inc. to reflect a strategic shift toward developing the metaverse—an interconnected digital ecosystem spanning virtual and augmented reality technologies. In 2023, Meta was ranked 31st on the Forbes Global 2000 list of the world's largest public companies. As of 2022, it was the world's third-largest spender on research and development, with R&D expenses totaling US$35.3 billion. History Facebook filed for an initial public offering (IPO) on January 1, 2012. The preliminary prospectus stated that the company sought to raise $5 billion, had 845 million monthly active users, and a website accruing 2.7 billion likes and comments daily. After the IPO, Zuckerberg would retain 22% of the total shares and 57% of the total voting power in Facebook. Underwriters valued the shares at $38 each, valuing the company at $104 billion, the largest valuation yet for a newly public company. On May 16, one day before the IPO, Facebook announced it would sell 25% more shares than originally planned due to high demand. The IPO raised $16 billion, making it the third-largest in US history (slightly ahead of AT&T Mobility and behind only General Motors and Visa). The stock price left the company with a higher market capitalization than all but a few U.S. corporations—surpassing heavyweights such as Amazon, McDonald's, Disney, and Kraft Foods—and made Zuckerberg's stock worth $19 billion. The New York Times stated that the offering overcame questions about Facebook's difficulties in attracting advertisers to transform the company into a "must-own stock". Jimmy Lee of JPMorgan Chase described it as "the next great blue-chip". Writers at TechCrunch, on the other hand, expressed skepticism, stating, "That's a big multiple to live up to, and Facebook will likely need to add bold new revenue streams to justify the mammoth valuation." Trading in the stock, which began on May 18, was delayed that day due to technical problems with the Nasdaq exchange. The stock struggled to stay above the IPO price for most of the day, forcing underwriters to buy back shares to support the price. At the closing bell, shares were valued at $38.23, only $0.23 above the IPO price and down $3.82 from the opening bell value. The opening was widely described by the financial press as a disappointment. The stock set a new record for trading volume of an IPO. On May 25, 2012, the stock ended its first full week of trading at $31.91, a 16.5% decline. On May 22, 2012, regulators from Wall Street's Financial Industry Regulatory Authority announced that they had begun to investigate whether banks underwriting Facebook had improperly shared information only with select clients rather than the general public. Massachusetts Secretary of State William F. Galvin subpoenaed Morgan Stanley over the same issue. The allegations sparked "fury" among some investors and led to the immediate filing of several lawsuits, one of them a class action suit claiming more than $2.5 billion in losses due to the IPO. Bloomberg estimated that retail investors may have lost approximately $630 million on Facebook stock since its debut. S&P Global Ratings added Facebook to its S&P 500 index on December 21, 2013. On May 2, 2014, Zuckerberg announced that the company would be changing its internal motto from "Move fast and break things" to "Move fast with stable infrastructure". The earlier motto had been described as Zuckerberg's "prime directive to his developers and team" in a 2009 interview in Business Insider, in which he also said, "Unless you are breaking stuff, you are not moving fast enough." In November 2016, Facebook announced the Microsoft Windows client of gaming service Facebook Gameroom, formerly Facebook Games Arcade, at the Unity Technologies developers conference. The client allows Facebook users to play "native" games in addition to its web games. The service was closed in June 2021. Lasso was a short-video sharing app from Facebook similar to TikTok that was launched on iOS and Android in 2018 and was aimed at teenagers. On July 2, 2020, Facebook announced that Lasso would be shutting down on July 10. In 2018, the Oculus lead Jason Rubin sent his 50-page vision document titled "The Metaverse" to Facebook's leadership. In the document, Rubin acknowledged that Facebook's virtual reality business had not caught on as expected, despite the hundreds of millions of dollars spent on content for early adopters. He also urged the company to execute fast and invest heavily in the vision, to shut out HTC, Apple, Google and other competitors in the VR space. Regarding other players' participation in the metaverse vision, he called for the company to build the "metaverse" to prevent their competitors from "being in the VR business in a meaningful way at all". In May 2019, Facebook founded Libra Networks, reportedly to develop their own stablecoin cryptocurrency. Later, it was reported that Libra was being supported by financial companies such as Visa, Mastercard, PayPal and Uber. The consortium of companies was expected to pool in $10 million each to fund the launch of the cryptocurrency coin named Libra. Depending on when it would receive approval from the Swiss Financial Market Supervisory authority to operate as a payments service, the Libra Association had planned to launch a limited format cryptocurrency in 2021. Libra was renamed Diem, before being shut down and sold in January 2022 after backlash from Swiss government regulators and the public. During the COVID-19 pandemic, the use of online services, including Facebook, grew globally. Zuckerberg predicted this would be a "permanent acceleration" that would continue after the pandemic. Facebook hired aggressively, growing from 48,268 employees in March 2020 to more than 87,000 by September 2022. Following a period of intense scrutiny and damaging whistleblower leaks, news started to emerge on October 21, 2021 about Facebook's plan to rebrand the company and change its name. In the Q3 2021 earnings call on October 25, Mark Zuckerberg discussed the ongoing criticism of the company's social services and the way it operates, and pointed to the pivoting efforts to building the metaverse – without mentioning the rebranding and the name change. The metaverse vision and the name change from Facebook, Inc. to Meta Platforms was introduced at Facebook Connect on October 28, 2021. Based on Facebook's PR campaign, the name change reflects the company's shifting long term focus of building the metaverse, a digital extension of the physical world by social media, virtual reality and augmented reality features. "Meta" had been registered as a trademark in the United States in 2018 (after an initial filing in 2015) for marketing, advertising, and computer services, by a Canadian company that provided big data analysis of scientific literature. This company was acquired in 2017 by the Chan Zuckerberg Initiative (CZI), a foundation established by Zuckerberg and his wife, Priscilla Chan, and became one of their projects. Following the rebranding announcement, CZI announced that it had already decided to deprioritize the earlier Meta project, thus it would be transferring its rights to the name to Meta Platforms, and the previous project would end in 2022. Soon after the rebranding, in early February 2022, Meta reported a greater-than-expected decline in profits in the fourth quarter of 2021. It reported no growth in monthly users, and indicated it expected revenue growth to stall. It also expected measures taken by Apple Inc. to protect user privacy to cost it some $10 billion in advertisement revenue, an amount equal to roughly 8% of its revenue for 2021. In meeting with Meta staff the day after earnings were reported, Zuckerberg blamed competition for user attention, particularly from video-based apps such as TikTok. The 27% reduction in the company's share price which occurred in reaction to the news eliminated some $230 billion of value from Meta's market capitalization. Bloomberg described the decline as "an epic rout that, in its sheer scale, is unlike anything Wall Street or Silicon Valley has ever seen". Zuckerberg's net worth fell by as much as $31 billion. Zuckerberg owns 13% of Meta, and the holding makes up the bulk of his wealth. According to published reports by Bloomberg on March 30, 2022, Meta turned over data such as phone numbers, physical addresses, and IP addresses to hackers posing as law enforcement officials using forged documents. The law enforcement requests sometimes included forged signatures of real or fictional officials. When asked about the allegations, a Meta representative said, "We review every data request for legal sufficiency and use advanced systems and processes to validate law enforcement requests and detect abuse." In June 2022, Sheryl Sandberg, the chief operating officer of 14 years, announced she would step down that year. Zuckerberg said that Javier Olivan would replace Sandberg, though in a “more traditional” role. In March 2022, Meta (except Meta-owned WhatsApp) and Instagram were banned in Russia and added to the Russian list of terrorist and extremist organizations for alleged Russophobia and hate speech (up to genocidal calls) amid the ongoing Russian invasion of Ukraine. Meta appealed against the ban, but it was upheld by a Moscow court in June of the same year. Also in March 2022, Meta and Italian eyewear giant Luxottica released Ray-Ban Stories, a series of smartglasses which could play music and take pictures. Meta and Luxottica parent company EssilorLuxottica declined to disclose sales on the line of products as of September 2022, though Meta has expressed satisfaction with its customer feedback. In July 2022, Meta saw its first year-on-year revenue decline when its total revenue slipped by 1% to $28.8bn. Analysts and journalists accredited the loss to its advertising business, which has been limited by Apple's app tracking transparency feature and the number of people who have opted not to be tracked by Meta apps. Zuckerberg also accredited the decline to increasing competition from TikTok. On October 27, 2022, Meta's market value dropped to $268 billion, a loss of around $700 billion compared to 2021, and its shares fell by 24%. It lost its spot among the top 20 US companies by market cap, despite reaching the top 5 in the previous year. In November 2022, Meta laid off 11,000 employees, 13% of its workforce. Zuckerberg said the decision to aggressively increase Meta's investments had been a mistake, as he had wrongly predicted that the surge in e-commerce would last beyond the COVID-19 pandemic. He also attributed the decline to increased competition, a global economic downturn and "ads signal loss". Plans to lay off a further 10,000 employees began in April 2023. The layoffs were part of a general downturn in the technology industry, alongside layoffs by companies including Google, Amazon, Tesla, Snap, Twitter and Lyft. Starting from 2022, Meta scrambled to catch up to other tech companies in adopting specialized artificial intelligence hardware and software. It had been using less expensive CPUs instead of GPUs for AI work, but that approach turned out to be less efficient. The company gifted the Inter-university Consortium for Political and Social Research $1.3 million to finance the Social Media Archive's aim to make their data available to social science research. In 2023, Ireland's Data Protection Commissioner imposed a record EUR 1.2 billion fine on Meta for transferring data from Europe to the United States without adequate protections for EU citizens.: 250 In March 2023, Meta announced a new round of layoffs that would cut 10,000 employees and close 5,000 open positions to make the company more efficient. Meta revenue surpassed analyst expectations for the first quarter of 2023 after announcing that it was increasing its focus on AI. On July 6, Meta launched a new app, Threads, a competitor to Twitter. Meta announced its artificial intelligence model Llama 2 in July 2023, available for commercial use via partnerships with major cloud providers like Microsoft. It was the first project to be unveiled out of Meta's generative AI group after it was set up in February. It would not charge access or usage but instead operate with an open-source model to allow Meta to ascertain what improvements need to be made. Prior to this announcement, Meta said it had no plans to release Llama 2 for commercial use. An earlier version of Llama was released to academics. In August 2023, Meta announced its permanent removal of news content from Facebook and Instagram in Canada due to the Online News Act, which requires Canadian news outlets to be compensated for content shared on its platform. The Online News Act was in effect by year-end, but Meta will not participate in the regulatory process. In October 2023, Zuckerberg said that AI would be Meta's biggest investment area in 2024. Meta finished 2023 as one of the best-performing technology stocks of the year, with its share price up 150 percent. Its stock reached an all-time high in January 2024, bringing Meta within 2% of achieving $1 trillion market capitalization. In November 2023 Meta Platforms launched an ad-free service in Europe, allowing subscribers to opt-out of personal data being collected for targeted advertising. A group of 28 European organizations, including Max Schrems' advocacy group NOYB, the Irish Council for Civil Liberties, Wikimedia Europe, and the Electronic Privacy Information Center, signed a 2024 letter to the European Data Protection Board (EDPB) expressing concern that this subscriber model would undermine privacy protections, specifically GDPR data protection standards. Meta removed the Facebook and Instagram accounts of Iran's Supreme Leader Ali Khamenei in February 2024, citing repeated violations of its Dangerous Organizations & Individuals policy. As of March, Meta was under investigation by the FDA for alleged use of their social media platforms to sell illegal drugs. On 16 May 2024, the European Commission began an investigation into Meta over concerns related to child safety. In May 2023, Iraqi social media influencer Esaa Ahmed-Adnan encountered a troubling issue when Instagram removed his posts, citing false copyright violations despite his content being original and free from copyrighted material. He discovered that extortionists were behind these takedowns, offering to restore his content for $3,000 or provide ongoing protection for $1,000 per month. This scam, exploiting Meta’s rights management tools, became widespread in the Middle East, revealing a gap in Meta’s enforcement in developing regions. An Iraqi nonprofit Tech4Peace’s founder, Aws al-Saadi helped Ahmed-Adnan and others, but the restoration process was slow, leading to significant financial losses for many victims, including prominent figures like Ammar al-Hakim. This situation highlighted Meta’s challenges in balancing global growth with effective content moderation and protection. On 16 September 2024, Meta announced it had banned Russian state media outlets from its platforms worldwide due to concerns about "foreign interference activity." This decision followed allegations that RT and its employees funneled $10 million through shell companies to secretly fund influence campaigns on various social media channels. Meta's actions were part of a broader effort to counter Russian covert influence operations, which had intensified since the invasion. At its 2024 Connect conference, Meta presented Orion, its first pair of augmented reality glasses. Though Orion was originally intended to be sold to consumers, the manufacturing process turned out to be too complex and expensive. Instead, the company pivoted to producing a small number of the glasses to be used internally. On 4 October 2024, Meta announced about its new AI model called Movie Gen, capable of generating realistic video and audio clips based on user prompts. Meta stated it would not release Movie Gen for open development, preferring to collaborate directly with content creators and integrate it into its products by the following year. The model was built using a combination of licensed and publicly available datasets. On October 31, 2024, ProPublica published an investigation into deceptive political advertisement scams that sometimes use hundreds of hijacked profiles and facebook pages run by organized networks of scammers. The authors cited spotty enforcement by Meta as a major reason for the extent of the issue. In November 2024, TechCrunch reported that Meta were considering building a $10bn global underwater cable spanning 25,000 miles. In the same month, Meta closed down 2 million accounts on Facebook and Instagram that were linked to scam centers in Myanmar, Laos, Cambodia, the Philippines, and the United Arab Emirates doing pig butchering scams. In December 2024, Meta announced that, beginning February 2025, they would require advertisers to run ads about financial services in Australia to verify information about who are the beneficiary and the payer in a bid to regulate scams. On December 4, 2024, Meta announced it will invest US$10 billion for its largest AI data center in northeast Louisiana, powered by natural gas facilities. On the 11th of that month, Meta experienced a global outage, impacting accounts on all of their social media and messaging applications. Outage reports from DownDetector reached 70,000+ and 100,000+ within minutes for Instagram and Facebook, respectively. In January 2025, Meta announced plans to roll back its diversity, equity, and inclusion (DEI) initiatives, citing shifts in the "legal and policy landscape" in the United States following the 2024 presidential election. The decision followed reports that CEO Mark Zuckerberg sought to align the company more closely with the incoming Trump administration, including changes to content moderation policies and executive leadership. The new content moderation policies continued to bar insults about a person's intellect or mental illness, but made an exception to allow calling LGBTQ people mentally ill because they are gay or transgender. Later that month, Meta agreed to pay $25 million to settle a 2021 lawsuit brought by Donald Trump for suspending his social media accounts after the January 6 riots. Changes to Meta's moderation policies were controversial among its oversight board, with a significant divide in opinion between the board's US conservatives and its global members. In June 2025, Meta Platforms Inc. has decided to make a multibillion-dollar investment into artificial intelligence startup Scale AI. The financing could exceed $10 billion in value which would make it one of the largest private company funding events of all time. In October 2025, it was announced that Meta would be laying off 600 employees in the artificial intelligence unit to perform better and simpler. They referred to their AI unit as "bloated" and are seeking to trim down the department. This mass layoff is going to impact Meta’s AI infrastructure units, Fundamental Artificial Intelligence Research unit (FAIR) and other product-related positions. Mergers and acquisitions Meta has acquired multiple companies (often identified as talent acquisitions). One of its first major acquisitions was in April 2012, when it acquired Instagram for approximately US$1 billion in cash and stock. In October 2013, Facebook, Inc. acquired Onavo, an Israeli mobile web analytics company. In February 2014, Facebook, Inc. announced it would buy mobile messaging company WhatsApp for US$19 billion in cash and stock. The acquisition was completed on October 6. Later that year, Facebook bought Oculus VR for $2.3 billion in cash and stock, which released its first consumer virtual reality headset in 2016. In late November 2019, Facebook, Inc. announced the acquisition of the game developer Beat Games, responsible for developing one of that year's most popular VR games, Beat Saber. In Late 2022, after Facebook Inc rebranded to Meta Platforms Inc, Oculus was rebranded to Meta Quest. In May 2020, Facebook, Inc. announced it had acquired Giphy for a reported cash price of $400 million. It will be integrated with the Instagram team. However, in August 2021, UK's Competition and Markets Authority (CMA) stated that Facebook, Inc. might have to sell Giphy, after an investigation found that the deal between the two companies would harm competition in display advertising market. Facebook, Inc. was fined $70 million by CMA for deliberately failing to report all information regarding the acquisition and the ongoing antitrust investigation. In October 2022, the CMA ruled for a second time that Meta be required to divest Giphy, stating that Meta already controls half of the advertising in the UK. Meta agreed to the sale, though it stated that it disagrees with the decision itself. In May 2023, Giphy was divested to Shutterstock for $53 million. In November 2020, Facebook, Inc. announced that it planned to purchase the customer-service platform and chatbot specialist startup Kustomer to promote companies to use their platform for business. It has been reported that Kustomer valued at slightly over $1 billion. The deal was closed in February 2022 after regulatory approval. In September 2022, Meta acquired Lofelt, a Berlin-based haptic tech startup. In December 2025, it was announced Meta had acquired the AI-wearables startup, Limitless. In the same month, they also acquired another AI startup, Manus AI, for $2 billion. Manus announced in December that its platform had achieved $100mm in recurring revenue just 8 months after its launch and Meta said it will scale the platform to many other businesses. In January 2026, it was announced Meta proposed acquisition of Manus was undergoing preliminary scrutiny by Chinese regulators. The examination concerns the cross-border transfer of artificial intelligence technology developed in China. Lobbying In 2020, Facebook, Inc. spent $19.7 million on lobbying, hiring 79 lobbyists. In 2019, it had spent $16.7 million on lobbying and had a team of 71 lobbyists, up from $12.6 million and 51 lobbyists in 2018. Facebook was the largest spender of lobbying money among the Big Tech companies in 2020. The lobbying team includes top congressional aide John Branscome, who was hired in September 2021, to help the company fend off threats from Democratic lawmakers and the Biden administration. In December 2024, Meta donated $1 million to the inauguration fund for then-President-elect Donald Trump. In 2025, Meta was listed among the donors funding the construction of the White House State Ballroom. Partnerships February 2026, Meta announced a long-term partnership with Nvidia. Censorship In August 2024, Mark Zuckerberg sent a letter to Jim Jordan indicating that during the COVID-19 pandemic the Biden administration repeatedly asked Meta to limit certain COVID-19 content, including humor and satire, on Facebook and Instagram. In 2016 Meta hired Jordana Cutler, formerly an employee at the Israeli Embassy to the United States, as its policy chief for Israel and the Jewish Diaspora. In this role, Cutler pushed for the censorship of accounts belonging to Students for Justice in Palestine chapters in the United States. Critics have said that Cutler's position gives the Israeli government an undue influence over Meta policy, and that few countries have such high levels of contact with Meta policymakers. Following the election of Donald Trump in 2025, various sources noted possible censorship related to the Democratic Party on Instagram and other Meta platforms. In February 2025, a Meta rep flagged journalist Gil Duran's article and other "critiques of tech industry figures" as spam or sensitive content, limiting their reach. In March 2025, Meta attempted to block former employee Sarah Wynn-Williams from promoting or further distributing her memoir, Careless People, that includes allegations of unaddressed sexual harassment in the workplace by senior executives. The New York Times reports that the arbitration is among Meta's most forcible attempts to repudiate a former employee's account of workplace dynamics. Publisher Macmillan reacted to the ruling by the Emergency International Arbitral Tribunal by stating that it will ignore its provisions. As of 15 March 2025[update], hardback and digital versions of Careless People were being offered for sale by major online retailers. From October 2025, Meta began removing and restricting access for accounts related to LGBTQ, reproductive health and abortion information pages on its platforms. Martha Dimitratou, executive director of Repro Uncensored, called Meta's shadow-banning of these issues "One of the biggest waves of censorship we are seeing". Disinformation concerns Since its inception, Meta has been accused of being a host for fake news and misinformation. In the wake of the 2016 United States presidential election, Zuckerberg began to take steps to eliminate the prevalence of fake news, as the platform had been criticized for its potential influence on the outcome of the election. The company initially partnered with ABC News, the Associated Press, FactCheck.org, Snopes and PolitiFact for its fact-checking initiative; as of 2018, it had over 40 fact-checking partners across the world, including The Weekly Standard. A May 2017 review by The Guardian found that the platform's fact-checking initiatives of partnering with third-party fact-checkers and publicly flagging fake news were regularly ineffective, and appeared to be having minimal impact in some cases. In 2018, journalists working as fact-checkers for the company criticized the partnership, stating that it had produced minimal results and that the company had ignored their concerns. In 2024 Meta's decision to continue to disseminate a falsified video of US president Joe Biden, even after it had been proven to be fake, attracted criticism and concern. In January 2025, Meta ended its use of third-party fact-checkers in favor of a user-run community notes system similar to the one used on X. While Zuckerberg supported these changes, saying that the amount of censorship on the platform was excessive, the decision received criticism by fact-checking institutions, stating that the changes would make it more difficult for users to identify misinformation. Meta also faced criticism for weakening its policies on hate speech that were designed to protect minorities and LGBTQ+ individuals from bullying and discrimination. While moving its content review teams from California to Texas, Meta changed their hateful conduct policy to eliminate restrictions on anti-LGBT and anti-immigrant hate speech, as well as explicitly allowing users to accuse LGBT people of being mentally ill or abnormal based on their sexual orientation or gender identity. In January 2025, Meta faced significant criticism for its role in removing LGBTQ+ content from its platforms, amid its broader efforts to address anti-LGBTQ+ hate speech. The removal of LGBTQ+ themes was noted as part of the wider crackdown on content deemed to violate its community guidelines. Meta's content moderation policies, which were designed to combat harmful speech and protect users from discrimination, inadvertently led to the removal or restriction of LGBTQ+ content, particularly posts highlighting LGBTQ+ identities, support, or political issues. According to reports, LGBTQ+ posts, including those that simply celebrated pride or advocated for LGBTQ+ rights, were flagged and removed for reasons that some critics argue were vague or inconsistently applied. Many LGBTQ+ activists and users on Meta's platforms expressed concern that such actions stifled visibility and expression, potentially isolating LGBTQ+ individuals and communities, especially in spaces that were historically important for outreach and support. Lawsuits Numerous lawsuits have been filed against the company, both when it was known as Facebook, Inc., and as Meta Platforms. In March 2020, the Office of the Australian Information Commissioner (OAIC) sued Facebook, for significant and persistent infringements of the rule on privacy involving the Cambridge Analytica fiasco. Every violation of the Privacy Act is subject to a theoretical cumulative liability of $1.7 million. The OAIC estimated that a total of 311,127 Australians had been exposed. On December 8, 2020, the U.S. Federal Trade Commission and 46 states (excluding Alabama, Georgia, South Carolina, and South Dakota), the District of Columbia and the territory of Guam, launched Federal Trade Commission v. Facebook as an antitrust lawsuit against Facebook. The lawsuit concerns Facebook's acquisition of two competitors—Instagram and WhatsApp—and the ensuing monopolistic situation. FTC alleges that Facebook holds monopolistic power in the U.S. social networking market and seeks to force the company to divest from Instagram and WhatsApp to break up the conglomerate. William Kovacic, a former chairman of the Federal Trade Commission, argued the case will be difficult to win as it would require the government to create a counterfactual argument of an internet where the Facebook-WhatsApp-Instagram entity did not exist, and prove that harmed competition or consumers. In November 2025, it was ruled that Meta did not violate antitrust laws and holds no monopoly in the market. On December 24, 2021, a court in Russia fined Meta for $27 million after the company declined to remove unspecified banned content. The fine was reportedly tied to the company's annual revenue in the country. In May 2022, a lawsuit was filed in Kenya against Meta and its local outsourcing company Sama. Allegedly, Meta has poor working conditions in Kenya for workers moderating Facebook posts. According to the lawsuit, 260 screeners were declared redundant with confusing reasoning. The lawsuit seeks financial compensation and an order that outsourced moderators be given the same health benefits and pay scale as Meta employees. In June 2022, 8 lawsuits were filed across the U.S. over the allege that excessive exposure to platforms including Facebook and Instagram has led to attempted or actual suicides, eating disorders and sleeplessness, among other issues. The litigation follows a former Facebook employee's testimony in Congress that the company refused to take responsibility. The company noted that tools have been developed for parents to keep track of their children's activity on Instagram and set time limits, in addition to Meta's "Take a break" reminders. In addition, the company is providing resources specific to eating disorders as well as developing AI to prevent children under the age of 13 signing up for Facebook or Instagram. In June 2022, Meta settled a lawsuit with the US Department of Justice. The lawsuit, which was filed in 2019, alleged that the company enabled housing discrimination through targeted advertising, as it allowed homeowners and landlords to run housing ads excluding people based on sex, race, religion, and other characteristics. The U.S. Department of Justice stated that this was in violation of the Fair Housing Act. Meta was handed a penalty of $115,054 and given until December 31, 2022, to shadow the algorithm tool. In January 2023, Meta was fined €390 million for violations of the European Union General Data Protection Regulation. In May 2023, the European Data Protection Board fined Meta a record €1.2 billion for breaching European Union data privacy laws by transferring personal data of Facebook users to servers in the U.S. In July 2024, Meta agreed to pay the state of Texas US$1.4 billion to settle a lawsuit brought by Texas Attorney General Ken Paxton accusing the company of collecting users' biometric data without consent, setting a record for the largest privacy-related settlement ever obtained by a state attorney general. In October 2024, Meta Platforms faced lawsuits in Japan from 30 plaintiffs who claimed they were defrauded by fake investment ads on Facebook and Instagram, featuring false celebrity endorsements. The plaintiffs are seeking approximately $2.8 million in damages. In April 2025, the Kenyan High Court ruled that a US$2.4 billion lawsuit in which three plaintiffs claim that Facebook inflamed civil violence in Ethiopia in 2021 could proceed. In April 2025, Meta was fined €200 million ($230 million) for breaking the Digital Markets Act, by imposing a “consent or pay” system that forces users to either allow their personal data to be used to target advertisements, or pay a subscription fee for advertising-free versions of Facebook and Instagram. In late April 2025, a case was filed against Meta in Ghana over the alleged psychological distress experienced by content moderators employed to take down disturbing social media content including depictions of murders, extreme violence and child sexual abuse. Meta moved the moderation service to the Ghanaian capital of Accra after legal issues in the previous location Kenya. The new moderation company is Teleperformance, a multinational corporation with a history of worker's rights violation. Reports suggests the conditions are worse here than in the previous Kenyan location, with many workers afraid of speaking out due to fear of returning to conflict zones. Workers reported developing mental illnesses, attempted suicides, and low pay. In 26 January 2026, a New Mexico state court case was filed, suggesting that Mark Zuckerberg approved allowing minors to access artificial intelligence chatbot companions that safety staffers warned were capable of sexual interactions. In 2020, the company UReputation, which had been involved in several cases concerning the management of digital armies[clarification needed], filed a lawsuit against Facebook, accusing it of unlawfully transmitting personal data to third parties. Legal actions were initiated in Tunisia, France, and the United States. In 2025, the United States District court for the Northern District of Georgia approved a discovery procedure, allowing UReputation to access documents and evidence held by Meta. Structure Meta's key management consists of: As of October 2022[update], Meta had 83,553 employees worldwide. As of June 2024[update], Meta's board consisted of the following directors; Meta Platforms is mainly owned by institutional investors, who hold around 80% of all shares. Insiders control the majority of voting shares. The three largest individual investors in 2024 were Mark Zuckerberg, Sheryl Sandberg and Christopher K. Cox. The largest shareholders in late 2024/early 2025 were: Roger McNamee, an early Facebook investor and Zuckerberg's former mentor, said Facebook had "the most centralized decision-making structure I have ever encountered in a large company". Facebook co-founder Chris Hughes has stated that chief executive officer Mark Zuckerberg has too much power, that the company is now a monopoly, and that, as a result, it should be split into multiple smaller companies. In an op-ed in The New York Times, Hughes said he was concerned that Zuckerberg had surrounded himself with a team that did not challenge him, and that it is the U.S. government's job to hold him accountable and curb his "unchecked power". He also said that "Mark's power is unprecedented and un-American." Several U.S. politicians agreed with Hughes. European Union Commissioner for Competition Margrethe Vestager stated that splitting Facebook should be done only as "a remedy of the very last resort", and that it would not solve Facebook's underlying problems. Revenue Facebook ranked No. 34 in the 2020 Fortune 500 list of the largest United States corporations by revenue, with almost $86 billion in revenue most of it coming from advertising. One analysis of 2017 data determined that the company earned US$20.21 per user from advertising. According to New York, since its rebranding, Meta has reportedly lost $500 billion as a result of new privacy measures put in place by companies such as Apple and Google which prevents Meta from gathering users' data. In February 2015, Facebook announced it had reached two million active advertisers, with most of the gain coming from small businesses. An active advertiser was defined as an entity that had advertised on the Facebook platform in the last 28 days. In March 2016, Facebook announced it had reached three million active advertisers with more than 70% from outside the United States. Prices for advertising follow a variable pricing model based on auctioning ad placements, and potential engagement levels of the advertisement itself. Similar to other online advertising platforms like Google and Twitter, targeting of advertisements is one of the chief merits of digital advertising compared to traditional media. Marketing on Meta is employed through two methods based on the viewing habits, likes and shares, and purchasing data of the audience, namely targeted audiences and "look alike" audiences. The U.S. IRS challenged the valuation Facebook used when it transferred IP from the U.S. to Facebook Ireland (now Meta Platforms Ireland) in 2010 (which Facebook Ireland then revalued higher before charging out), as it was building its double Irish tax structure. The case is ongoing and Meta faces a potential fine of $3–5bn. The U.S. Tax Cuts and Jobs Act of 2017 changed Facebook's global tax calculations. Meta Platforms Ireland is subject to the U.S. GILTI tax of 10.5% on global intangible profits (i.e. Irish profits). On the basis that Meta Platforms Ireland Limited is paying some tax, the effective minimum US tax for Facebook Ireland will be circa 11%. In contrast, Meta Platforms Inc. would incur a special IP tax rate of 13.125% (the FDII rate) if its Irish business relocated to the U.S. Tax relief in the U.S. (21% vs. Irish at the GILTI rate) and accelerated capital expensing, would make this effective U.S. rate around 12%. The insignificance of the U.S./Irish tax difference was demonstrated when Facebook moved 1.5bn non-EU accounts to the U.S. to limit exposure to GDPR. Facilities Users outside of the U.S. and Canada contract with Meta's Irish subsidiary, Meta Platforms Ireland Limited (formerly Facebook Ireland Limited), allowing Meta to avoid US taxes for all users in Europe, Asia, Australia, Africa and South America. Meta is making use of the Double Irish arrangement which allows it to pay 2–3% corporation tax on all international revenue. In 2010, Facebook opened its fourth office, in Hyderabad, India, which houses online advertising and developer support teams and provides support to users and advertisers. In India, Meta is registered as Facebook India Online Services Pvt Ltd. It also has offices or planned sites in Chittagong, Bangladesh; Dublin, Ireland; and Austin, Texas, among other cities. Facebook opened its London headquarters in 2017 in Fitzrovia in central London. Facebook opened an office in Cambridge, Massachusetts in 2018. The offices were initially home to the "Connectivity Lab", a group focused on bringing Internet access to those who do not have access to the Internet. In April 2019, Facebook opened its Taiwan headquarters in Taipei. In March 2022, Meta opened new regional headquarters in Dubai. In September 2023, it was reported that Meta had paid £149m to British Land to break the lease on Triton Square London office. Meta reportedly had another 18 years left on its lease on the site. As of 2023, Facebook operated 21 data centers. It committed to purchase 100% renewable energy and to reduce its greenhouse gas emissions 75% by 2020. Its data center technologies include Fabric Aggregator, a distributed network system that accommodates larger regions and varied traffic patterns. Reception US Representative Alexandria Ocasio-Cortez responded in a tweet to Zuckerberg's announcement about Meta, saying: "Meta as in 'we are a cancer to democracy metastasizing into a global surveillance and propaganda machine for boosting authoritarian regimes and destroying civil society ... for profit!'" Ex-Facebook employee Frances Haugen and whistleblower behind the Facebook Papers responded to the rebranding efforts by expressing doubts about the company's ability to improve while led by Mark Zuckerberg, and urged the chief executive officer to resign. In November 2021, a video published by Inspired by Iceland went viral, in which a Zuckerberg look-alike promoted the Icelandverse, a place of "enhanced actual reality without silly looking headsets". In a December 2021 interview, SpaceX and Tesla chief executive officer Elon Musk said he could not see a compelling use-case for the VR-driven metaverse, adding: "I don't see someone strapping a frigging screen to their face all day." In January 2022, Louise Eccles of The Sunday Times logged into the metaverse with the intention of making a video guide. She wrote: Initially, my experience with the Oculus went well. I attended work meetings as an avatar and tried an exercise class set in the streets of Paris. The headset enabled me to feel the thrill of carving down mountains on a snowboard and the adrenaline rush of climbing a mountain without ropes. Yet switching to the social apps, where you mingle with strangers also using VR headsets, it was at times predatory and vile. Eccles described being sexually harassed by another user, as well as "accents from all over the world, American, Indian, English, Australian, using racist, sexist, homophobic and transphobic language". She also encountered users as young as 7 years old on the platform, despite Oculus headsets being intended for users over 13. See also References External links 37°29′06″N 122°08′54″W / 37.48500°N 122.14833°W / 37.48500; -122.14833 |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Social_history] | [TOKENS: 6063] |
Contents Social history Social history, often called history from below, is a field of history that looks at the lived experience of the past. Historians who write social history are called social historians. Social history came to prominence in the 1960s, spreading from schools of thought in the United Kingdom and France which posited that the Great Man view of history was inaccurate because it did not adequately explain how societies changed. Instead, social historians wanted to show that change arose from within society, complicating the popular belief that powerful leaders were the source of dynamism. While social history came from the Marxist view of history (historical materialism), the cultural turn and linguistic turn saw the number of sub-fields expand as well as the emergence of other approaches to social history, including a social liberal approach and a more ambiguous critical theory approach. In its "golden age" it was a major field in the 1960s and 1970s among young historians, and still is well represented in history departments in Britain, Canada, France, Germany and the United States. In the two decades from 1975 to 1995, the proportion of professors of history in American universities identifying with social history rose from 31% to 41%, while the proportion of political historians fell from 40% to 30%. In the history departments of British and Irish universities in 2014, of the 3410 faculty members reporting, 878 (26%) identified themselves with social history while political history came next with 841 (25%). "Old" social history There is an important distinction between old social history and new social history that exists in what are now sub-fields of social history that predate the 1960s.[clarification needed] E. P. Thompson identified labour history as the central concern of new social historians because of its " Whiggish narratives", such as the term "labour movement" which, he says, erroneously suggests the constant progression toward the perfect future.: 13 [better source needed] The older social history included numerous topics that were not part of mainstream historiography, which was then political, military, diplomatic, constitutional history, the history of great men and intellectual history. It was a hodgepodge without a central theme, and it often included political movements, such as populism, that were "social" in the sense of being outside the elite system.[clarification needed] The emergence of "new" social history The popular view is that new social history emerged in the 1960s with the publication of Thompson's The Making of the English Working Class (1963). Writing in 1966 in The Times Literary Supplement, Thompson described his approach as "history from below" and explained that it had come from earlier developments within the French Annales School. According to C. J. Coventry, new social history arose in the 1930s at the University of Cambridge with the Communist Party Historians Group. Citing the reflections of Eric Hobsbawm, a contemporary of Thompson's and a fellow member of the Historians' Group, Coventry shows that the "new" social history popularly associated with Thompson's "history from below" was in fact a conscious revival of historical materialism by young British Marxist intellectuals under the tutelage of the Cambridge economist Maurice Dobb. If so, the foundational text of social history is Karl Marx's The Eighteenth Brumaire of Louis Bonaparte (1852), which is marked by its society-wide approach and consideration of everyday people. It was not until the 1960s, however, that social history gained popularity and scholarship flourished. This was when, according to Thompson, "social history truly came into being, with historians reflecting on their aristocratic and middle-class preoccupations, their veneration of elites (especially Great Men), their Protestant moralising and misanthropic tendencies". What is social history? There are many definitions of social history, most of them isolated to national historiographies. The most consequential definition of social history is the one Thompson provided. Thompson saw his "history from below" approach as an attempt to reveal the "social nexus" through which broadscale change occurs. This is reflective of his historical materialism. However, Thompson's 1963 book was disproportionately concerned with the lived experience of forgotten or everyday people. The disparity between a society-wide approach (historical materialism) and the narrower preoccupation with giving voice to the voicesless (justice-seeking) is the basis of present-day confusion about the definition of social history. The confusion arose from Thompson's own inner political turmoil. Staughton Lynd sees Thompson's career as a gradual departure from Marxism until, in his last interview, he declined to describe himself as a Marxist. Where Thompson had said he did not believe in "theory with a capital T" and Marxism, Lynd shows that Thompson's departure was actually much more gradual, beginning with the 1956 Hungarian Uprising. The highly influential, but confused, definition used by Thompson was not resolved in part because of the cultural turn and the decline of Marxism on the left in the 1970s and 1980s. The popular phrase "history from below" used in social history first arose in French scholarship before spreading to British scholarship and then elsewhere. Georges Lefebvre first used the phrase "histoire vue d'en bas et non d'en haut" (history seen from below and not from above) in 1932 when praising Albert Mathiez for seeking to tell the "histoire des masses et non de vedettes" (history of the masses and not of starlets). The phrase "people's history" was first used in the title of British historian A. L. Morton's 1938 book, A People's History of England. Yet it was E. P. Thompson's essay History from Below in The Times Literary Supplement (1966) which brought the phrase to the forefront of historiography from the 1970s.: 113 Notably, "History From Below" appeared as the title of the Thompson article, put there by an anonymous editor. The popular phrase has been criticised for implying that social history is overly concerned with the views of insignificant people when it is precisely concerned with how the masses influence events, not just "Great Men". However, society lost its class consciousness in the late 1970s and early 1980s, social history shed its historical materialism. In the words of Elizabeth Fox-Genovese and Eugene Genovese, post-Marxist social history became concerned with "the bedrooms, bathrooms, and kitchens of each one’s favourite victims". Social history in national contexts Social history is associated in the United Kingdom with the work of E. P. Thompson in particular, and his studies The Making of the English Working Class and Whigs and Hunters: The Origin of the Black Act. Emerging after the second world war, it was consciously opposed to traditional history's focus on 'great men', which it counter-posed with 'History from below'. Thus in the UK social history has often had a strong political impetus, and can be contrasted sharply with traditional history's (partial) documentation of the exploits of the powerful, within limited diplomatic and political spheres, and its reliance on archival sources and methods (see historical method and archive) that exclude the voices of less powerful groups within society. Social history has used a much wider range of sources and methods than traditional history and source criticism, in order to gain a broader view of the past. Methods have often including quantitative data analysis and, importantly, oral history which creates an opportunity to glean perspectives and experiences of those people within society that are unlikely to be documented within archives. Eric Hobsbawm was an important UK social historian, who has both produced extensive social history of the UK, and has written also on the theory and politics of UK social history. Hobsbawn and E. P. Thompson were both involved in the pioneering History Workshop Journal and Past & Present. Ireland has its own historiography. In United States historiography, history from below is referred to as "history from the bottom-up" and is called "peoples history", associated in popular consciousness with Howard Zinn and his 1980 book A People's History of the United States. Charles Tilly argues the tasks of the social historian are 1) "documenting large structural changes; 2) reconstructing the experiences of ordinary people in the course of those changes; and (3) connecting the two". The intellectual foundations of the “history from below” approach were further shaped by post–World War II developments. During the Cold War years, historians increasingly adopted quantitative methods, applying social-scientific models to the study of voter behavior, social mobility, and economic trends. This era witnessed the rise of the so-called “social science history,” which sought to render historical inquiry systematic and analytical. Within this context, the proponents of the “New Economic History” (Cliometrics), such as Robert Fogel and Douglass North, employed mathematical models and economic data to reinterpret major historical processes. However, this approach was criticized for its tendency to reduce complex human experiences to numerical expressions. The founding of the Social Science History Association in 1976 marked a decisive institutionalization of this methodological orientation. Americanist Paul E. Johnson recalls the heady early promise of the movement in the late 1960s: The Social Science History Association was formed in 1976 to bring together scholars from numerous disciplines interested in social history. It is still active and publishes Social Science History quarterly. The field is also the specialty of the Journal of Social History, edited since 1967 by Peter Stearns It covers such topics as gender relations; race in American history; the history of personal relationships; consumerism; sexuality; the social history of politics; crime and punishment, and history of the senses. Most of the major historical journals have coverage as well. From the 1960s onward, social history expanded its scope beyond structural and economic analyses to include questions of identity and culture. The civil rights movement, second-wave feminism, and the Vietnam War prompted historians to reconsider grand narratives and to focus instead on the everyday experiences of marginalized groups. Analytical categories such as gender, race, ethnicity, and lifestyle emerged as central to historical inquiry. W. E. B. Du Bois’s Black Reconstruction in America (1935) was rediscovered as a pioneering work in this regard. By the 1980s, the “linguistic turn” and postmodern debates had drawn attention to the narrative and discursive dimensions of history. Scholars such as Joan Scott and William Sewell emphasized the constitutive role of language and discourse in shaping social reality. However, after 1990 social history was increasingly challenged by cultural history, which emphasizes language and the importance of beliefs and assumptions and their causal role in group behavior. Social history has dominated French historiography since the 1920s, thanks to the central role of the Annales School. Its journal Annales focuses attention on the synthesizing of historical patterns identified from social, economic, and cultural history, statistics, medical reports, family studies, and even psychoanalysis. Social history developed within the West German discipline of history during the 1950s-60s as the successor to national history, which was discredited in the aftermath of National Socialism. The German brand of the "history of society" or Alltagsgeschichte – Gesellschaftsgeschichte – has been known from its beginning in the 1960s for its application of sociological and political modernization theories to German history. Modernization theory was presented by Hans-Ulrich Wehler (1931–2014) and his Bielefeld School as the way to transform "traditional" German history, that is, national political history, centered on a few "great men," into an integrated and comparative history of German society encompassing societal structures outside politics. Wehler drew upon the modernization theory of Max Weber and concepts from Karl Marx, Otto Hintze, Gustav Schmoller, Werner Sombart and Thorstein Veblen. In the 1970s and early 1980s, German historians of society, led by Wehler and Jürgen Kocka of the "Bielefeld School", gained dominance in Germany by applying both modernization theories and social science methods. From the 1980s, however, they were increasingly criticized by proponents of the "cultural turn" for not incorporating culture in the history of society, for reducing politics to society, and for reducing individuals to structures. Historians of society inverted the traditional positions they criticized (analogously with Marx's inversion of Hegel). As a result, the problems involved in the positions criticized were not resolved, but only turned on their heads. The traditional focus on individuals was inverted in a modern focus on structures, the traditional focus on culture was inverted in a modern focus on structures, and traditional emphatic understanding was inverted in modern causal explanation. Jürgen Kocka finds two meanings to "social history." At the simplest level, it was the subdivision of history that focused on social structures and processes. In that regard, it stood in contrast to political or economic history. The second meaning was broader, and the Germans called it Gesellschaftsgeschichte. It is the history of an entire society from a social-historical viewpoint. The English historian G. M. Trevelyan saw it as the bridging point between economic and political history, reflecting that, "[w]ithout social history, economic history is barren and political history unintelligible." While the field has often been viewed negatively as history with the politics left out, it has also been defended as "history with the people put back in." In Germany the Gesellschaftsgeschichte movement introduced a vast range of topics, as Kocka, a leader of the Bielefeld School recalls: Before World War II, political history was in decline and an effort was made to introduce social history in the style of the French Annales School. After the war only Marxist interpretations were allowed. With the end of Communism in Hungary in 1989. Marxist historiography collapsed and social history came into its own, especially the study of the demographic patterns of the early modern period. Research priorities have shifted toward urban history and the conditions of everyday life. When the Soviet Union dissolved in 1991, large parts of the Soviet archives were opened. The historians' data base leapt from a limited range of sources to a vast array of records created by modern bureaucracies. Social history flourished. Social history had a "golden age" in Canada in the 1970s, and continues to flourish among scholars. Its strengths include demography, women, labour, and urban studies. Events of Africa's general social history since the twentieth century refer[clarification needed] to the colonial era for most of the countries with the exception of Ethiopia and Liberia, which were never colonized.[citation needed] Major processes in the continent involve resistance, independence, reconstruction, self-rule, and the process of modern politics including the formation of the African Union. Post-colonial milestones towards stability, economic growth, and unity have been made with continuous developments.[citation needed] Natural phenomena and subsequent economic effects have been more pronounced, for example in Ethiopia, followed by ethnic-based social crises and violence in the twenty-first century — that led to the mass migration of youth and skilled workers. Political and economic stability with respect to measures taken by international donor groups such as sanctions and subsequent responses from various nationals to such measures and Pan-Africanism are other dimensions of Africa's social history. In Australia, social history took on a non-Marxist concern for revealing the lives of people who had previously been neglected by older generations of historians. The two most significant social historians of Australian historiography, Ann Curthoys and Humphrey McQueen have both identified a lack of interest in social history among scholars compared with other national historiographies and a general non-Marxist, a-theoretical approach to social history among Australian social historians. Scholars generally see the first application of social history as McQueen's A New Britannia (1970), although some believe Russel Ward's The Australian Legend (1958) may have been a prototype new social history. Subfields The study of the lives of ordinary people was revolutionized in the 1960s by the introduction of sophisticated quantitative and demographic methods, often using individual data from the census and from local registers of births, marriages, deaths and taxes, as well as theoretical models from sociology such as social mobility. H-DEMOG is a daily email discussion group that covers the field broadly. Historical demography is the study of population history and demographic processes, usually using census or similar statistical data. It became an important specialty inside social history, with strong connections with the larger field of demography, as in the study of the Demographic Transition. Black history or African-American history studies African Americans and Africans in American history. The Association for the Study of African American Life and History was founded by Carter G. Woodson in 1915 and has 2500 members and publishes the Journal of African American History, formerly the Journal of Negro History. Since 1926 it has sponsored Black History Month every February. Ethnic history is especially important in the US and Canada, where major encyclopedias helped define the field. It covers the history of ethnic groups (usually not including Black or Native Americans[citation needed]). Typical approaches include critical ethnic studies; comparative ethnic studies; critical race studies; Asian-American, and Latino/a or Chicano/a studies. In recent years Chicano/Chicana studies has become important as the Hispanic population has become the largest minority in the US. Labor history, deals with labor unions and the social history of workers. See for example Labor history of the United States The Study Group on International Labor and Working-Class History was established: 1971 and has a membership of 1000. It publishes International Labor and Working-Class History. H-LABOR is a daily email-based discussion group formed in 1993 that reaches over a thousand scholars and advanced students. the Labor and Working-Class History Association formed in 1988 and publishes Labor: Studies in Working-Class History. Kirk (2010) surveys labour historiography in Britain since the formation of the Society for the Study of Labour History in 1960. He reports that labour history has been mostly pragmatic, eclectic and empirical; it has played an important role in historiographical debates, such as those revolving around history from below, institutionalism versus the social history of labour, class, populism, gender, language, postmodernism and the turn to politics. Kirk rejects suggestions that the field is declining, and stresses its innovation, modification and renewal. Kirk also detects a move into conservative insularity and academicism. He recommends a more extensive and critical engagement with the kinds of comparative, transnational and global concerns increasingly popular among labour historians elsewhere, and calls for a revival of public and political interest in the topics. Meanwhile, Navickas, (2011) examines recent scholarship including the histories of collective action, environment and human ecology, and gender issues, with a focus on work by James Epstein, Malcolm Chase, and Peter Jones. Women's history exploded into prominence in the 1970s, and is now well represented in every geographical topic; increasingly it includes gender history. Social history uses the approach of women's history to understand the experiences of ordinary women, as opposed to "Great Women," in the past. Feminist women's historians such as Joan Kelly have critiqued early studies of social history for being too focused on the male experience. Gender history focuses on the categories, discourses and experiences of femininity and masculinity as they develop over time. Gender history gained prominence after it was conceptualized in 1986 by Joan W. Scott in her article "Gender: A Useful Category of Historical Analysis." Many social historians use Scott's concept of "perceived differences" to study how gender relations in the past have unfolded and continue to unfold. In keeping with the cultural turn, many social historians are also gender historians who study how discourses interact with everyday experiences. The History of the family emerged as a separate field in the 1970s, with close ties to anthropology and sociology. The trend was especially pronounced in the US and Canada. It emphasizes demographic patterns and public policy, but is quite separate from genealogy, though often drawing on the same primary sources, such as censuses and family records. The influential pioneering study Women, Work, and Family (1978) was done by Louise A. Tilly and Joan W. Scott. It broke new ground with their broad interpretive framework and emphasis on the variable factors shaping women's place in the family and economy in France and England. The study considered the interaction of production, or traditional labor, and reproduction, the work of caring for children and families, in its analysis of women's wage labor and thus helped to bring together labor and family history. Much work has been done on the dichotomy in women's lives between the private sphere and the public. For a recent worldwide overview covering 7000 years see Maynes and Waltner's 2012 book and ebook, The Family: A World History (2012). For comprehensive coverage of the American case, see Marilyn Coleman and Lawrence Ganong, eds. The Social History of the American Family: An Encyclopedia (4 vol, 2014). The history of childhood is a growing subfield. For much of the 20th century, the dominant American historiography, as exemplified by Ellwood Patterson Cubberley (1868–1941) at Stanford, emphasized the rise of American education as a powerful force for literacy, democracy, and equal opportunity, and a firm basis for higher education and advanced research institutions. It was a story of enlightenment and modernization triumphing over ignorance, cost-cutting, and narrow traditionalism whereby parents tried to block their children's intellectual access to the wider world. Teachers dedicated to the public interest, reformers with a wide vision, and public support from the civic-minded community were the heroes. The textbooks help inspire students to become public schools teachers and thereby fulfill their own civic mission. The crisis came in the 1960s, when a new generation of New Left scholars and students rejected the traditional celebratory accounts, and identified the educational system as the villain for many of America's weaknesses, failures, and crimes. Michael Katz (1939–2014) states they: The old guard fought back and bitter historiographical contests, with the younger students and scholars largely promoting the proposition that schools were not the solution to America's ills, they were in part the cause of Americans problems. The fierce battles of the 1960s died out by the 1990s, but enrollment in education history courses never recovered. By the 1980s, compromise had been worked out, with all sides focusing on the heavily bureaucratic nature of the American public schooling. In recent years most histories of education deal with institutions or focus on the ideas histories of major reformers, but a new social history has recently emerged, focused on who were the students in terms of social background and social mobility. In the US attention has often focused on minority and ethnic students. In Britain, Raftery et al. (2007) looks at the historiography on social change and education in Ireland, Scotland, and Wales, with particular reference to 19th-century schooling. They developed distinctive systems of schooling in the 19th century that reflected not only their relationship to England but also significant contemporaneous economic and social change. This article seeks to create a basis for comparative work by identifying research that has treated this period, offering brief analytical commentaries on some key works, discussing developments in educational historiography, and pointing to lacunae in research. Historians have recently looked at the relationship between schooling and urban growth by studying educational institutions as agents in class formation, relating urban schooling to changes in the shape of cities, linking urbanization with social reform movements, and examining the material conditions affecting child life and the relationship between schools and other agencies that socialize the young. The most economics-minded historians have sought to relate education to changes in the quality of labor, productivity and economic growth, and rates of return on investment in education. A major recent exemplar is Claudia Goldin and Lawrence F. Katz, The Race between Education and Technology (2009), on the social and economic history of 20th-century American schooling. The "new urban history" emerged in the 1950s in Britain and in the 1960s in the US. It looked at the "city as process" and, often using quantitative methods, to learn more about the inarticulate masses in the cities, as opposed to the mayors and elites. A major early study was Stephan Thernstrom's Poverty and Progress: Social Mobility in a Nineteenth Century City (1964), which used census records to study Newburyport, Massachusetts, 1850–1880. A seminal, landmark book, it sparked interest in the 1960s and 1970s in quantitative methods, census sources, "bottom-up" history, and the measurement of upward social mobility by different ethnic groups. Other exemplars of the new urban history included Kathleen Conzen, Immigrant Milwaukee, 1836-1860 (1976); Alan Dawley, Class and Community: The Industrial Revolution in Lynn (1975; 2nd ed. 2000); Michael B. Katz, The People of Hamilton, Canada West (1976); Eric H. Monkkonen, The Dangerous Class: Crime and Poverty in Columbus Ohio 1860-1865 (1975); and Michael P. Weber, Social Change in an Industrial Town: Patterns of Progress in Warren, Pennsylvania, From Civil War to World War I. (1976). Representative comparative studies include Leonardo Benevolo, The European City (1993); Christopher R. Friedrichs, The Early Modern City, 1450-1750 (1995), and James L. McClain, John M. Merriman, and Ugawa Kaoru. eds. Edo and Paris (1994) (Edo was the old name for Tokyo). There were no overarching social history theories that emerged developed to explain urban development. Inspiration from urban geography and sociology, as well as a concern with workers (as opposed to labor union leaders), families, ethnic groups, racial segregation, and women's roles have proven useful. Historians now view the contending groups within the city as "agents" who shape the direction of urbanization. The subfield has flourished in Australia—where most people live in cities. Agricultural history handles the economic and technological dimensions, while rural history handles the social dimension. Burchardt (2007) evaluates the state of modern English rural history and identifies an "orthodox" school, focused on the economic history of agriculture. This historiography has made impressive progress in quantifying and explaining the output and productivity achievements of English farming since the "agricultural revolution." The celebratory style of the orthodox school was challenged by a dissident tradition emphasizing the social costs of agricultural progress, notably inclosure, which removed much common resource and lead to riots for some 300 years. Recently, a new school, associated with the journal Rural History, has broken away from this narrative of agricultural change, elaborating a wider social history. The work of Alun Howkins has been pivotal in the recent historiography, in relation to these three traditions. Howkins, like his precursors, is constrained by an increasingly anachronistic equation of the countryside with agriculture.[citation needed] Geographers and sociologists have developed a concept of a "post-productivist" countryside, dominated by consumption and representation that may have something to offer historians, in conjunction with the well-established historiography of the "rural idyll." Most American rural history has focused on the American South—overwhelmingly rural until the 1950s—but there is a "new rural history" of the North as well. Instead of becoming agrarian capitalists, farmers held onto preindustrial capitalist values emphasizing family and community. Rural areas maintained population stability; kinship ties determined rural immigrant settlement and community structures; and the defeminization of farm work encouraged the rural version of the "women's sphere." These findings strongly contrast with those in the old frontier history as well as those found in the new urban history. The historiography of religion focuses mostly on theology and church organization and development. Recently the study of the social history or religious behavior and belief has become important. Political history While the study of elites and political institutions has produced a vast body of scholarship, the impact after 1960 of social historians has shifted emphasis onto the politics of ordinary people—especially voters and collective movements. Political historians responded with the "new political history," which has shifted attention to political cultures. Some scholars have recently applied a cultural approach to political history. Some political historians complain that social historians are likely to put too much stress on the dimensions of class, gender and race, reflecting a leftist political agenda that assumes outsiders in politics are more interesting than the actual decision makers. Social history, with its leftist political origins, initially sought to link state power to everyday experience in the 1960s. Yet by the 1970s, social historians increasingly excluded analyses of state power from its focus. Social historians have recently engaged with political history through studies of the relationships between state formation, power and everyday life with the theoretical tools of cultural hegemony and governmentality. See also Notes Bibliography External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Brazilian_Armed_Forces] | [TOKENS: 2526] |
Contents Brazilian Armed Forces The Brazilian Armed Forces (Portuguese: Forças Armadas Brasileiras, IPA: [ˈfoʁsɐz ɐʁˈmadɐz bɾaziˈlejɾɐs]) are the unified military forces of the Federative Republic of Brazil. They consist of three service branches, the Brazilian Army, Brazilian Navy and Brazilian Air Force. Brazil's armed forces are the second largest in the Americas, after the United States, and the largest in Latin America and the Southern Hemisphere by the level of military equipment, with 334,500 active-duty troops and officers. Brazilian soldiers were in Haiti from 2004 until 2017, leading the United Nations Stabilization Mission (MINUSTAH). Organization The Armed Forces of Brazil are divided into 3 branches: The Military Police (state police) alongside the Military Firefighters Corps are described as an auxiliary and reserve force of the Army. All military branches are part of the Ministry of Defence. The Brazilian Navy which is the oldest of the Brazilian Armed Forces, includes the Brazilian Marine Corps and the Brazilian Naval Aviation.[citation needed] There is compulsory military service for those aged 18–45; conscript service obligation – 10 to 12 months; voluntary service is allowed from age 17–45. An increasing percentage of the ranks are "long-service" volunteer professionals; women were allowed to serve in the armed forces beginning in the early 1980s when the Brazilian Army became the first army in South America to accept women into career ranks; women serve in Navy and Air Force only in Women's Reserve Corps. South America is a relatively peaceful continent in which wars are a rare event; as a result, Brazil has not had its territory invaded since 1865 during the Paraguayan War. Additionally, Brazil lacks contested territorial disputes with any of its neighbours and neither does it have rivalries, like Chile and Bolivia have with each other. However, Brazil is the only country besides China and Russia that has land borders with 10 or more nations. Moreover, Brazil has 16,880 kilometers (10,490 mi) of land borders and 7,367 km (4,578 mi) of coastline to be patrolled and defended. Overall, the Armed Forces have to defend 8.5 million km2 (around 3.2 million sq. mi.) of land and patrol 4.4 million km2 (around 1.7 million sq. mi.) of territorial waters – or Blue Amazon, as the Brazilian Navy calls them. To achieve this mission, significant manpower and funding is required.[citation needed] Military history of Brazil Since 1648 the Brazilian Armed Forces have been relied upon to fight in defense of Brazilian sovereignty and to suppress civil rebellions. The Brazilian military also has several times intervened militarily to overthrow the Brazilian government. The Brazilian Armed Forces were subordinated to the Emperor, its Commander-in-Chief. He was aided by the Ministers of War and Navy in regard to matters concerning the Army and the Armada, respectively. Traditionally, the Ministers of War and Navy were civilians but there were some exceptions. The model chosen was the British parliamentary or Anglo-American system, in which "the country's Armed Forces observed unrestricted obedience to the civilian government while maintaining distance from political decisions and decisions referring to borders' security". The military personnel were allowed to run and serve in political offices while staying on active duty. However, they did not represent the Army or the Armada but instead the population of the city or province where elected. Dom Pedro I chose nine military personnel as Senators and five (out of 14) to the State Council. During the Regency, two were chosen to the Senate and none to the State Council as there was no Council at the time. Dom Pedro II chose four military personnel to become Senators during the 1840s, two in the 1850s and three until the end of his reign. He also chose seven military personnel to be State Counselors during the 1840s and 1850s and three after that. It has built a tradition of participating in UN peacekeeping missions such as in Haiti and East Timor. Below a list of some of the historical events in which the Brazilian Armed Forces took part: Brazilian Expeditionary Force, initially composed of an infantry division, eventually covered all Brazilian military forces who participated in the conflict, including the Brazilian Air Force who did a remarkable job in the last nine months of war with 445 missions executed. Offensive: 2546, Defensive: 4. The Republican period experienced several military coups d'état in the 75 years between 1889 and 1964, such as:[citation needed] Ministry of Defence On 10 July 1999, the Ministry of Defence was created, with the abolition of the EMFA and the merger of all three ministries of the Armed Forces (Army, Navy and Air Force) into a singular ministry of the Cabinet. Joint Staff of the Armed Forces is an agency of the Ministry of Defense of Brazil, which centralizes the coordination of command of the armed forces: Army, Navy and Air Force. It was created by Complementary Law No. 136 of 25 August 2010, and has in Ordinance No. 1429 its operating guidelines. Advising the Minister of Defense in the upper direction of the armed forces, aiming the organization, preparation and employment, in order to fulfill its constitutional mission and its subsidiaries assignments, with the goals strategic planning and the joint use of the military services. It is up to JSAF plan together and integrated employment of staff of the Navy, Army and Air Force, optimizing the use of the military and logistical support in the defense of the country and in peacekeeping, humanitarian and rescue operations; border security; and civil defense actions. The body has its powers and duties according to the Regimental Structure approved by Decree 7.9744, April 1, 2013. Since its inception, the JSAF has worked with the Central Administration of the Ministry of Defence, on the Esplanade of Ministries in Brasilia (DF). The head of the JSAF is private of a general officer of the last post, active or reserve, designated by the Ministry of Defence and appointed by the president. Their hierarchical level is the same of the military commanders of the Navy, Army and Air Force. Under the coordination of the Joint Armed Forces also operates the Committee of Chiefs of Staffs of the military services. The current head of JSAF is the Admiral Renato Rodrigues de Aguiar Freire. Brazilian Army The Army High Command of Brazil is formed by the Army Commander and other army generals in active service. The country current has sixteen active 4-star generals, several of them in command posts. The mission of ACE includes the selection of a list of candidates to the post of commander, the prospection of regional and global political situations, among others roles. The Brazilian Army Readiness Forces (Forças de Prontidão do Exército Brasileiro in Portuguese) is a 15,000-strong division meant to operate in real missions of conventional combat, law and order and interagency operations within the Brazilian territory or as divisional forces abroad led by officers from the General Staff of the Readiness Forces subordinate to the Army High Command. Brazilian Navy The navy (Portuguese: Marinha do Brasil) has eight bases throughout Brazil. Brazilian Air Force The Brazilian Air Force (Portuguese: Força Aérea Brasileira, [ˌfoʁsaˈɛɾjɐ bɾaziˈlejɾɐ], also known as FAB, [ˈfabi] or [ˌɛfiaˈbe]) is the second-largest air force in the Americas (behind only the United States) and has around 70,000 active personnel. The FAB is subdivided into four operational commands. Brazilian aerospace command The Aerospace Operations Command is a Brazilian air and space command created in 2017 and is part of the Brazilian Air Force. It is responsible for planning, coordinating, executing and controlling the country's air and space operations. The Brazilian Navy and Brazilian Army also are part of the organization. Troop relocation Brazil has the need to patrol its 16,880 kilometers (10,490 mi) of land borders. Since the 1990s Brazil has been relocating its forces in accordance to this national security requirement. Between 1992 and 2008, the 1st, 2nd and 16th Jungle Infantry Brigades, the 3rd Infantry Battalion, the 19th Logistics Battalion, and the 22nd Army Police Platoon were transferred by the Army from the states of Rio de Janeiro and Rio Grande do Sul to the Amazon region in accordance with the friendship policy with Argentina. After those redeployments the number of Army troops in that region rose to 25,000. Also relocated from the state of Rio de Janeiro were the 1st and 3rd Tank Regiments, now stationed in the city of Santa Maria, in the state of Rio Grande do Sul. However, despite those efforts, the presence of the Armed Forces on the border regions of the Brazilian Amazon continues to be sparse and disperse, given the fact that the Army has just 28 border detachments in that area, a total of 1,600 soldiers, or 1 man for every 7 km (4.3 mi) of borders. More redeployments are expected since the states of Rio de Janeiro, Minas Gerais and Espírito Santo still concentrate over 49,000 soldiers. In May 2008, the Navy announced new plans to reposition its forces throughout Brazil. Communications and territorial surveillance The Brazilian territory corresponds to 47.3% of the South American continent, and its land border is over 16.000 km and 4,5 million km2 of sea territory. With the objective of ensuring Brazil's sovereignty, strategic monitoring and communications projects have been launched in recent years. The Geostationary Defense and Strategic Communications Satellites or SGDC, are geostationary communication satellites developed by the Brazilian Air Force and the Brazilian Space Agency, created with the objective of operating strategic military, government and civil communications, also offering broadband internet throughout the national territory. The first satellite called SGDC-1, was launched in 2017 and the SGDC-2 has planned to launch in 2022. The Space Operations Center (COPE) was inaugurated in 2020, subordinated to the Aerospace Operations Command, with the objective of operating the satellites. The Integrated Border Monitoring System (SISFRON) is a border system developed by the Brazilian Army for supporting operational employment decisions, operating in an integrated manner with all defense systems in the country, whose purpose is to strengthen the presence and capacity for monitoring and action in the national land border strip. It was conceived at the initiative of the Army Command, as a result of the approval of the National Defense Strategy in 2008, which guides the organization of the Armed Forces. SISFRON is planned to eventually cover the 16,886 kilometers of the border line, favoring the employment of organizations subordinate to the North, West, Southern and the Amazon military commands. The Blue Amazon Management System, is a surveillance system planned by the Brazilian Navy, in order to oversee the "Blue Amazon", the country's exclusive economic zone and continental shelf, a resource-rich area covering about 4,500,000 km2 (1,700,000 sq mi)[needs update] off the Brazilian coast. This area is home to a huge diversity of marine species, valuable metallic minerals and other mineral resources, petroleum, and the world's second largest rare-earth reserve. The SisGAAz will integrate equipment and systems composed of radars incorporated on land and vessels, as well as high resolution cameras and features such as the fusion of information received from collaborative systems. The Link-BR2 is a datalink developed by the Air Force and the Brazilian defence company AEL Sistemas, this technology allow the exchange of data such radar information, videos and images with other units of the three branches anytime and anywhere, using an advanced encrypted protocol with a high degree of security. Future See also References Bibliography External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Special:BookSources/978-0-684-83267-8] | [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 |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Al-Sarafand] | [TOKENS: 1706] |
Contents Al-Sarafand Al-Sarafand (Arabic: الصرفند) was a Palestinian Arab village near the Mediterranean shore south of Haifa. In Ottoman tax records, it is shown that the village had a population of 61 inhabitants in 1596. According to a land and population survey by Sami Hadawi, al-Sarafand's population was 290 in 1945, entirely Arab. Etymology Sarafand or Sarafend (Ṣarafand / صرفند) is an Arabic rendition of the Phoenician place-name *Ṣrpt. Al-Sarafand was known to the Crusaders as Sarepta Yudee. History Pottery remains from the late Roman era and Byzantine era have been found here. Ayyubid forces captured al-Sarafand from the Crusaders in 1187-1188. The village appears in the waqf of the tomb (turba) and madrasa of amir Qurqamaz in Egypt. In 1517 the village of 'Sarafanda' was incorporated into the Ottoman Empire with the rest of Palestine. During the 16th and 17th centuries, it belonged to the Turabay Emirate (1517-1683), which encompassed also the Jezreel Valley, Haifa, Jenin, Beit She'an Valley, northern Jabal Nablus, Bilad al-Ruha/Ramot Menashe, and the northern part of the Sharon plain. From Ottoman records it is known that in 1596 Sarafand was a village in the nahiya ("subdistrict") of Shafa, ( liwa' ("district") of Lajjun), with a population of 11 Muslim households, an estimated 61 persons. Villagers paid a fixed tax-rate of 25% to the authorities for the crops that they cultivated, which included wheat, barley, summer crops such as corn, beans, melons, and vegetables, and raising goats; a total of 8,500 akçe. In 1799, it appeared as the village Sarfend on the map that Pierre Jacotin compiled that year. In 1859 the village of Sarafand was described as being situated on a ridge between a plain and the beach. Consul Rogers estimated that 150 people lived in it and cultivated 16 faddans. Four years later, Victor Guérin stated that the population size was not exceeding 300. According to the PEF's Survey of Western Palestine, who visited in 1873; "North of this village there is a system of rock- cut tombs, sixteen in all. Eight have each three loculi under arcosolia, and in three cases the rolling stones which closed the doors lie beside them. One of these stones was 3 feet diameter, and 1 foot thick, weighing probably about 6 cwt. Five of the tombs are single loculi, open in front, cut in the face of the cliff under arcosolia; two of the tombs have only two loculi each, and one is blocked up. This group presents the best examples found by the Survey party of the rolling stone arrangement for a tomb door." A population list from about 1887 showed that Sarafand had about 270 inhabitants; all Muslims. In the 1922 census of Palestine, conducted by the British Mandate authorities, Sarafand had a population of 204; all Muslims, decreasing in the 1931 census to 188; still all Muslim, in a total of 38 houses. The village economy depended on agriculture, animal husbandry and salt making. In the 1945 statistics, the village had a population of 290 Muslims, and the village's lands spanned 5,409 dunams. The population was entirely Muslim. A total of 3,244 dunums of land was allocated to cereals; 22 dunums were irrigated or used for orchards, while 6 dunams were built-up (urban) land. During the 1947–1948 civil war in Mandatory Palestine, the inhabitants were ethnically cleansed in several stages. Most fled in early May towards al-Tira and when al-Tira was depopulated they left for Jenin. Some returned and remained in al-Sarafand until Israeli forces — composed of the Carmeli and Alexandroni Brigades — assaulted the village on July 16, 1948. At the time, Arab Liberation Army volunteers and local militia were defending al-Sarafand. Most of the inhabitants fled to the southeast line of Wadi Ara, where the Iraqi Army was stationed. Later, they crossed the Jordan River, and since then the majority of al-Sarafand’s refugees have been living in Jordan. Only one former resident of al-Sarafand remained in Israel. The village houses were not immediately demolished by the Israelis and remained empty for many years. When they were eventually destroyed, the mosque was the only building spared. Petersen inspected the village mosque and adjacent vaults in 1994, and described the mosque as "a tall rectangular box-like building standing on a terrace near the top of the ridge on which it was built. The mosque is entered through a doorway in the middle of the north wall. The interior is divided into two long cross-vaulted bays resting on six large piers. There are four windows in west wall facing the sea. The mihrab is placed in the centre of the south wall and can be seen on the exterior as a rectangular projection. To the west of the mihrab are the remains of a minbar (now destroyed). The lower sections of the wall are approximately 1 m. thick, whilst the upper part of the south and north walls are considerably thinner (0.3 m.). Although the present building does not appear to be very old (late nineteenth or early twentieth centuries) it does appear to in incorporate an earlier structure which is visible in the exterior walls. To the south of the mosque is a rectangular area of ruins (approximately 30m x 40m) containing several barrel-vaulted chambers. Three of these are still accessible; one on the north side nearest the mosque, and two on the south side next to the quarry cliff. Each vault is about 7m long; one is 2.52m wide and the other is 3.52m wide. More intensive investigation could reveal a basic plan of this structure." Mosque restoration In 1999, the 'Aqsa Society for the Preservation of Islamic Holy Sites decided to restore al-Sarafand’s mosque. In May 2000, while restoration was on the verge of completion, the mosque was destroyed overnight by a bulldozer. The perpetrator was never identified. The activists covered the ruins by a large tent and maintained a vigil at the site. Removal of the tent was negotiated with the Israeli authorities. It was agreed that the site would be fenced to protect it, but that did not happen and the activists built a more permanent structure. The latter was demolished by the police in March 2002, but the ruined mosque continues to be used for Friday prayers. According to the Or Commission report, Israeli authorities did not grant a license for rebuilding the mosque after the demolition; a decision that contributed to the souring of relations between local Muslim residents and the authorities. The Or Commission report also claims that activities by Islamic organizations such as the aforementioned society may be using religious pretenses to further political aims. The commission describes such actions as a factor in 'inflaming' the Muslim population in Israel against the authorities, and cites the Sarafand mosque episode, with Muslims' attempts to restore the mosque and Jewish attempts to stop them, as an example of the 'shifting of dynamics' of the relationship between Muslims and the Israeli authorities. The Israeli new historian Ilan Pappe has a different story of the events. He writes:"The mosque was a hundred years old when the Israeli government gave the go-ahead to have it bull-dozed on 25 july 2000 ignoring a petition addressed to the then prime minister Ehud Barak, beseeching him not to authorise this official act of vandalism." See also References Bibliography External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/List_of_films_about_computers] | [TOKENS: 64] |
Contents List of films about computers This is a list of films about computers, featuring fictional films in which activities involving computers play a central role in the development of the plot. Artificial intelligence plots Computers as plot devices Hacking as a plot narrative Virtual reality Viruses Programming Websites Communications Supernatural War Space Anime See also References External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Endothermic_reaction] | [TOKENS: 827] |
Contents Endothermic process An endothermic process is a chemical or physical process that absorbs heat from its surroundings. In terms of thermodynamics, it is a thermodynamic process with an increase in the enthalpy H (or internal energy U) of the system. In an endothermic process, the heat that a system absorbs is thermal energy transfer into the system. Thus, an endothermic reaction generally leads to an increase in the temperature of the system and a decrease in that of the surroundings. The term was coined by 19th-century French chemist Marcellin Berthelot. The term endothermic comes from the Greek ἔνδον (endon) meaning 'within' and θερμ- (therm) meaning 'hot' or 'warm'. An endothermic process may be a chemical process, such as dissolving ammonium nitrate (NH4NO3) in water (H2O), or a physical process, such as the melting of ice cubes. The opposite of an endothermic process is an exothermic process, one that releases or "gives out" energy, usually in the form of heat and sometimes as electrical energy. Thus, endo in endothermic refers to energy or heat going in, and exo in exothermic refers to energy or heat going out. In each term (endothermic and exothermic) the prefix refers to where heat (or electrical energy) goes as the process occurs. In chemistry Due to bonds breaking and forming during various processes (changes in state, chemical reactions), there is usually a change in energy. If the energy of the forming bonds is greater than the energy of the breaking bonds, then energy is released. This is known as an exothermic reaction. However, if more energy is needed to break the bonds than the energy being released, energy is taken up. Therefore, it is an endothermic reaction. Details Whether a process can occur spontaneously depends not only on the enthalpy change but also on the entropy change (∆S) and absolute temperature T. If a process is a spontaneous process at a certain temperature, the products have a lower Gibbs free energy G = H – TS than the reactants (an exergonic process), even if the enthalpy of the products is higher. Thus, an endothermic process usually requires a favorable entropy increase (∆S > 0) in the system that overcomes the unfavorable increase in enthalpy so that still ∆G < 0. While endothermic phase transitions into more disordered states of higher entropy, e.g. melting and vaporization, are common, spontaneous chemical processes at moderate temperatures are rarely endothermic. The enthalpy increase ∆H ≫ 0 in a hypothetical strongly endothermic process usually results in ∆G = ∆H – T∆S > 0, which means that the process will not occur (unless driven by electrical or photon energy). An example of an endothermic and exergonic process is Examples Distinction between endothermic and endotherm The terms "endothermic" and "endotherm" are both derived from Greek ἔνδον endon "within" and θέρμη thermē "heat", but depending on context, they can have very different meanings. In physics, thermodynamics applies to processes involving a system and its surroundings, and the term "endothermic" is used to describe a reaction where energy is taken "(with)in" by the system (vs. an "exothermic" reaction, which releases energy "outwards"). In biology, thermoregulation is the ability of an organism to maintain its body temperature, and the term "endotherm" refers to an organism that can do so from "within" by using the heat released by its internal bodily functions (vs. an "ectotherm", which relies on external, environmental heat sources) to maintain an adequate temperature. References External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Mars#cite_ref-Mallama_and_Hilton_21-0] | [TOKENS: 11899] |
Contents Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", for its orange-red appearance. Mars is a desert-like rocky planet with a tenuous atmosphere that is primarily carbon dioxide (CO2). At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from −153 to 20 °C (−243 to 68 °F), and cosmic radiation is high. Mars retains some water, in the ground as well as thinly in the atmosphere, forming cirrus clouds, fog, frost, larger polar regions of permafrost and ice caps (with seasonal CO2 snow), but no bodies of liquid surface water. Its surface gravity is roughly a third of Earth's or double that of the Moon. Its diameter, 6,779 km (4,212 mi), is about half the Earth's, or twice the Moon's, and its surface area is the size of all the dry land of Earth. Fine dust is prevalent across the surface and the atmosphere, being picked up and spread at the low Martian gravity even by the weak wind of the tenuous atmosphere. The terrain of Mars roughly follows a north-south divide, the Martian dichotomy, with the northern hemisphere mainly consisting of relatively flat, low lying plains, and the southern hemisphere of cratered highlands. Geologically, the planet is fairly active with marsquakes trembling underneath the ground, but also hosts many enormous volcanoes that are extinct (the tallest is Olympus Mons, 21.9 km or 13.6 mi tall), as well as one of the largest canyons in the Solar System (Valles Marineris, 4,000 km or 2,500 mi long). Mars has two natural satellites that are small and irregular in shape: Phobos and Deimos. With a significant axial tilt of 25 degrees, Mars experiences seasons, like Earth (which has an axial tilt of 23.5 degrees). A Martian solar year is equal to 1.88 Earth years (687 Earth days), a Martian solar day (sol) is equal to 24.6 hours. Mars formed along with the other planets approximately 4.5 billion years ago. During the martian Noachian period (4.5 to 3.5 billion years ago), its surface was marked by meteor impacts, valley formation, erosion, the possible presence of water oceans and the loss of its magnetosphere. The Hesperian period (beginning 3.5 billion years ago and ending 3.3–2.9 billion years ago) was dominated by widespread volcanic activity and flooding that carved immense outflow channels. The Amazonian period, which continues to the present, is the currently dominating and remaining influence on geological processes. Because of Mars's geological history, the possibility of past or present life on Mars remains an area of active scientific investigation, with some possible traces needing further examination. Being visible with the naked eye in Earth's sky as a red wandering star, Mars has been observed throughout history, acquiring diverse associations in different cultures. In 1963 the first flight to Mars took place with Mars 1, but communication was lost en route. The first successful flyby exploration of Mars was conducted in 1965 with Mariner 4. In 1971 Mariner 9 entered orbit around Mars, being the first spacecraft to orbit any body other than the Moon, Sun or Earth; following in the same year were the first uncontrolled impact (Mars 2) and first successful landing (Mars 3) on Mars. Probes have been active on Mars continuously since 1997. At times, more than ten probes have simultaneously operated in orbit or on the surface, more than at any other planet beyond Earth. Mars is an often proposed target for future crewed exploration missions, though no such mission is currently planned. Natural history Scientists have theorized that during the Solar System's formation, Mars was created as the result of a random process of run-away accretion of material from the protoplanetary disk that orbited the Sun. Mars has many distinctive chemical features caused by its position in the Solar System. Elements with comparatively low boiling points, such as chlorine, phosphorus, and sulfur, are much more common on Mars than on Earth; these elements were probably pushed outward by the young Sun's energetic solar wind. After the formation of the planets, the inner Solar System may have been subjected to the so-called Late Heavy Bombardment. About 60% of the surface of Mars shows a record of impacts from that era, whereas much of the remaining surface is probably underlain by immense impact basins caused by those events. However, more recent modeling has disputed the existence of the Late Heavy Bombardment. There is evidence of an enormous impact basin in the Northern Hemisphere of Mars, spanning 10,600 by 8,500 kilometres (6,600 by 5,300 mi), or roughly four times the size of the Moon's South Pole–Aitken basin, which would be the largest impact basin yet discovered if confirmed. It has been hypothesized that the basin was formed when Mars was struck by a Pluto-sized body about four billion years ago. The event, thought to be the cause of the Martian hemispheric dichotomy, created the smooth Borealis basin that covers 40% of the planet. A 2023 study shows evidence, based on the orbital inclination of Deimos (a small moon of Mars), that Mars may once have had a ring system 3.5 billion years to 4 billion years ago. This ring system may have been formed from a moon, 20 times more massive than Phobos, orbiting Mars billions of years ago; and Phobos would be a remnant of that ring. Epochs: The geological history of Mars can be split into many periods, but the following are the three primary periods: Geological activity is still taking place on Mars. The Athabasca Valles is home to sheet-like lava flows created about 200 million years ago. Water flows in the grabens called the Cerberus Fossae occurred less than 20 million years ago, indicating equally recent volcanic intrusions. The Mars Reconnaissance Orbiter has captured images of avalanches. Physical characteristics Mars is approximately half the diameter of Earth or twice that of the Moon, with a surface area only slightly less than the total area of Earth's dry land. Mars is less dense than Earth, having about 15% of Earth's volume and 11% of Earth's mass, resulting in about 38% of Earth's surface gravity. Mars is the only presently known example of a desert planet, a rocky planet with a surface akin to that of Earth's deserts. The red-orange appearance of the Martian surface is caused by iron(III) oxide (nanophase Fe2O3) and the iron(III) oxide-hydroxide mineral goethite. It can look like butterscotch; other common surface colors include golden, brown, tan, and greenish, depending on the minerals present. Like Earth, Mars is differentiated into a dense metallic core overlaid by less dense rocky layers. The outermost layer is the crust, which is on average about 42–56 kilometres (26–35 mi) thick, with a minimum thickness of 6 kilometres (3.7 mi) in Isidis Planitia, and a maximum thickness of 117 kilometres (73 mi) in the southern Tharsis plateau. For comparison, Earth's crust averages 27.3 ± 4.8 km in thickness. The most abundant elements in the Martian crust are silicon, oxygen, iron, magnesium, aluminum, calcium, and potassium. Mars is confirmed to be seismically active; in 2019, it was reported that InSight had detected and recorded over 450 marsquakes and related events. Beneath the crust is a silicate mantle responsible for many of the tectonic and volcanic features on the planet's surface. The upper Martian mantle is a low-velocity zone, where the velocity of seismic waves is lower than surrounding depth intervals. The mantle appears to be rigid down to the depth of about 250 km, giving Mars a very thick lithosphere compared to Earth. Below this the mantle gradually becomes more ductile, and the seismic wave velocity starts to grow again. The Martian mantle does not appear to have a thermally insulating layer analogous to Earth's lower mantle; instead, below 1050 km in depth, it becomes mineralogically similar to Earth's transition zone. At the bottom of the mantle lies a basal liquid silicate layer approximately 150–180 km thick. The Martian mantle appears to be highly heterogenous, with dense fragments up to 4 km across, likely injected deep into the planet by colossal impacts ~4.5 billion years ago; high-frequency waves from eight marsquakes slowed as they passed these localized regions, and modeling indicates the heterogeneities are compositionally distinct debris preserved because Mars lacks plate tectonics and has a sluggishly convecting interior that prevents complete homogenization. Mars's iron and nickel core is at least partially molten, and may have a solid inner core. It is around half of Mars's radius, approximately 1650–1675 km, and is enriched in light elements such as sulfur, oxygen, carbon, and hydrogen. The temperature of the core is estimated to be 2000–2400 K, compared to 5400–6230 K for Earth's solid inner core. In 2025, based on data from the InSight lander, a group of researchers reported the detection of a solid inner core 613 kilometres (381 mi) ± 67 kilometres (42 mi) in radius. Mars is a terrestrial planet with a surface that consists of minerals containing silicon and oxygen, metals, and other elements that typically make up rock. The Martian surface is primarily composed of tholeiitic basalt, although parts are more silica-rich than typical basalt and may be similar to andesitic rocks on Earth, or silica glass. Regions of low albedo suggest concentrations of plagioclase feldspar, with northern low albedo regions displaying higher than normal concentrations of sheet silicates and high-silicon glass. Parts of the southern highlands include detectable amounts of high-calcium pyroxenes. Localized concentrations of hematite and olivine have been found. Much of the surface is deeply covered by finely grained iron(III) oxide dust. The Phoenix lander returned data showing Martian soil to be slightly alkaline and containing elements such as magnesium, sodium, potassium and chlorine. These nutrients are found in soils on Earth, and are necessary for plant growth. Experiments performed by the lander showed that the Martian soil has a basic pH of 7.7, and contains 0.6% perchlorate by weight, concentrations that are toxic to humans. Streaks are common across Mars and new ones appear frequently on steep slopes of craters, troughs, and valleys. The streaks are dark at first and get lighter with age. The streaks can start in a tiny area, then spread out for hundreds of metres. They have been seen to follow the edges of boulders and other obstacles in their path. The commonly accepted hypotheses include that they are dark underlying layers of soil revealed after avalanches of bright dust or dust devils. Several other explanations have been put forward, including those that involve water or even the growth of organisms. Environmental radiation levels on the surface are on average 0.64 millisieverts of radiation per day, and significantly less than the radiation of 1.84 millisieverts per day or 22 millirads per day during the flight to and from Mars. For comparison the radiation levels in low Earth orbit, where Earth's space stations orbit, are around 0.5 millisieverts of radiation per day. Hellas Planitia has the lowest surface radiation at about 0.342 millisieverts per day, featuring lava tubes southwest of Hadriacus Mons with potentially levels as low as 0.064 millisieverts per day, comparable to radiation levels during flights on Earth. Although Mars has no evidence of a structured global magnetic field, observations show that parts of the planet's crust have been magnetized, suggesting that alternating polarity reversals of its dipole field have occurred in the past. This paleomagnetism of magnetically susceptible minerals is similar to the alternating bands found on Earth's ocean floors. One hypothesis, published in 1999 and re-examined in October 2005 (with the help of the Mars Global Surveyor), is that these bands suggest plate tectonic activity on Mars four billion years ago, before the planetary dynamo ceased to function and the planet's magnetic field faded. Geography and features Although better remembered for mapping the Moon, Johann Heinrich von Mädler and Wilhelm Beer were the first areographers. They began by establishing that most of Mars's surface features were permanent and by more precisely determining the planet's rotation period. In 1840, Mädler combined ten years of observations and drew the first map of Mars. Features on Mars are named from a variety of sources. Albedo features are named for classical mythology. Craters larger than roughly 50 km are named for deceased scientists and writers and others who have contributed to the study of Mars. Smaller craters are named for towns and villages of the world with populations of less than 100,000. Large valleys are named for the word "Mars" or "star" in various languages; smaller valleys are named for rivers. Large albedo features retain many of the older names but are often updated to reflect new knowledge of the nature of the features. For example, Nix Olympica (the snows of Olympus) has become Olympus Mons (Mount Olympus). The surface of Mars as seen from Earth is divided into two kinds of areas, with differing albedo. The paler plains covered with dust and sand rich in reddish iron oxides were once thought of as Martian "continents" and given names like Arabia Terra (land of Arabia) or Amazonis Planitia (Amazonian plain). The dark features were thought to be seas, hence their names Mare Erythraeum, Mare Sirenum and Aurorae Sinus. The largest dark feature seen from Earth is Syrtis Major Planum. The permanent northern polar ice cap is named Planum Boreum. The southern cap is called Planum Australe. Mars's equator is defined by its rotation, but the location of its Prime Meridian was specified, as was Earth's (at Greenwich), by choice of an arbitrary point; Mädler and Beer selected a line for their first maps of Mars in 1830. After the spacecraft Mariner 9 provided extensive imagery of Mars in 1972, a small crater (later called Airy-0), located in the Sinus Meridiani ("Middle Bay" or "Meridian Bay"), was chosen by Merton E. Davies, Harold Masursky, and Gérard de Vaucouleurs for the definition of 0.0° longitude to coincide with the original selection. Because Mars has no oceans, and hence no "sea level", a zero-elevation surface had to be selected as a reference level; this is called the areoid of Mars, analogous to the terrestrial geoid. Zero altitude was defined by the height at which there is 610.5 Pa (6.105 mbar) of atmospheric pressure. This pressure corresponds to the triple point of water, and it is about 0.6% of the sea level surface pressure on Earth (0.006 atm). For mapping purposes, the United States Geological Survey divides the surface of Mars into thirty cartographic quadrangles, each named for a classical albedo feature it contains. In April 2023, The New York Times reported an updated global map of Mars based on images from the Hope spacecraft. A related, but much more detailed, global Mars map was released by NASA on 16 April 2023. The vast upland region Tharsis contains several massive volcanoes, which include the shield volcano Olympus Mons. The edifice is over 600 km (370 mi) wide. Because the mountain is so large, with complex structure at its edges, giving a definite height to it is difficult. Its local relief, from the foot of the cliffs which form its northwest margin to its peak, is over 21 km (13 mi), a little over twice the height of Mauna Kea as measured from its base on the ocean floor. The total elevation change from the plains of Amazonis Planitia, over 1,000 km (620 mi) to the northwest, to the summit approaches 26 km (16 mi), roughly three times the height of Mount Everest, which in comparison stands at just over 8.8 kilometres (5.5 mi). Consequently, Olympus Mons is either the tallest or second-tallest mountain in the Solar System; the only known mountain which might be taller is the Rheasilvia peak on the asteroid Vesta, at 20–25 km (12–16 mi). The dichotomy of Martian topography is striking: northern plains flattened by lava flows contrast with the southern highlands, pitted and cratered by ancient impacts. It is possible that, four billion years ago, the Northern Hemisphere of Mars was struck by an object one-tenth to two-thirds the size of Earth's Moon. If this is the case, the Northern Hemisphere of Mars would be the site of an impact crater 10,600 by 8,500 kilometres (6,600 by 5,300 mi) in size, or roughly the area of Europe, Asia, and Australia combined, surpassing Utopia Planitia and the Moon's South Pole–Aitken basin as the largest impact crater in the Solar System. Mars is scarred by 43,000 impact craters with a diameter of 5 kilometres (3.1 mi) or greater. The largest exposed crater is Hellas, which is 2,300 kilometres (1,400 mi) wide and 7,000 metres (23,000 ft) deep, and is a light albedo feature clearly visible from Earth. There are other notable impact features, such as Argyre, which is around 1,800 kilometres (1,100 mi) in diameter, and Isidis, which is around 1,500 kilometres (930 mi) in diameter. Due to the smaller mass and size of Mars, the probability of an object colliding with the planet is about half that of Earth. Mars is located closer to the asteroid belt, so it has an increased chance of being struck by materials from that source. Mars is more likely to be struck by short-period comets, i.e., those that lie within the orbit of Jupiter. Martian craters can[discuss] have a morphology that suggests the ground became wet after the meteor impact. The large canyon, Valles Marineris (Latin for 'Mariner Valleys, also known as Agathodaemon in the old canal maps), has a length of 4,000 kilometres (2,500 mi) and a depth of up to 7 kilometres (4.3 mi). The length of Valles Marineris is equivalent to the length of Europe and extends across one-fifth the circumference of Mars. By comparison, the Grand Canyon on Earth is only 446 kilometres (277 mi) long and nearly 2 kilometres (1.2 mi) deep. Valles Marineris was formed due to the swelling of the Tharsis area, which caused the crust in the area of Valles Marineris to collapse. In 2012, it was proposed that Valles Marineris is not just a graben, but a plate boundary where 150 kilometres (93 mi) of transverse motion has occurred, making Mars a planet with possibly a two-tectonic plate arrangement. Images from the Thermal Emission Imaging System (THEMIS) aboard NASA's Mars Odyssey orbiter have revealed seven possible cave entrances on the flanks of the volcano Arsia Mons. The caves, named after loved ones of their discoverers, are collectively known as the "seven sisters". Cave entrances measure from 100 to 252 metres (328 to 827 ft) wide and they are estimated to be at least 73 to 96 metres (240 to 315 ft) deep. Because light does not reach the floor of most of the caves, they may extend much deeper than these lower estimates and widen below the surface. "Dena" is the only exception; its floor is visible and was measured to be 130 metres (430 ft) deep. The interiors of these caverns may be protected from micrometeoroids, UV radiation, solar flares and high energy particles that bombard the planet's surface. Martian geysers (or CO2 jets) are putative sites of small gas and dust eruptions that occur in the south polar region of Mars during the spring thaw. "Dark dune spots" and "spiders" – or araneiforms – are the two most visible types of features ascribed to these eruptions. Similarly sized dust will settle from the thinner Martian atmosphere sooner than it would on Earth. For example, the dust suspended by the 2001 global dust storms on Mars only remained in the Martian atmosphere for 0.6 years, while the dust from Mount Pinatubo took about two years to settle. However, under current Martian conditions, the mass movements involved are generally much smaller than on Earth. Even the 2001 global dust storms on Mars moved only the equivalent of a very thin dust layer – about 3 μm thick if deposited with uniform thickness between 58° north and south of the equator. Dust deposition at the two rover sites has proceeded at a rate of about the thickness of a grain every 100 sols. Atmosphere Mars lost its magnetosphere 4 billion years ago, possibly because of numerous asteroid strikes, so the solar wind interacts directly with the Martian ionosphere, lowering the atmospheric density by stripping away atoms from the outer layer. Both Mars Global Surveyor and Mars Express have detected ionized atmospheric particles trailing off into space behind Mars, and this atmospheric loss is being studied by the MAVEN orbiter. Compared to Earth, the atmosphere of Mars is quite rarefied. Atmospheric pressure on the surface today ranges from a low of 30 Pa (0.0044 psi) on Olympus Mons to over 1,155 Pa (0.1675 psi) in Hellas Planitia, with a mean pressure at the surface level of 600 Pa (0.087 psi). The highest atmospheric density on Mars is equal to that found 35 kilometres (22 mi) above Earth's surface. The resulting mean surface pressure is only 0.6% of Earth's 101.3 kPa (14.69 psi). The scale height of the atmosphere is about 10.8 kilometres (6.7 mi), which is higher than Earth's 6 kilometres (3.7 mi), because the surface gravity of Mars is only about 38% of Earth's. The atmosphere of Mars consists of about 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water. The atmosphere is quite dusty, containing particulates about 1.5 μm in diameter which give the Martian sky a tawny color when seen from the surface. It may take on a pink hue due to iron oxide particles suspended in it. Despite repeated detections of methane on Mars, there is no scientific consensus as to its origin. One suggestion is that methane exists on Mars and that its concentration fluctuates seasonally. The existence of methane could be produced by non-biological process such as serpentinization involving water, carbon dioxide, and the mineral olivine, which is known to be common on Mars, or by Martian life. Compared to Earth, its higher concentration of atmospheric CO2 and lower surface pressure may be why sound is attenuated more on Mars, where natural sources are rare apart from the wind. Using acoustic recordings collected by the Perseverance rover, researchers concluded that the speed of sound there is approximately 240 m/s for frequencies below 240 Hz, and 250 m/s for those above. Auroras have been detected on Mars. Because Mars lacks a global magnetic field, the types and distribution of auroras there differ from those on Earth; rather than being mostly restricted to polar regions as is the case on Earth, a Martian aurora can encompass the planet. In September 2017, NASA reported radiation levels on the surface of the planet Mars were temporarily doubled, and were associated with an aurora 25 times brighter than any observed earlier, due to a massive, and unexpected, solar storm in the middle of the month. Mars has seasons, alternating between its northern and southern hemispheres, similar to on Earth. Additionally the orbit of Mars has, compared to Earth's, a large eccentricity and approaches perihelion when it is summer in its southern hemisphere and winter in its northern, and aphelion when it is winter in its southern hemisphere and summer in its northern. As a result, the seasons in its southern hemisphere are more extreme and the seasons in its northern are milder than would otherwise be the case. The summer temperatures in the south can be warmer than the equivalent summer temperatures in the north by up to 30 °C (54 °F). Martian surface temperatures vary from lows of about −110 °C (−166 °F) to highs of up to 35 °C (95 °F) in equatorial summer. The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure (about 1% that of the atmosphere of Earth), and the low thermal inertia of Martian soil. The planet is 1.52 times as far from the Sun as Earth, resulting in just 43% of the amount of sunlight. Mars has the largest dust storms in the Solar System, reaching speeds of over 160 km/h (100 mph). These can vary from a storm over a small area, to gigantic storms that cover the entire planet. They tend to occur when Mars is closest to the Sun, and have been shown to increase global temperature. Seasons also produce dry ice covering polar ice caps. Hydrology While Mars contains water in larger amounts, most of it is dust covered water ice at the Martian polar ice caps. The volume of water ice in the south polar ice cap, if melted, would be enough to cover most of the surface of the planet with a depth of 11 metres (36 ft). Water in its liquid form cannot persist on the surface due to Mars's low atmospheric pressure, which is less than 1% that of Earth. Only at the lowest of elevations are the pressure and temperature high enough for liquid water to exist for short periods. Although little water is present in the atmosphere, there is enough to produce clouds of water ice and different cases of snow and frost, often mixed with snow of carbon dioxide dry ice. Landforms visible on Mars strongly suggest that liquid water has existed on the planet's surface. Huge linear swathes of scoured ground, known as outflow channels, cut across the surface in about 25 places. These are thought to be a record of erosion caused by the catastrophic release of water from subsurface aquifers, though some of these structures have been hypothesized to result from the action of glaciers or lava. One of the larger examples, Ma'adim Vallis, is 700 kilometres (430 mi) long, much greater than the Grand Canyon, with a width of 20 kilometres (12 mi) and a depth of 2 kilometres (1.2 mi) in places. It is thought to have been carved by flowing water early in Mars's history. The youngest of these channels is thought to have formed only a few million years ago. Elsewhere, particularly on the oldest areas of the Martian surface, finer-scale, dendritic networks of valleys are spread across significant proportions of the landscape. Features of these valleys and their distribution strongly imply that they were carved by runoff resulting from precipitation in early Mars history. Subsurface water flow and groundwater sapping may play important subsidiary roles in some networks, but precipitation was probably the root cause of the incision in almost all cases. Along craters and canyon walls, there are thousands of features that appear similar to terrestrial gullies. The gullies tend to be in the highlands of the Southern Hemisphere and face the Equator; all are poleward of 30° latitude. A number of authors have suggested that their formation process involves liquid water, probably from melting ice, although others have argued for formation mechanisms involving carbon dioxide frost or the movement of dry dust. No partially degraded gullies have formed by weathering and no superimposed impact craters have been observed, indicating that these are young features, possibly still active. Other geological features, such as deltas and alluvial fans preserved in craters, are further evidence for warmer, wetter conditions at an interval or intervals in earlier Mars history. Such conditions necessarily require the widespread presence of crater lakes across a large proportion of the surface, for which there is independent mineralogical, sedimentological and geomorphological evidence. Further evidence that liquid water once existed on the surface of Mars comes from the detection of specific minerals such as hematite and goethite, both of which sometimes form in the presence of water. The chemical signature of water vapor on Mars was first unequivocally demonstrated in 1963 by spectroscopy using an Earth-based telescope. In 2004, Opportunity detected the mineral jarosite. This forms only in the presence of acidic water, showing that water once existed on Mars. The Spirit rover found concentrated deposits of silica in 2007 that indicated wet conditions in the past, and in December 2011, the mineral gypsum, which also forms in the presence of water, was found on the surface by NASA's Mars rover Opportunity. It is estimated that the amount of water in the upper mantle of Mars, represented by hydroxyl ions contained within Martian minerals, is equal to or greater than that of Earth at 50–300 parts per million of water, which is enough to cover the entire planet to a depth of 200–1,000 metres (660–3,280 ft). On 18 March 2013, NASA reported evidence from instruments on the Curiosity rover of mineral hydration, likely hydrated calcium sulfate, in several rock samples including the broken fragments of "Tintina" rock and "Sutton Inlier" rock as well as in veins and nodules in other rocks like "Knorr" rock and "Wernicke" rock. Analysis using the rover's DAN instrument provided evidence of subsurface water, amounting to as much as 4% water content, down to a depth of 60 centimetres (24 in), during the rover's traverse from the Bradbury Landing site to the Yellowknife Bay area in the Glenelg terrain. In September 2015, NASA announced that they had found strong evidence of hydrated brine flows in recurring slope lineae, based on spectrometer readings of the darkened areas of slopes. These streaks flow downhill in Martian summer, when the temperature is above −23 °C, and freeze at lower temperatures. These observations supported earlier hypotheses, based on timing of formation and their rate of growth, that these dark streaks resulted from water flowing just below the surface. However, later work suggested that the lineae may be dry, granular flows instead, with at most a limited role for water in initiating the process. A definitive conclusion about the presence, extent, and role of liquid water on the Martian surface remains elusive. Researchers suspect much of the low northern plains of the planet were covered with an ocean hundreds of meters deep, though this theory remains controversial. In March 2015, scientists stated that such an ocean might have been the size of Earth's Arctic Ocean. This finding was derived from the ratio of protium to deuterium in the modern Martian atmosphere compared to that ratio on Earth. The amount of Martian deuterium (D/H = 9.3 ± 1.7 10−4) is five to seven times the amount on Earth (D/H = 1.56 10−4), suggesting that ancient Mars had significantly higher levels of water. Results from the Curiosity rover had previously found a high ratio of deuterium in Gale Crater, though not significantly high enough to suggest the former presence of an ocean. Other scientists caution that these results have not been confirmed, and point out that Martian climate models have not yet shown that the planet was warm enough in the past to support bodies of liquid water. Near the northern polar cap is the 81.4 kilometres (50.6 mi) wide Korolev Crater, which the Mars Express orbiter found to be filled with approximately 2,200 cubic kilometres (530 cu mi) of water ice. In November 2016, NASA reported finding a large amount of underground ice in the Utopia Planitia region. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior (which is 12,100 cubic kilometers). During observations from 2018 through 2021, the ExoMars Trace Gas Orbiter spotted indications of water, probably subsurface ice, in the Valles Marineris canyon system. Orbital motion Mars's average distance from the Sun is roughly 230 million km (143 million mi), and its orbital period is 687 (Earth) days. The solar day (or sol) on Mars is only slightly longer than an Earth day: 24 hours, 39 minutes, and 35.244 seconds. A Martian year is equal to 1.8809 Earth years, or 1 year, 320 days, and 18.2 hours. The gravitational potential difference and thus the delta-v needed to transfer between Mars and Earth is the second lowest for Earth. The axial tilt of Mars is 25.19° relative to its orbital plane, which is similar to the axial tilt of Earth. As a result, Mars has seasons like Earth, though on Mars they are nearly twice as long because its orbital period is that much longer. In the present day, the orientation of the north pole of Mars is close to the star Deneb. Mars has a relatively pronounced orbital eccentricity of about 0.09; of the seven other planets in the Solar System, only Mercury has a larger orbital eccentricity. It is known that in the past, Mars has had a much more circular orbit. At one point, 1.35 million Earth years ago, Mars had an eccentricity of roughly 0.002, much less than that of Earth today. Mars's cycle of eccentricity is 96,000 Earth years compared to Earth's cycle of 100,000 years. Mars has its closest approach to Earth (opposition) in a synodic period of 779.94 days. It should not be confused with Mars conjunction, where the Earth and Mars are at opposite sides of the Solar System and form a straight line crossing the Sun. The average time between the successive oppositions of Mars, its synodic period, is 780 days; but the number of days between successive oppositions can range from 764 to 812. The distance at close approach varies between about 54 and 103 million km (34 and 64 million mi) due to the planets' elliptical orbits, which causes comparable variation in angular size. At their furthest Mars and Earth can be as far as 401 million km (249 million mi) apart. Mars comes into opposition from Earth every 2.1 years. The planets come into opposition near Mars's perihelion in 2003, 2018 and 2035, with the 2020 and 2033 events being particularly close to perihelic opposition. The mean apparent magnitude of Mars is +0.71 with a standard deviation of 1.05. Because the orbit of Mars is eccentric, the magnitude at opposition from the Sun can range from about −3.0 to −1.4. The minimum brightness is magnitude +1.86 when the planet is near aphelion and in conjunction with the Sun. At its brightest, Mars (along with Jupiter) is second only to Venus in apparent brightness. Mars usually appears distinctly yellow, orange, or red. When farthest away from Earth, it is more than seven times farther away than when it is closest. Mars is usually close enough for particularly good viewing once or twice at 15-year or 17-year intervals. Optical ground-based telescopes are typically limited to resolving features about 300 kilometres (190 mi) across when Earth and Mars are closest because of Earth's atmosphere. As Mars approaches opposition, it begins a period of retrograde motion, which means it will appear to move backwards in a looping curve with respect to the background stars. This retrograde motion lasts for about 72 days, and Mars reaches its peak apparent brightness in the middle of this interval. Moons Mars has two relatively small (compared to Earth's) natural moons, Phobos (about 22 km (14 mi) in diameter) and Deimos (about 12 km (7.5 mi) in diameter), which orbit at 9,376 km (5,826 mi) and 23,460 km (14,580 mi) around the planet. The origin of both moons is unclear, although a popular theory states that they were asteroids captured into Martian orbit. Both satellites were discovered in 1877 by Asaph Hall and were named after the characters Phobos (the deity of panic and fear) and Deimos (the deity of terror and dread), twins from Greek mythology who accompanied their father Ares, god of war, into battle. Mars was the Roman equivalent to Ares. In modern Greek, the planet retains its ancient name Ares (Aris: Άρης). From the surface of Mars, the motions of Phobos and Deimos appear different from that of the Earth's satellite, the Moon. Phobos rises in the west, sets in the east, and rises again in just 11 hours. Deimos, being only just outside synchronous orbit – where the orbital period would match the planet's period of rotation – rises as expected in the east, but slowly. Because the orbit of Phobos is below a synchronous altitude, tidal forces from Mars are gradually lowering its orbit. In about 50 million years, it could either crash into Mars's surface or break up into a ring structure around the planet. The origin of the two satellites is not well understood. Their low albedo and carbonaceous chondrite composition have been regarded as similar to asteroids, supporting a capture theory. The unstable orbit of Phobos would seem to point toward a relatively recent capture. But both have circular orbits near the equator, which is unusual for captured objects, and the required capture dynamics are complex. Accretion early in the history of Mars is plausible, but would not account for a composition resembling asteroids rather than Mars itself, if that is confirmed. Mars may have yet-undiscovered moons, smaller than 50 to 100 metres (160 to 330 ft) in diameter, and a dust ring is predicted to exist between Phobos and Deimos. A third possibility for their origin as satellites of Mars is the involvement of a third body or a type of impact disruption. More-recent lines of evidence for Phobos having a highly porous interior, and suggesting a composition containing mainly phyllosilicates and other minerals known from Mars, point toward an origin of Phobos from material ejected by an impact on Mars that reaccreted in Martian orbit, similar to the prevailing theory for the origin of Earth's satellite. Although the visible and near-infrared (VNIR) spectra of the moons of Mars resemble those of outer-belt asteroids, the thermal infrared spectra of Phobos are reported to be inconsistent with chondrites of any class. It is also possible that Phobos and Deimos were fragments of an older moon, formed by debris from a large impact on Mars, and then destroyed by a more recent impact upon the satellite. More recently, a study conducted by a team of researchers from multiple countries suggests that a lost moon, at least fifteen times the size of Phobos, may have existed in the past. By analyzing rocks which point to tidal processes on the planet, it is possible that these tides may have been regulated by a past moon. Human observations and exploration The history of observations of Mars is marked by oppositions of Mars when the planet is closest to Earth and hence is most easily visible, which occur every couple of years. Even more notable are the perihelic oppositions of Mars, which are distinguished because Mars is close to perihelion, making it even closer to Earth. The ancient Sumerians named Mars Nergal, the god of war and plague. During Sumerian times, Nergal was a minor deity of little significance, but, during later times, his main cult center was the city of Nineveh. In Mesopotamian texts, Mars is referred to as the "star of judgement of the fate of the dead". The existence of Mars as a wandering object in the night sky was also recorded by the ancient Egyptian astronomers and, by 1534 BCE, they were familiar with the retrograde motion of the planet. By the period of the Neo-Babylonian Empire, the Babylonian astronomers were making regular records of the positions of the planets and systematic observations of their behavior. For Mars, they knew that the planet made 37 synodic periods, or 42 circuits of the zodiac, every 79 years. They invented arithmetic methods for making minor corrections to the predicted positions of the planets. In Ancient Greece, the planet was known as Πυρόεις. Commonly, the Greek name for the planet now referred to as Mars, was Ares. It was the Romans who named the planet Mars, for their god of war, often represented by the sword and shield of the planet's namesake. In the fourth century BCE, Aristotle noted that Mars disappeared behind the Moon during an occultation, indicating that the planet was farther away. Ptolemy, a Greek living in Alexandria, attempted to address the problem of the orbital motion of Mars. Ptolemy's model and his collective work on astronomy was presented in the multi-volume collection later called the Almagest (from the Arabic for "greatest"), which became the authoritative treatise on Western astronomy for the next fourteen centuries. Literature from ancient China confirms that Mars was known by Chinese astronomers by no later than the fourth century BCE. In the East Asian cultures, Mars is traditionally referred to as the "fire star" (火星) based on the Wuxing system. In 1609 Johannes Kepler published a 10 year study of Martian orbit, using the diurnal parallax of Mars, measured by Tycho Brahe, to make a preliminary calculation of the relative distance to the planet. From Brahe's observations of Mars, Kepler deduced that the planet orbited the Sun not in a circle, but in an ellipse. Moreover, Kepler showed that Mars sped up as it approached the Sun and slowed down as it moved farther away, in a manner that later physicists would explain as a consequence of the conservation of angular momentum.: 433–437 In 1610 the first use of a telescope for astronomical observation, including Mars, was performed by Italian astronomer Galileo Galilei. With the telescope the diurnal parallax of Mars was again measured in an effort to determine the Sun-Earth distance. This was first performed by Giovanni Domenico Cassini in 1672. The early parallax measurements were hampered by the quality of the instruments. The only occultation of Mars by Venus observed was that of 13 October 1590, seen by Michael Maestlin at Heidelberg. By the 19th century, the resolution of telescopes reached a level sufficient for surface features to be identified. On 5 September 1877, a perihelic opposition to Mars occurred. The Italian astronomer Giovanni Schiaparelli used a 22-centimetre (8.7 in) telescope in Milan to help produce the first detailed map of Mars. These maps notably contained features he called canali, which, with the possible exception of the natural canyon Valles Marineris, were later shown to be an optical illusion. These canali were supposedly long, straight lines on the surface of Mars, to which he gave names of famous rivers on Earth. His term, which means "channels" or "grooves", was popularly mistranslated in English as "canals". Influenced by the observations, the orientalist Percival Lowell founded an observatory which had 30- and 45-centimetre (12- and 18-in) telescopes. The observatory was used for the exploration of Mars during the last good opportunity in 1894, and the following less favorable oppositions. He published several books on Mars and life on the planet, which had a great influence on the public. The canali were independently observed by other astronomers, like Henri Joseph Perrotin and Louis Thollon in Nice, using one of the largest telescopes of that time. The seasonal changes (consisting of the diminishing of the polar caps and the dark areas formed during Martian summers) in combination with the canals led to speculation about life on Mars, and it was a long-held belief that Mars contained vast seas and vegetation. As bigger telescopes were used, fewer long, straight canali were observed. During observations in 1909 by Antoniadi with an 84-centimetre (33 in) telescope, irregular patterns were observed, but no canali were seen. The first spacecraft from Earth to visit Mars was Mars 1 of the Soviet Union, which flew by in 1963, but contact was lost en route. NASA's Mariner 4 followed and became the first spacecraft to successfully transmit from Mars; launched on 28 November 1964, it made its closest approach to the planet on 15 July 1965. Mariner 4 detected the weak Martian radiation belt, measured at about 0.1% that of Earth, and captured the first images of another planet from deep space. Once spacecraft visited the planet during the 1960s and 1970s, many previous concepts of Mars were radically broken. After the results of the Viking life-detection experiments, the hypothesis of a dead planet was generally accepted. The data from Mariner 9 and Viking allowed better maps of Mars to be made. Until 1997 and after Viking 1 shut down in 1982, Mars was only visited by three unsuccessful probes, two flying past without contact (Phobos 1, 1988; Mars Observer, 1993), and one (Phobos 2 1989) malfunctioning in orbit before reaching its destination Phobos. In 1997 Mars Pathfinder became the first successful rover mission beyond the Moon and started together with Mars Global Surveyor (operated until late 2006) an uninterrupted active robotic presence at Mars that has lasted until today. It produced complete, extremely detailed maps of the Martian topography, magnetic field and surface minerals. Starting with these missions a range of new improved crewless spacecraft, including orbiters, landers, and rovers, have been sent to Mars, with successful missions by the NASA (United States), Jaxa (Japan), ESA, United Kingdom, ISRO (India), Roscosmos (Russia), the United Arab Emirates, and CNSA (China) to study the planet's surface, climate, and geology, uncovering the different elements of the history and dynamic of the hydrosphere of Mars and possible traces of ancient life. As of 2023[update], Mars is host to ten functioning spacecraft. Eight are in orbit: 2001 Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter, MAVEN, ExoMars Trace Gas Orbiter, the Hope orbiter, and the Tianwen-1 orbiter. Another two are on the surface: the Mars Science Laboratory Curiosity rover and the Perseverance rover. Collected maps are available online at websites including Google Mars. NASA provides two online tools: Mars Trek, which provides visualizations of the planet using data from 50 years of exploration, and Experience Curiosity, which simulates traveling on Mars in 3-D with Curiosity. Planned missions to Mars include: As of February 2024[update], debris from these types of missions has reached over seven tons. Most of it consists of crashed and inactive spacecraft as well as discarded components. In April 2024, NASA selected several companies to begin studies on providing commercial services to further enable robotic science on Mars. Key areas include establishing telecommunications, payload delivery and surface imaging. Habitability and habitation During the late 19th century, it was widely accepted in the astronomical community that Mars had life-supporting qualities, including the presence of oxygen and water. However, in 1894 W. W. Campbell at Lick Observatory observed the planet and found that "if water vapor or oxygen occur in the atmosphere of Mars it is in quantities too small to be detected by spectroscopes then available". That observation contradicted many of the measurements of the time and was not widely accepted. Campbell and V. M. Slipher repeated the study in 1909 using better instruments, but with the same results. It was not until the findings were confirmed by W. S. Adams in 1925 that the myth of the Earth-like habitability of Mars was finally broken. However, even in the 1960s, articles were published on Martian biology, putting aside explanations other than life for the seasonal changes on Mars. The current understanding of planetary habitability – the ability of a world to develop environmental conditions favorable to the emergence of life – favors planets that have liquid water on their surface. Most often this requires the orbit of a planet to lie within the habitable zone, which for the Sun is estimated to extend from within the orbit of Earth to about that of Mars. During perihelion, Mars dips inside this region, but Mars's thin (low-pressure) atmosphere prevents liquid water from existing over large regions for extended periods. The past flow of liquid water demonstrates the planet's potential for habitability. Recent evidence has suggested that any water on the Martian surface may have been too salty and acidic to support regular terrestrial life. The environmental conditions on Mars are a challenge to sustaining organic life: the planet has little heat transfer across its surface, it has poor insulation against bombardment by the solar wind due to the absence of a magnetosphere and has insufficient atmospheric pressure to retain water in a liquid form (water instead sublimes to a gaseous state). Mars is nearly, or perhaps totally, geologically dead; the end of volcanic activity has apparently stopped the recycling of chemicals and minerals between the surface and interior of the planet. Evidence suggests that the planet was once significantly more habitable than it is today, but whether living organisms ever existed there remains unknown. The Viking probes of the mid-1970s carried experiments designed to detect microorganisms in Martian soil at their respective landing sites and had positive results, including a temporary increase in CO2 production on exposure to water and nutrients. This sign of life was later disputed by scientists, resulting in a continuing debate, with NASA scientist Gilbert Levin asserting that Viking may have found life. A 2014 analysis of Martian meteorite EETA79001 found chlorate, perchlorate, and nitrate ions in sufficiently high concentrations to suggest that they are widespread on Mars. UV and X-ray radiation would turn chlorate and perchlorate ions into other, highly reactive oxychlorines, indicating that any organic molecules would have to be buried under the surface to survive. Small quantities of methane and formaldehyde detected by Mars orbiters are both claimed to be possible evidence for life, as these chemical compounds would quickly break down in the Martian atmosphere. Alternatively, these compounds may instead be replenished by volcanic or other geological means, such as serpentinite. Impact glass, formed by the impact of meteors, which on Earth can preserve signs of life, has also been found on the surface of the impact craters on Mars. Likewise, the glass in impact craters on Mars could have preserved signs of life, if life existed at the site. The Cheyava Falls rock discovered on Mars in June 2024 has been designated by NASA as a "potential biosignature" and was core sampled by the Perseverance rover for possible return to Earth and further examination. Although highly intriguing, no definitive final determination on a biological or abiotic origin of this rock can be made with the data currently available. Several plans for a human mission to Mars have been proposed, but none have come to fruition. The NASA Authorization Act of 2017 directed NASA to study the feasibility of a crewed Mars mission in the early 2030s; the resulting report concluded that this would be unfeasible. In addition, in 2021, China was planning to send a crewed Mars mission in 2033. Privately held companies such as SpaceX have also proposed plans to send humans to Mars, with the eventual goal to settle on the planet. As of 2024, SpaceX has proceeded with the development of the Starship launch vehicle with the goal of Mars colonization. In plans shared with the company in April 2024, Elon Musk envisions the beginning of a Mars colony within the next twenty years. This would be enabled by the planned mass manufacturing of Starship and initially sustained by resupply from Earth, and in situ resource utilization on Mars, until the Mars colony reaches full self sustainability. Any future human mission to Mars will likely take place within the optimal Mars launch window, which occurs every 26 months. The moon Phobos has been proposed as an anchor point for a space elevator. Besides national space agencies and space companies, groups such as the Mars Society and The Planetary Society advocate for human missions to Mars. In culture Mars is named after the Roman god of war (Greek Ares), but was also associated with the demi-god Heracles (Roman Hercules) by ancient Greek astronomers, as detailed by Aristotle. This association between Mars and war dates back at least to Babylonian astronomy, in which the planet was named for the god Nergal, deity of war and destruction. It persisted into modern times, as exemplified by Gustav Holst's orchestral suite The Planets, whose famous first movement labels Mars "The Bringer of War". The planet's symbol, a circle with a spear pointing out to the upper right, is also used as a symbol for the male gender. The symbol dates from at least the 11th century, though a possible predecessor has been found in the Greek Oxyrhynchus Papyri. The idea that Mars was populated by intelligent Martians became widespread in the late 19th century. Schiaparelli's "canali" observations combined with Percival Lowell's books on the subject put forward the standard notion of a planet that was a drying, cooling, dying world with ancient civilizations constructing irrigation works. Many other observations and proclamations by notable personalities added to what has been termed "Mars Fever". In the present day, high-resolution mapping of the surface of Mars has revealed no artifacts of habitation, but pseudoscientific speculation about intelligent life on Mars still continues. Reminiscent of the canali observations, these speculations are based on small scale features perceived in the spacecraft images, such as "pyramids" and the "Face on Mars". In his book Cosmos, planetary astronomer Carl Sagan wrote: "Mars has become a kind of mythic arena onto which we have projected our Earthly hopes and fears." The depiction of Mars in fiction has been stimulated by its dramatic red color and by nineteenth-century scientific speculations that its surface conditions might support not just life but intelligent life. This gave way to many science fiction stories involving these concepts, such as H. G. Wells's The War of the Worlds, in which Martians seek to escape their dying planet by invading Earth; Ray Bradbury's The Martian Chronicles, in which human explorers accidentally destroy a Martian civilization; as well as Edgar Rice Burroughs's series Barsoom, C. S. Lewis's novel Out of the Silent Planet (1938), and a number of Robert A. Heinlein stories before the mid-sixties. Since then, depictions of Martians have also extended to animation. A comic figure of an intelligent Martian, Marvin the Martian, appeared in Haredevil Hare (1948) as a character in the Looney Tunes animated cartoons of Warner Brothers, and has continued as part of popular culture to the present. After the Mariner and Viking spacecraft had returned pictures of Mars as a lifeless and canal-less world, these ideas about Mars were abandoned; for many science-fiction authors, the new discoveries initially seemed like a constraint, but eventually the post-Viking knowledge of Mars became itself a source of inspiration for works like Kim Stanley Robinson's Mars trilogy. See also Notes References Further reading External links Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Local Sheet → Local Volume → Virgo Supercluster → Laniakea Supercluster → Pisces–Cetus Supercluster Complex → Local Hole → Observable universe → UniverseEach arrow (→) may be read as "within" or "part of". |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/List_of_pioneers_in_computer_science] | [TOKENS: 50] |
Contents List of pioneers in computer science This is a list of people who made transformative breakthroughs in the creation, development and imagining of what computers could do. Pioneers ~ Items marked with a tilde are circa dates. See also References External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Jurisprudence] | [TOKENS: 6936] |
Contents Jurisprudence Jurisprudence, also known as theory of law or philosophy of law, is the examination in a general perspective of what law is and what it ought to be. It investigates issues such as the definition of law; legal validity; legal norms and values; and the relationship between law and other fields of study, including economics, ethics, history, sociology, and political philosophy. Modern jurisprudence began in the 18th century and was based on the first principles of natural law, civil law, and the law of nations. Contemporary philosophy of law addresses problems internal to law and legal systems and problems of law as a social institution that relates to the larger political and social context in which it exists. Jurisprudence can be divided into categories both by the type of question scholars seek to answer and by the theories of jurisprudence, or schools of thought, regarding how those questions are best answered: The terms "philosophy of law" and "jurisprudence" are often used interchangeably, though jurisprudence sometimes encompasses forms of reasoning that fit into economics or sociology. Overview Whereas lawyers are interested in what the law is on a specific issue in a specific jurisdiction, analytical philosophers of law are interested in identifying the features of law shared across cultures, times, and places. Taken together, these foundational features of law offer the kind of universal definition philosophers are after. The general approach allows philosophers to ask questions about, for example, what separates law from morality, politics, or practical reason. While the field has traditionally focused on giving an account of law's nature, some scholars have begun to examine the nature of domains within law, e.g. tort law, contract law, or criminal law. These scholars focus on what makes certain domains of law distinctive and how one domain differs from another. A particularly fecund area of research has been the distinction between tort law and criminal law, which more generally bears on the difference between civil and criminal law. In addition to analytic jurisprudence, legal philosophy is also concerned with normative theories of law. "Normative jurisprudence involves normative, evaluative, and otherwise prescriptive questions about the law." Etymology and terminology The English word is derived from the Latin, iurisprudentia. Iuris is the genitive form of ius meaning law, and prudentia meaning prudence (also: discretion, foresight, forethought, circumspection). It refers to the exercise of good judgment, common sense, and caution, especially in the conduct of practical matters. The word first appeared in written English in 1628, at a time when the word prudence meant knowledge of, or skill in, a matter. It may have entered English via the French jurisprudence, which appeared earlier. History Ancient jurisprudence begins with various Dharmaśāstra texts of India. Dharmasutras of Āpastaṃba and Baudhāyana are examples. In Ancient China, the Daoists, Confucians, and Legalists all had competing theories of jurisprudence. Jurisprudence in ancient Rome had its origins with the periti—experts in the jus mos maiorum (traditional law), a body of oral laws and customs. Praetors established a working body of laws by judging whether or not singular cases were capable of being prosecuted either by the edicta, the annual pronunciation of prosecutable offences, or in extraordinary situations, additions made to the edicta. A iudex (originally a magistrate, later a private individual appointed to judge a specific case) would then prescribe a remedy according to the facts of the case. The sentences of the iudex were supposed to be simple interpretations of the traditional customs, but—apart from considering what traditional customs applied in each case—soon developed a more equitable interpretation, coherently adapting the law to newer social exigencies. The law was then adjusted with evolving institutiones (legal concepts), while remaining in the traditional mode. Praetors were replaced in the 3rd century BC by a laical body of prudentes. Admission to this body was conditional upon proof of competence or experience. Under the Roman Empire, schools of law were created, and practice of the law became more academic. From the early Roman Empire to the 3rd century, a relevant body of literature was produced by groups of scholars, including the Proculians and Sabinians. The scientific nature of the studies was unprecedented in ancient times. After the 3rd century, juris prudentia became a more bureaucratic activity, with few notable authors. It was during the Eastern Roman Empire (5th century) that legal studies were once again undertaken in depth, and it is from this cultural movement that Justinian's Corpus Juris Civilis was born. Modern jurisprudence began in the 18th century and was based on the first principles of natural law, civil law, and the law of nations. Natural law Natural law holds that there are rational objective limits to the power of rulers, the foundations of law are accessible through reason, and it is from these laws of nature that human laws gain force. The moral theory of natural law asserts that law is inherent in nature and constitutive of morality, at least in part, and that an objective moral order, external to human legal systems, underlies natural law. On this view, while legislators can enact and even successfully enforce immoral laws, such laws are legally invalid. The view is captured by the maxim: "an unjust law is no law at all", where 'unjust' means 'contrary to the natural law.' Natural law theory has medieval origins in the philosophy of Thomas Aquinas, especially in his Treatise on law. In late 20th century, John Finnis revived interest in the theory and provided a modern reworking of it. For one, Finnis has argued that the maxim "an unjust law is no law at all" is a poor guide to the classical Thomist position. In its general sense, natural law theory may be compared to both state-of-nature law and general law understood on the basis of being analogous to the laws of physical science. Natural law is often contrasted to positive law which asserts law as the product of human activity and human volition. Another approach to natural-law jurisprudence generally asserts that human law must be in response to compelling reasons for action. There are two readings of the natural-law jurisprudential stance. Aristotle is often said to be the father of natural law. Like his philosophical forefathers Socrates and Plato, Aristotle posited the existence of natural justice or natural right (dikaion physikon, δικαίον φυσικόν, Latin ius naturale). His association with natural law is largely due to how he was interpreted by Thomas Aquinas. This was based on Aquinas' conflation of natural law and natural right, the latter of which Aristotle posits in Book V of the Nicomachean Ethics (Book IV of the Eudemian Ethics). Aquinas's influence was such as to affect a number of early translations of these passages, though more recent translations render them more literally. Aristotle's theory of justice is bound up in his idea of the golden mean. Indeed, his treatment of what he calls "political justice" derives from his discussion of "the just" as a moral virtue derived as the mean between opposing vices, just like every other virtue he describes. His longest discussion of his theory of justice occurs in Nicomachean Ethics and begins by asking what sort of mean a just act is. He argues that the term "justice" actually refers to two different but related ideas: general justice and particular justice. When a person's actions toward others are completely virtuous in all matters, Aristotle calls them "just" in the sense of "general justice"; as such, this idea of justice is more or less coextensive with virtue. "Particular" or "partial justice", by contrast, is the part of "general justice" or the individual virtue that is concerned with treating others equitably. Aristotle moves from this unqualified discussion of justice to a qualified view of political justice, by which he means something close to the subject of modern jurisprudence. Of political justice, Aristotle argues that it is partly derived from nature and partly a matter of convention. This can be taken as a statement that is similar to the views of modern natural law theorists. But it must also be remembered that Aristotle is describing a view of morality, not a system of law, and therefore his remarks as to nature are about the grounding of the morality enacted as law, not the laws themselves. The best evidence of Aristotle's having thought there was a natural law comes from the Rhetoric, where Aristotle notes that, aside from the "particular" laws that each people has set up for itself, there is a "common" law that is according to nature. The context of this remark, however, suggests only that Aristotle thought that it could be rhetorically advantageous to appeal to such a law, especially when the "particular" law of one's own city was adverse to the case being made, not that there actually was such a law. Aristotle, moreover, considered certain candidates for a universally valid, natural law to be wrong. Aristotle's theoretical paternity of the natural law tradition is consequently disputed. Thomas Aquinas is the foremost classical proponent of natural theology, and the father of the Thomistic school of philosophy, for a long time the primary philosophical approach of the Roman Catholic Church. The work for which he is best known is the Summa Theologiae. One of the thirty-five Doctors of the Church, he is considered by many Catholics to be the Church's greatest theologian. Consequently, many institutions of learning have been named after him. Aquinas distinguished four kinds of law: eternal, natural, divine, and human: Natural law is based on "first principles": ... this is the first precept of the law, that good is to be done and promoted, and evil is to be avoided. All other precepts of the natural law are based on this ... The desires to live and to procreate are counted by Aquinas among those basic (natural) human values on which all other human values are based. Francisco de Vitoria was perhaps the first to develop a theory of ius gentium (law of nations), and thus is an important figure in the transition to modernity. He extrapolated his ideas of legitimate sovereign power to international affairs, concluding that such affairs ought to be determined by forms respecting of the rights of all and that the common good of the world should take precedence before the good of any single state. This meant that relations between states ought to pass from being justified by force to being justified by law and justice. Some scholars have upset the standard account of the origins of International law, which emphasises the seminal text De iure belli ac pacis by Hugo Grotius, and argued for Vitoria and, later, Suárez's importance as forerunners and, potentially, founders of the field. Others, such as Koskenniemi, have argued that none of these humanist and scholastic thinkers can be understood to have founded international law in the modern sense, instead placing its origins in the post-1870 period. Francisco Suárez, regarded as among the greatest scholastics after Aquinas, subdivided the concept of ius gentium. Working with already well-formed categories, he carefully distinguished ius inter gentes from ius intra gentes. Ius inter gentes (which corresponds to modern international law) was something common to the majority of countries, although, being positive law, not natural law, it was not necessarily universal. On the other hand, ius intra gentes, or civil law, is specific to each nation. Writing after World War II, Lon L. Fuller defended a secular and procedural form of natural law. He emphasised that the (natural) law must meet certain formal requirements (such as being impartial and publicly knowable). To the extent that an institutional system of social control falls short of these requirements, Fuller argued, we are less inclined to recognise it as a system of law, or to give it our respect. Thus, the law must have a morality that goes beyond the societal rules under which laws are made. Sophisticated positivist and natural law theories sometimes resemble each other and may have certain points in common. Identifying a particular theorist as a positivist or a natural law theorist sometimes involves matters of emphasis and degree, and the particular influences on the theorist's work. The natural law theorists of the distant past, such as Aquinas and John Locke made no distinction between analytic and normative jurisprudence, while modern natural law theorists, such as John Finnis, who claim to be positivists, still argue that law is moral by nature. In his book Natural Law and Natural Rights (1980, 2011), John Finnis provides a restatement of natural law doctrine. Analytic jurisprudence Unlike experimental jurisprudence, which investigates the content of legal concepts using the methods of social science, analytical jurisprudence seeks to provide a general account of the nature of law through the tools of conceptual analysis. The account is general in the sense of targeting universal features of law that hold at all times and places. Analytic, or clarificatory, jurisprudence takes a neutral point of view and uses descriptive language when referring to various aspects of legal systems. This was a philosophical development that rejected natural law's fusing of what law is and what it ought to be. David Hume argued, in A Treatise of Human Nature, that people invariably slip from describing what the world is to asserting that we therefore ought to follow a particular course of action. But as a matter of pure logic, one cannot conclude that we ought to do something merely because something is the case. So analysing and clarifying the way the world is must be treated as a strictly separate question from normative and evaluative questions of what ought to be done. The most important questions of analytic jurisprudence are: "What are laws?"; "What is the law?"; "What is the relationship between law and power/sociology?"; and "What is the relationship between law and morality?" Legal positivism is the dominant theory, although there is a growing number of critics who offer their own interpretations. Historical jurisprudence came to prominence during the debate on the proposed codification of German law. In his book On the Vocation of Our Age for Legislation and Jurisprudence, Friedrich Carl von Savigny argued that Germany did not have a legal language that would support codification because the traditions, customs, and beliefs of the German people did not include a belief in a code. Historicists believe that law originates with society. An effort systematically to inform jurisprudence from sociological insights developed from the beginning of the twentieth century, as sociology began to establish itself as a distinct social science, especially in the United States and in continental Europe. In Germany, Austria and France, the work of the "free law" theorists (e.g. Ernst Fuchs, Hermann Kantorowicz, Eugen Ehrlich and François Gény) encouraged the use of sociological insights in the development of legal and juristic theory. The most internationally influential advocacy for a "sociological jurisprudence" occurred in the United States, where, throughout the first half of the twentieth century, Roscoe Pound, for many years the Dean of Harvard Law School, used this term to characterise his legal philosophy. In the United States, many later writers followed Pound's lead or developed distinctive approaches to sociological jurisprudence. In Australia, Julius Stone strongly defended and developed Pound's ideas. In the 1930s, a significant split between the sociological jurists and the American legal realists emerged. In the second half of the twentieth century, sociological jurisprudence as a distinct movement declined as jurisprudence came more strongly under the influence of analytical legal philosophy; but with increasing criticism of dominant orientations of legal philosophy in English-speaking countries in the present century, it has attracted renewed interest. Increasingly, its contemporary focus is on providing theoretical resources for jurists to aid their understanding of new types of regulation (for example, the diverse kinds of developing transnational law) and the increasingly important interrelations of law and culture, especially in multicultural Western societies.[a] As an approach to jurisprudence, sociological jurisprudence uses the resources of social science to serve value-oriented juristic purposes. As such, it should be distinguished from sociology of law which as a field of social science has no necessary commitment to juristic aims. Legal positivism is the view that the content of law is dependent on social facts and that a legal system's existence is not constrained by morality. Within legal positivism, theorists agree that law's content is a product of social facts, but theorists disagree whether law's validity can be explained by incorporating moral values. Legal positivists who argue against the incorporation of moral values to explain law's validity are labeled exclusive (or hard) legal positivists. Joseph Raz's legal positivism is an example of exclusive legal positivism. Legal positivists who argue that law's validity can be explained by incorporating moral values are labeled inclusive (or soft) legal positivists. The legal positivist theories of H. L. A. Hart and Jules Coleman are examples of inclusive legal positivism. Legal positivism has traditionally been associated with three doctrines: the pedigree thesis, the separability thesis, and the discretion thesis. The pedigree thesis says that the right way to determine whether a directive is law is to look at the directive's source. The thesis claims that it is the fact that the directive was issued by the proper official within a legitimate government, for example, that determines the directive's legal validity—not the directive's moral or practical merits. The separability thesis states that law is conceptually distinct from morality. While law might contain morality, the separability thesis states that "it is in no sense a necessary truth that laws reproduce or satisfy certain demands of morality, though in fact they have often done so." Legal positivists disagree about the extent of the separability thesis. Exclusive legal positivists, notably Joseph Raz, go further than the standard thesis and deny that it is possible for morality to be a part of law at all. The discretion thesis states that judges create new law when they are given discretion to adjudicate cases where existing law underdetermines the result. Hobbes was a social contractarian and believed that the law had peoples' tacit consent. He believed that society was formed from a state of nature to protect people from the state of war that would exist otherwise. In Leviathan, Hobbes argues that without an ordered society life would be "solitary, poor, nasty, brutish and short." It is commonly said that Hobbes's views on human nature were influenced by his times. The English Civil War and the Cromwellian dictatorship had taken place; and, in reacting to that, Hobbes felt that absolute authority vested in a monarch, whose subjects obeyed the law, was the basis of a civilized society. John Austin and Jeremy Bentham were early legal positivists who sought to provide a descriptive account of law that describes the law as it is. Austin explained the descriptive focus for legal positivism by saying, "The existence of law is one thing; its merit and demerit another. Whether it be or be not is one enquiry; whether it be or be not conformable to an assumed standard, is a different enquiry." For Austin and Bentham, a society is governed by a sovereign who has de facto authority. Through the sovereign's authority come laws, which for Austin and Bentham are commands backed by sanctions for non-compliance. Along with Hume, Bentham was an early and staunch supporter of the utilitarian concept, and was an avid prison reformer, advocate for democracy, and firm atheist. Bentham's views about law and jurisprudence were popularized by his student John Austin. Austin was the first chair of law at the new University of London, from 1829. Austin's utilitarian answer to "what is law?" was that law is "commands, backed by threat of sanctions, from a sovereign, to whom people have a habit of obedience". H. L. A. Hart criticized Austin and Bentham's early legal positivism because the command theory failed to account for individual's compliance with the law. Hans Kelsen is considered one of the preeminent jurists of the 20th century and has been highly influential in Europe and Latin America, although less so in common law countries. His Pure Theory of Law describes law as "binding norms", while at the same time refusing to evaluate those norms. That is, "legal science" is to be separated from "legal politics". Central to the Pure Theory of Law is the notion of a 'basic norm' (Grundnorm)—a hypothetical norm, presupposed by the jurist, from which all "lower" norms in the hierarchy of a legal system, beginning with constitutional law, are understood to derive their authority or the extent to which they are binding. Kelsen contends that the extent to which legal norms are binding, their specifically "legal" character, can be understood without tracing it ultimately to some suprahuman source such as God, personified Nature or—of great importance in his time—a personified State or Nation. In the English-speaking world, the most influential legal positivist of the twentieth century was H. L. A. Hart, professor of jurisprudence at Oxford University. Hart argued that the law should be understood as a system of social rules. In The Concept of Law, Hart rejected Kelsen's views that sanctions were essential to law and that a normative social phenomenon, like law, cannot be grounded in non-normative social facts. Hart claimed that law is the union of primary rules and secondary rules. Primary rules require individuals to act or not act in certain ways and create duties for the governed to obey. Secondary rules are rules that confer authority to create new primary rules or modify existing ones. Secondary rules are divided into rules of adjudication (how to resolve legal disputes), rules of change (how laws are amended), and the rule of recognition (how laws are identified as valid). The validity of a legal system comes from the "rule of recognition", which is a customary practice of officials (especially barristers and judges) who identify certain acts and decisions as sources of law. In 1981, Neil MacCormick wrote a pivotal book on Hart (second edition published in 2008), which further refined and offered some important criticisms that led MacCormick to develop his own theory (the best example of which is his Institutions of Law, 2007). Other important critiques include those of Ronald Dworkin, John Finnis, and Joseph Raz. In recent years, debates on the nature of law have become increasingly fine-grained. One important debate is within legal positivism. One school is sometimes called "exclusive legal positivism" and is associated with the view that the legal validity of a norm can never depend on its moral correctness. A second school is labeled "inclusive legal positivism", a major proponent of which is Wil Waluchow, and is associated with the view that moral considerations may, but do not necessarily, determine the legal validity of a norm. Joseph Raz's theory of legal positivism argues against the incorporation of moral values to explain law's validity. In Raz's 1979 book The Authority of Law, he criticised what he called the "weak social thesis" to explain law. He formulates the weak social thesis as "(a) Sometimes the identification of some laws turn on moral arguments, but also with, (b) In all legal systems the identification of some law turns on moral argument." Raz argues that law's authority is identifiable purely through social sources, without reference to moral reasoning. This view he calls "the sources thesis". Raz suggests that any categorisation of rules beyond their role as authority is better left to sociology than to jurisprudence. Some philosophers used to contend that positivism was the theory that held that there was "no necessary connection" between law and morality; but influential contemporary positivists—including Joseph Raz, John Gardner, and Leslie Green—reject that view. Raz claims it is a necessary truth that there are vices that a legal system cannot possibly have (for example, it cannot commit rape or murder). Legal realism is the view that a theory of law should be descriptive and account for the reasons why judges decide cases as they do. Legal realism had some affinities with the sociology of law and sociological jurisprudence. The essential tenet of legal realism is that all law is made by humans and thus should account for reasons besides legal rules that led to a legal decision. There are two separate schools of legal realism: American legal realism and Scandinavian legal realism. American legal realism grew out of the writings of Oliver Wendell Holmes. At the start of Holmes's The Common Law, he claims that "[t]he life of the law has not been logic: it has been experience". This view was a reaction to legal formalism that was popular the time due to the Christopher Columbus Langdell. Holmes's writings on jurisprudence also laid the foundations for the predictive theory of law. In his article "The Path of the Law", Holmes argues that "the object of [legal] study...is prediction, the prediction of the incidence of the public force through the instrumentality of the courts." For the American legal realists of the early twentieth century, legal realism sought to describe the way judges decide cases. For legal realists such as Jerome Frank, judges start with the facts before them and then move to legal principles. Before legal realism, theories of jurisprudence turned this method around where judges were thought to begin with legal principles and then look to facts. It has become common today to identify Justice Oliver Wendell Holmes Jr., as the main precursor of American Legal Realism (other influences include Roscoe Pound, Karl Llewellyn, and Justice Benjamin Cardozo). Karl Llewellyn, another founder of the U.S. legal realism movement, similarly believed that the law is little more than putty in the hands of judges who are able to shape the outcome of cases based on their personal values or policy choices. The Scandinavian school of legal realism argued that law can be explained through the empirical methods used by social scientists. Prominent Scandinavian legal realists are Alf Ross, Axel Hägerström, and Karl Olivecrona. Scandinavian legal realists also took a naturalist approach to law. Despite its decline in popularity, legal realism continues to influence a wide spectrum of jurisprudential schools today, including critical legal studies, feminist legal theory, critical race theory, sociology of law, and law and economics. Critical legal studies are a new theory of jurisprudence that has developed since the 1970s. In 1977 a group of members of the Law and Society Association struck out on a new theoretical direction. The legal ideas of Peter Gabel, Morton Horwitz, Duncan Kennedy, Karl Klare, Mark Tushnet, and Roberto Unger have now found influence in many law schools. The theory can generally be traced to American legal realism and is considered "the first movement in legal theory and legal scholarship in the United States to have espoused a committed Left political stance and perspective". It holds that the law is largely contradictory, and can be best analyzed as an expression of the policy goals of a dominant social group. Roberto Mangabeira Unger and other authors in the movement contrast critical legal studies as a method, critical in approach, from the impersonal purposes and principles made necessary in legal reasoning such as formalism. He writes that it was "consequently also by rejecting judges as the chief addressees of legal analysis, and refusing to take the question—how should judges decide cases?—as the defining problem in jurisprudence." According to Unger the new American legal analysis will unlock the democratic potential of free societies in the same way earlier capitalistic economies benefited from the protection of private rights such as contracts and property. Constitutionalism is "a compound of ideas, attitudes, and patterns of behavior elaborating the principle that the authority of government derives from and is limited by a body of fundamental law". American legal philosopher Ronald Dworkin's legal theory attacks legal positivists that separate law's content from morality. In his book Law's Empire, Dworkin argued that law is an "interpretive" concept that requires barristers to find the best-fitting and most just solution to a legal dispute, given their constitutional traditions. According to him, law is not entirely based on social facts, but includes the best moral justification for the institutional facts and practices that form a society's legal tradition. It follows from Dworkin's view that one cannot know whether a society has a legal system in force, or what any of its laws are, until one knows some truths about the moral justifications of the social and political practices of that society. It is consistent with Dworkin's view—in contrast with the views of legal positivists or legal realists—that no-one in a society may know what its laws are, because no-one may know the best moral justification for its practices. Interpretation, according to Dworkin's "integrity theory of law", has two dimensions. To count as an interpretation, the reading of a text must meet the criterion of "fit". Of those interpretations that fit, however, Dworkin maintains that the correct interpretation is the one that portrays the practices of the community in their best light, or makes them "the best that they can be". But many writers have doubted whether there is a single best moral justification for the complex practices of any given community, and others have doubted whether, even if there is, it should be counted as part of the law of that community. Consequences of the operation of legal rules or legal procedures—or of the behavior of legal actors (such as lawyers and judges)—may be either beneficial (therapeutic) or harmful (anti-therapeutic) to people. Therapeutic jurisprudence ("TJ") studies law as a social force (or agent) and uses social science methods and data to study the extent to which a legal rule or practice affects the psychological well-being of the people it impacts. Normative jurisprudence In addition to the question, "What is law?", legal philosophy is also concerned with normative, or "evaluative" theories of law. What is the goal or purpose of law? What moral or political theories provide a foundation for the law? What is the proper function of law? What sorts of acts should be subject to punishment, and what sorts of punishment should be permitted? What is justice? What rights do we have? Is there a duty to obey the law? What value has the rule of law? Some of the different schools and leading thinkers are discussed below. Aretaic moral theories, such as contemporary virtue ethics, emphasize the role of character in morality. Virtue jurisprudence is the view that the laws should promote the development of virtuous character in citizens. Historically, this approach has been mainly associated with Aristotle or Thomas Aquinas. Contemporary virtue jurisprudence is inspired by philosophical work on virtue ethics. Deontology is the "theory of duty or moral obligation". The philosopher Immanuel Kant formulated one influential deontological theory of law. He argued that any rule we follow must be able to be universally applied, i.e. we must be willing for everyone to follow that rule. A contemporary deontological approach can be found in the work of the legal philosopher Ronald Dworkin. Utilitarianism is the view that the laws should be crafted so as to produce the best consequences for the greatest number of people. Historically, utilitarian thinking about law has been associated with the philosopher Jeremy Bentham. John Stuart Mill was a pupil of Bentham's and was the torch bearer for utilitarian philosophy throughout the late nineteenth century. In contemporary legal theory, the utilitarian approach is frequently championed by scholars who work in the law and economics tradition. John Rawls was an American philosopher; a professor of political philosophy at Harvard University; and author of A Theory of Justice (1971), Political Liberalism, Justice as Fairness: A Restatement, and The Law of Peoples. He is widely considered one of the most important English-language political philosophers of the 20th century. His theory of justice uses a method called "original position" to ask us which principles of justice we would choose to regulate the basic institutions of our society if we were behind a "veil of ignorance". Imagine we do not know who we are—our race, sex, wealth, status, class, or any distinguishing feature—so that we would not be biased in our own favour. Rawls argued from this "original position" that we would choose exactly the same political liberties for everyone, like freedom of speech, the right to vote, and so on. Also, we would choose a system where there is only inequality because that produces incentives enough for the economic well-being of all society, especially the poorest. This is Rawls's famous "difference principle". Justice is fairness, in the sense that the fairness of the original position of choice guarantees the fairness of the principles chosen in that position. There are many other normative approaches to the philosophy of law, including constitutionalism, critical legal studies and libertarian theories of law. Experimental jurisprudence Experimental jurisprudence seeks to investigate the content of legal concepts using the methods of social science, unlike the philosophical methods of traditional jurisprudence. List of philosophers of law See also References Bibliography Further reading External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Sirin,_Baysan] | [TOKENS: 1288] |
Contents Sirin, Baysan Sirin (Arabic: سرين), was a Palestinian Arab village located 17 kilometers (11 mi) north of Beisan. The village was depopulated and destroyed in 1948. Only the village cemetery and one house remain standing, along with the remains of a mosaic pavement and a vaulted spring dating to the Byzantine period. Mentioned in historical documents, the 1596 census indicated it had 45 households; by 1945, the number of inhabitants had risen to 810. History The village dated back to the Roman period. Near a spring were two fallen blocks, apparently lintels, which had the appearance of dating back to the Byzantine period. Several other remains from the Byzantine era were also found in the village, including a Greek inscription and parts of a mosaic pavement. Conder suggested that it was identical with the Sirin, a place inhabited by Samaritans in the 7th century. In 1168, during the Crusader period, the village was known as Losserin. That year it was sold by a certain Simon Chevron to the Hospitalliers. In 1994, Andrew Petersen visited Sirin, and inspected a rectangular (10 x 12 meters) tower structure. It had two entrances, one to the north and one to the south, where the south side was the original, older part. The masonry and arches indicate that the original structure dates to the Crusader era, while the later northern entrance dated to an Ottoman reconstruction. Like other villages in Palestine, Sirin fell under the rule of the Ottoman Empire between 1517 and 1918. During the 16th and 17th centuries, Sitin al-Turab, as the village was called, belonged to the Turabay Emirate (1517-1683), which encompassed also the Jezreel Valley, Haifa, Jenin, Beit She'an Valley, northern Jabal Nablus, Bilad al-Ruha/Ramot Menashe, and the northern part of the Sharon plain. In the 1596 tax records, Sirin formed part of the nahiya (subdistrict) of Jenin under the liwa' ("district") of Lajjun, with a population of 45 Muslim household. Villagers paid a fixed tax rate of 25% on a number of crops, including wheat and barley, as well as on goats and beehives; a total of 20,600 akçe. A map by Pierre Jacotin from Napoleon's invasion of 1799 showed the place, named as Serin. James Silk Buckingham, who visited the village in 1816, transcribes its name as "Sereen" and describes it as being made up of about thirty to forty houses with half a dozen Bedouin tents located close to it. In 1838 Edward Robinson noted it as one of the villages at the brow of the Jordan valley, together with Awlam. In 1859, the English consul estimated the population to be about 100 inhabitants, who cultivated 35 faddans of land In 1875 Victor Guérin found the village to have 400 inhabitants. He further noted an ancient tower, each side measuring 14 steps. The remains of two churches were seen, one of them had been transformed into a mosque. There was also a Wali nearby, called Neby Sirin. In 1882, the PEF's Survey of Western Palestine described the village of Sirin as being an adobe village of moderate size, surrounded by hedges of prickly pear. In the 1922 census of Palestine, conducted by the authorities of Mandatory Palestine, Sirin had a population of 681; 621 Muslims and 60 Christians, where all the Christians were Roman Catholics. The population had decreased slightly by the 1931 census to 630; 562 Muslims and 68 Christians, in a total of 161 houses. In the 1945 statistics, the population was 810; 620 Muslims and 190 Christians and the total land area was 28,445 dunums. Of the land, 413 dunums were used for plantations and irrigable land, 15,813 for cereals, while a total of 131 dunums were classified as built-up land. First evacuated in April 1948 by Jewish forces, by June 1948, some of the inhabitants had returned. Permanently depopulated by Israeli troops in the summer of 1948, Sirin was then completely destroyed. Benny Morris writes that Sirin was one of the first of approximately two dozen villages that were evacuated on Arab orders in April–May 1948 for "pre-invasion military reasons." However Ilan Pappe writes that the village had not been evacuated and that it expected that it "would be exempt from the fate of the nearby villages", due to its good connections with Jewish authorities, but that it was nonetheless occupied by Jewish troops on May 12, 1948, expelling the population and destroying the mosque, church and monastery. When Israeli troops entered Sirin in June 1948, they that about 100 inhabitants had returned. After checking their IDs and searching for weapons (finding only some knives), the troops left the village. A report from the battalion's intelligence officer recommended, "the Arabs should be ejected from the area, the young men should be arrested, and the crops confiscated ..." Sirin, along with the villages of Hadatha, 'Ulam, and Ma'dhar, were all ethnically cleansed by Israeli troops in the summer of 1948. Walid Khalidi described all that was left of the village structures of Sirin in 1992: "The cemetery and one house (which serves as a storage room for straw) are all that remain of Sirin. Stone rubble surrounded by clusters of cactuses can be seen on the site. The site itself is used as a stockyard for cattle. The spring in the middle of the site is covered with a stone structure. Some of the land around the village is planted in cotton." In 1994, Andrew Petersen visited Sirin and inspected the ruins of a Crusader tower. See also References Bibliography External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Middle_Eastern_dance] | [TOKENS: 432] |
Contents Middle Eastern dance Middle Eastern dance, sometimes called oriental dance, comprises a variety of dancing styles historically associated with ethnic groups in the Middle East. It may include influences from other parts of the world, such as Western dance, and may also be present in regions that have overlapping or shared ethnic or cultural demographics with the Middle East (namely North Africa, which is part of the Arab world) per se. The Middle East is generally understood as a region that comprises the majority of West Asia, albeit including Egypt and excluding the Caucasus. Tentative list Middle Eastern Arab dance encompasses historical dancing styles among Arabs in the Arabian Peninsula and the Levant, as well as Iraq and Egypt. It includes the following: ardah, baladi, belly dancing, dabke, deheyeh, fann at-tanbura, hosa, khaleegy, mizmar, raqs sharqi, shamadan, tahtib, tanoura, and yowlah. The Armenians are an ethnic group who, while indigenous to the Armenian highlands, have historically inhabited and culturally impacted parts of modern-day Turkey, Lebanon, and Iran, among other countries. Consequently, Armenian dance has been present in the Middle East for centuries, including: berd, kochari, shalakho, tamzara, and yarkhushta. Assyrian folk dance: khigga. See: Greek Cypriot dance and Turkish Cypriot dance. Kurdish dance: dilan. A highly stylized, graceful form that evolved from 19th century Qajar court dances. It emphasizes fluid upper body movements, intricate hand and finger work and expressive facial gestures. Modern versions often incorporate elements of ballet. Persian dance: classical Persian dance. Turkish dance is a diverse art form shaped by Central Asian roots, Anatolian history, Islamic influence, and the expansion of the Ottoman Empire. It ranges from highly spiritual rituals to high energy regional folk dances. Turkish dance: Çiftetelli, halay. Jewish dance: Hora, Tza'ad Teimani, Israeli folk dance See also References Further reading External links |
======================================== |
[SOURCE: https://en.wikipedia.org/wiki/Mars#cite_ref-Mallama_and_Hilton_21-3] | [TOKENS: 11899] |
Contents Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", for its orange-red appearance. Mars is a desert-like rocky planet with a tenuous atmosphere that is primarily carbon dioxide (CO2). At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from −153 to 20 °C (−243 to 68 °F), and cosmic radiation is high. Mars retains some water, in the ground as well as thinly in the atmosphere, forming cirrus clouds, fog, frost, larger polar regions of permafrost and ice caps (with seasonal CO2 snow), but no bodies of liquid surface water. Its surface gravity is roughly a third of Earth's or double that of the Moon. Its diameter, 6,779 km (4,212 mi), is about half the Earth's, or twice the Moon's, and its surface area is the size of all the dry land of Earth. Fine dust is prevalent across the surface and the atmosphere, being picked up and spread at the low Martian gravity even by the weak wind of the tenuous atmosphere. The terrain of Mars roughly follows a north-south divide, the Martian dichotomy, with the northern hemisphere mainly consisting of relatively flat, low lying plains, and the southern hemisphere of cratered highlands. Geologically, the planet is fairly active with marsquakes trembling underneath the ground, but also hosts many enormous volcanoes that are extinct (the tallest is Olympus Mons, 21.9 km or 13.6 mi tall), as well as one of the largest canyons in the Solar System (Valles Marineris, 4,000 km or 2,500 mi long). Mars has two natural satellites that are small and irregular in shape: Phobos and Deimos. With a significant axial tilt of 25 degrees, Mars experiences seasons, like Earth (which has an axial tilt of 23.5 degrees). A Martian solar year is equal to 1.88 Earth years (687 Earth days), a Martian solar day (sol) is equal to 24.6 hours. Mars formed along with the other planets approximately 4.5 billion years ago. During the martian Noachian period (4.5 to 3.5 billion years ago), its surface was marked by meteor impacts, valley formation, erosion, the possible presence of water oceans and the loss of its magnetosphere. The Hesperian period (beginning 3.5 billion years ago and ending 3.3–2.9 billion years ago) was dominated by widespread volcanic activity and flooding that carved immense outflow channels. The Amazonian period, which continues to the present, is the currently dominating and remaining influence on geological processes. Because of Mars's geological history, the possibility of past or present life on Mars remains an area of active scientific investigation, with some possible traces needing further examination. Being visible with the naked eye in Earth's sky as a red wandering star, Mars has been observed throughout history, acquiring diverse associations in different cultures. In 1963 the first flight to Mars took place with Mars 1, but communication was lost en route. The first successful flyby exploration of Mars was conducted in 1965 with Mariner 4. In 1971 Mariner 9 entered orbit around Mars, being the first spacecraft to orbit any body other than the Moon, Sun or Earth; following in the same year were the first uncontrolled impact (Mars 2) and first successful landing (Mars 3) on Mars. Probes have been active on Mars continuously since 1997. At times, more than ten probes have simultaneously operated in orbit or on the surface, more than at any other planet beyond Earth. Mars is an often proposed target for future crewed exploration missions, though no such mission is currently planned. Natural history Scientists have theorized that during the Solar System's formation, Mars was created as the result of a random process of run-away accretion of material from the protoplanetary disk that orbited the Sun. Mars has many distinctive chemical features caused by its position in the Solar System. Elements with comparatively low boiling points, such as chlorine, phosphorus, and sulfur, are much more common on Mars than on Earth; these elements were probably pushed outward by the young Sun's energetic solar wind. After the formation of the planets, the inner Solar System may have been subjected to the so-called Late Heavy Bombardment. About 60% of the surface of Mars shows a record of impacts from that era, whereas much of the remaining surface is probably underlain by immense impact basins caused by those events. However, more recent modeling has disputed the existence of the Late Heavy Bombardment. There is evidence of an enormous impact basin in the Northern Hemisphere of Mars, spanning 10,600 by 8,500 kilometres (6,600 by 5,300 mi), or roughly four times the size of the Moon's South Pole–Aitken basin, which would be the largest impact basin yet discovered if confirmed. It has been hypothesized that the basin was formed when Mars was struck by a Pluto-sized body about four billion years ago. The event, thought to be the cause of the Martian hemispheric dichotomy, created the smooth Borealis basin that covers 40% of the planet. A 2023 study shows evidence, based on the orbital inclination of Deimos (a small moon of Mars), that Mars may once have had a ring system 3.5 billion years to 4 billion years ago. This ring system may have been formed from a moon, 20 times more massive than Phobos, orbiting Mars billions of years ago; and Phobos would be a remnant of that ring. Epochs: The geological history of Mars can be split into many periods, but the following are the three primary periods: Geological activity is still taking place on Mars. The Athabasca Valles is home to sheet-like lava flows created about 200 million years ago. Water flows in the grabens called the Cerberus Fossae occurred less than 20 million years ago, indicating equally recent volcanic intrusions. The Mars Reconnaissance Orbiter has captured images of avalanches. Physical characteristics Mars is approximately half the diameter of Earth or twice that of the Moon, with a surface area only slightly less than the total area of Earth's dry land. Mars is less dense than Earth, having about 15% of Earth's volume and 11% of Earth's mass, resulting in about 38% of Earth's surface gravity. Mars is the only presently known example of a desert planet, a rocky planet with a surface akin to that of Earth's deserts. The red-orange appearance of the Martian surface is caused by iron(III) oxide (nanophase Fe2O3) and the iron(III) oxide-hydroxide mineral goethite. It can look like butterscotch; other common surface colors include golden, brown, tan, and greenish, depending on the minerals present. Like Earth, Mars is differentiated into a dense metallic core overlaid by less dense rocky layers. The outermost layer is the crust, which is on average about 42–56 kilometres (26–35 mi) thick, with a minimum thickness of 6 kilometres (3.7 mi) in Isidis Planitia, and a maximum thickness of 117 kilometres (73 mi) in the southern Tharsis plateau. For comparison, Earth's crust averages 27.3 ± 4.8 km in thickness. The most abundant elements in the Martian crust are silicon, oxygen, iron, magnesium, aluminum, calcium, and potassium. Mars is confirmed to be seismically active; in 2019, it was reported that InSight had detected and recorded over 450 marsquakes and related events. Beneath the crust is a silicate mantle responsible for many of the tectonic and volcanic features on the planet's surface. The upper Martian mantle is a low-velocity zone, where the velocity of seismic waves is lower than surrounding depth intervals. The mantle appears to be rigid down to the depth of about 250 km, giving Mars a very thick lithosphere compared to Earth. Below this the mantle gradually becomes more ductile, and the seismic wave velocity starts to grow again. The Martian mantle does not appear to have a thermally insulating layer analogous to Earth's lower mantle; instead, below 1050 km in depth, it becomes mineralogically similar to Earth's transition zone. At the bottom of the mantle lies a basal liquid silicate layer approximately 150–180 km thick. The Martian mantle appears to be highly heterogenous, with dense fragments up to 4 km across, likely injected deep into the planet by colossal impacts ~4.5 billion years ago; high-frequency waves from eight marsquakes slowed as they passed these localized regions, and modeling indicates the heterogeneities are compositionally distinct debris preserved because Mars lacks plate tectonics and has a sluggishly convecting interior that prevents complete homogenization. Mars's iron and nickel core is at least partially molten, and may have a solid inner core. It is around half of Mars's radius, approximately 1650–1675 km, and is enriched in light elements such as sulfur, oxygen, carbon, and hydrogen. The temperature of the core is estimated to be 2000–2400 K, compared to 5400–6230 K for Earth's solid inner core. In 2025, based on data from the InSight lander, a group of researchers reported the detection of a solid inner core 613 kilometres (381 mi) ± 67 kilometres (42 mi) in radius. Mars is a terrestrial planet with a surface that consists of minerals containing silicon and oxygen, metals, and other elements that typically make up rock. The Martian surface is primarily composed of tholeiitic basalt, although parts are more silica-rich than typical basalt and may be similar to andesitic rocks on Earth, or silica glass. Regions of low albedo suggest concentrations of plagioclase feldspar, with northern low albedo regions displaying higher than normal concentrations of sheet silicates and high-silicon glass. Parts of the southern highlands include detectable amounts of high-calcium pyroxenes. Localized concentrations of hematite and olivine have been found. Much of the surface is deeply covered by finely grained iron(III) oxide dust. The Phoenix lander returned data showing Martian soil to be slightly alkaline and containing elements such as magnesium, sodium, potassium and chlorine. These nutrients are found in soils on Earth, and are necessary for plant growth. Experiments performed by the lander showed that the Martian soil has a basic pH of 7.7, and contains 0.6% perchlorate by weight, concentrations that are toxic to humans. Streaks are common across Mars and new ones appear frequently on steep slopes of craters, troughs, and valleys. The streaks are dark at first and get lighter with age. The streaks can start in a tiny area, then spread out for hundreds of metres. They have been seen to follow the edges of boulders and other obstacles in their path. The commonly accepted hypotheses include that they are dark underlying layers of soil revealed after avalanches of bright dust or dust devils. Several other explanations have been put forward, including those that involve water or even the growth of organisms. Environmental radiation levels on the surface are on average 0.64 millisieverts of radiation per day, and significantly less than the radiation of 1.84 millisieverts per day or 22 millirads per day during the flight to and from Mars. For comparison the radiation levels in low Earth orbit, where Earth's space stations orbit, are around 0.5 millisieverts of radiation per day. Hellas Planitia has the lowest surface radiation at about 0.342 millisieverts per day, featuring lava tubes southwest of Hadriacus Mons with potentially levels as low as 0.064 millisieverts per day, comparable to radiation levels during flights on Earth. Although Mars has no evidence of a structured global magnetic field, observations show that parts of the planet's crust have been magnetized, suggesting that alternating polarity reversals of its dipole field have occurred in the past. This paleomagnetism of magnetically susceptible minerals is similar to the alternating bands found on Earth's ocean floors. One hypothesis, published in 1999 and re-examined in October 2005 (with the help of the Mars Global Surveyor), is that these bands suggest plate tectonic activity on Mars four billion years ago, before the planetary dynamo ceased to function and the planet's magnetic field faded. Geography and features Although better remembered for mapping the Moon, Johann Heinrich von Mädler and Wilhelm Beer were the first areographers. They began by establishing that most of Mars's surface features were permanent and by more precisely determining the planet's rotation period. In 1840, Mädler combined ten years of observations and drew the first map of Mars. Features on Mars are named from a variety of sources. Albedo features are named for classical mythology. Craters larger than roughly 50 km are named for deceased scientists and writers and others who have contributed to the study of Mars. Smaller craters are named for towns and villages of the world with populations of less than 100,000. Large valleys are named for the word "Mars" or "star" in various languages; smaller valleys are named for rivers. Large albedo features retain many of the older names but are often updated to reflect new knowledge of the nature of the features. For example, Nix Olympica (the snows of Olympus) has become Olympus Mons (Mount Olympus). The surface of Mars as seen from Earth is divided into two kinds of areas, with differing albedo. The paler plains covered with dust and sand rich in reddish iron oxides were once thought of as Martian "continents" and given names like Arabia Terra (land of Arabia) or Amazonis Planitia (Amazonian plain). The dark features were thought to be seas, hence their names Mare Erythraeum, Mare Sirenum and Aurorae Sinus. The largest dark feature seen from Earth is Syrtis Major Planum. The permanent northern polar ice cap is named Planum Boreum. The southern cap is called Planum Australe. Mars's equator is defined by its rotation, but the location of its Prime Meridian was specified, as was Earth's (at Greenwich), by choice of an arbitrary point; Mädler and Beer selected a line for their first maps of Mars in 1830. After the spacecraft Mariner 9 provided extensive imagery of Mars in 1972, a small crater (later called Airy-0), located in the Sinus Meridiani ("Middle Bay" or "Meridian Bay"), was chosen by Merton E. Davies, Harold Masursky, and Gérard de Vaucouleurs for the definition of 0.0° longitude to coincide with the original selection. Because Mars has no oceans, and hence no "sea level", a zero-elevation surface had to be selected as a reference level; this is called the areoid of Mars, analogous to the terrestrial geoid. Zero altitude was defined by the height at which there is 610.5 Pa (6.105 mbar) of atmospheric pressure. This pressure corresponds to the triple point of water, and it is about 0.6% of the sea level surface pressure on Earth (0.006 atm). For mapping purposes, the United States Geological Survey divides the surface of Mars into thirty cartographic quadrangles, each named for a classical albedo feature it contains. In April 2023, The New York Times reported an updated global map of Mars based on images from the Hope spacecraft. A related, but much more detailed, global Mars map was released by NASA on 16 April 2023. The vast upland region Tharsis contains several massive volcanoes, which include the shield volcano Olympus Mons. The edifice is over 600 km (370 mi) wide. Because the mountain is so large, with complex structure at its edges, giving a definite height to it is difficult. Its local relief, from the foot of the cliffs which form its northwest margin to its peak, is over 21 km (13 mi), a little over twice the height of Mauna Kea as measured from its base on the ocean floor. The total elevation change from the plains of Amazonis Planitia, over 1,000 km (620 mi) to the northwest, to the summit approaches 26 km (16 mi), roughly three times the height of Mount Everest, which in comparison stands at just over 8.8 kilometres (5.5 mi). Consequently, Olympus Mons is either the tallest or second-tallest mountain in the Solar System; the only known mountain which might be taller is the Rheasilvia peak on the asteroid Vesta, at 20–25 km (12–16 mi). The dichotomy of Martian topography is striking: northern plains flattened by lava flows contrast with the southern highlands, pitted and cratered by ancient impacts. It is possible that, four billion years ago, the Northern Hemisphere of Mars was struck by an object one-tenth to two-thirds the size of Earth's Moon. If this is the case, the Northern Hemisphere of Mars would be the site of an impact crater 10,600 by 8,500 kilometres (6,600 by 5,300 mi) in size, or roughly the area of Europe, Asia, and Australia combined, surpassing Utopia Planitia and the Moon's South Pole–Aitken basin as the largest impact crater in the Solar System. Mars is scarred by 43,000 impact craters with a diameter of 5 kilometres (3.1 mi) or greater. The largest exposed crater is Hellas, which is 2,300 kilometres (1,400 mi) wide and 7,000 metres (23,000 ft) deep, and is a light albedo feature clearly visible from Earth. There are other notable impact features, such as Argyre, which is around 1,800 kilometres (1,100 mi) in diameter, and Isidis, which is around 1,500 kilometres (930 mi) in diameter. Due to the smaller mass and size of Mars, the probability of an object colliding with the planet is about half that of Earth. Mars is located closer to the asteroid belt, so it has an increased chance of being struck by materials from that source. Mars is more likely to be struck by short-period comets, i.e., those that lie within the orbit of Jupiter. Martian craters can[discuss] have a morphology that suggests the ground became wet after the meteor impact. The large canyon, Valles Marineris (Latin for 'Mariner Valleys, also known as Agathodaemon in the old canal maps), has a length of 4,000 kilometres (2,500 mi) and a depth of up to 7 kilometres (4.3 mi). The length of Valles Marineris is equivalent to the length of Europe and extends across one-fifth the circumference of Mars. By comparison, the Grand Canyon on Earth is only 446 kilometres (277 mi) long and nearly 2 kilometres (1.2 mi) deep. Valles Marineris was formed due to the swelling of the Tharsis area, which caused the crust in the area of Valles Marineris to collapse. In 2012, it was proposed that Valles Marineris is not just a graben, but a plate boundary where 150 kilometres (93 mi) of transverse motion has occurred, making Mars a planet with possibly a two-tectonic plate arrangement. Images from the Thermal Emission Imaging System (THEMIS) aboard NASA's Mars Odyssey orbiter have revealed seven possible cave entrances on the flanks of the volcano Arsia Mons. The caves, named after loved ones of their discoverers, are collectively known as the "seven sisters". Cave entrances measure from 100 to 252 metres (328 to 827 ft) wide and they are estimated to be at least 73 to 96 metres (240 to 315 ft) deep. Because light does not reach the floor of most of the caves, they may extend much deeper than these lower estimates and widen below the surface. "Dena" is the only exception; its floor is visible and was measured to be 130 metres (430 ft) deep. The interiors of these caverns may be protected from micrometeoroids, UV radiation, solar flares and high energy particles that bombard the planet's surface. Martian geysers (or CO2 jets) are putative sites of small gas and dust eruptions that occur in the south polar region of Mars during the spring thaw. "Dark dune spots" and "spiders" – or araneiforms – are the two most visible types of features ascribed to these eruptions. Similarly sized dust will settle from the thinner Martian atmosphere sooner than it would on Earth. For example, the dust suspended by the 2001 global dust storms on Mars only remained in the Martian atmosphere for 0.6 years, while the dust from Mount Pinatubo took about two years to settle. However, under current Martian conditions, the mass movements involved are generally much smaller than on Earth. Even the 2001 global dust storms on Mars moved only the equivalent of a very thin dust layer – about 3 μm thick if deposited with uniform thickness between 58° north and south of the equator. Dust deposition at the two rover sites has proceeded at a rate of about the thickness of a grain every 100 sols. Atmosphere Mars lost its magnetosphere 4 billion years ago, possibly because of numerous asteroid strikes, so the solar wind interacts directly with the Martian ionosphere, lowering the atmospheric density by stripping away atoms from the outer layer. Both Mars Global Surveyor and Mars Express have detected ionized atmospheric particles trailing off into space behind Mars, and this atmospheric loss is being studied by the MAVEN orbiter. Compared to Earth, the atmosphere of Mars is quite rarefied. Atmospheric pressure on the surface today ranges from a low of 30 Pa (0.0044 psi) on Olympus Mons to over 1,155 Pa (0.1675 psi) in Hellas Planitia, with a mean pressure at the surface level of 600 Pa (0.087 psi). The highest atmospheric density on Mars is equal to that found 35 kilometres (22 mi) above Earth's surface. The resulting mean surface pressure is only 0.6% of Earth's 101.3 kPa (14.69 psi). The scale height of the atmosphere is about 10.8 kilometres (6.7 mi), which is higher than Earth's 6 kilometres (3.7 mi), because the surface gravity of Mars is only about 38% of Earth's. The atmosphere of Mars consists of about 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water. The atmosphere is quite dusty, containing particulates about 1.5 μm in diameter which give the Martian sky a tawny color when seen from the surface. It may take on a pink hue due to iron oxide particles suspended in it. Despite repeated detections of methane on Mars, there is no scientific consensus as to its origin. One suggestion is that methane exists on Mars and that its concentration fluctuates seasonally. The existence of methane could be produced by non-biological process such as serpentinization involving water, carbon dioxide, and the mineral olivine, which is known to be common on Mars, or by Martian life. Compared to Earth, its higher concentration of atmospheric CO2 and lower surface pressure may be why sound is attenuated more on Mars, where natural sources are rare apart from the wind. Using acoustic recordings collected by the Perseverance rover, researchers concluded that the speed of sound there is approximately 240 m/s for frequencies below 240 Hz, and 250 m/s for those above. Auroras have been detected on Mars. Because Mars lacks a global magnetic field, the types and distribution of auroras there differ from those on Earth; rather than being mostly restricted to polar regions as is the case on Earth, a Martian aurora can encompass the planet. In September 2017, NASA reported radiation levels on the surface of the planet Mars were temporarily doubled, and were associated with an aurora 25 times brighter than any observed earlier, due to a massive, and unexpected, solar storm in the middle of the month. Mars has seasons, alternating between its northern and southern hemispheres, similar to on Earth. Additionally the orbit of Mars has, compared to Earth's, a large eccentricity and approaches perihelion when it is summer in its southern hemisphere and winter in its northern, and aphelion when it is winter in its southern hemisphere and summer in its northern. As a result, the seasons in its southern hemisphere are more extreme and the seasons in its northern are milder than would otherwise be the case. The summer temperatures in the south can be warmer than the equivalent summer temperatures in the north by up to 30 °C (54 °F). Martian surface temperatures vary from lows of about −110 °C (−166 °F) to highs of up to 35 °C (95 °F) in equatorial summer. The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure (about 1% that of the atmosphere of Earth), and the low thermal inertia of Martian soil. The planet is 1.52 times as far from the Sun as Earth, resulting in just 43% of the amount of sunlight. Mars has the largest dust storms in the Solar System, reaching speeds of over 160 km/h (100 mph). These can vary from a storm over a small area, to gigantic storms that cover the entire planet. They tend to occur when Mars is closest to the Sun, and have been shown to increase global temperature. Seasons also produce dry ice covering polar ice caps. Hydrology While Mars contains water in larger amounts, most of it is dust covered water ice at the Martian polar ice caps. The volume of water ice in the south polar ice cap, if melted, would be enough to cover most of the surface of the planet with a depth of 11 metres (36 ft). Water in its liquid form cannot persist on the surface due to Mars's low atmospheric pressure, which is less than 1% that of Earth. Only at the lowest of elevations are the pressure and temperature high enough for liquid water to exist for short periods. Although little water is present in the atmosphere, there is enough to produce clouds of water ice and different cases of snow and frost, often mixed with snow of carbon dioxide dry ice. Landforms visible on Mars strongly suggest that liquid water has existed on the planet's surface. Huge linear swathes of scoured ground, known as outflow channels, cut across the surface in about 25 places. These are thought to be a record of erosion caused by the catastrophic release of water from subsurface aquifers, though some of these structures have been hypothesized to result from the action of glaciers or lava. One of the larger examples, Ma'adim Vallis, is 700 kilometres (430 mi) long, much greater than the Grand Canyon, with a width of 20 kilometres (12 mi) and a depth of 2 kilometres (1.2 mi) in places. It is thought to have been carved by flowing water early in Mars's history. The youngest of these channels is thought to have formed only a few million years ago. Elsewhere, particularly on the oldest areas of the Martian surface, finer-scale, dendritic networks of valleys are spread across significant proportions of the landscape. Features of these valleys and their distribution strongly imply that they were carved by runoff resulting from precipitation in early Mars history. Subsurface water flow and groundwater sapping may play important subsidiary roles in some networks, but precipitation was probably the root cause of the incision in almost all cases. Along craters and canyon walls, there are thousands of features that appear similar to terrestrial gullies. The gullies tend to be in the highlands of the Southern Hemisphere and face the Equator; all are poleward of 30° latitude. A number of authors have suggested that their formation process involves liquid water, probably from melting ice, although others have argued for formation mechanisms involving carbon dioxide frost or the movement of dry dust. No partially degraded gullies have formed by weathering and no superimposed impact craters have been observed, indicating that these are young features, possibly still active. Other geological features, such as deltas and alluvial fans preserved in craters, are further evidence for warmer, wetter conditions at an interval or intervals in earlier Mars history. Such conditions necessarily require the widespread presence of crater lakes across a large proportion of the surface, for which there is independent mineralogical, sedimentological and geomorphological evidence. Further evidence that liquid water once existed on the surface of Mars comes from the detection of specific minerals such as hematite and goethite, both of which sometimes form in the presence of water. The chemical signature of water vapor on Mars was first unequivocally demonstrated in 1963 by spectroscopy using an Earth-based telescope. In 2004, Opportunity detected the mineral jarosite. This forms only in the presence of acidic water, showing that water once existed on Mars. The Spirit rover found concentrated deposits of silica in 2007 that indicated wet conditions in the past, and in December 2011, the mineral gypsum, which also forms in the presence of water, was found on the surface by NASA's Mars rover Opportunity. It is estimated that the amount of water in the upper mantle of Mars, represented by hydroxyl ions contained within Martian minerals, is equal to or greater than that of Earth at 50–300 parts per million of water, which is enough to cover the entire planet to a depth of 200–1,000 metres (660–3,280 ft). On 18 March 2013, NASA reported evidence from instruments on the Curiosity rover of mineral hydration, likely hydrated calcium sulfate, in several rock samples including the broken fragments of "Tintina" rock and "Sutton Inlier" rock as well as in veins and nodules in other rocks like "Knorr" rock and "Wernicke" rock. Analysis using the rover's DAN instrument provided evidence of subsurface water, amounting to as much as 4% water content, down to a depth of 60 centimetres (24 in), during the rover's traverse from the Bradbury Landing site to the Yellowknife Bay area in the Glenelg terrain. In September 2015, NASA announced that they had found strong evidence of hydrated brine flows in recurring slope lineae, based on spectrometer readings of the darkened areas of slopes. These streaks flow downhill in Martian summer, when the temperature is above −23 °C, and freeze at lower temperatures. These observations supported earlier hypotheses, based on timing of formation and their rate of growth, that these dark streaks resulted from water flowing just below the surface. However, later work suggested that the lineae may be dry, granular flows instead, with at most a limited role for water in initiating the process. A definitive conclusion about the presence, extent, and role of liquid water on the Martian surface remains elusive. Researchers suspect much of the low northern plains of the planet were covered with an ocean hundreds of meters deep, though this theory remains controversial. In March 2015, scientists stated that such an ocean might have been the size of Earth's Arctic Ocean. This finding was derived from the ratio of protium to deuterium in the modern Martian atmosphere compared to that ratio on Earth. The amount of Martian deuterium (D/H = 9.3 ± 1.7 10−4) is five to seven times the amount on Earth (D/H = 1.56 10−4), suggesting that ancient Mars had significantly higher levels of water. Results from the Curiosity rover had previously found a high ratio of deuterium in Gale Crater, though not significantly high enough to suggest the former presence of an ocean. Other scientists caution that these results have not been confirmed, and point out that Martian climate models have not yet shown that the planet was warm enough in the past to support bodies of liquid water. Near the northern polar cap is the 81.4 kilometres (50.6 mi) wide Korolev Crater, which the Mars Express orbiter found to be filled with approximately 2,200 cubic kilometres (530 cu mi) of water ice. In November 2016, NASA reported finding a large amount of underground ice in the Utopia Planitia region. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior (which is 12,100 cubic kilometers). During observations from 2018 through 2021, the ExoMars Trace Gas Orbiter spotted indications of water, probably subsurface ice, in the Valles Marineris canyon system. Orbital motion Mars's average distance from the Sun is roughly 230 million km (143 million mi), and its orbital period is 687 (Earth) days. The solar day (or sol) on Mars is only slightly longer than an Earth day: 24 hours, 39 minutes, and 35.244 seconds. A Martian year is equal to 1.8809 Earth years, or 1 year, 320 days, and 18.2 hours. The gravitational potential difference and thus the delta-v needed to transfer between Mars and Earth is the second lowest for Earth. The axial tilt of Mars is 25.19° relative to its orbital plane, which is similar to the axial tilt of Earth. As a result, Mars has seasons like Earth, though on Mars they are nearly twice as long because its orbital period is that much longer. In the present day, the orientation of the north pole of Mars is close to the star Deneb. Mars has a relatively pronounced orbital eccentricity of about 0.09; of the seven other planets in the Solar System, only Mercury has a larger orbital eccentricity. It is known that in the past, Mars has had a much more circular orbit. At one point, 1.35 million Earth years ago, Mars had an eccentricity of roughly 0.002, much less than that of Earth today. Mars's cycle of eccentricity is 96,000 Earth years compared to Earth's cycle of 100,000 years. Mars has its closest approach to Earth (opposition) in a synodic period of 779.94 days. It should not be confused with Mars conjunction, where the Earth and Mars are at opposite sides of the Solar System and form a straight line crossing the Sun. The average time between the successive oppositions of Mars, its synodic period, is 780 days; but the number of days between successive oppositions can range from 764 to 812. The distance at close approach varies between about 54 and 103 million km (34 and 64 million mi) due to the planets' elliptical orbits, which causes comparable variation in angular size. At their furthest Mars and Earth can be as far as 401 million km (249 million mi) apart. Mars comes into opposition from Earth every 2.1 years. The planets come into opposition near Mars's perihelion in 2003, 2018 and 2035, with the 2020 and 2033 events being particularly close to perihelic opposition. The mean apparent magnitude of Mars is +0.71 with a standard deviation of 1.05. Because the orbit of Mars is eccentric, the magnitude at opposition from the Sun can range from about −3.0 to −1.4. The minimum brightness is magnitude +1.86 when the planet is near aphelion and in conjunction with the Sun. At its brightest, Mars (along with Jupiter) is second only to Venus in apparent brightness. Mars usually appears distinctly yellow, orange, or red. When farthest away from Earth, it is more than seven times farther away than when it is closest. Mars is usually close enough for particularly good viewing once or twice at 15-year or 17-year intervals. Optical ground-based telescopes are typically limited to resolving features about 300 kilometres (190 mi) across when Earth and Mars are closest because of Earth's atmosphere. As Mars approaches opposition, it begins a period of retrograde motion, which means it will appear to move backwards in a looping curve with respect to the background stars. This retrograde motion lasts for about 72 days, and Mars reaches its peak apparent brightness in the middle of this interval. Moons Mars has two relatively small (compared to Earth's) natural moons, Phobos (about 22 km (14 mi) in diameter) and Deimos (about 12 km (7.5 mi) in diameter), which orbit at 9,376 km (5,826 mi) and 23,460 km (14,580 mi) around the planet. The origin of both moons is unclear, although a popular theory states that they were asteroids captured into Martian orbit. Both satellites were discovered in 1877 by Asaph Hall and were named after the characters Phobos (the deity of panic and fear) and Deimos (the deity of terror and dread), twins from Greek mythology who accompanied their father Ares, god of war, into battle. Mars was the Roman equivalent to Ares. In modern Greek, the planet retains its ancient name Ares (Aris: Άρης). From the surface of Mars, the motions of Phobos and Deimos appear different from that of the Earth's satellite, the Moon. Phobos rises in the west, sets in the east, and rises again in just 11 hours. Deimos, being only just outside synchronous orbit – where the orbital period would match the planet's period of rotation – rises as expected in the east, but slowly. Because the orbit of Phobos is below a synchronous altitude, tidal forces from Mars are gradually lowering its orbit. In about 50 million years, it could either crash into Mars's surface or break up into a ring structure around the planet. The origin of the two satellites is not well understood. Their low albedo and carbonaceous chondrite composition have been regarded as similar to asteroids, supporting a capture theory. The unstable orbit of Phobos would seem to point toward a relatively recent capture. But both have circular orbits near the equator, which is unusual for captured objects, and the required capture dynamics are complex. Accretion early in the history of Mars is plausible, but would not account for a composition resembling asteroids rather than Mars itself, if that is confirmed. Mars may have yet-undiscovered moons, smaller than 50 to 100 metres (160 to 330 ft) in diameter, and a dust ring is predicted to exist between Phobos and Deimos. A third possibility for their origin as satellites of Mars is the involvement of a third body or a type of impact disruption. More-recent lines of evidence for Phobos having a highly porous interior, and suggesting a composition containing mainly phyllosilicates and other minerals known from Mars, point toward an origin of Phobos from material ejected by an impact on Mars that reaccreted in Martian orbit, similar to the prevailing theory for the origin of Earth's satellite. Although the visible and near-infrared (VNIR) spectra of the moons of Mars resemble those of outer-belt asteroids, the thermal infrared spectra of Phobos are reported to be inconsistent with chondrites of any class. It is also possible that Phobos and Deimos were fragments of an older moon, formed by debris from a large impact on Mars, and then destroyed by a more recent impact upon the satellite. More recently, a study conducted by a team of researchers from multiple countries suggests that a lost moon, at least fifteen times the size of Phobos, may have existed in the past. By analyzing rocks which point to tidal processes on the planet, it is possible that these tides may have been regulated by a past moon. Human observations and exploration The history of observations of Mars is marked by oppositions of Mars when the planet is closest to Earth and hence is most easily visible, which occur every couple of years. Even more notable are the perihelic oppositions of Mars, which are distinguished because Mars is close to perihelion, making it even closer to Earth. The ancient Sumerians named Mars Nergal, the god of war and plague. During Sumerian times, Nergal was a minor deity of little significance, but, during later times, his main cult center was the city of Nineveh. In Mesopotamian texts, Mars is referred to as the "star of judgement of the fate of the dead". The existence of Mars as a wandering object in the night sky was also recorded by the ancient Egyptian astronomers and, by 1534 BCE, they were familiar with the retrograde motion of the planet. By the period of the Neo-Babylonian Empire, the Babylonian astronomers were making regular records of the positions of the planets and systematic observations of their behavior. For Mars, they knew that the planet made 37 synodic periods, or 42 circuits of the zodiac, every 79 years. They invented arithmetic methods for making minor corrections to the predicted positions of the planets. In Ancient Greece, the planet was known as Πυρόεις. Commonly, the Greek name for the planet now referred to as Mars, was Ares. It was the Romans who named the planet Mars, for their god of war, often represented by the sword and shield of the planet's namesake. In the fourth century BCE, Aristotle noted that Mars disappeared behind the Moon during an occultation, indicating that the planet was farther away. Ptolemy, a Greek living in Alexandria, attempted to address the problem of the orbital motion of Mars. Ptolemy's model and his collective work on astronomy was presented in the multi-volume collection later called the Almagest (from the Arabic for "greatest"), which became the authoritative treatise on Western astronomy for the next fourteen centuries. Literature from ancient China confirms that Mars was known by Chinese astronomers by no later than the fourth century BCE. In the East Asian cultures, Mars is traditionally referred to as the "fire star" (火星) based on the Wuxing system. In 1609 Johannes Kepler published a 10 year study of Martian orbit, using the diurnal parallax of Mars, measured by Tycho Brahe, to make a preliminary calculation of the relative distance to the planet. From Brahe's observations of Mars, Kepler deduced that the planet orbited the Sun not in a circle, but in an ellipse. Moreover, Kepler showed that Mars sped up as it approached the Sun and slowed down as it moved farther away, in a manner that later physicists would explain as a consequence of the conservation of angular momentum.: 433–437 In 1610 the first use of a telescope for astronomical observation, including Mars, was performed by Italian astronomer Galileo Galilei. With the telescope the diurnal parallax of Mars was again measured in an effort to determine the Sun-Earth distance. This was first performed by Giovanni Domenico Cassini in 1672. The early parallax measurements were hampered by the quality of the instruments. The only occultation of Mars by Venus observed was that of 13 October 1590, seen by Michael Maestlin at Heidelberg. By the 19th century, the resolution of telescopes reached a level sufficient for surface features to be identified. On 5 September 1877, a perihelic opposition to Mars occurred. The Italian astronomer Giovanni Schiaparelli used a 22-centimetre (8.7 in) telescope in Milan to help produce the first detailed map of Mars. These maps notably contained features he called canali, which, with the possible exception of the natural canyon Valles Marineris, were later shown to be an optical illusion. These canali were supposedly long, straight lines on the surface of Mars, to which he gave names of famous rivers on Earth. His term, which means "channels" or "grooves", was popularly mistranslated in English as "canals". Influenced by the observations, the orientalist Percival Lowell founded an observatory which had 30- and 45-centimetre (12- and 18-in) telescopes. The observatory was used for the exploration of Mars during the last good opportunity in 1894, and the following less favorable oppositions. He published several books on Mars and life on the planet, which had a great influence on the public. The canali were independently observed by other astronomers, like Henri Joseph Perrotin and Louis Thollon in Nice, using one of the largest telescopes of that time. The seasonal changes (consisting of the diminishing of the polar caps and the dark areas formed during Martian summers) in combination with the canals led to speculation about life on Mars, and it was a long-held belief that Mars contained vast seas and vegetation. As bigger telescopes were used, fewer long, straight canali were observed. During observations in 1909 by Antoniadi with an 84-centimetre (33 in) telescope, irregular patterns were observed, but no canali were seen. The first spacecraft from Earth to visit Mars was Mars 1 of the Soviet Union, which flew by in 1963, but contact was lost en route. NASA's Mariner 4 followed and became the first spacecraft to successfully transmit from Mars; launched on 28 November 1964, it made its closest approach to the planet on 15 July 1965. Mariner 4 detected the weak Martian radiation belt, measured at about 0.1% that of Earth, and captured the first images of another planet from deep space. Once spacecraft visited the planet during the 1960s and 1970s, many previous concepts of Mars were radically broken. After the results of the Viking life-detection experiments, the hypothesis of a dead planet was generally accepted. The data from Mariner 9 and Viking allowed better maps of Mars to be made. Until 1997 and after Viking 1 shut down in 1982, Mars was only visited by three unsuccessful probes, two flying past without contact (Phobos 1, 1988; Mars Observer, 1993), and one (Phobos 2 1989) malfunctioning in orbit before reaching its destination Phobos. In 1997 Mars Pathfinder became the first successful rover mission beyond the Moon and started together with Mars Global Surveyor (operated until late 2006) an uninterrupted active robotic presence at Mars that has lasted until today. It produced complete, extremely detailed maps of the Martian topography, magnetic field and surface minerals. Starting with these missions a range of new improved crewless spacecraft, including orbiters, landers, and rovers, have been sent to Mars, with successful missions by the NASA (United States), Jaxa (Japan), ESA, United Kingdom, ISRO (India), Roscosmos (Russia), the United Arab Emirates, and CNSA (China) to study the planet's surface, climate, and geology, uncovering the different elements of the history and dynamic of the hydrosphere of Mars and possible traces of ancient life. As of 2023[update], Mars is host to ten functioning spacecraft. Eight are in orbit: 2001 Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter, MAVEN, ExoMars Trace Gas Orbiter, the Hope orbiter, and the Tianwen-1 orbiter. Another two are on the surface: the Mars Science Laboratory Curiosity rover and the Perseverance rover. Collected maps are available online at websites including Google Mars. NASA provides two online tools: Mars Trek, which provides visualizations of the planet using data from 50 years of exploration, and Experience Curiosity, which simulates traveling on Mars in 3-D with Curiosity. Planned missions to Mars include: As of February 2024[update], debris from these types of missions has reached over seven tons. Most of it consists of crashed and inactive spacecraft as well as discarded components. In April 2024, NASA selected several companies to begin studies on providing commercial services to further enable robotic science on Mars. Key areas include establishing telecommunications, payload delivery and surface imaging. Habitability and habitation During the late 19th century, it was widely accepted in the astronomical community that Mars had life-supporting qualities, including the presence of oxygen and water. However, in 1894 W. W. Campbell at Lick Observatory observed the planet and found that "if water vapor or oxygen occur in the atmosphere of Mars it is in quantities too small to be detected by spectroscopes then available". That observation contradicted many of the measurements of the time and was not widely accepted. Campbell and V. M. Slipher repeated the study in 1909 using better instruments, but with the same results. It was not until the findings were confirmed by W. S. Adams in 1925 that the myth of the Earth-like habitability of Mars was finally broken. However, even in the 1960s, articles were published on Martian biology, putting aside explanations other than life for the seasonal changes on Mars. The current understanding of planetary habitability – the ability of a world to develop environmental conditions favorable to the emergence of life – favors planets that have liquid water on their surface. Most often this requires the orbit of a planet to lie within the habitable zone, which for the Sun is estimated to extend from within the orbit of Earth to about that of Mars. During perihelion, Mars dips inside this region, but Mars's thin (low-pressure) atmosphere prevents liquid water from existing over large regions for extended periods. The past flow of liquid water demonstrates the planet's potential for habitability. Recent evidence has suggested that any water on the Martian surface may have been too salty and acidic to support regular terrestrial life. The environmental conditions on Mars are a challenge to sustaining organic life: the planet has little heat transfer across its surface, it has poor insulation against bombardment by the solar wind due to the absence of a magnetosphere and has insufficient atmospheric pressure to retain water in a liquid form (water instead sublimes to a gaseous state). Mars is nearly, or perhaps totally, geologically dead; the end of volcanic activity has apparently stopped the recycling of chemicals and minerals between the surface and interior of the planet. Evidence suggests that the planet was once significantly more habitable than it is today, but whether living organisms ever existed there remains unknown. The Viking probes of the mid-1970s carried experiments designed to detect microorganisms in Martian soil at their respective landing sites and had positive results, including a temporary increase in CO2 production on exposure to water and nutrients. This sign of life was later disputed by scientists, resulting in a continuing debate, with NASA scientist Gilbert Levin asserting that Viking may have found life. A 2014 analysis of Martian meteorite EETA79001 found chlorate, perchlorate, and nitrate ions in sufficiently high concentrations to suggest that they are widespread on Mars. UV and X-ray radiation would turn chlorate and perchlorate ions into other, highly reactive oxychlorines, indicating that any organic molecules would have to be buried under the surface to survive. Small quantities of methane and formaldehyde detected by Mars orbiters are both claimed to be possible evidence for life, as these chemical compounds would quickly break down in the Martian atmosphere. Alternatively, these compounds may instead be replenished by volcanic or other geological means, such as serpentinite. Impact glass, formed by the impact of meteors, which on Earth can preserve signs of life, has also been found on the surface of the impact craters on Mars. Likewise, the glass in impact craters on Mars could have preserved signs of life, if life existed at the site. The Cheyava Falls rock discovered on Mars in June 2024 has been designated by NASA as a "potential biosignature" and was core sampled by the Perseverance rover for possible return to Earth and further examination. Although highly intriguing, no definitive final determination on a biological or abiotic origin of this rock can be made with the data currently available. Several plans for a human mission to Mars have been proposed, but none have come to fruition. The NASA Authorization Act of 2017 directed NASA to study the feasibility of a crewed Mars mission in the early 2030s; the resulting report concluded that this would be unfeasible. In addition, in 2021, China was planning to send a crewed Mars mission in 2033. Privately held companies such as SpaceX have also proposed plans to send humans to Mars, with the eventual goal to settle on the planet. As of 2024, SpaceX has proceeded with the development of the Starship launch vehicle with the goal of Mars colonization. In plans shared with the company in April 2024, Elon Musk envisions the beginning of a Mars colony within the next twenty years. This would be enabled by the planned mass manufacturing of Starship and initially sustained by resupply from Earth, and in situ resource utilization on Mars, until the Mars colony reaches full self sustainability. Any future human mission to Mars will likely take place within the optimal Mars launch window, which occurs every 26 months. The moon Phobos has been proposed as an anchor point for a space elevator. Besides national space agencies and space companies, groups such as the Mars Society and The Planetary Society advocate for human missions to Mars. In culture Mars is named after the Roman god of war (Greek Ares), but was also associated with the demi-god Heracles (Roman Hercules) by ancient Greek astronomers, as detailed by Aristotle. This association between Mars and war dates back at least to Babylonian astronomy, in which the planet was named for the god Nergal, deity of war and destruction. It persisted into modern times, as exemplified by Gustav Holst's orchestral suite The Planets, whose famous first movement labels Mars "The Bringer of War". The planet's symbol, a circle with a spear pointing out to the upper right, is also used as a symbol for the male gender. The symbol dates from at least the 11th century, though a possible predecessor has been found in the Greek Oxyrhynchus Papyri. The idea that Mars was populated by intelligent Martians became widespread in the late 19th century. Schiaparelli's "canali" observations combined with Percival Lowell's books on the subject put forward the standard notion of a planet that was a drying, cooling, dying world with ancient civilizations constructing irrigation works. Many other observations and proclamations by notable personalities added to what has been termed "Mars Fever". In the present day, high-resolution mapping of the surface of Mars has revealed no artifacts of habitation, but pseudoscientific speculation about intelligent life on Mars still continues. Reminiscent of the canali observations, these speculations are based on small scale features perceived in the spacecraft images, such as "pyramids" and the "Face on Mars". In his book Cosmos, planetary astronomer Carl Sagan wrote: "Mars has become a kind of mythic arena onto which we have projected our Earthly hopes and fears." The depiction of Mars in fiction has been stimulated by its dramatic red color and by nineteenth-century scientific speculations that its surface conditions might support not just life but intelligent life. This gave way to many science fiction stories involving these concepts, such as H. G. Wells's The War of the Worlds, in which Martians seek to escape their dying planet by invading Earth; Ray Bradbury's The Martian Chronicles, in which human explorers accidentally destroy a Martian civilization; as well as Edgar Rice Burroughs's series Barsoom, C. S. Lewis's novel Out of the Silent Planet (1938), and a number of Robert A. Heinlein stories before the mid-sixties. Since then, depictions of Martians have also extended to animation. A comic figure of an intelligent Martian, Marvin the Martian, appeared in Haredevil Hare (1948) as a character in the Looney Tunes animated cartoons of Warner Brothers, and has continued as part of popular culture to the present. After the Mariner and Viking spacecraft had returned pictures of Mars as a lifeless and canal-less world, these ideas about Mars were abandoned; for many science-fiction authors, the new discoveries initially seemed like a constraint, but eventually the post-Viking knowledge of Mars became itself a source of inspiration for works like Kim Stanley Robinson's Mars trilogy. See also Notes References Further reading External links Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Local Sheet → Local Volume → Virgo Supercluster → Laniakea Supercluster → Pisces–Cetus Supercluster Complex → Local Hole → Observable universe → UniverseEach arrow (→) may be read as "within" or "part of". |
======================================== |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.