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[SOURCE: https://www.theverge.com/politics] | [TOKENS: 1481] |
Politics Big tech companies tend to make a lot of enemies — but there are none more powerful than the US government. Apple, Google, Amazon, and Meta are regularly called in front of Congress to fend off monopoly accusations — and lawmakers bring up bills to rein in the companies just as often. The Federal Trade Commission has taken a particularly central role, leading a lawsuit to sever Facebook and Instagram while blocking new acquisitions for Oculus and the company’s virtual reality wing. Like it or not, these regulatory fights will play a huge role in deciding the future of tech — and neither side is playing nice. Regulators noticed Polymarket and Kalshi rake in cash on sports bets. So now prediction markets are cosplaying as the future of news. On Friday morning, the court ruled against the Trump administration (pdf) in the case of Learning Resources, Inc. v. Trump, about whether the International Emergency Economic Powers Act (IEEPA) gave the president the power to impose sweeping tariffs on imports from more than 100 countries. The immediate impact of the ruling is not clear, as the president may try to use other justifications for the tariffs and everything that has followed. The NYT, WSJ, and CNBC have more coverage. Prediction: This is going to be a mess for the Trump right. The FCC has an “enforcement action underway,” Carr said, according to Deadline. This week, Stephen Colbert said CBS banned him from airing his own interview with Talarico, a Democratic state representative from Texas who is running for the US Senate. [Deadline] The US has been working on an online portal at “freedom.gov” that would let Europeans see content their governments have banned, Reuters reports. A planned launch last week was apparently delayed, and State Department officials have expressed concerns about the project. Freedom.gov currently links to a Cloudflare Access page with the National Design Studio logo. [Reuters] California regulators killed a proposal that would have imposed fees on gas-burning furnaces and water heaters that release smog-forming pollutants. More than 20,000 comments they received opposing the proposal were generated by a single AI platform, some addressed from people with no idea their names had been used. [Los Angeles Times] A coalition including the American Public Health Association, American Lung Association, and Sierra Club have filed suit against the Trump administration for repealing the landmark ‘endangerment finding.’ The repeal — if successful — could strip away the Environmental Protection Agency’s ability to to regulate planet-heating pollution. [NBC News] Europe’s privacy watchdog has opened yet another investigation into the millions of sexualized images, some of children, produced and shared on the platform last month. It joins the EU’s DSA effort already underway, whatever France is doing, and a few more in the UK. [FT] First came Jmail, then Jikipedia. The Epstein files have yielded a lot so far, but I didn’t expect a whole new tech ecosystem to be among them. alectrem: at this rate they’re going to make a whole platform of web services and IPO before all the files are even released Get the day’s best comment and more in my free newsletter, The Verge Daily. In a letter sent to Congress Saturday, the Attorney General said that the DOJ had released “all ‘records, documents, communications and investigative materials in the possession of the Department’” in accordance with the Epstein Files Transparency Act. She also included a list of over 300 people mentioned in the files. Google, Reddit, Discord, and Meta have received “hundreds” of subpoenas from the DHS in recent months, according to a report from The New York Times. The agency is reportedly asking the platforms for the names, email addresses, phone numbers, and other information associated with accounts that “track or criticize” ICE. [The New York Times] Kamala Harris’ campaign account, @KamalaHQ, has rebranded as a digital rapid response operation. The less densely populated areas outside the Twin Cities make it harder for protesters and observers to organize. Senate Democrats blocked a bill funding the Department of Homeland Security on Thursday, which could trigger a temporary shutdown of the department. The vote was 52 to 47, with just one Democrat — Sen. John Fetterman — voting in favor. “We will not support an extension of the status quo,” Senate Majority Leader Chuck Schumer said before the vote. [Politico] There are plenty of good reasons to have your doubts about Telegram CEO Pavel Durov, but he’s right — if understandably self-serving — in criticizing Russia’s “authoritarian” restrictions on both Telegram and WhatsApp. Cr4shMyCar: Heartbreaking: worst person you know makes a great point Get the day’s best comment and more in my free newsletter, The Verge Daily. The sudden closure of El Paso airspace yesterday came after US customs officials fired an anti-drone laser on loan from the Department of Defense without coordination with the FAA. And, according to The New York Times, it wasn’t triggered by “Mexican cartel drones breaching US airspace” as the administration claimed: Officials targeted what they thought was a drug cartel drone, but turned out to be a party balloon. Federal Trade Commission Chair Andrew Ferguson warned Apple’s news product could violate a law against deceptive business practices if its alleged promotion of some ideological content violates its terms of service. Ferguson doesn’t cite specific terms it might have violated, but urges a “comprehensive review” to ensure they’re consistent. For the past year, the Times has been using LLMs to create what’s internally known as the “Manosphere Report,” according to Nieman Lab. The AI-generated reports include episode transcripts and summaries for around 80 primarily right-wing podcasts, including the Ben Shapiro Show, Red Scare, and The Clay Travis & Buck Sexton Show. [Nieman Lab] The Foundation for Individual Rights and Expression (FIRE) is suing Attorney General Pam Bondi and Department of Homeland Security Secretary Kristi Noem for their alleged roles urging Meta and Apple to remove a Facebook group and app documenting ICE agents. FIRE claims they unconstitutionally coerced companies to censor speech. In a statement, DHS Assistant Secretary Tricia McLaughlin accused FIRE of spinning “this correct decision for Apple to remove these apps as them caving to pressure instead of helping prevent further harm to federal officers.” Update: Added DHS statement. [The Foundation for Individual Rights and Expression] You should always assume that anything online about you might well stay there forever, but don’t worry: so long as you have the budget of Jeffrey Epstein, you can probably make it go away. Cav_man: The internet never forgets anything unless you’re wealthy enough in which case it devolopes a healthy sense of amnesia. Get the day’s best comment and more in my free newsletter, The Verge Daily. Plus: DC thinks Bezos is a bastard; Newsmax goes to war with Nexstar; and more in this week’s Regulator. According to recently released documents, the convicted sex offender had a vast network of people working to whitewash his digital presence. Pagination Most Popular The Verge Daily A free daily digest of the news that matters most. This is the title for the native ad © 2026 Vox Media, LLC. All Rights Reserved |
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[SOURCE: https://en.wikipedia.org/wiki/Extraterrestrial_life#cite_ref-20] | [TOKENS: 11349] |
Contents Extraterrestrial life Extraterrestrial life, or alien life (colloquially aliens), is life that originates from another world rather than on Earth. No extraterrestrial life has yet been scientifically or conclusively detected. Such life might range from simple forms such as prokaryotes to intelligent beings, possibly bringing forth civilizations that might be far more, or far less, advanced than humans. The Drake equation speculates about the existence of sapient life elsewhere in the universe. The science of extraterrestrial life is known as astrobiology. Speculation about inhabited worlds beyond Earth dates back to antiquity. Early Christian writers, including Augustine, discussed ideas from thinkers like Democritus and Epicurus about countless worlds in the vast universe. Pre-modern writers typically assumed extraterrestrial "worlds" were inhabited by living beings. William Vorilong, in the 15th century, acknowledged the possibility Jesus could have visited extraterrestrial worlds to redeem their inhabitants.: 26 In 1440, Nicholas of Cusa suggested Earth is a "brilliant star"; he theorized that all celestial bodies, even the Sun, could host life. Descartes wrote that there were no means to prove the stars were not inhabited by "intelligent creatures", but their existence was a matter of speculation.: 67 In comparison to the life-abundant Earth, the vast majority of intrasolar and extrasolar planets and moons have harsh surface conditions and disparate atmospheric chemistry, or lack an atmosphere. However, there are many extreme and chemically harsh ecosystems on Earth that do support forms of life and are often hypothesized to be the origin of life on Earth. Examples include life surrounding hydrothermal vents, acidic hot springs, and volcanic lakes, as well as halophiles and the deep biosphere. Since the mid-20th century, researchers have searched for extraterrestrial life and intelligence. Solar system studies focus on Venus, Mars, Europa, and Titan, while exoplanet discoveries now total 6,022 confirmed planets in 4,490 systems as of October 2025. Depending on the category of search, methods range from analysis of telescope and specimen data to radios used to detect and transmit interstellar communication. Interstellar travel remains largely hypothetical, with only the Voyager 1 and Voyager 2 probes confirmed to have entered the interstellar medium. The concept of extraterrestrial life, especially intelligent life, has greatly influenced culture and fiction. A key debate centers on contacting extraterrestrial intelligence: some advocate active attempts, while others warn it could be risky, given human history of exploiting other societies. Context Initially, after the Big Bang, the universe was too hot to allow life. It is estimated that the temperature of the universe was around 10 billion Kelvin at the one-second mark. Roughly 15 million years later, it cooled to temperate levels, though the elements of organic life were yet nonexistent. The only freely available elements at that point were hydrogen and helium. Carbon and oxygen (and later, water) would not appear until 50 million years later, created through stellar fusion. At that point, the difficulty for life to appear was not the temperature, but the scarcity of free heavy elements. Planetary systems emerged, and the first organic compounds may have formed in the protoplanetary disk of dust grains that would eventually create rocky planets like Earth. Although Earth was in a molten state after its birth and may have burned any organics that fell on it, it would have been more receptive once it cooled down. Once the right conditions on Earth were met, life started by a chemical process known as abiogenesis. Alternatively, life may have formed less frequently, then spread—by meteoroids, for example—between habitable planets in a process called panspermia. During most of its stellar evolution, stars combine hydrogen nuclei to make helium nuclei by stellar fusion, and the comparatively lighter weight of helium allows the star to release the extra energy. The process continues until the star uses all of its available fuel, with the speed of consumption being related to the size of the star. During its last stages, stars start combining helium nuclei to form carbon nuclei. The larger stars can further combine carbon nuclei to create oxygen and silicon, oxygen into neon and sulfur, and so on until iron. Ultimately, the star blows much of its content back into the stellar medium, where it would join clouds that would eventually become new generations of stars and planets. Many of those materials are the raw components of life on Earth. As this process takes place in all the universe, said materials are ubiquitous in the cosmos and not a rarity from the Solar System. Earth is a planet in the Solar System, a planetary system formed by a star at the center, the Sun, and the objects that orbit it: other planets, moons, asteroids, and comets. The sun is part of the Milky Way, a galaxy. The Milky Way is part of the Local Group, a galaxy group that is in turn part of the Laniakea Supercluster. The universe is composed of all similar structures in existence. The immense distances between celestial objects are a difficulty for studying extraterrestrial life. So far, humans have only set foot on the Moon and sent robotic probes to other planets and moons in the Solar System. Although probes can withstand conditions that may be lethal to humans, the distances cause time delays: the New Horizons took nine years after launch to reach Pluto. No probe has ever reached extrasolar planetary systems. The Voyager 2 left the Solar System at a speed of 50,000 kilometers per hour; if it headed towards the Alpha Centauri system, the closest one to Earth at 4.4 light years, it would reach it in 100,000 years. Under current technology, such systems can only be studied by telescopes, which have limitations. It is estimated that dark matter has a larger amount of combined matter than stars and gas clouds, but as it plays no role in the stellar evolution of stars and planets, it is usually not taken into account by astrobiology. There is an area around a star, the circumstellar habitable zone or "Goldilocks zone", wherein water may be at the right temperature to exist in liquid form at a planetary surface. This area is neither too close to the star, where water would become steam, nor too far away, where water would be frozen as ice. However, although useful as an approximation, planetary habitability is complex and defined by several factors. Being in the habitable zone is not enough for a planet to be habitable, not even to actually have such liquid water. Venus is located in the solar system's habitable zone, but does not have liquid water because of the conditions of its atmosphere. Jovian planets or gas giants are not considered habitable even if they orbit close enough to their stars as hot Jupiters, due to crushing atmospheric pressures. The actual distances for the habitable zones vary according to the type of star, and even the solar activity of each specific star influences the local habitability. The type of star also defines the time the habitable zone will exist, as its presence and limits will change along with the star's stellar evolution. The Big Bang occurred 13.8 billion years ago, the Solar System was formed 4.6 billion years ago, and the first hominids appeared 6 million years ago. Life on other planets may have started, evolved, given birth to extraterrestrial intelligences, and perhaps even faced a planetary extinction event millions or billions of years ago. When considered from a cosmic perspective, the brief times of existence of Earth's species may suggest that extraterrestrial life may be equally fleeting under such a scale. During a period of about 7 million years, from about 10 to 17 million years after the Big Bang, the background temperature was between 373 and 273 K (100 and 0 °C; 212 and 32 °F), allowing the possibility of liquid water if any planets existed. Avi Loeb (2014) speculated that primitive life might in principle have appeared during this window, which he called "the Habitable Epoch of the Early Universe". Life on Earth is quite ubiquitous across the planet and has adapted over time to almost all the available environments in it, extremophiles and the deep biosphere thrive at even the most hostile ones. As a result, it is inferred that life in other celestial bodies may be equally adaptive. However, the origin of life is unrelated to its ease of adaptation and may have stricter requirements. A celestial body may not have any life on it, even if it were habitable. Likelihood of existence Life in the cosmos beyond Earth has been observed. The hypothesis of ubiquitous extraterrestrial life relies on three main ideas. The first one, the size of the universe, allows for plenty of planets to have a similar habitability to Earth, and the age of the universe gives enough time for a long process analog to the history of Earth to happen there. The second is that the substances that make life, such as carbon and water, are ubiquitous in the universe. The third is that the physical laws are universal, which means that the forces that would facilitate or prevent the existence of life would be the same ones as on Earth. According to this argument, made by scientists such as Carl Sagan and Stephen Hawking, it would be improbable for life not to exist somewhere else other than Earth. This argument is embodied in the Copernican principle, which states that Earth does not occupy a unique position in the Universe, and the mediocrity principle, which states that there is nothing special about life on Earth. Other authors consider instead that life in the cosmos, or at least multicellular life, may actually be rare. The Rare Earth hypothesis maintains that life on Earth is possible because of a series of factors that range from the location in the galaxy and the configuration of the Solar System to local characteristics of the planet, and that it is unlikely that another planet simultaneously meets all such requirements. The proponents of this hypothesis consider that very little evidence suggests the existence of extraterrestrial life and that, at this point, it is just a desired result and not a reasonable scientific explanation for any gathered data. In 1961, astronomer and astrophysicist Frank Drake devised the Drake equation as a way to stimulate scientific dialogue at a meeting on the search for extraterrestrial intelligence (SETI). The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy. The Drake equation is:: xix where: and Drake's proposed estimates are as follows, but numbers on the right side of the equation are agreed as speculative and open to substitution: 10,000 = 5 ⋅ 0.5 ⋅ 2 ⋅ 1 ⋅ 0.2 ⋅ 1 ⋅ 10,000 {\displaystyle 10{,}000=5\cdot 0.5\cdot 2\cdot 1\cdot 0.2\cdot 1\cdot 10{,}000} [better source needed] The Drake equation has proved controversial since, although it is written as a math equation, none of its values were known at the time. Although some values may eventually be measured, others are based on social sciences and are not knowable by their very nature. This does not allow one to make noteworthy conclusions from the equation. Based on observations from the Hubble Space Telescope, there are nearly 2 trillion galaxies in the observable universe. It is estimated that at least ten percent of all Sun-like stars have a system of planets. In other words, there are 6.25×1018 stars with planets orbiting them in the observable universe. Even if it is assumed that only one out of a billion of these stars has planets supporting life, there would be some 6.25 billion life-supporting planetary systems in the observable universe. A 2013 study based on results from the Kepler spacecraft estimated that the Milky Way contains at least as many planets as it does stars, resulting in 100–400 billion exoplanets. The Nebular hypothesis that explains the formation of the Solar System and other planetary systems would suggest that those can have several configurations, and not all of them may have rocky planets within the habitable zone. The apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilisations and the lack of evidence for such civilisations is known as the Fermi paradox. Dennis W. Sciama claimed that life's existence in the universe depends on various fundamental constants. Zhi-Wei Wang and Samuel L. Braunstein suggest that a random universe capable of supporting life is likely to be just barely able to do so, giving a potential explanation to the Fermi paradox. Biochemical basis If extraterrestrial life exists, it could range from simple microorganisms and multicellular organisms similar to animals or plants, to complex alien intelligences akin to humans. When scientists talk about extraterrestrial life, they consider all those types. Although it is possible that extraterrestrial life may have other configurations, scientists use the hierarchy of lifeforms from Earth for simplicity, as it is the only one known to exist. The first basic requirement for life is an environment with non-equilibrium thermodynamics, which means that the thermodynamic equilibrium must be broken by a source of energy. The traditional sources of energy in the cosmos are the stars, such as for life on Earth, which depends on the energy of the sun. However, there are other alternative energy sources, such as volcanoes, plate tectonics, and hydrothermal vents. There are ecosystems on Earth in deep areas of the ocean that do not receive sunlight, and take energy from black smokers instead. Magnetic fields and radioactivity have also been proposed as sources of energy, although they would be less efficient ones. Life on Earth requires water in a liquid state as a solvent in which biochemical reactions take place. It is highly unlikely that an abiogenesis process can start within a gaseous or solid medium: the atom speeds, either too fast or too slow, make it difficult for specific ones to meet and start chemical reactions. A liquid medium also allows the transport of nutrients and substances required for metabolism. Sufficient quantities of carbon and other elements, along with water, might enable the formation of living organisms on terrestrial planets with a chemical make-up and temperature range similar to that of Earth. Life based on ammonia rather than water has been suggested as an alternative, though this solvent appears less suitable than water. It is also conceivable that there are forms of life whose solvent is a liquid hydrocarbon, such as methane, ethane or propane. Another unknown aspect of potential extraterrestrial life would be the chemical elements that would compose it. Life on Earth is largely composed of carbon, but there could be other hypothetical types of biochemistry. A replacement for carbon would need to be able to create complex molecules, store information required for evolution, and be freely available in the medium. To create DNA, RNA, or a close analog, such an element should be able to bind its atoms with many others, creating complex and stable molecules. It should be able to create at least three covalent bonds: two for making long strings and at least a third to add new links and allow for diverse information. Only nine elements meet this requirement: boron, nitrogen, phosphorus, arsenic, antimony (three bonds), carbon, silicon, germanium and tin (four bonds). As for abundance, carbon, nitrogen, and silicon are the most abundant ones in the universe, far more than the others. On Earth's crust the most abundant of those elements is silicon, in the Hydrosphere it is carbon and in the atmosphere, it is carbon and nitrogen. Silicon, however, has disadvantages over carbon. The molecules formed with silicon atoms are less stable, and more vulnerable to acids, oxygen, and light. An ecosystem of silicon-based lifeforms would require very low temperatures, high atmospheric pressure, an atmosphere devoid of oxygen, and a solvent other than water. The low temperatures required would add an extra problem, the difficulty to kickstart a process of abiogenesis to create life in the first place. Norman Horowitz, head of the Jet Propulsion Laboratory bioscience section for the Mariner and Viking missions from 1965 to 1976 considered that the great versatility of the carbon atom makes it the element most likely to provide solutions, even exotic solutions, to the problems of survival of life on other planets. However, he also considered that the conditions found on Mars were incompatible with carbon based life. Even if extraterrestrial life is based on carbon and uses water as a solvent, like Earth life, it may still have a radically different biochemistry. Life is generally considered to be a product of natural selection. It has been proposed that to undergo natural selection a living entity must have the capacity to replicate itself, the capacity to avoid damage/decay, and the capacity to acquire and process resources in support of the first two capacities. Life on Earth may have started with an RNA world and later evolved to its current form, where some of the RNA tasks were transferred to DNA and proteins. Extraterrestrial life may still be stuck using RNA, or evolve into other configurations. It is unclear if our biochemistry is the most efficient one that could be generated, or which elements would follow a similar pattern. However, it is likely that, even if cells had a different composition to those from Earth, they would still have a cell membrane. Life on Earth jumped from prokaryotes to eukaryotes and from unicellular organisms to multicellular organisms through evolution. So far no alternative process to achieve such a result has been conceived, even if hypothetical. Evolution requires life to be divided into individual organisms, and no alternative organisation has been satisfactorily proposed either. At the basic level, membranes define the limit of a cell, between it and its environment, while remaining partially open to exchange energy and resources with it. The evolution from simple cells to eukaryotes, and from them to multicellular lifeforms, is not guaranteed. The Cambrian explosion took place thousands of millions of years after the origin of life, and its causes are not fully known yet. On the other hand, the jump to multicellularity took place several times, which suggests that it could be a case of convergent evolution, and so likely to take place on other planets as well. Palaeontologist Simon Conway Morris considers that convergent evolution would lead to kingdoms similar to our plants and animals, and that many features are likely to develop in alien animals as well, such as bilateral symmetry, limbs, digestive systems and heads with sensory organs. Scientists from the University of Oxford analysed it from the perspective of evolutionary theory and wrote in a study in the International Journal of Astrobiology that aliens may be similar to humans. The planetary context would also have an influence: a planet with higher gravity would have smaller animals, and other types of stars can lead to non-green photosynthesizers. The amount of energy available would also affect biodiversity, as an ecosystem sustained by black smokers or hydrothermal vents would have less energy available than those sustained by a star's light and heat, and so its lifeforms would not grow beyond a certain complexity. There is also research in assessing the capacity of life for developing intelligence. It has been suggested that this capacity arises with the number of potential niches a planet contains, and that the complexity of life itself is reflected in the information density of planetary environments, which in turn can be computed from its niches. It is common knowledge that the conditions on other planets in the solar system, in addition to the many galaxies outside of the Milky Way galaxy, are very harsh and seem to be too extreme to harbor any life. The environmental conditions on these planets can have intense UV radiation paired with extreme temperatures, lack of water, and much more that can lead to conditions that don't seem to favor the creation or maintenance of extraterrestrial life. However, there has been much historical evidence that some of the earliest and most basic forms of life on Earth originated in some extreme environments that seem unlikely to have harbored life at least at one point in Earth's history. Fossil evidence as well as many historical theories backed up by years of research and studies have marked environments like hydrothermal vents or acidic hot springs as some of the first places that life could have originated on Earth. These environments can be considered extreme when compared to the typical ecosystems that the majority of life on Earth now inhabit, as hydrothermal vents are scorching hot due to the magma escaping from the Earth's mantle and meeting the much colder oceanic water. Even in today's world, there can be a diverse population of bacteria found inhabiting the area surrounding these hydrothermal vents which can suggest that some form of life can be supported even in the harshest of environments like the other planets in the solar system. The aspects of these harsh environments that make them ideal for the origin of life on Earth, as well as the possibility of creation of life on other planets, is the chemical reactions forming spontaneously. For example, the hydrothermal vents found on the ocean floor are known to support many chemosynthetic processes which allow organisms to utilize energy through reduced chemical compounds that fix carbon. In return, these reactions will allow for organisms to live in relatively low oxygenated environments while maintaining enough energy to support themselves. The early Earth environment was reducing and therefore, these carbon fixing compounds were necessary for the survival and possible origin of life on Earth. With the little amount of information that scientists have found regarding the atmosphere on other planets in the Milky Way galaxy and beyond, the atmospheres are most likely reducing or with very low oxygen levels, especially when compared with Earth's atmosphere. If there were the necessary elements and ions on these planets, the same carbon fixing, reduced chemical compounds occurring around hydrothermal vents could also occur on these planets' surfaces and possibly result in the origin of extraterrestrial life. Planetary habitability in the Solar System The Solar System has a wide variety of planets, dwarf planets, and moons, and each one is studied for its potential to host life. Each one has its own specific conditions that may benefit or harm life. So far, the only lifeforms found are those from Earth. No extraterrestrial intelligence other than humans exists or has ever existed within the Solar System. Astrobiologist Mary Voytek points out that it would be unlikely to find large ecosystems, as they would have already been detected by now. The inner Solar System is likely devoid of life. However, Venus is still of interest to astrobiologists, as it is a terrestrial planet that was likely similar to Earth in its early stages and developed in a different way. There is a greenhouse effect, the surface is the hottest in the Solar System, sulfuric acid clouds, all surface liquid water is lost, and it has a thick carbon-dioxide atmosphere with huge pressure. Comparing both helps to understand the precise differences that lead to beneficial or harmful conditions for life. And despite the conditions against life on Venus, there are suspicions that microbial life-forms may still survive in high-altitude clouds. Mars is a cold and almost airless desert, inhospitable to life. However, recent studies revealed that water on Mars used to be quite abundant, forming rivers, lakes, and perhaps even oceans. Mars may have been habitable back then, and life on Mars may have been possible. But when the planetary core ceased to generate a magnetic field, solar winds removed the atmosphere and the planet became vulnerable to solar radiation. Ancient life-forms may still have left fossilised remains, and microbes may still survive deep underground. As mentioned, the gas giants and ice giants are unlikely to contain life. The most distant solar system bodies, found in the Kuiper Belt and outwards, are locked in permanent deep-freeze, but cannot be ruled out completely. Although the giant planets themselves are highly unlikely to have life, there is much hope to find it on moons orbiting these planets. Europa, from the Jovian system, has a subsurface ocean below a thick layer of ice. Ganymede and Callisto also have subsurface oceans, but life is less likely in them because water is sandwiched between layers of solid ice. Europa would have contact between the ocean and the rocky surface, which helps the chemical reactions. It may be difficult to dig so deep in order to study those oceans, though. Enceladus, a tiny moon of Saturn with another subsurface ocean, may not need to be dug, as it releases water to space in eruption columns. The space probe Cassini flew inside one of these, but could not make a full study because NASA did not expect this phenomenon and did not equip the probe to study ocean water. Still, Cassini detected complex organic molecules, salts, evidence of hydrothermal activity, hydrogen, and methane. Titan is the only celestial body in the Solar System besides Earth that has liquid bodies on the surface. It has rivers, lakes, and rain of hydrocarbons, methane, and ethane, and even a cycle similar to Earth's water cycle. This special context encourages speculations about lifeforms with different biochemistry, but the cold temperatures would make such chemistry take place at a very slow pace. Water is rock-solid on the surface, but Titan does have a subsurface water ocean like several other moons. However, it is of such a great depth that it would be very difficult to access it for study. Scientific search The science that searches and studies life in the universe, both on Earth and elsewhere, is called astrobiology. With the study of Earth's life, the only known form of life, astrobiology seeks to study how life starts and evolves and the requirements for its continuous existence. This helps to determine what to look for when searching for life in other celestial bodies. This is a complex area of study, and uses the combined perspectives of several scientific disciplines, such as astronomy, biology, chemistry, geology, oceanography, and atmospheric sciences. The scientific search for extraterrestrial life is being carried out both directly and indirectly. As of September 2017[update], 3,667 exoplanets in 2,747 systems have been identified, and other planets and moons in the Solar System hold the potential for hosting primitive life such as microorganisms. As of 8 February 2021, an updated status of studies considering the possible detection of lifeforms on Venus (via phosphine) and Mars (via methane) was reported. Scientists search for biosignatures within the Solar System by studying planetary surfaces and examining meteorites. Some claim to have identified evidence that microbial life has existed on Mars. In 1996, a controversial report stated that structures resembling nanobacteria were discovered in a meteorite, ALH84001, formed of rock ejected from Mars. Although all the unusual properties of the meteorite were eventually explained as the result of inorganic processes, the controversy over its discovery laid the groundwork for the development of astrobiology. An experiment on the two Viking Mars landers reported gas emissions from heated Martian soil samples that some scientists argue are consistent with the presence of living microorganisms. Lack of corroborating evidence from other experiments on the same samples suggests that a non-biological reaction is a more likely hypothesis. In February 2005 NASA scientists reported they may have found some evidence of extraterrestrial life on Mars. The two scientists, Carol Stoker and Larry Lemke of NASA's Ames Research Center, based their claim on methane signatures found in Mars's atmosphere resembling the methane production of some forms of primitive life on Earth, as well as on their own study of primitive life near the Rio Tinto river in Spain. NASA officials soon distanced NASA from the scientists' claims, and Stoker herself backed off from her initial assertions. In November 2011, NASA launched the Mars Science Laboratory that landed the Curiosity rover on Mars. It is designed to assess the past and present habitability on Mars using a variety of scientific instruments. The rover landed on Mars at Gale Crater in August 2012. A group of scientists at Cornell University started a catalog of microorganisms, with the way each one reacts to sunlight. The goal is to help with the search for similar organisms in exoplanets, as the starlight reflected by planets rich in such organisms would have a specific spectrum, unlike that of starlight reflected from lifeless planets. If Earth was studied from afar with this system, it would reveal a shade of green, as a result of the abundance of plants with photosynthesis. In August 2011, NASA studied meteorites found on Antarctica, finding adenine, guanine, hypoxanthine, and xanthine. Adenine and guanine are components of DNA, and the others are used in other biological processes. The studies ruled out pollution of the meteorites on Earth, as those components would not be freely available the way they were found in the samples. This discovery suggests that several organic molecules that serve as building blocks of life may be generated within asteroids and comets. In October 2011, scientists reported that cosmic dust contains complex organic compounds ("amorphous organic solids with a mixed aromatic-aliphatic structure") that could be created naturally, and rapidly, by stars. It is still unclear if those compounds played a role in the creation of life on Earth, but Sun Kwok, of the University of Hong Kong, thinks so. "If this is the case, life on Earth may have had an easier time getting started as these organics can serve as basic ingredients for life." In August 2012, and in a world first, astronomers at Copenhagen University reported the detection of a specific sugar molecule, glycolaldehyde, in a distant star system. The molecule was found around the protostellar binary IRAS 16293-2422, which is located 400 light years from Earth. Glycolaldehyde is needed to form ribonucleic acid, or RNA, which is similar in function to DNA. This finding suggests that complex organic molecules may form in stellar systems prior to the formation of planets, eventually arriving on young planets early in their formation. In December 2023, astronomers reported the first time discovery, in the plumes of Enceladus, moon of the planet Saturn, of hydrogen cyanide, a possible chemical essential for life as we know it, as well as other organic molecules, some of which are yet to be better identified and understood. According to the researchers, "these [newly discovered] compounds could potentially support extant microbial communities or drive complex organic synthesis leading to the origin of life." Although most searches are focused on the biology of extraterrestrial life, an extraterrestrial intelligence capable enough to develop a civilization may be detectable by other means as well. Technology may generate technosignatures, effects on the native planet that may not be caused by natural causes. There are three main types of techno-signatures considered: interstellar communications, effects on the atmosphere, and planetary-sized structures such as Dyson spheres. Organizations such as the SETI Institute search the cosmos for potential forms of communication. They started with radio waves, and now search for laser pulses as well. The challenge for this search is that there are natural sources of such signals as well, such as gamma-ray bursts and supernovae, and the difference between a natural signal and an artificial one would be in its specific patterns. Astronomers intend to use artificial intelligence for this, as it can manage large amounts of data and is devoid of biases and preconceptions. Besides, even if there is an advanced extraterrestrial civilization, there is no guarantee that it is transmitting radio communications in the direction of Earth. The length of time required for a signal to travel across space means that a potential answer may arrive decades or centuries after the initial message. The atmosphere of Earth is rich in nitrogen dioxide as a result of air pollution, which can be detectable. The natural abundance of carbon, which is also relatively reactive, makes it likely to be a basic component of the development of a potential extraterrestrial technological civilization, as it is on Earth. Fossil fuels may likely be generated and used on such worlds as well. The abundance of chlorofluorocarbons in the atmosphere can also be a clear technosignature, considering their role in ozone depletion. Light pollution may be another technosignature, as multiple lights on the night side of a rocky planet can be a sign of advanced technological development. However, modern telescopes are not strong enough to study exoplanets with the required level of detail to perceive it. The Kardashev scale proposes that a civilization may eventually start consuming energy directly from its local star. This would require giant structures built next to it, called Dyson spheres. Those speculative structures would cause an excess infrared radiation, that telescopes may notice. The infrared radiation is typical of young stars, surrounded by dusty protoplanetary disks that will eventually form planets. An older star such as the Sun would have no natural reason to have excess infrared radiation. The presence of heavy elements in a star's light-spectrum is another potential biosignature; such elements would (in theory) be found if the star were being used as an incinerator/repository for nuclear waste products. Some astronomers search for extrasolar planets that may be conducive to life, narrowing the search to terrestrial planets within the habitable zones of their stars. Since 1992, over four thousand exoplanets have been discovered (6,128 planets in 4,584 planetary systems including 1,017 multiple planetary systems as of 30 October 2025). The extrasolar planets so far discovered range in size from that of terrestrial planets similar to Earth's size to that of gas giants larger than Jupiter. The number of observed exoplanets is expected to increase greatly in the coming years.[better source needed] The Kepler space telescope has also detected a few thousand candidate planets, of which about 11% may be false positives. There is at least one planet on average per star. About 1 in 5 Sun-like stars[a] have an "Earth-sized"[b] planet in the habitable zone,[c] with the nearest expected to be within 12 light-years distance from Earth. Assuming 200 billion stars in the Milky Way,[d] that would be 11 billion potentially habitable Earth-sized planets in the Milky Way, rising to 40 billion if red dwarfs are included. The rogue planets in the Milky Way possibly number in the trillions. The nearest known exoplanet is Proxima Centauri b, located 4.2 light-years (1.3 pc) from Earth in the southern constellation of Centaurus. As of March 2014[update], the least massive exoplanet known is PSR B1257+12 A, which is about twice the mass of the Moon. The most massive planet listed on the NASA Exoplanet Archive is DENIS-P J082303.1−491201 b, about 29 times the mass of Jupiter, although according to most definitions of a planet, it is too massive to be a planet and may be a brown dwarf instead. Almost all of the planets detected so far are within the Milky Way, but there have also been a few possible detections of extragalactic planets. The study of planetary habitability also considers a wide range of other factors in determining the suitability of a planet for hosting life. One sign that a planet probably already contains life is the presence of an atmosphere with significant amounts of oxygen, since that gas is highly reactive and generally would not last long without constant replenishment. This replenishment occurs on Earth through photosynthetic organisms. One way to analyse the atmosphere of an exoplanet is through spectrography when it transits its star, though this might only be feasible with dim stars like white dwarfs. History and cultural impact The modern concept of extraterrestrial life is based on assumptions that were not commonplace during the early days of astronomy. The first explanations for the celestial objects seen in the night sky were based on mythology. Scholars from Ancient Greece were the first to consider that the universe is inherently understandable and rejected explanations based on supernatural incomprehensible forces, such as the myth of the Sun being pulled across the sky in the chariot of Apollo. They had not developed the scientific method yet and based their ideas on pure thought and speculation, but they developed precursor ideas to it, such as that explanations had to be discarded if they contradict observable facts. The discussions of those Greek scholars established many of the pillars that would eventually lead to the idea of extraterrestrial life, such as Earth being round and not flat. The cosmos was first structured in a geocentric model that considered that the sun and all other celestial bodies revolve around Earth. However, they did not consider them as worlds. In Greek understanding, the world was composed by both Earth and the celestial objects with noticeable movements. Anaximander thought that the cosmos was made from apeiron, a substance that created the world, and that the world would eventually return to the cosmos. Eventually two groups emerged, the atomists that thought that matter at both Earth and the cosmos was equally made of small atoms of the classical elements (earth, water, fire and air), and the Aristotelians who thought that those elements were exclusive of Earth and that the cosmos was made of a fifth one, the aether. Atomist Epicurus thought that the processes that created the world, its animals and plants should have created other worlds elsewhere, along with their own animals and plants. Aristotle thought instead that all the earth element naturally fell towards the center of the universe, and that would make it impossible for other planets to exist elsewhere. Under that reasoning, Earth was not only in the center, it was also the only planet in the universe. Cosmic pluralism, the plurality of worlds, or simply pluralism, describes the philosophical belief in numerous "worlds" in addition to Earth, which might harbor extraterrestrial life. The earliest recorded assertion of extraterrestrial human life is found in ancient scriptures of Jainism. There are multiple "worlds" mentioned in Jain scriptures that support human life. These include, among others, Bharat Kshetra, Mahavideh Kshetra, Airavat Kshetra, and Hari kshetra. Medieval Muslim writers like Fakhr al-Din al-Razi and Muhammad al-Baqir supported cosmic pluralism on the basis of the Qur'an. Chaucer's poem The House of Fame engaged in medieval thought experiments that postulated the plurality of worlds. However, those ideas about other worlds were different from the current knowledge about the structure of the universe, and did not postulate the existence of planetary systems other than the Solar System. When those authors talk about other worlds, they talk about places located at the center of their own systems, and with their own stellar vaults and cosmos surrounding them. The Greek ideas and the disputes between atomists and Aristotelians outlived the fall of the Greek empire. The Great Library of Alexandria compiled information about it, part of which was translated by Islamic scholars and thus survived the end of the Library. Baghdad combined the knowledge of the Greeks, the Indians, the Chinese and its own scholars, and the knowledge expanded through the Byzantine Empire. From there it eventually returned to Europe by the time of the Middle Ages. However, as the Greek atomist doctrine held that the world was created by random movements of atoms, with no need for a creator deity, it became associated with atheism, and the dispute intertwined with religious ones. Still, the Church did not react to those topics in a homogeneous way, and there were stricter and more permissive views within the church itself. The first known mention of the term 'panspermia' was in the writings of the 5th-century BC Greek philosopher Anaxagoras. He proposed the idea that life exists everywhere. By the time of the late Middle Ages there were many known inaccuracies in the geocentric model, but it was kept in use because naked eye observations provided limited data. Nicolaus Copernicus started the Copernican Revolution by proposing that the planets revolve around the sun rather than Earth. His proposal had little acceptance at first because, as he kept the assumption that orbits were perfect circles, his model led to as many inaccuracies as the geocentric one. Tycho Brahe improved the available data with naked-eye observatories, which worked with highly complex sextants and quadrants. Tycho could not make sense of his observations, but Johannes Kepler did: orbits were not perfect circles, but ellipses. This knowledge benefited the Copernican model, which worked now almost perfectly. The invention of the telescope a short time later, perfected by Galileo Galilei, clarified the final doubts, and the paradigm shift was completed. Under this new understanding, the notion of extraterrestrial life became feasible: if Earth is but just a planet orbiting around a star, there may be planets similar to Earth elsewhere. The astronomical study of distant bodies also proved that physical laws are the same elsewhere in the universe as on Earth, with nothing making the planet truly special. The new ideas were met with resistance from the Catholic church. Galileo was tried for the heliocentric model, which was considered heretical, and forced to recant it. The best-known early-modern proponent of ideas of extraterrestrial life was the Italian philosopher Giordano Bruno, who argued in the 16th century for an infinite universe in which every star is surrounded by its own planetary system. Bruno wrote that other worlds "have no less virtue nor a nature different to that of our earth" and, like Earth, "contain animals and inhabitants". Bruno's belief in the plurality of worlds was one of the charges leveled against him by the Venetian Holy Inquisition, which tried and executed him. The heliocentric model was further strengthened by the postulation of the theory of gravity by Sir Isaac Newton. This theory provided the mathematics that explains the motions of all things in the universe, including planetary orbits. By this point, the geocentric model was definitely discarded. By this time, the use of the scientific method had become a standard, and new discoveries were expected to provide evidence and rigorous mathematical explanations. Science also took a deeper interest in the mechanics of natural phenomena, trying to explain not just the way nature works but also the reasons for working that way. There was very little actual discussion about extraterrestrial life before this point, as the Aristotelian ideas remained influential while geocentrism was still accepted. When it was finally proved wrong, it not only meant that Earth was not the center of the universe, but also that the lights seen in the sky were not just lights, but physical objects. The notion that life may exist in them as well soon became an ongoing topic of discussion, although one with no practical ways to investigate. The possibility of extraterrestrials remained a widespread speculation as scientific discovery accelerated. William Herschel, the discoverer of Uranus, was one of many 18th–19th-century astronomers who believed that the Solar System is populated by alien life. Other scholars of the period who championed "cosmic pluralism" included Immanuel Kant and Benjamin Franklin. At the height of the Enlightenment, even the Sun and Moon were considered candidates for extraterrestrial inhabitants. Speculation about life on Mars increased in the late 19th century, following telescopic observation of apparent Martian canals – which soon, however, turned out to be optical illusions. Despite this, in 1895, American astronomer Percival Lowell published his book Mars, followed by Mars and its Canals in 1906, proposing that the canals were the work of a long-gone civilisation. Spectroscopic analysis of Mars's atmosphere began in earnest in 1894, when U.S. astronomer William Wallace Campbell showed that neither water nor oxygen was present in the Martian atmosphere. By 1909 better telescopes and the best perihelic opposition of Mars since 1877 conclusively put an end to the canal hypothesis. As a consequence of the belief in the spontaneous generation there was little thought about the conditions of each celestial body: it was simply assumed that life would thrive anywhere. This theory was disproved by Louis Pasteur in the 19th century. Popular belief in thriving alien civilisations elsewhere in the solar system still remained strong until Mariner 4 and Mariner 9 provided close images of Mars, which debunked forever the idea of the existence of Martians and decreased the previous expectations of finding alien life in general. The end of the spontaneous generation belief forced investigation into the origin of life. Although abiogenesis is the more accepted theory, a number of authors reclaimed the term "panspermia" and proposed that life was brought to Earth from elsewhere. Some of those authors are Jöns Jacob Berzelius (1834), Kelvin (1871), Hermann von Helmholtz (1879) and, somewhat later, by Svante Arrhenius (1903). The science fiction genre, although not so named during the time, developed during the late 19th century. The expansion of the genre of extraterrestrials in fiction influenced the popular perception over the real-life topic, making people eager to jump to conclusions about the discovery of aliens. Science marched at a slower pace, some discoveries fueled expectations and others dashed excessive hopes. For example, with the advent of telescopes, most structures seen on the Moon or Mars were immediately attributed to Selenites or Martians, and later ones (such as more powerful telescopes) revealed that all such discoveries were natural features. A famous case is the Cydonia region of Mars, first imaged by the Viking 1 orbiter. The low-resolution photos showed a rock formation that resembled a human face, but later spacecraft took photos in higher detail that showed that there was nothing special about the site. The search and study of extraterrestrial life became a science of its own, astrobiology. Also known as exobiology, this discipline is studied by the NASA, the ESA, the INAF, and others. Astrobiology studies life from Earth as well, but with a cosmic perspective. For example, abiogenesis is of interest to astrobiology, not because of the origin of life on Earth, but for the chances of a similar process taking place in other celestial bodies. Many aspects of life, from its definition to its chemistry, are analyzed as either likely to be similar in all forms of life across the cosmos or only native to Earth. Astrobiology, however, remains constrained by the current lack of extraterrestrial life-forms to study, as all life on Earth comes from the same ancestor, and it is hard to infer general characteristics from a group with a single example to analyse. The 20th century came with great technological advances, speculations about future hypothetical technologies, and an increased basic knowledge of science by the general population thanks to science divulgation through the mass media. The public interest in extraterrestrial life and the lack of discoveries by mainstream science led to the emergence of pseudosciences that provided affirmative, if questionable, answers to the existence of aliens. Ufology claims that many unidentified flying objects (UFOs) would be spaceships from alien species, and ancient astronauts hypothesis claim that aliens would have visited Earth in antiquity and prehistoric times but people would have failed to understand it by then. Most UFOs or UFO sightings can be readily explained as sightings of Earth-based aircraft (including top-secret aircraft), known astronomical objects or weather phenomenons, or as hoaxes. Looking beyond the pseudosciences, Lewis White Beck strove to elevate the level of public discourse on the topic of extraterrestrial life by tracing the evolution of philosophical thought over the centuries from ancient times into the modern era. His review of the contributions made by Lucretius, Plutarch, Aristotle, Copernicus, Immanuel Kant, John Wilkins, Charles Darwin and Karl Marx demonstrated that even in modern times, humanity could be profoundly influenced in its search for extraterrestrial life by subtle and comforting archetypal ideas which are largely derived from firmly held religious, philosophical and existential belief systems. On a positive note, however, Beck further argued that even if the search for extraterrestrial life proves to be unsuccessful, the endeavor itself could have beneficial consequences by assisting humanity in its attempt to actualize superior ways of living here on Earth. By the 21st century, it was accepted that multicellular life in the Solar System can only exist on Earth, but the interest in extraterrestrial life increased regardless. This is a result of the advances in several sciences. The knowledge of planetary habitability allows to consider on scientific terms the likelihood of finding life at each specific celestial body, as it is known which features are beneficial and harmful for life. Astronomy and telescopes also improved to the point exoplanets can be confirmed and even studied, increasing the number of search places. Life may still exist elsewhere in the Solar System in unicellular form, but the advances in spacecraft allow to send robots to study samples in situ, with tools of growing complexity and reliability. Although no extraterrestrial life has been found and life may still be just a rarity from Earth, there are scientific reasons to suspect that it can exist elsewhere, and technological advances that may detect it if it does. Many scientists are optimistic about the chances of finding alien life. In the words of SETI's Frank Drake, "All we know for sure is that the sky is not littered with powerful microwave transmitters". Drake noted that it is entirely possible that advanced technology results in communication being carried out in some way other than conventional radio transmission. At the same time, the data returned by space probes, and giant strides in detection methods, have allowed science to begin delineating habitability criteria on other worlds, and to confirm that at least other planets are plentiful, though aliens remain a question mark. The Wow! signal, detected in 1977 by a SETI project, remains a subject of speculative debate. On the other hand, other scientists are pessimistic. Jacques Monod wrote that "Man knows at last that he is alone in the indifferent immensity of the universe, whence which he has emerged by chance". In 2000, geologist and paleontologist Peter Ward and astrobiologist Donald Brownlee published a book entitled Rare Earth: Why Complex Life is Uncommon in the Universe.[better source needed] In it, they discussed the Rare Earth hypothesis, in which they claim that Earth-like life is rare in the universe, whereas microbial life is common. Ward and Brownlee are open to the idea of evolution on other planets that is not based on essential Earth-like characteristics such as DNA and carbon. As for the possible risks, theoretical physicist Stephen Hawking warned in 2010 that humans should not try to contact alien life forms. He warned that aliens might pillage Earth for resources. "If aliens visit us, the outcome would be much as when Columbus landed in America, which didn't turn out well for the Native Americans", he said. Jared Diamond had earlier expressed similar concerns. On 20 July 2015, Hawking and Russian billionaire Yuri Milner, along with the SETI Institute, announced a well-funded effort, called the Breakthrough Initiatives, to expand efforts to search for extraterrestrial life. The group contracted the services of the 100-meter Robert C. Byrd Green Bank Telescope in West Virginia in the United States and the 64-meter Parkes Telescope in New South Wales, Australia. On 13 February 2015, scientists (including Geoffrey Marcy, Seth Shostak, Frank Drake and David Brin) at a convention of the American Association for the Advancement of Science, discussed Active SETI and whether transmitting a message to possible intelligent extraterrestrials in the Cosmos was a good idea; one result was a statement, signed by many, that a "worldwide scientific, political and humanitarian discussion must occur before any message is sent". Government responses The 1967 Outer Space Treaty and the 1979 Moon Agreement define rules of planetary protection against potentially hazardous extraterrestrial life. COSPAR also provides guidelines for planetary protection. A committee of the United Nations Office for Outer Space Affairs had in 1977 discussed for a year strategies for interacting with extraterrestrial life or intelligence. The discussion ended without any conclusions. As of 2010, the UN lacks response mechanisms for the case of an extraterrestrial contact. One of the NASA divisions is the Office of Safety and Mission Assurance (OSMA), also known as the Planetary Protection Office. A part of its mission is to "rigorously preclude backward contamination of Earth by extraterrestrial life." In 2016, the Chinese Government released a white paper detailing its space program. According to the document, one of the research objectives of the program is the search for extraterrestrial life. It is also one of the objectives of the Chinese Five-hundred-meter Aperture Spherical Telescope (FAST) program. In 2020, Dmitry Rogozin, the head of the Russian space agency, said the search for extraterrestrial life is one of the main goals of deep space research. He also acknowledged the possibility of existence of primitive life on other planets of the Solar System. The French space agency has an office for the study of "non-identified aero spatial phenomena". The agency is maintaining a publicly accessible database of such phenomena, with over 1600 detailed entries. According to the head of the office, the vast majority of entries have a mundane explanation; but for 25% of entries, their extraterrestrial origin can neither be confirmed nor denied. In 2020, chairman of the Israel Space Agency Isaac Ben-Israel stated that the probability of detecting life in outer space is "quite large". But he disagrees with his former colleague Haim Eshed who stated that there are contacts between an advanced alien civilisation and some of Earth's governments. In fiction Although the idea of extraterrestrial peoples became feasible once astronomy developed enough to understand the nature of planets, they were not thought of as being any different from humans. Having no scientific explanation for the origin of mankind and its relation to other species, there was no reason to expect them to be any other way. This was changed by the 1859 book On the Origin of Species by Charles Darwin, which proposed the theory of evolution. Now with the notion that evolution on other planets may take other directions, science fiction authors created bizarre aliens, clearly distinct from humans. A usual way to do that was to add body features from other animals, such as insects or octopuses. Costuming and special effects feasibility alongside budget considerations forced films and TV series to tone down the fantasy, but these limitations lessened since the 1990s with the advent of computer-generated imagery (CGI), and later on as CGI became more effective and less expensive. Real-life events sometimes captivate people's imagination and this influences the works of fiction. For example, during the Barney and Betty Hill incident, the first recorded claim of an alien abduction, the couple reported that they were abducted and experimented on by aliens with oversized heads, big eyes, pale grey skin, and small noses, a description that eventually became the grey alien archetype once used in works of fiction. See also Notes References Further reading External links |
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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". |
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[SOURCE: https://www.theverge.com/law] | [TOKENS: 1847] |
Law These days, some of tech’s most important decisions are being made inside courtrooms. Google and Facebook are fending off antitrust accusations, while patent suits determine how much control of their own products they can have. The slow fight over Section 230 of the Communications Decency Act threatens platforms like Twitter and YouTube with untold liability suits for the content they host. Gig economy companies like Uber and Airbnb are fighting for their very existence as their workers push for the protections of full-time employees. In each case, judges and juries are setting the rules about exactly how far tech companies can push the envelope and exactly how much protection everyday people have. This is where we keep track of those legal fights and the broader principles behind them. When you move fast and break things, it shouldn’t be too much of a surprise when you end up in court. On Friday morning, the court ruled against the Trump administration (pdf) in the case of Learning Resources, Inc. v. Trump, about whether the International Emergency Economic Powers Act (IEEPA) gave the president the power to impose sweeping tariffs on imports from more than 100 countries. The immediate impact of the ruling is not clear, as the president may try to use other justifications for the tariffs and everything that has followed. The NYT, WSJ, and CNBC have more coverage. Otherwise, the TikTok parent will face “immediate litigation” for copyright infringement of Netflix’s Stranger Things, KPop Demon Hunters, Squid Game, and Bridgerton franchises: “Seedance acts as a high-speed piracy engine, generating mass quantities of unauthorized derivative works utilizing Netflix’s iconic characters, worlds, and scripted narratives. Netflix will not stand by and watch ByteDance treat our valued IP as free, public domain clip art.” Disney, Paramount, and Hollywood trade groups are equally concerned. I’m in downtown Los Angeles where a state judge is hearing the first of several landmark trials about how social media allegedly harmed a teen girl going by K.G.M. We expect to hear from Meta CEO Mark Zuckerberg this week. Bridget McCormack of the American Arbitration Association on AI-powered courts and the future of law. Fed up with increasing subscription prices, viewers embrace rogue streaming boxes. A Washington Post report digs into one 67-year-old man’s experience being targeted by a warrantless administrative subpoena that doesn’t need sign off from a judge or jury. Among their demands, which they wanted dating back to Sept. 1: the day, time and duration of all his online sessions; every associated IP and physical address; a list of each service he used; any alternate usernames and email addresses; the date he opened his account; his credit card, driver’s license and Social Security numbers. The Paris Prosecutor’s office announced that it’s abandoning X after French police raided the offices of Elon Musk’s social media network on Tuesday, part of a year-long investigation into whether X’s algorithm was used to interfere in French politics. Here’s a machine translation of its departing post: “A search is being carried out at the French premises of X by the cybercrime unit of the Paris public prosecutor’s office, together with @CyberGEND and @Europol, as part of the investigation opened in January 2025. The Paris public prosecutor’s office is leaving X. Find us on Lkd and Insta.” US District Judge Margaret Garnett dismissed two of the charges Mangione faced in the killing of UnitedHealthcare CEO Brian Thompson last year, and doing so, removed the death penalty as a punishment for a potential jury to consider when the case goes to trial. With less than two days before a partial government shutdown over funding for the Department of Homeland Security, Republican leadership is trying to dodge the hard work. “I think right now the conversation should be between the White House and Democrats,” Senate Majority Leader John Thune (R-S.D.) said. “The White House obviously is open to negotiation.” Democratic leaders, meanwhile, repeatedly put the onus on Thune for getting a deal. “We have to pass the bill here,” Sen. Patty Murray (Wash.), the top Democratic appropriator, told reporters. “He’s the majority leader.” Today’s reports from Hunterbrook Media and Pablo Torre Finds Out claim the company’s hardware is seemingly easily obtained and popularly used in Russia’s war effort through already-sanctioned distributors and other middlemen. Ubiquiti, which was fined $500k in 2014 over “reckless disregard” for Iran sanctions, did not respond to a request for comment. As reported by NBC News, FBI director Kash Patel said the probe was inspired by conservative journalist Cam Higby, who claims to have “infiltrated” Signal groups from around Minneapolis that were allegedly obstructing law enforcement and tracking ICE agents’ movements. “We immediately opened up that investigation, because that sort of Signal chat — being coordinated with individuals not just locally in Minnesota, but maybe even around the country — if that leads to a break in the federal statute or a violation of some law, then we are going to arrest people.” The legal system is flawed — could AI actually make it better? Gregory Bovino, the Border Patrol commander known for getting into social media fights with people criticizing ICE’s presence in Minnesota, has reportedly been removed from his job as “Commander at large” and will return to his former job in California, where he is expected to retire. A Department of Homeland Security spokesperson denied that Bovino had been “relieved of his duties”, but nothing rules out the possibility that he’s being Mike Waltz’ed. [The Atlantic] Some plurals are just more fun than others to say — this commenter gets it. The Schpongler: Must feel so good to use the plural “attorneys general” at a scale like this. It’s like “senators elect”, “notaries public”, or “Bigs Mac”. Get the day’s best comment and more in my free newsletter, The Verge Daily. A pair of bipartisan lawmakers introduced the Transparency and Responsibility for Artificial Intelligence Networks (TRAIN) Act in the House, letting copyright holders see if AI models were trained on their work. It’s already been introduced in the Senate, and counts the Recording Industry Association of America and SAG-AFTRA among its endorsers. [Congresswoman Madeleine Dean] The Democratic state AGs think they’re the only officials standing up to Trump. They are probably right. The governor’s call to film ICE is part of an attempt to protect states’ rights — but not like that. Two individuals who were driving dump trucks to the construction site in Richland Parish, Louisiana, were arrested on Wednesday. Local law enforcement says ICE “did not enter the Meta site at any time,” but told Bloomberg that agents were sweeping for identification of workers en route to the site. [Bloomberg.com] Powell’s statement says the Fed received grand jury subpoenas “threatening a criminal indictment related to my testimony before the Senate Banking Committee last June,” about historic building renovations. But, he said, it’s actually retaliation for setting interest rates based on “what will serve the public, rather than following the preferences of the President.” The WSJ, CNBC, and NYT have more reporting. Real people died while Trump treated war like a meme stock. In June, the New York state legislature passed a bill requiring social media companies to display warnings about the potential mental health harms of using their products. Now the governor has officially signed the bill into law. The announcement of the signing says that: To combat the mental health risks of using harmful features of social media platforms that prolong use, this legislation will require social media companies to display warning labels on their platforms when a young user initially uses the predatory feature and periodically thereafter, based on continued use. [Governor Kathy Hochul] The CEO of the Center for Countering Digital Hate (CCDH) is suing Trump administration officials after they targeted him for deportation from the US because of his online content moderation work. On Thursday morning, he announced that US District Judge Vernon Broderick granted a TRO and preliminary injunction blocking his arrest or detainment. A hearing has been scheduled for Monday. [DocumentCloud] The Trump administration just sanctioned five people, including Center for Countering Digital Hate (CCDH) founder Imran Ahmed, over their work in content moderation and anti-disinformation. On Wednesday he filed a lawsuit (pdf) to stop their “unconstitutional attempt to arrest and expel him.” Ahmed: My life’s work is to protect children from the dangers of unregulated social media and AI and fight the spread of antisemitism online. That mission has pitted me against big tech executives – and Elon Musk in particular – multiple times. I am proud to call the United States my home. My wife and daughter are American, and instead of spending Christmas with them, I am fighting to prevent my unlawful deportation from my home country. Pagination Most Popular The Verge Daily A free daily digest of the news that matters most. This is the title for the native ad © 2026 Vox Media, LLC. All Rights Reserved |
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[SOURCE: https://en.wikipedia.org/wiki/BBC_News#1950s] | [TOKENS: 8810] |
Contents BBC News BBC News is an operational business division of the British Broadcasting Corporation (BBC) responsible for the gathering and broadcasting of news and current affairs in the UK and around the world. The department is the world's largest broadcast news organisation and generates about 120 hours of radio and television output each day, as well as online news coverage. The service has over 5,500 journalists working across its output including in 50 foreign news bureaus where more than 250 foreign correspondents are stationed. Deborah Turness has been the CEO of news and current affairs since September 2022. In 2019, it was reported in an Ofcom report that the BBC spent £136m on news during the period April 2018 to March 2019. BBC News' domestic, global and online news divisions are housed within the largest live newsroom in Europe, in Broadcasting House in central London. Parliamentary coverage is produced and broadcast from studios in London. Through BBC English Regions, the BBC also has regional centres across England and national news centres in Northern Ireland, Scotland and Wales. All nations and English regions produce their own local news programmes and other current affairs and sport programmes. The BBC is a quasi-autonomous corporation authorised by royal charter, making it operationally independent of the government. As of 2024, the BBC reaches an average of 450 million people per week, with the BBC World Service accounting for 320 million people. History This is London calling – 2LO calling. Here is the first general news bulletin, copyright by Reuters, Press Association, Exchange Telegraph and Central News. — BBC news programme opening during the 1920s The British Broadcasting Company broadcast its first radio bulletin from radio station 2LO on 14 November 1922. Wishing to avoid competition, newspaper publishers persuaded the government to ban the BBC from broadcasting news before 7 pm, and to force it to use wire service copy instead of reporting on its own. The BBC gradually gained the right to edit the copy and, in 1934, created its own news operation. However, it could not broadcast news before 6 p.m. until World War II. In addition to news, Gaumont British and Movietone cinema newsreels had been broadcast on the TV service since 1936, with the BBC producing its own equivalent Television Newsreel programme from January 1948. A weekly Children's Newsreel was inaugurated on 23 April 1950, to around 350,000 receivers. The network began simulcasting its radio news on television in 1946, with a still picture of Big Ben. Televised bulletins began on 5 July 1954, broadcast from leased studios within Alexandra Palace in London. The public's interest in television and live events was stimulated by Elizabeth II's coronation in 1953. It is estimated that up to 27 million people viewed the programme in the UK, overtaking radio's audience of 12 million for the first time. Those live pictures were fed from 21 cameras in central London to Alexandra Palace for transmission, and then on to other UK transmitters opened in time for the event. That year, there were around two million TV Licences held in the UK, rising to over three million the following year, and four and a half million by 1955. Television news, although physically separate from its radio counterpart, was still firmly under radio news' control in the 1950s. Correspondents provided reports for both outlets, and the first televised bulletin, shown on 5 July 1954 on the then BBC television service and presented by Richard Baker, involved his providing narration off-screen while stills were shown. This was then followed by the customary Television Newsreel with a recorded commentary by John Snagge (and on other occasions by Andrew Timothy). On-screen newsreaders were introduced a year later in 1955 – Kenneth Kendall (the first to appear in vision), Robert Dougall, and Richard Baker—three weeks before ITN's launch on 21 September 1955. Mainstream television production had started to move out of Alexandra Palace in 1950 to larger premises – mainly at Lime Grove Studios in Shepherd's Bush, west London – taking Current Affairs (then known as Talks Department) with it. It was from here that the first Panorama, a new documentary programme, was transmitted on 11 November 1953, with Richard Dimbleby becoming anchor in 1955. In 1958, Hugh Carleton Greene became head of News and Current Affairs. On 1 January 1960, Greene became Director-General. Greene made changes that were aimed at making BBC reporting more similar to its competitor ITN, which had been highly rated by study groups held by Greene. A newsroom was created at Alexandra Palace, television reporters were recruited and given the opportunity to write and voice their own scripts, without having to cover stories for radio too. On 20 June 1960, Nan Winton, the first female BBC network newsreader, appeared in vision. 19 September 1960 saw the start of the radio news and current affairs programme The Ten O'clock News. BBC2 started transmission on 20 April 1964 and began broadcasting a new show, Newsroom. The World at One, a lunchtime news programme, began on 4 October 1965 on the then Home Service, and the year before News Review had started on television. News Review was a summary of the week's news, first broadcast on Sunday, 26 April 1964 on BBC 2 and harking back to the weekly Newsreel Review of the Week, produced from 1951, to open programming on Sunday evenings–the difference being that this incarnation had subtitles for the deaf and hard-of-hearing. As this was the decade before electronic caption generation, each superimposition ("super") had to be produced on paper or card, synchronised manually to studio and news footage, committed to tape during the afternoon, and broadcast early evening. Thus Sundays were no longer a quiet day for news at Alexandra Palace. The programme ran until the 1980s – by then using electronic captions, known as Anchor – to be superseded by Ceefax subtitling (a similar Teletext format), and the signing of such programmes as See Hear (from 1981). On Sunday 17 September 1967, The World This Weekend, a weekly news and current affairs programme, launched on what was then Home Service, but soon-to-be Radio 4. Preparations for colour began in the autumn of 1967 and on Thursday 7 March 1968 Newsroom on BBC2 moved to an early evening slot, becoming the first UK news programme to be transmitted in colour – from Studio A at Alexandra Palace. News Review and Westminster (the latter a weekly review of Parliamentary happenings) were "colourised" shortly after. However, much of the insert material was still in black and white, as initially only a part of the film coverage shot in and around London was on colour reversal film stock, and all regional and many international contributions were still in black and white. Colour facilities at Alexandra Palace were technically very limited for the next eighteen months, as it had only one RCA colour Quadruplex videotape machine and, eventually two Pye plumbicon colour telecines–although the news colour service started with just one. Black and white national bulletins on BBC 1 continued to originate from Studio B on weekdays, along with Town and Around, the London regional "opt out" programme broadcast throughout the 1960s (and the BBC's first regional news programme for the South East), until it started to be replaced by Nationwide on Tuesday to Thursday from Lime Grove Studios early in September 1969. Town and Around was never to make the move to Television Centre – instead it became London This Week which aired on Mondays and Fridays only, from the new TVC studios. The BBC moved production out of Alexandra Palace in 1969. BBC Television News resumed operations the next day with a lunchtime bulletin on BBC1 – in black and white – from Television Centre, where it remained until March 2013. This move to a smaller studio with better technical facilities allowed Newsroom and News Review to replace back projection with colour-separation overlay. During the 1960s, satellite communication had become possible; however, it was some years before digital line-store conversion was able to undertake the process seamlessly. On 14 September 1970, the first Nine O'Clock News was broadcast on television. Robert Dougall presented the first week from studio N1 – described by The Guardian as "a sort of polystyrene padded cell"—the bulletin having been moved from the earlier time of 20.50 as a response to the ratings achieved by ITN's News at Ten, introduced three years earlier on the rival ITV. Richard Baker and Kenneth Kendall presented subsequent weeks, thus echoing those first television bulletins of the mid-1950s. Angela Rippon became the first female news presenter of the Nine O'Clock News in 1975. Her work outside the news was controversial at the time, appearing on The Morecambe and Wise Christmas Show in 1976 singing and dancing. The first edition of John Craven's Newsround, initially intended only as a short series and later renamed just Newsround, came from studio N3 on 4 April 1972. Afternoon television news bulletins during the mid to late 1970s were broadcast from the BBC newsroom itself, rather than one of the three news studios. The newsreader would present to camera while sitting on the edge of a desk; behind him staff would be seen working busily at their desks. This period corresponded with when the Nine O'Clock News got its next makeover, and would use a CSO background of the newsroom from that very same camera each weekday evening. Also in the mid-1970s, the late night news on BBC2 was briefly renamed Newsnight, but this was not to last, or be the same programme as we know today – that would be launched in 1980 – and it soon reverted to being just a news summary with the early evening BBC2 news expanded to become Newsday. News on radio was to change in the 1970s, and on Radio 4 in particular, brought about by the arrival of new editor Peter Woon from television news and the implementation of the Broadcasting in the Seventies report. These included the introduction of correspondents into news bulletins where previously only a newsreader would present, as well as the inclusion of content gathered in the preparation process. New programmes were also added to the daily schedule, PM and The World Tonight as part of the plan for the station to become a "wholly speech network". Newsbeat launched as the news service on Radio 1 on 10 September 1973. On 23 September 1974, a teletext system which was launched to bring news content on television screens using text only was launched. Engineers originally began developing such a system to bring news to deaf viewers, but the system was expanded. The Ceefax service became much more diverse before it ceased on 23 October 2012: it not only had subtitling for all channels, it also gave information such as weather, flight times and film reviews. By the end of the decade, the practice of shooting on film for inserts in news broadcasts was declining, with the introduction of ENG technology into the UK. The equipment would gradually become less cumbersome – the BBC's first attempts had been using a Philips colour camera with backpack base station and separate portable Sony U-matic recorder in the latter half of the decade. In 1980, the Iranian Embassy Siege had been shot electronically by the BBC Television News Outside broadcasting team, and the work of reporter Kate Adie, broadcasting live from Prince's Gate, was nominated for BAFTA actuality coverage, but this time beaten by ITN for the 1980 award. Newsnight, the news and current affairs programme, was due to go on air on 23 January 1980, although trade union disagreements meant that its launch from Lime Grove was postponed by a week. On 27 August 1981 Moira Stuart became the first African Caribbean female newsreader to appear on British television. By 1982, ENG technology had become sufficiently reliable for Bernard Hesketh to use an Ikegami camera to cover the Falklands War, coverage for which he won the "Royal Television Society Cameraman of the Year" award and a BAFTA nomination – the first time that BBC News had relied upon an electronic camera, rather than film, in a conflict zone. BBC News won the BAFTA for its actuality coverage, however the event has become remembered in television terms for Brian Hanrahan's reporting where he coined the phrase "I'm not allowed to say how many planes joined the raid, but I counted them all out and I counted them all back" to circumvent restrictions, and which has become cited as an example of good reporting under pressure. The first BBC breakfast television programme, Breakfast Time also launched during the 1980s, on 17 January 1983 from Lime Grove Studio E and two weeks before its ITV rival TV-am. Frank Bough, Selina Scott, and Nick Ross helped to wake viewers with a relaxed style of presenting. The Six O'Clock News first aired on 3 September 1984, eventually becoming the most watched news programme in the UK (however, since 2006 it has been overtaken by the BBC News at Ten). In October 1984, images of millions of people starving to death in the Ethiopian famine were shown in Michael Buerk's Six O'Clock News reports. The BBC News crew were the first to document the famine, with Buerk's report on 23 October describing it as "a biblical famine in the 20th century" and "the closest thing to hell on Earth". The BBC News report shocked Britain, motivating its citizens to inundate relief agencies, such as Save the Children, with donations, and to bring global attention to the crisis in Ethiopia. The news report was also watched by Bob Geldof, who would organise the charity single "Do They Know It's Christmas?" to raise money for famine relief followed by the Live Aid concert in July 1985. Starting in 1981, the BBC gave a common theme to its main news bulletins with new electronic titles–a set of computer-animated "stripes" forming a circle on a red background with a "BBC News" typescript appearing below the circle graphics, and a theme tune consisting of brass and keyboards. The Nine used a similar (striped) number 9. The red background was replaced by a blue from 1985 until 1987. By 1987, the BBC had decided to re-brand its bulletins and established individual styles again for each one with differing titles and music, the weekend and holiday bulletins branded in a similar style to the Nine, although the "stripes" introduction continued to be used until 1989 on occasions where a news bulletin was screened out of the running order of the schedule. In 1987, John Birt resurrected the practice of correspondents working for both TV and radio with the introduction of bi-media journalism. During the 1990s, a wider range of services began to be offered by BBC News, with the split of BBC World Service Television to become BBC World (news and current affairs), and BBC Prime (light entertainment). Content for a 24-hour news channel was thus required, followed in 1997 with the launch of domestic equivalent BBC News 24. Rather than set bulletins, ongoing reports and coverage was needed to keep both channels functioning and meant a greater emphasis in budgeting for both was necessary. In 1998, after 66 years at Broadcasting House, the BBC Radio News operation moved to BBC Television Centre. New technology, provided by Silicon Graphics, came into use in 1993 for a re-launch of the main BBC 1 bulletins, creating a virtual set which appeared to be much larger than it was physically. The relaunch also brought all bulletins into the same style of set with only small changes in colouring, titles, and music to differentiate each. A computer generated cut-glass sculpture of the BBC coat of arms was the centrepiece of the programme titles until the large scale corporate rebranding of news services in 1999. In November 1997, BBC News Online was launched, following individual webpages for major news events such as the 1996 Olympic Games, 1997 general election, and the death of Princess Diana. In 1999, the biggest relaunch occurred, with BBC One bulletins, BBC World, BBC News 24, and BBC News Online all adopting a common style. One of the most significant changes was the gradual adoption of the corporate image by the BBC regional news programmes, giving a common style across local, national and international BBC television news. This also included Newyddion, the main news programme of Welsh language channel S4C, produced by BBC News Wales. Following the relaunch of BBC News in 1999, regional headlines were included at the start of the BBC One news bulletins in 2000. The English regions did however lose five minutes at the end of their bulletins, due to a new headline round-up at 18:55. 2000 also saw the Nine O'Clock News moved to the later time of 22:00. This was in response to ITN who had just moved their popular News at Ten programme to 23:00. ITN briefly returned News at Ten but following poor ratings when head-to-head against the BBC's Ten O'Clock News, the ITN bulletin was moved to 22.30, where it remained until 14 January 2008. The retirement in 2009 of Peter Sissons and departure of Michael Buerk from the Ten O'Clock News led to changes in the BBC One bulletin presenting team on 20 January 2003. The Six O'Clock News became double headed with George Alagiah and Sophie Raworth after Huw Edwards and Fiona Bruce moved to present the Ten. A new set design featuring a projected fictional newsroom backdrop was introduced, followed on 16 February 2004 by new programme titles to match those of BBC News 24. BBC News 24 and BBC World introduced a new style of presentation in December 2003, that was slightly altered on 5 July 2004 to mark 50 years of BBC Television News. On 7 March 2005 director general Mark Thompson launched the "Creative Futures" project to restructure the organisation. The individual positions of editor of the One and Six O'Clock News were replaced by a new daytime position in November 2005. Kevin Bakhurst became the first Controller of BBC News 24, replacing the position of editor. Amanda Farnsworth became daytime editor while Craig Oliver was later named editor of the Ten O'Clock News. Bulletins received new titles and a new set design in May 2006, to allow for Breakfast to move into the main studio for the first time since 1997. The new set featured Barco videowall screens with a background of the London skyline used for main bulletins and originally an image of cirrus clouds against a blue sky for Breakfast. This was later replaced following viewer criticism. The studio bore similarities with the ITN-produced ITV News in 2004, though ITN uses a CSO Virtual studio rather than the actual screens at BBC News. BBC News became part of a new BBC Journalism group in November 2006 as part of a restructuring of the BBC. The then-Director of BBC News, Helen Boaden reported to the then-Deputy Director-General and head of the journalism group, Mark Byford until he was made redundant in 2010. On 18 October 2007, ED Mark Thompson announced a six-year plan, "Delivering Creative Futures" (based on his project begun in March 2005), merging the television current affairs department into a new "News Programmes" division. Thompson's announcement, in response to a £2 billion shortfall in funding, would, he said, deliver "a smaller but fitter BBC" in the digital age, by cutting its payroll and, in 2013, selling Television Centre. The various separate newsrooms for television, radio and online operations were merged into a single multimedia newsroom. Programme making within the newsrooms was brought together to form a multimedia programme making department. BBC World Service director Peter Horrocks said that the changes would achieve efficiency at a time of cost-cutting at the BBC. In his blog, he wrote that by using the same resources across the various broadcast media meant fewer stories could be covered, or by following more stories, there would be fewer ways to broadcast them. A new graphics and video playout system was introduced for production of television bulletins in January 2007. This coincided with a new structure to BBC World News bulletins, editors favouring a section devoted to analysing the news stories reported on. The first new BBC News bulletin since the Six O'Clock News was announced in July 2007 following a successful trial in the Midlands. The summary, lasting 90 seconds, has been broadcast at 20:00 on weekdays since December 2007 and bears similarities with 60 Seconds on BBC Three, but also includes headlines from the various BBC regions and a weather summary. As part of a long-term cost cutting programme, bulletins were renamed the BBC News at One, Six and Ten respectively in April 2008 while BBC News 24 was renamed BBC News and moved into the same studio as the bulletins at BBC Television Centre. BBC World was renamed BBC World News and regional news programmes were also updated with the new presentation style, designed by Lambie-Nairn. 2008 also saw tri-media introduced across TV, radio, and online. The studio moves also meant that Studio N9, previously used for BBC World, was closed, and operations moved to the previous studio of BBC News 24. Studio N9 was later refitted to match the new branding, and was used for the BBC's UK local elections and European elections coverage in early June 2009. A strategy review of the BBC in March 2010, confirmed that having "the best journalism in the world" would form one of five key editorial policies, as part of changes subject to public consultation and BBC Trust approval. After a period of suspension in late 2012, Helen Boaden ceased to be the Director of BBC News. On 16 April 2013, incoming BBC Director-General Tony Hall named James Harding, a former editor of The Times of London newspaper as Director of News and Current Affairs. From August 2012 to March 2013, all news operations moved from Television Centre to new facilities in the refurbished and extended Broadcasting House, in Portland Place. The move began in October 2012, and also included the BBC World Service, which moved from Bush House following the expiry of the BBC's lease. This new extension to the north and east, referred to as "New Broadcasting House", includes several new state-of-the-art radio and television studios centred around an 11-storey atrium. The move began with the domestic programme The Andrew Marr Show on 2 September 2012, and concluded with the move of the BBC News channel and domestic news bulletins on 18 March 2013. The newsroom houses all domestic bulletins and programmes on both television and radio, as well as the BBC World Service international radio networks and the BBC World News international television channel. BBC News and CBS News established an editorial and newsgathering partnership in 2017, replacing an earlier long-standing partnership between BBC News and ABC News. In an October 2018 Simmons Research survey of 38 news organisations, BBC News was ranked the fourth most trusted news organisation by Americans, behind CBS News, ABC News and The Wall Street Journal. In January 2020 the BBC announced a BBC News savings target of £80 million per year by 2022, involving about 450 staff reductions from the current 6,000. BBC director of news and current affairs Fran Unsworth said there would be further moves toward digital broadcasting, in part to attract back a youth audience, and more pooling of reporters to stop separate teams covering the same news. A further 70 staff reductions were announced in July 2020. BBC Three began airing the news programme The Catch Up in February 2022. It is presented by Levi Jouavel, Kirsty Grant, and Callum Tulley and aims to get the channel's target audience (16 to 34-year olds) to make sense of the world around them while also highlighting optimistic stories. Compared to its predecessor 60 Seconds, The Catch Up is three times longer, running for about three minutes and not airing during weekends. According to its annual report as of December 2021[update], India has the largest number of people using BBC services in the world. In May 2025, following the earthquake that hit Myanmar and Thailand, a television news bulletin (BBC News Myanmar) from the Burmese service using a vacated Voice of America satellite frequency began its broadcasts. Programming and reporting In November 2023, BBC News joined with the International Consortium of Investigative Journalists, Paper Trail Media [de] and 69 media partners including Distributed Denial of Secrets and the Organised Crime and Corruption Reporting Project (OCCRP) and more than 270 journalists in 55 countries and territories to produce the 'Cyprus Confidential' report on the financial network which supports the regime of Vladimir Putin, mostly with connections to Cyprus, and showed Cyprus to have strong links with high-up figures in the Kremlin, some of whom have been sanctioned. Government officials including Cyprus president Nikos Christodoulides and European lawmakers began responding to the investigation's findings in less than 24 hours, calling for reforms and launching probes. BBC News is responsible for the news programmes and documentary content on the BBC's general television channels, as well as the news coverage on the BBC News Channel in the UK, and 22 hours of programming for the corporation's international BBC World News channel. Coverage for BBC Parliament is carried out on behalf of the BBC at Millbank Studios, though BBC News provides editorial and journalistic content. BBC News content is also output onto the BBC's digital interactive television services under the BBC Red Button brand, and until 2012, on the Ceefax teletext system. The music on all BBC television news programmes was introduced in 1999 and composed by David Lowe. It was part of the re-branding which commenced in 1999 and features 'BBC Pips'. The general theme was used on bulletins on BBC One, News 24, BBC World and local news programmes in the BBC's Nations and Regions. Lowe was also responsible for the music on Radio One's Newsbeat. The theme has had several changes since 1999, the latest in March 2013. The BBC Arabic Television news channel launched on 11 March 2008, a Persian-language channel followed on 14 January 2009, broadcasting from the Peel wing of Broadcasting House; both include news, analysis, interviews, sports and highly cultural programmes and are run by the BBC World Service and funded from a grant-in-aid from the British Foreign Office (and not the television licence). The BBC Verify service was launched in 2023 to fact-check news stories, followed by BBC Verify Live in 2025. BBC Radio News produces bulletins for the BBC's national radio stations and provides content for local BBC radio stations via the General News Service (GNS), a BBC-internal news distribution service. BBC News does not produce the BBC's regional news bulletins, which are produced individually by the BBC nations and regions themselves. The BBC World Service broadcasts to some 150 million people in English as well as 27 languages across the globe. BBC Radio News is a patron of the Radio Academy. BBC News Online is the BBC's news website. Launched in November 1997, it is one of the most popular news websites, with 1.2 billion website visits in April 2021, as well as being used by 60% of the UK's internet users for news. The website contains international news coverage as well as entertainment, sport, science, and political news. Mobile apps for Android, iOS and Windows Phone systems have been provided since 2010. Many television and radio programmes are also available to view on the BBC iPlayer and BBC Sounds services. The BBC News channel is also available to view 24 hours a day, while video and radio clips are also available within online news articles. In October 2019, BBC News Online launched a mirror on the dark web anonymity network Tor in an effort to circumvent censorship. Criticism The BBC is required by its charter to be free from both political and commercial influence and answers only to its viewers and listeners. This political objectivity is sometimes questioned. For instance, The Daily Telegraph (3 August 2005) carried a letter from the KGB defector Oleg Gordievsky, referring to it as "The Red Service". Books have been written on the subject, including anti-BBC works like Truth Betrayed by W J West and The Truth Twisters by Richard Deacon. The BBC has been accused of bias by Conservative MPs. The BBC's Editorial Guidelines on Politics and Public Policy state that while "the voices and opinions of opposition parties must be routinely aired and challenged", "the government of the day will often be the primary source of news". The BBC is regularly accused by the government of the day of bias in favour of the opposition and, by the opposition, of bias in favour of the government. Similarly, during times of war, the BBC is often accused by the UK government, or by strong supporters of British military campaigns, of being overly sympathetic to the view of the enemy. An edition of Newsnight at the start of the Falklands War in 1982 was described as "almost treasonable" by John Page, MP, who objected to Peter Snow saying "if we believe the British". During the first Gulf War, critics of the BBC took to using the satirical name "Baghdad Broadcasting Corporation". During the Kosovo War, the BBC were labelled the "Belgrade Broadcasting Corporation" (suggesting favouritism towards the FR Yugoslavia government over ethnic Albanian rebels) by British ministers, although Slobodan Milosević (then FRY president) claimed that the BBC's coverage had been biased against his nation. Conversely, some of those who style themselves anti-establishment in the United Kingdom or who oppose foreign wars have accused the BBC of pro-establishment bias or of refusing to give an outlet to "anti-war" voices. Following the 2003 invasion of Iraq, a study by the Cardiff University School of Journalism of the reporting of the war found that nine out of 10 references to weapons of mass destruction during the war assumed that Iraq possessed them, and only one in 10 questioned this assumption. It also found that, out of the main British broadcasters covering the war, the BBC was the most likely to use the British government and military as its source. It was also the least likely to use independent sources, like the Red Cross, who were more critical of the war. When it came to reporting Iraqi casualties, the study found fewer reports on the BBC than on the other three main channels. The report's author, Justin Lewis, wrote "Far from revealing an anti-war BBC, our findings tend to give credence to those who criticised the BBC for being too sympathetic to the government in its war coverage. Either way, it is clear that the accusation of BBC anti-war bias fails to stand up to any serious or sustained analysis." Prominent BBC appointments are constantly assessed by the British media and political establishment for signs of political bias. The appointment of Greg Dyke as Director-General was highlighted by press sources because Dyke was a Labour Party member and former activist, as well as a friend of Tony Blair. The BBC's former Political Editor, Nick Robinson, was some years ago a chairman of the Young Conservatives and did, as a result, attract informal criticism from the former Labour government, but his predecessor Andrew Marr faced similar claims from the right because he was editor of The Independent, a liberal-leaning newspaper, before his appointment in 2000. Mark Thompson, former Director-General of the BBC, admitted the organisation has been biased "towards the left" in the past. He said, "In the BBC I joined 30 years ago, there was, in much of current affairs, in terms of people's personal politics, which were quite vocal, a massive bias to the left". He then added, "The organization did struggle then with impartiality. Now it is a completely different generation. There is much less overt tribalism among the young journalists who work for the BBC." Following the EU referendum in 2016, some critics suggested that the BBC was biased in favour of leaving the EU. For instance, in 2018, the BBC received complaints from people who took issue that the BBC was not sufficiently covering anti-Brexit marches while giving smaller-scale events hosted by former UKIP leader Nigel Farage more airtime. On the other hand, a poll released by YouGov showed that 45% of people who voted to leave the EU thought that the BBC was 'actively anti-Brexit' compared to 13% of the same kinds of voters who think the BBC is pro-Brexit. In 2008, the BBC Hindi was criticised by some Indian outlets for referring to the terrorists who carried out the 2008 Mumbai attacks as "gunmen". The response to this added to prior criticism from some Indian commentators suggesting that the BBC may have an Indophobic bias. In March 2015, the BBC was criticised for a BBC Storyville documentary interviewing one of the rapists in India. In spite of a ban ordered by the Indian High court, the BBC still aired the documentary "India's Daughter" outside India. BBC News was at the centre of a political controversy following the 2003 invasion of Iraq. Three BBC News reports (Andrew Gilligan's on Today, Gavin Hewitt's on The Ten O'Clock News and another on Newsnight) quoted an anonymous source that stated the British government (particularly the Prime Minister's office) had embellished the September Dossier with misleading exaggerations of Iraq's weapons of mass destruction capabilities. The government denounced the reports and accused the corporation of poor journalism. In subsequent weeks the corporation stood by the report, saying that it had a reliable source. Following intense media speculation, David Kelly was named in the press as the source for Gilligan's story on 9 July 2003. Kelly was found dead, by suicide, in a field close to his home early on 18 July. An inquiry led by Lord Hutton was announced by the British government the following day to investigate the circumstances leading to Kelly's death, concluding that "Dr. Kelly took his own life." In his report on 28 January 2004, Lord Hutton concluded that Gilligan's original accusation was "unfounded" and the BBC's editorial and management processes were "defective". In particular, it specifically criticised the chain of management that caused the BBC to defend its story. The BBC Director of News, Richard Sambrook, the report said, had accepted Gilligan's word that his story was accurate in spite of his notes being incomplete. Davies had then told the BBC Board of Governors that he was happy with the story and told the Prime Minister that a satisfactory internal inquiry had taken place. The Board of Governors, under the chairman's, Gavyn Davies, guidance, accepted that further investigation of the Government's complaints were unnecessary. Because of the criticism in the Hutton report, Davies resigned on the day of publication. BBC News faced an important test, reporting on itself with the publication of the report, but by common consent (of the Board of Governors) managed this "independently, impartially and honestly". Davies' resignation was followed by the resignation of Director General, Greg Dyke, the following day, and the resignation of Gilligan on 30 January. While undoubtedly a traumatic experience for the corporation, an ICM poll in April 2003 indicated that it had sustained its position as the best and most trusted provider of news. The BBC has faced accusations of holding both anti-Israel and anti-Palestine bias. Douglas Davis, the London correspondent of The Jerusalem Post, has described the BBC's coverage of the Arab–Israeli conflict as "a relentless, one-dimensional portrayal of Israel as a demonic, criminal state and Israelis as brutal oppressors [which] bears all the hallmarks of a concerted campaign of vilification that, wittingly or not, has the effect of delegitimising the Jewish state and pumping oxygen into a dark old European hatred that dared not speak its name for the past half-century.". However two large independent studies, one conducted by Loughborough University and the other by Glasgow University's Media Group concluded that Israeli perspectives are given greater coverage. Critics of the BBC argue that the Balen Report proves systematic bias against Israel in headline news programming. The Daily Mail and The Daily Telegraph criticised the BBC for spending hundreds of thousands of British tax payers' pounds from preventing the report being released to the public. Jeremy Bowen, the Middle East Editor for BBC world news, was singled out specifically for bias by the BBC Trust which concluded that he violated "BBC guidelines on accuracy and impartiality." An independent panel appointed by the BBC Trust was set up in 2006 to review the impartiality of the BBC's coverage of the Israeli–Palestinian conflict. The panel's assessment was that "apart from individual lapses, there was little to suggest deliberate or systematic bias." While noting a "commitment to be fair accurate and impartial" and praising much of the BBC's coverage the independent panel concluded "that BBC output does not consistently give a full and fair account of the conflict. In some ways the picture is incomplete and, in that sense, misleading." It notes that, "the failure to convey adequately the disparity in the Israeli and Palestinian experience, [reflects] the fact that one side is in control and the other lives under occupation". Writing in the Financial Times, Philip Stephens, one of the panellists, later accused the BBC's director-general, Mark Thompson, of misrepresenting the panel's conclusions. He further opined "My sense is that BBC news reporting has also lost a once iron-clad commitment to objectivity and a necessary respect for the democratic process. If I am right, the BBC, too, is lost". Mark Thompson published a rebuttal in the FT the next day. The description by one BBC correspondent reporting on the funeral of Yassir Arafat that she had been left with tears in her eyes led to other questions of impartiality, particularly from Martin Walker in a guest opinion piece in The Times, who picked out the apparent case of Fayad Abu Shamala, the BBC Arabic Service correspondent, who told a Hamas rally on 6 May 2001, that journalists in Gaza were "waging the campaign shoulder to shoulder together with the Palestinian people". Walker argues that the independent inquiry was flawed for two reasons. Firstly, because the time period over which it was conducted (August 2005 to January 2006) surrounded the Israeli withdrawal from Gaza and Ariel Sharon's stroke, which produced more positive coverage than usual. Furthermore, he wrote, the inquiry only looked at the BBC's domestic coverage, and excluded output on the BBC World Service and BBC World. Tom Gross accused the BBC of glorifying Hamas suicide bombers, and condemned its policy of inviting guests such as Jenny Tonge and Tom Paulin who have compared Israeli soldiers to Nazis. Writing for the BBC, Paulin said Israeli soldiers should be "shot dead" like Hitler's S.S, and said he could "understand how suicide bombers feel". The BBC also faced criticism for not airing a Disasters Emergency Committee aid appeal for Palestinians who suffered in Gaza during 22-day war there between late 2008 and early 2009. Most other major UK broadcasters did air this appeal, but rival Sky News did not. British journalist Julie Burchill has accused BBC of creating a "climate of fear" for British Jews over its "excessive coverage" of Israel compared to other nations. In light of the Gaza war, the BBC suspended seven Arab journalists over allegations of expressing support for Hamas via social media. BBC and ABC share video segments and reporters as needed in producing their newscasts. with the BBC showing ABC World News Tonight with David Muir in the UK. However, in July 2017, the BBC announced a new partnership with CBS News allows both organisations to share video, editorial content, and additional newsgathering resources in New York, London, Washington and around the world. BBC News subscribes to wire services from leading international agencies including PA Media (formerly Press Association), Reuters, and Agence France-Presse. In April 2017, the BBC dropped Associated Press in favour of an enhanced service from AFP. BBC News reporters and broadcasts are now and have in the past been banned in several countries primarily for reporting which has been unfavourable to the ruling government. For example, correspondents were banned by the former apartheid regime of South Africa. The BBC was banned in Zimbabwe under Mugabe for eight years as a terrorist organisation until being allowed to operate again over a year after the 2008 elections. The BBC was banned in Burma (officially Myanmar) after their coverage and commentary on anti-government protests there in September 2007. The ban was lifted four years later in September 2011. Other cases have included Uzbekistan, China, and Pakistan. BBC Persian, the BBC's Persian language news site, was blocked from the Iranian internet in 2006. The BBC News website was made available in China again in March 2008, but as of October 2014[update], was blocked again. In June 2015, the Rwandan government placed an indefinite ban on BBC broadcasts following the airing of a controversial documentary regarding the 1994 Rwandan genocide, Rwanda's Untold Story, broadcast on BBC2 on 1 October 2014. The UK's Foreign Office recognised "the hurt caused in Rwanda by some parts of the documentary". In February 2017, reporters from the BBC (as well as the Daily Mail, The New York Times, Politico, CNN, and others) were denied access to a United States White House briefing. In 2017, BBC India was banned for a period of five years from covering all national parks and sanctuaries in India. Following the withdrawal of CGTN's UK broadcaster licence on 4 February 2021 by Ofcom, China banned BBC News from airing in China. See also References External links |below = Category }} |
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[SOURCE: https://www.wired.com/tag/wired-events/] | [TOKENS: 139] |
WIRED Events WIRED events reinvigorate how business professionals define their strategies in rapidly evolving industries. By introducing attendees to the most compelling innovators, inventors and entrepreneurs who are changing the status quo, WIRED events challenge attendees to think like a disruptor and empower them in future-proofing their businesses. US Events UK Events © 2026 Condé Nast. All rights reserved. WIRED may earn a portion of sales from products that are purchased through our site as part of our Affiliate Partnerships with retailers. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of Condé Nast. Ad Choices |
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[SOURCE: https://www.wired.com/collection/wiredinsider/] | [TOKENS: 114] |
WIRED Insider AI is Making Our Volatile Planet More Predictable Where in the World Will We Go Next? AI is Set to Revolutionize Corporate HR The meaning of a millisecond in the world of McLaren Racing © 2026 Condé Nast. All rights reserved. WIRED may earn a portion of sales from products that are purchased through our site as part of our Affiliate Partnerships with retailers. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of Condé Nast. Ad Choices |
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[SOURCE: https://en.wikipedia.org/wiki/GNU_Manifesto] | [TOKENS: 546] |
GNU Manifesto The GNU Manifesto is a call-to-action by Richard Stallman encouraging participation and support of the GNU Project's goal in developing the GNU free computer operating system. The GNU Manifesto was published in March 1985 in Dr. Dobb's Journal. It is held in high regard within the free software movement as a fundamental philosophical source. The full text is included with GNU software such as Emacs, and is publicly available. Background Some parts of the GNU Manifesto began as an announcement of the GNU Project posted by Richard Stallman on September 27, 1983, in form of an email on Usenet newsgroups. The project's aim was to give computer users freedom and control over their computers by collaboratively developing and providing software that is based on Stallman's idea of software freedom (although the written definition did not exist until February 1986). The manifesto was written to familiarize more people with these concepts, and to find more support in the form of work, funding, programs and hardware. The GNU Manifesto was published with its title and full written form in 1985 but was updated slightly in 1987. Summary The GNU Manifesto opens with an explanation of what the GNU Project is, and what is the current, at the time, progress in creation of the GNU operating system. The system, although based on, and compatible with Unix, is meant by the author to have many improvements over it, which are listed in detail in the manifesto. One of the major driving points behind the GNU project, according to Stallman, was the rapid (at the time) trend toward Unix and its various components becoming proprietary (i.e. closed-source and non-libre) software. The manifesto lays a philosophical basis for launching the project, and importance of bringing it to fruition — proprietary software is a way to divide users, who are no longer able to help each other. Stallman refuses to write proprietary software as a sign of solidarity with them. The author provides many reasons for why the project and software freedom is beneficial to users, although he agrees that its wide adoption will make the work of programmers less profitable. A large part of the GNU Manifesto is focused on rebutting possible objections to GNU Project's goals. They include the programmer's need to make a living, the issue of advertising and distributing free software, and the perceived need of a profit incentive. Inspired by GNU Manifesto Throughout history, the GNU Manifesto has inspired various other UNIX-related manifestos. Based on it, 10 years later, a popular magazine Linux Focus released its manifesto. 20 years later, a popular illustrations publisher has published their Linux developer manifesto.[failed verification] See also References External links |
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[SOURCE: https://huggingface.co/datasets/Raziel1234/WebBooks?duplicate=true] | [TOKENS: 90] |
Datasets: Raziel1234 / WebBooks like 0 Books Corpus Dataset Overview This dataset is a large collection of text lines extracted from free books available on Project Gutenberg. The dataset is primarily composed of literary texts, including classical literature and science fiction. It is designed for training custom language models focused on book-style text generation. Dataset Structure Each line in the corpus represents a cleaned sentence or paragraph extracted from the HTML of Project Gutenberg books. Features Usage |
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[SOURCE: https://www.theverge.com/cyber-security] | [TOKENS: 982] |
Security Cybersecurity is the rickety scaffolding supporting everything you do online. For every new feature or app, there are a thousand different ways it can break – and a hundred of those can be exploited by criminals for data breaches, identity theft, or outright cyber heists. Staying ahead of those exploits is a full-time job, and one of the most lucrative and sought-after skills in the tech industry. All too often, it’s something up-and-coming companies decide to skip out on, only to pay the price later on. Lockdown Mode is “not necessary” for most people and “tightly constrains how ChatGPT can interact with external systems to reduce the risk of prompt injection–based data exfiltration,” according to OpenAI. [OpenAI] Yes, Wyze has had its own issues, but this video is pretty funny. Researchers raised alarms when over 400 malicious skills were uploaded to ClawHub and GitHub in just one week. That prompted an outcry, so OpenClaw partnered with VirusTotal to scan third-party skills. The company acknowledges it’s not a “silver bullet,” but it should provide at least some reassurance to concerned users. 404 Media reports that security researcher Jamieson O’Reilly found a vulnerability that allows humans to control OpenClaw’s AI agents on Moltbook — the network that recently went viral for hosting “discussions” between supposed AI bots. Wiz dug into the misconfiguration as well, uncovering 1.5 million exposed API keys and 35,000 email addresses. Moltbook has since secured the database. [404 Media] Two days after Nick Benson asked for donated dashcams in order to document the behavior of federal immigration agents flooding his city, Renee Nicole Good was shot and killed by federal agent Jonathan Ross. ”It was immediately clear that ICE was lying about it,” Benson told 404 Media. Donations have jumped since then, and Benson distributes the cameras to local community organizers and whoever wants them. [404 Media] The company says an “unauthorized individual gained access to certain Betterment systems through social engineering” to send the message on Friday. Betterment believes the individual accessed information like “certain names, email addresses, physical addresses, phone numbers, and birthdates,” though so far, its investigation has shown that no passwords were compromised. [Betterment] Seems a lot of people got password reset requests from Instagram over the last few days, including several Verge staffers and members of their family. The email might look legit. It might even have that little blue checkmark in Gmail. But, it probably came from a scammer. Honestly, it’s best practice to never click links in emails anyway. In June, Aflac disclosed a data breach involving a “sophisticated cybercrime group” that stole names, social security numbers, contact information, health data, and more from its systems. The insurance provider has now revealed just how many people are affected, adding that it is currently “not aware of any fraudulent use of personal information.” [SecurityWeek] On Thursday, Trust Wallet announced a “security incident” affecting version 2.68 of its Chrome extension. Binance founder Changpeng Zhao confirmed that Trust Wallet “will cover” the losses and that the team is investigating the hack. [CoinDesk] The feature was first piloted in the UK earlier this year, and works by automatically warning users when they launch eligible financial apps while screen sharing during calls with numbers that aren’t in the device’s contact list. The warning forces a 30-second pause period that aims to “break the spell of the scammers’ social engineering,” according to Google. An exposed dataset from the license plate surveillance company Flock, which is known to work with the US Border Patrol and ICE via local police, showed that some of the AI annotators paid to classify American license plates are located in the Philippines. After 404 Media contacted Flock for comment, the dataset disappeared. The infrastructure buildout will add nearly 1.3 gigawatts of capacity for AI and cost up to $50 billion, the company said. US government customers will have access to both AWS Trainium AI chips and NVIDIA chips, and Amazon said it plans to start building the data centers in 2026. On November 12, hackers stole account records and legal agreements from a company you’ve probably never heard of: SitusAMC. It handles commercial real estate and residential loans for the likes of JPMorgan Chase and Citi, who were among Situs’ Wall Street clients notified about the breach, the New York Times reported. [The New York Times] Pagination Most Popular The Verge Daily A free daily digest of the news that matters most. This is the title for the native ad © 2026 Vox Media, LLC. All Rights Reserved |
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[SOURCE: https://www.mako.co.il/nexter] | [TOKENS: 723] |
דיגיטל המנכ"לים שסירבו להחזיק ידיים - ועוררו סערה"כשאתה בפרויקט קבוצתי עם מישהו שאתה לא סובל" 2 טריליון דולר נמחקו: אפוקליפסת ה-AI כבר פהאזהרת המשקיעים אחרי מחיקת ענק בענף ה-SaaS "הייתי מקיאה בעבודה, הגוף ידע שמשהו לא בסדר"נעקצה ע"י נוכל הטינדר - ויצאה למלחמה בהונאות "כשאתה בפרויקט קבוצתי עם מישהו שאתה לא סובל" אזהרת המשקיעים אחרי מחיקת ענק בענף ה-SaaS נעקצה ע"י נוכל הטינדר - ויצאה למלחמה בהונאות הוא צפוי להגיע לישראל במהלך השבועות הקרובים איך להשתמש במודל החדש של קלוד קוד? מדריך ענקיות הטק בצרה: המשפט שעלול לשנות הכול ניסינו את הטבעת החכמה שעזרה לנו לישון וגם: האוזניות הכי יפות שראינו השנה האופו הזה עולה רק 1,400 שקל וכנראה יספק אתכם איך להשתמש במודל החדש של קלוד קוד? מדריך מעכשיו אפשר לצאת מרשימות תפוצה בלחיצה אחת משחקי הגיימינג שטובים לבריאות |
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[SOURCE: https://en.wikipedia.org/wiki/BBC_News#1970s] | [TOKENS: 8810] |
Contents BBC News BBC News is an operational business division of the British Broadcasting Corporation (BBC) responsible for the gathering and broadcasting of news and current affairs in the UK and around the world. The department is the world's largest broadcast news organisation and generates about 120 hours of radio and television output each day, as well as online news coverage. The service has over 5,500 journalists working across its output including in 50 foreign news bureaus where more than 250 foreign correspondents are stationed. Deborah Turness has been the CEO of news and current affairs since September 2022. In 2019, it was reported in an Ofcom report that the BBC spent £136m on news during the period April 2018 to March 2019. BBC News' domestic, global and online news divisions are housed within the largest live newsroom in Europe, in Broadcasting House in central London. Parliamentary coverage is produced and broadcast from studios in London. Through BBC English Regions, the BBC also has regional centres across England and national news centres in Northern Ireland, Scotland and Wales. All nations and English regions produce their own local news programmes and other current affairs and sport programmes. The BBC is a quasi-autonomous corporation authorised by royal charter, making it operationally independent of the government. As of 2024, the BBC reaches an average of 450 million people per week, with the BBC World Service accounting for 320 million people. History This is London calling – 2LO calling. Here is the first general news bulletin, copyright by Reuters, Press Association, Exchange Telegraph and Central News. — BBC news programme opening during the 1920s The British Broadcasting Company broadcast its first radio bulletin from radio station 2LO on 14 November 1922. Wishing to avoid competition, newspaper publishers persuaded the government to ban the BBC from broadcasting news before 7 pm, and to force it to use wire service copy instead of reporting on its own. The BBC gradually gained the right to edit the copy and, in 1934, created its own news operation. However, it could not broadcast news before 6 p.m. until World War II. In addition to news, Gaumont British and Movietone cinema newsreels had been broadcast on the TV service since 1936, with the BBC producing its own equivalent Television Newsreel programme from January 1948. A weekly Children's Newsreel was inaugurated on 23 April 1950, to around 350,000 receivers. The network began simulcasting its radio news on television in 1946, with a still picture of Big Ben. Televised bulletins began on 5 July 1954, broadcast from leased studios within Alexandra Palace in London. The public's interest in television and live events was stimulated by Elizabeth II's coronation in 1953. It is estimated that up to 27 million people viewed the programme in the UK, overtaking radio's audience of 12 million for the first time. Those live pictures were fed from 21 cameras in central London to Alexandra Palace for transmission, and then on to other UK transmitters opened in time for the event. That year, there were around two million TV Licences held in the UK, rising to over three million the following year, and four and a half million by 1955. Television news, although physically separate from its radio counterpart, was still firmly under radio news' control in the 1950s. Correspondents provided reports for both outlets, and the first televised bulletin, shown on 5 July 1954 on the then BBC television service and presented by Richard Baker, involved his providing narration off-screen while stills were shown. This was then followed by the customary Television Newsreel with a recorded commentary by John Snagge (and on other occasions by Andrew Timothy). On-screen newsreaders were introduced a year later in 1955 – Kenneth Kendall (the first to appear in vision), Robert Dougall, and Richard Baker—three weeks before ITN's launch on 21 September 1955. Mainstream television production had started to move out of Alexandra Palace in 1950 to larger premises – mainly at Lime Grove Studios in Shepherd's Bush, west London – taking Current Affairs (then known as Talks Department) with it. It was from here that the first Panorama, a new documentary programme, was transmitted on 11 November 1953, with Richard Dimbleby becoming anchor in 1955. In 1958, Hugh Carleton Greene became head of News and Current Affairs. On 1 January 1960, Greene became Director-General. Greene made changes that were aimed at making BBC reporting more similar to its competitor ITN, which had been highly rated by study groups held by Greene. A newsroom was created at Alexandra Palace, television reporters were recruited and given the opportunity to write and voice their own scripts, without having to cover stories for radio too. On 20 June 1960, Nan Winton, the first female BBC network newsreader, appeared in vision. 19 September 1960 saw the start of the radio news and current affairs programme The Ten O'clock News. BBC2 started transmission on 20 April 1964 and began broadcasting a new show, Newsroom. The World at One, a lunchtime news programme, began on 4 October 1965 on the then Home Service, and the year before News Review had started on television. News Review was a summary of the week's news, first broadcast on Sunday, 26 April 1964 on BBC 2 and harking back to the weekly Newsreel Review of the Week, produced from 1951, to open programming on Sunday evenings–the difference being that this incarnation had subtitles for the deaf and hard-of-hearing. As this was the decade before electronic caption generation, each superimposition ("super") had to be produced on paper or card, synchronised manually to studio and news footage, committed to tape during the afternoon, and broadcast early evening. Thus Sundays were no longer a quiet day for news at Alexandra Palace. The programme ran until the 1980s – by then using electronic captions, known as Anchor – to be superseded by Ceefax subtitling (a similar Teletext format), and the signing of such programmes as See Hear (from 1981). On Sunday 17 September 1967, The World This Weekend, a weekly news and current affairs programme, launched on what was then Home Service, but soon-to-be Radio 4. Preparations for colour began in the autumn of 1967 and on Thursday 7 March 1968 Newsroom on BBC2 moved to an early evening slot, becoming the first UK news programme to be transmitted in colour – from Studio A at Alexandra Palace. News Review and Westminster (the latter a weekly review of Parliamentary happenings) were "colourised" shortly after. However, much of the insert material was still in black and white, as initially only a part of the film coverage shot in and around London was on colour reversal film stock, and all regional and many international contributions were still in black and white. Colour facilities at Alexandra Palace were technically very limited for the next eighteen months, as it had only one RCA colour Quadruplex videotape machine and, eventually two Pye plumbicon colour telecines–although the news colour service started with just one. Black and white national bulletins on BBC 1 continued to originate from Studio B on weekdays, along with Town and Around, the London regional "opt out" programme broadcast throughout the 1960s (and the BBC's first regional news programme for the South East), until it started to be replaced by Nationwide on Tuesday to Thursday from Lime Grove Studios early in September 1969. Town and Around was never to make the move to Television Centre – instead it became London This Week which aired on Mondays and Fridays only, from the new TVC studios. The BBC moved production out of Alexandra Palace in 1969. BBC Television News resumed operations the next day with a lunchtime bulletin on BBC1 – in black and white – from Television Centre, where it remained until March 2013. This move to a smaller studio with better technical facilities allowed Newsroom and News Review to replace back projection with colour-separation overlay. During the 1960s, satellite communication had become possible; however, it was some years before digital line-store conversion was able to undertake the process seamlessly. On 14 September 1970, the first Nine O'Clock News was broadcast on television. Robert Dougall presented the first week from studio N1 – described by The Guardian as "a sort of polystyrene padded cell"—the bulletin having been moved from the earlier time of 20.50 as a response to the ratings achieved by ITN's News at Ten, introduced three years earlier on the rival ITV. Richard Baker and Kenneth Kendall presented subsequent weeks, thus echoing those first television bulletins of the mid-1950s. Angela Rippon became the first female news presenter of the Nine O'Clock News in 1975. Her work outside the news was controversial at the time, appearing on The Morecambe and Wise Christmas Show in 1976 singing and dancing. The first edition of John Craven's Newsround, initially intended only as a short series and later renamed just Newsround, came from studio N3 on 4 April 1972. Afternoon television news bulletins during the mid to late 1970s were broadcast from the BBC newsroom itself, rather than one of the three news studios. The newsreader would present to camera while sitting on the edge of a desk; behind him staff would be seen working busily at their desks. This period corresponded with when the Nine O'Clock News got its next makeover, and would use a CSO background of the newsroom from that very same camera each weekday evening. Also in the mid-1970s, the late night news on BBC2 was briefly renamed Newsnight, but this was not to last, or be the same programme as we know today – that would be launched in 1980 – and it soon reverted to being just a news summary with the early evening BBC2 news expanded to become Newsday. News on radio was to change in the 1970s, and on Radio 4 in particular, brought about by the arrival of new editor Peter Woon from television news and the implementation of the Broadcasting in the Seventies report. These included the introduction of correspondents into news bulletins where previously only a newsreader would present, as well as the inclusion of content gathered in the preparation process. New programmes were also added to the daily schedule, PM and The World Tonight as part of the plan for the station to become a "wholly speech network". Newsbeat launched as the news service on Radio 1 on 10 September 1973. On 23 September 1974, a teletext system which was launched to bring news content on television screens using text only was launched. Engineers originally began developing such a system to bring news to deaf viewers, but the system was expanded. The Ceefax service became much more diverse before it ceased on 23 October 2012: it not only had subtitling for all channels, it also gave information such as weather, flight times and film reviews. By the end of the decade, the practice of shooting on film for inserts in news broadcasts was declining, with the introduction of ENG technology into the UK. The equipment would gradually become less cumbersome – the BBC's first attempts had been using a Philips colour camera with backpack base station and separate portable Sony U-matic recorder in the latter half of the decade. In 1980, the Iranian Embassy Siege had been shot electronically by the BBC Television News Outside broadcasting team, and the work of reporter Kate Adie, broadcasting live from Prince's Gate, was nominated for BAFTA actuality coverage, but this time beaten by ITN for the 1980 award. Newsnight, the news and current affairs programme, was due to go on air on 23 January 1980, although trade union disagreements meant that its launch from Lime Grove was postponed by a week. On 27 August 1981 Moira Stuart became the first African Caribbean female newsreader to appear on British television. By 1982, ENG technology had become sufficiently reliable for Bernard Hesketh to use an Ikegami camera to cover the Falklands War, coverage for which he won the "Royal Television Society Cameraman of the Year" award and a BAFTA nomination – the first time that BBC News had relied upon an electronic camera, rather than film, in a conflict zone. BBC News won the BAFTA for its actuality coverage, however the event has become remembered in television terms for Brian Hanrahan's reporting where he coined the phrase "I'm not allowed to say how many planes joined the raid, but I counted them all out and I counted them all back" to circumvent restrictions, and which has become cited as an example of good reporting under pressure. The first BBC breakfast television programme, Breakfast Time also launched during the 1980s, on 17 January 1983 from Lime Grove Studio E and two weeks before its ITV rival TV-am. Frank Bough, Selina Scott, and Nick Ross helped to wake viewers with a relaxed style of presenting. The Six O'Clock News first aired on 3 September 1984, eventually becoming the most watched news programme in the UK (however, since 2006 it has been overtaken by the BBC News at Ten). In October 1984, images of millions of people starving to death in the Ethiopian famine were shown in Michael Buerk's Six O'Clock News reports. The BBC News crew were the first to document the famine, with Buerk's report on 23 October describing it as "a biblical famine in the 20th century" and "the closest thing to hell on Earth". The BBC News report shocked Britain, motivating its citizens to inundate relief agencies, such as Save the Children, with donations, and to bring global attention to the crisis in Ethiopia. The news report was also watched by Bob Geldof, who would organise the charity single "Do They Know It's Christmas?" to raise money for famine relief followed by the Live Aid concert in July 1985. Starting in 1981, the BBC gave a common theme to its main news bulletins with new electronic titles–a set of computer-animated "stripes" forming a circle on a red background with a "BBC News" typescript appearing below the circle graphics, and a theme tune consisting of brass and keyboards. The Nine used a similar (striped) number 9. The red background was replaced by a blue from 1985 until 1987. By 1987, the BBC had decided to re-brand its bulletins and established individual styles again for each one with differing titles and music, the weekend and holiday bulletins branded in a similar style to the Nine, although the "stripes" introduction continued to be used until 1989 on occasions where a news bulletin was screened out of the running order of the schedule. In 1987, John Birt resurrected the practice of correspondents working for both TV and radio with the introduction of bi-media journalism. During the 1990s, a wider range of services began to be offered by BBC News, with the split of BBC World Service Television to become BBC World (news and current affairs), and BBC Prime (light entertainment). Content for a 24-hour news channel was thus required, followed in 1997 with the launch of domestic equivalent BBC News 24. Rather than set bulletins, ongoing reports and coverage was needed to keep both channels functioning and meant a greater emphasis in budgeting for both was necessary. In 1998, after 66 years at Broadcasting House, the BBC Radio News operation moved to BBC Television Centre. New technology, provided by Silicon Graphics, came into use in 1993 for a re-launch of the main BBC 1 bulletins, creating a virtual set which appeared to be much larger than it was physically. The relaunch also brought all bulletins into the same style of set with only small changes in colouring, titles, and music to differentiate each. A computer generated cut-glass sculpture of the BBC coat of arms was the centrepiece of the programme titles until the large scale corporate rebranding of news services in 1999. In November 1997, BBC News Online was launched, following individual webpages for major news events such as the 1996 Olympic Games, 1997 general election, and the death of Princess Diana. In 1999, the biggest relaunch occurred, with BBC One bulletins, BBC World, BBC News 24, and BBC News Online all adopting a common style. One of the most significant changes was the gradual adoption of the corporate image by the BBC regional news programmes, giving a common style across local, national and international BBC television news. This also included Newyddion, the main news programme of Welsh language channel S4C, produced by BBC News Wales. Following the relaunch of BBC News in 1999, regional headlines were included at the start of the BBC One news bulletins in 2000. The English regions did however lose five minutes at the end of their bulletins, due to a new headline round-up at 18:55. 2000 also saw the Nine O'Clock News moved to the later time of 22:00. This was in response to ITN who had just moved their popular News at Ten programme to 23:00. ITN briefly returned News at Ten but following poor ratings when head-to-head against the BBC's Ten O'Clock News, the ITN bulletin was moved to 22.30, where it remained until 14 January 2008. The retirement in 2009 of Peter Sissons and departure of Michael Buerk from the Ten O'Clock News led to changes in the BBC One bulletin presenting team on 20 January 2003. The Six O'Clock News became double headed with George Alagiah and Sophie Raworth after Huw Edwards and Fiona Bruce moved to present the Ten. A new set design featuring a projected fictional newsroom backdrop was introduced, followed on 16 February 2004 by new programme titles to match those of BBC News 24. BBC News 24 and BBC World introduced a new style of presentation in December 2003, that was slightly altered on 5 July 2004 to mark 50 years of BBC Television News. On 7 March 2005 director general Mark Thompson launched the "Creative Futures" project to restructure the organisation. The individual positions of editor of the One and Six O'Clock News were replaced by a new daytime position in November 2005. Kevin Bakhurst became the first Controller of BBC News 24, replacing the position of editor. Amanda Farnsworth became daytime editor while Craig Oliver was later named editor of the Ten O'Clock News. Bulletins received new titles and a new set design in May 2006, to allow for Breakfast to move into the main studio for the first time since 1997. The new set featured Barco videowall screens with a background of the London skyline used for main bulletins and originally an image of cirrus clouds against a blue sky for Breakfast. This was later replaced following viewer criticism. The studio bore similarities with the ITN-produced ITV News in 2004, though ITN uses a CSO Virtual studio rather than the actual screens at BBC News. BBC News became part of a new BBC Journalism group in November 2006 as part of a restructuring of the BBC. The then-Director of BBC News, Helen Boaden reported to the then-Deputy Director-General and head of the journalism group, Mark Byford until he was made redundant in 2010. On 18 October 2007, ED Mark Thompson announced a six-year plan, "Delivering Creative Futures" (based on his project begun in March 2005), merging the television current affairs department into a new "News Programmes" division. Thompson's announcement, in response to a £2 billion shortfall in funding, would, he said, deliver "a smaller but fitter BBC" in the digital age, by cutting its payroll and, in 2013, selling Television Centre. The various separate newsrooms for television, radio and online operations were merged into a single multimedia newsroom. Programme making within the newsrooms was brought together to form a multimedia programme making department. BBC World Service director Peter Horrocks said that the changes would achieve efficiency at a time of cost-cutting at the BBC. In his blog, he wrote that by using the same resources across the various broadcast media meant fewer stories could be covered, or by following more stories, there would be fewer ways to broadcast them. A new graphics and video playout system was introduced for production of television bulletins in January 2007. This coincided with a new structure to BBC World News bulletins, editors favouring a section devoted to analysing the news stories reported on. The first new BBC News bulletin since the Six O'Clock News was announced in July 2007 following a successful trial in the Midlands. The summary, lasting 90 seconds, has been broadcast at 20:00 on weekdays since December 2007 and bears similarities with 60 Seconds on BBC Three, but also includes headlines from the various BBC regions and a weather summary. As part of a long-term cost cutting programme, bulletins were renamed the BBC News at One, Six and Ten respectively in April 2008 while BBC News 24 was renamed BBC News and moved into the same studio as the bulletins at BBC Television Centre. BBC World was renamed BBC World News and regional news programmes were also updated with the new presentation style, designed by Lambie-Nairn. 2008 also saw tri-media introduced across TV, radio, and online. The studio moves also meant that Studio N9, previously used for BBC World, was closed, and operations moved to the previous studio of BBC News 24. Studio N9 was later refitted to match the new branding, and was used for the BBC's UK local elections and European elections coverage in early June 2009. A strategy review of the BBC in March 2010, confirmed that having "the best journalism in the world" would form one of five key editorial policies, as part of changes subject to public consultation and BBC Trust approval. After a period of suspension in late 2012, Helen Boaden ceased to be the Director of BBC News. On 16 April 2013, incoming BBC Director-General Tony Hall named James Harding, a former editor of The Times of London newspaper as Director of News and Current Affairs. From August 2012 to March 2013, all news operations moved from Television Centre to new facilities in the refurbished and extended Broadcasting House, in Portland Place. The move began in October 2012, and also included the BBC World Service, which moved from Bush House following the expiry of the BBC's lease. This new extension to the north and east, referred to as "New Broadcasting House", includes several new state-of-the-art radio and television studios centred around an 11-storey atrium. The move began with the domestic programme The Andrew Marr Show on 2 September 2012, and concluded with the move of the BBC News channel and domestic news bulletins on 18 March 2013. The newsroom houses all domestic bulletins and programmes on both television and radio, as well as the BBC World Service international radio networks and the BBC World News international television channel. BBC News and CBS News established an editorial and newsgathering partnership in 2017, replacing an earlier long-standing partnership between BBC News and ABC News. In an October 2018 Simmons Research survey of 38 news organisations, BBC News was ranked the fourth most trusted news organisation by Americans, behind CBS News, ABC News and The Wall Street Journal. In January 2020 the BBC announced a BBC News savings target of £80 million per year by 2022, involving about 450 staff reductions from the current 6,000. BBC director of news and current affairs Fran Unsworth said there would be further moves toward digital broadcasting, in part to attract back a youth audience, and more pooling of reporters to stop separate teams covering the same news. A further 70 staff reductions were announced in July 2020. BBC Three began airing the news programme The Catch Up in February 2022. It is presented by Levi Jouavel, Kirsty Grant, and Callum Tulley and aims to get the channel's target audience (16 to 34-year olds) to make sense of the world around them while also highlighting optimistic stories. Compared to its predecessor 60 Seconds, The Catch Up is three times longer, running for about three minutes and not airing during weekends. According to its annual report as of December 2021[update], India has the largest number of people using BBC services in the world. In May 2025, following the earthquake that hit Myanmar and Thailand, a television news bulletin (BBC News Myanmar) from the Burmese service using a vacated Voice of America satellite frequency began its broadcasts. Programming and reporting In November 2023, BBC News joined with the International Consortium of Investigative Journalists, Paper Trail Media [de] and 69 media partners including Distributed Denial of Secrets and the Organised Crime and Corruption Reporting Project (OCCRP) and more than 270 journalists in 55 countries and territories to produce the 'Cyprus Confidential' report on the financial network which supports the regime of Vladimir Putin, mostly with connections to Cyprus, and showed Cyprus to have strong links with high-up figures in the Kremlin, some of whom have been sanctioned. Government officials including Cyprus president Nikos Christodoulides and European lawmakers began responding to the investigation's findings in less than 24 hours, calling for reforms and launching probes. BBC News is responsible for the news programmes and documentary content on the BBC's general television channels, as well as the news coverage on the BBC News Channel in the UK, and 22 hours of programming for the corporation's international BBC World News channel. Coverage for BBC Parliament is carried out on behalf of the BBC at Millbank Studios, though BBC News provides editorial and journalistic content. BBC News content is also output onto the BBC's digital interactive television services under the BBC Red Button brand, and until 2012, on the Ceefax teletext system. The music on all BBC television news programmes was introduced in 1999 and composed by David Lowe. It was part of the re-branding which commenced in 1999 and features 'BBC Pips'. The general theme was used on bulletins on BBC One, News 24, BBC World and local news programmes in the BBC's Nations and Regions. Lowe was also responsible for the music on Radio One's Newsbeat. The theme has had several changes since 1999, the latest in March 2013. The BBC Arabic Television news channel launched on 11 March 2008, a Persian-language channel followed on 14 January 2009, broadcasting from the Peel wing of Broadcasting House; both include news, analysis, interviews, sports and highly cultural programmes and are run by the BBC World Service and funded from a grant-in-aid from the British Foreign Office (and not the television licence). The BBC Verify service was launched in 2023 to fact-check news stories, followed by BBC Verify Live in 2025. BBC Radio News produces bulletins for the BBC's national radio stations and provides content for local BBC radio stations via the General News Service (GNS), a BBC-internal news distribution service. BBC News does not produce the BBC's regional news bulletins, which are produced individually by the BBC nations and regions themselves. The BBC World Service broadcasts to some 150 million people in English as well as 27 languages across the globe. BBC Radio News is a patron of the Radio Academy. BBC News Online is the BBC's news website. Launched in November 1997, it is one of the most popular news websites, with 1.2 billion website visits in April 2021, as well as being used by 60% of the UK's internet users for news. The website contains international news coverage as well as entertainment, sport, science, and political news. Mobile apps for Android, iOS and Windows Phone systems have been provided since 2010. Many television and radio programmes are also available to view on the BBC iPlayer and BBC Sounds services. The BBC News channel is also available to view 24 hours a day, while video and radio clips are also available within online news articles. In October 2019, BBC News Online launched a mirror on the dark web anonymity network Tor in an effort to circumvent censorship. Criticism The BBC is required by its charter to be free from both political and commercial influence and answers only to its viewers and listeners. This political objectivity is sometimes questioned. For instance, The Daily Telegraph (3 August 2005) carried a letter from the KGB defector Oleg Gordievsky, referring to it as "The Red Service". Books have been written on the subject, including anti-BBC works like Truth Betrayed by W J West and The Truth Twisters by Richard Deacon. The BBC has been accused of bias by Conservative MPs. The BBC's Editorial Guidelines on Politics and Public Policy state that while "the voices and opinions of opposition parties must be routinely aired and challenged", "the government of the day will often be the primary source of news". The BBC is regularly accused by the government of the day of bias in favour of the opposition and, by the opposition, of bias in favour of the government. Similarly, during times of war, the BBC is often accused by the UK government, or by strong supporters of British military campaigns, of being overly sympathetic to the view of the enemy. An edition of Newsnight at the start of the Falklands War in 1982 was described as "almost treasonable" by John Page, MP, who objected to Peter Snow saying "if we believe the British". During the first Gulf War, critics of the BBC took to using the satirical name "Baghdad Broadcasting Corporation". During the Kosovo War, the BBC were labelled the "Belgrade Broadcasting Corporation" (suggesting favouritism towards the FR Yugoslavia government over ethnic Albanian rebels) by British ministers, although Slobodan Milosević (then FRY president) claimed that the BBC's coverage had been biased against his nation. Conversely, some of those who style themselves anti-establishment in the United Kingdom or who oppose foreign wars have accused the BBC of pro-establishment bias or of refusing to give an outlet to "anti-war" voices. Following the 2003 invasion of Iraq, a study by the Cardiff University School of Journalism of the reporting of the war found that nine out of 10 references to weapons of mass destruction during the war assumed that Iraq possessed them, and only one in 10 questioned this assumption. It also found that, out of the main British broadcasters covering the war, the BBC was the most likely to use the British government and military as its source. It was also the least likely to use independent sources, like the Red Cross, who were more critical of the war. When it came to reporting Iraqi casualties, the study found fewer reports on the BBC than on the other three main channels. The report's author, Justin Lewis, wrote "Far from revealing an anti-war BBC, our findings tend to give credence to those who criticised the BBC for being too sympathetic to the government in its war coverage. Either way, it is clear that the accusation of BBC anti-war bias fails to stand up to any serious or sustained analysis." Prominent BBC appointments are constantly assessed by the British media and political establishment for signs of political bias. The appointment of Greg Dyke as Director-General was highlighted by press sources because Dyke was a Labour Party member and former activist, as well as a friend of Tony Blair. The BBC's former Political Editor, Nick Robinson, was some years ago a chairman of the Young Conservatives and did, as a result, attract informal criticism from the former Labour government, but his predecessor Andrew Marr faced similar claims from the right because he was editor of The Independent, a liberal-leaning newspaper, before his appointment in 2000. Mark Thompson, former Director-General of the BBC, admitted the organisation has been biased "towards the left" in the past. He said, "In the BBC I joined 30 years ago, there was, in much of current affairs, in terms of people's personal politics, which were quite vocal, a massive bias to the left". He then added, "The organization did struggle then with impartiality. Now it is a completely different generation. There is much less overt tribalism among the young journalists who work for the BBC." Following the EU referendum in 2016, some critics suggested that the BBC was biased in favour of leaving the EU. For instance, in 2018, the BBC received complaints from people who took issue that the BBC was not sufficiently covering anti-Brexit marches while giving smaller-scale events hosted by former UKIP leader Nigel Farage more airtime. On the other hand, a poll released by YouGov showed that 45% of people who voted to leave the EU thought that the BBC was 'actively anti-Brexit' compared to 13% of the same kinds of voters who think the BBC is pro-Brexit. In 2008, the BBC Hindi was criticised by some Indian outlets for referring to the terrorists who carried out the 2008 Mumbai attacks as "gunmen". The response to this added to prior criticism from some Indian commentators suggesting that the BBC may have an Indophobic bias. In March 2015, the BBC was criticised for a BBC Storyville documentary interviewing one of the rapists in India. In spite of a ban ordered by the Indian High court, the BBC still aired the documentary "India's Daughter" outside India. BBC News was at the centre of a political controversy following the 2003 invasion of Iraq. Three BBC News reports (Andrew Gilligan's on Today, Gavin Hewitt's on The Ten O'Clock News and another on Newsnight) quoted an anonymous source that stated the British government (particularly the Prime Minister's office) had embellished the September Dossier with misleading exaggerations of Iraq's weapons of mass destruction capabilities. The government denounced the reports and accused the corporation of poor journalism. In subsequent weeks the corporation stood by the report, saying that it had a reliable source. Following intense media speculation, David Kelly was named in the press as the source for Gilligan's story on 9 July 2003. Kelly was found dead, by suicide, in a field close to his home early on 18 July. An inquiry led by Lord Hutton was announced by the British government the following day to investigate the circumstances leading to Kelly's death, concluding that "Dr. Kelly took his own life." In his report on 28 January 2004, Lord Hutton concluded that Gilligan's original accusation was "unfounded" and the BBC's editorial and management processes were "defective". In particular, it specifically criticised the chain of management that caused the BBC to defend its story. The BBC Director of News, Richard Sambrook, the report said, had accepted Gilligan's word that his story was accurate in spite of his notes being incomplete. Davies had then told the BBC Board of Governors that he was happy with the story and told the Prime Minister that a satisfactory internal inquiry had taken place. The Board of Governors, under the chairman's, Gavyn Davies, guidance, accepted that further investigation of the Government's complaints were unnecessary. Because of the criticism in the Hutton report, Davies resigned on the day of publication. BBC News faced an important test, reporting on itself with the publication of the report, but by common consent (of the Board of Governors) managed this "independently, impartially and honestly". Davies' resignation was followed by the resignation of Director General, Greg Dyke, the following day, and the resignation of Gilligan on 30 January. While undoubtedly a traumatic experience for the corporation, an ICM poll in April 2003 indicated that it had sustained its position as the best and most trusted provider of news. The BBC has faced accusations of holding both anti-Israel and anti-Palestine bias. Douglas Davis, the London correspondent of The Jerusalem Post, has described the BBC's coverage of the Arab–Israeli conflict as "a relentless, one-dimensional portrayal of Israel as a demonic, criminal state and Israelis as brutal oppressors [which] bears all the hallmarks of a concerted campaign of vilification that, wittingly or not, has the effect of delegitimising the Jewish state and pumping oxygen into a dark old European hatred that dared not speak its name for the past half-century.". However two large independent studies, one conducted by Loughborough University and the other by Glasgow University's Media Group concluded that Israeli perspectives are given greater coverage. Critics of the BBC argue that the Balen Report proves systematic bias against Israel in headline news programming. The Daily Mail and The Daily Telegraph criticised the BBC for spending hundreds of thousands of British tax payers' pounds from preventing the report being released to the public. Jeremy Bowen, the Middle East Editor for BBC world news, was singled out specifically for bias by the BBC Trust which concluded that he violated "BBC guidelines on accuracy and impartiality." An independent panel appointed by the BBC Trust was set up in 2006 to review the impartiality of the BBC's coverage of the Israeli–Palestinian conflict. The panel's assessment was that "apart from individual lapses, there was little to suggest deliberate or systematic bias." While noting a "commitment to be fair accurate and impartial" and praising much of the BBC's coverage the independent panel concluded "that BBC output does not consistently give a full and fair account of the conflict. In some ways the picture is incomplete and, in that sense, misleading." It notes that, "the failure to convey adequately the disparity in the Israeli and Palestinian experience, [reflects] the fact that one side is in control and the other lives under occupation". Writing in the Financial Times, Philip Stephens, one of the panellists, later accused the BBC's director-general, Mark Thompson, of misrepresenting the panel's conclusions. He further opined "My sense is that BBC news reporting has also lost a once iron-clad commitment to objectivity and a necessary respect for the democratic process. If I am right, the BBC, too, is lost". Mark Thompson published a rebuttal in the FT the next day. The description by one BBC correspondent reporting on the funeral of Yassir Arafat that she had been left with tears in her eyes led to other questions of impartiality, particularly from Martin Walker in a guest opinion piece in The Times, who picked out the apparent case of Fayad Abu Shamala, the BBC Arabic Service correspondent, who told a Hamas rally on 6 May 2001, that journalists in Gaza were "waging the campaign shoulder to shoulder together with the Palestinian people". Walker argues that the independent inquiry was flawed for two reasons. Firstly, because the time period over which it was conducted (August 2005 to January 2006) surrounded the Israeli withdrawal from Gaza and Ariel Sharon's stroke, which produced more positive coverage than usual. Furthermore, he wrote, the inquiry only looked at the BBC's domestic coverage, and excluded output on the BBC World Service and BBC World. Tom Gross accused the BBC of glorifying Hamas suicide bombers, and condemned its policy of inviting guests such as Jenny Tonge and Tom Paulin who have compared Israeli soldiers to Nazis. Writing for the BBC, Paulin said Israeli soldiers should be "shot dead" like Hitler's S.S, and said he could "understand how suicide bombers feel". The BBC also faced criticism for not airing a Disasters Emergency Committee aid appeal for Palestinians who suffered in Gaza during 22-day war there between late 2008 and early 2009. Most other major UK broadcasters did air this appeal, but rival Sky News did not. British journalist Julie Burchill has accused BBC of creating a "climate of fear" for British Jews over its "excessive coverage" of Israel compared to other nations. In light of the Gaza war, the BBC suspended seven Arab journalists over allegations of expressing support for Hamas via social media. BBC and ABC share video segments and reporters as needed in producing their newscasts. with the BBC showing ABC World News Tonight with David Muir in the UK. However, in July 2017, the BBC announced a new partnership with CBS News allows both organisations to share video, editorial content, and additional newsgathering resources in New York, London, Washington and around the world. BBC News subscribes to wire services from leading international agencies including PA Media (formerly Press Association), Reuters, and Agence France-Presse. In April 2017, the BBC dropped Associated Press in favour of an enhanced service from AFP. BBC News reporters and broadcasts are now and have in the past been banned in several countries primarily for reporting which has been unfavourable to the ruling government. For example, correspondents were banned by the former apartheid regime of South Africa. The BBC was banned in Zimbabwe under Mugabe for eight years as a terrorist organisation until being allowed to operate again over a year after the 2008 elections. The BBC was banned in Burma (officially Myanmar) after their coverage and commentary on anti-government protests there in September 2007. The ban was lifted four years later in September 2011. Other cases have included Uzbekistan, China, and Pakistan. BBC Persian, the BBC's Persian language news site, was blocked from the Iranian internet in 2006. The BBC News website was made available in China again in March 2008, but as of October 2014[update], was blocked again. In June 2015, the Rwandan government placed an indefinite ban on BBC broadcasts following the airing of a controversial documentary regarding the 1994 Rwandan genocide, Rwanda's Untold Story, broadcast on BBC2 on 1 October 2014. The UK's Foreign Office recognised "the hurt caused in Rwanda by some parts of the documentary". In February 2017, reporters from the BBC (as well as the Daily Mail, The New York Times, Politico, CNN, and others) were denied access to a United States White House briefing. In 2017, BBC India was banned for a period of five years from covering all national parks and sanctuaries in India. Following the withdrawal of CGTN's UK broadcaster licence on 4 February 2021 by Ofcom, China banned BBC News from airing in China. See also References External links |below = Category }} |
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[SOURCE: https://en.wikipedia.org/wiki/Anobii] | [TOKENS: 364] |
Contents Anobii Anobii (stylized, anobii) is a social networking site aimed at readers. Its website was launched in 2006 by Greg Sung. It was acquired by the publisher Mondadori in 2014 from a venture backed by HMV, HarperCollins, Penguin, and Random House. The service allows individuals to catalog their books and rate, review and discusses them with other readers. The service is available via the Anobii website and iOS and Android apps. The apps allow individuals to barcode scan books and read both community and expert reviews. Anobii has readers in over 20 countries but is most popular in Italy. On 2 March 2011 it was announced that in 2010 Anobii had been acquired by a UK startup led by HMV and supported by HarperCollins, Penguin, and The Random House Group and that the company is working on a new version of the website with the possibility to buy books and most of all ebooks. On 12 June 2012, it was announced that HMV had sold its interest to UK supermarket company Sainsbury's for £1. In January 2013, it was announced that beta.anobii.com will be known as eBooks by Sainsbury's from 20 February 2013. Anobii.com will continue to exist as a social network for book lovers. In January 2014, Anobii Ltd was sold to the Italian publisher Arnoldo Mondadori Editore. On 29 May 2019, Anobii Ltd was sold to the Italian mobile apps and software developer, Ovolab. The word "Anobii" comes from Anobium Punctatum, the Latin name for the most common bookworm. See also References External links |
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[SOURCE: https://www.wired.com/tag/wired-consulting/] | [TOKENS: 437] |
WIRED ConsultingWIRED Consulting takes the unique WIRED network, knowledge and brand to commercial organisations—helping them to build internal knowledge, develop strategy and create thought-leading content that positions their brand at the cutting edge of trends. Discover more at consulting.wired.co.uk.AI is booming - but the debates are just beginningBusiness Lessons From An Unconventional Journey In BiotechWhy AI is now HR’s businessMeet the manufacturing Trailblazers taking on sustainability challengesMeet the professional services firms taking on the challenges of tomorrowHow AI scale-ups are fixing tech to fix the worldMeet the Trailblazers making agrifood fit for the futureThe New Anatomy Of HealthcareThe Checkout Innovations That Businesses Need To KnowThe Agentic AI Advantage: Hype, Reality, and What Comes NextImmersive engineering and the next industrial revolutionThe New AI Marketing PlaybookAre you a budding entrepreneur? Enter the Tata Varsity Pitch 2025Three hot AI debates that you need to have on your radarLiving Factories: What AI Agents Could Mean For IndustryMeet the visionaries taking on the world’s biggest problemsHow to Build an AI-Ready CultureWhat’s the Biggest Misconception About How AI Will Transform Professional Services?What Will it Take for the UK to Become a Global Tech Superpower?How Will Retailers Capture the Consumers of Tomorrow?What Emerging Trends Will Most Shape the Future of Food Production?What Bold Manufacturing Supply Chain Strategies Will be Needed in the Decade Ahead?How To Secure Investment For Ambitious GrowthUpgrading How We BuyMore Stories WIRED Consulting WIRED Consulting takes the unique WIRED network, knowledge and brand to commercial organisations—helping them to build internal knowledge, develop strategy and create thought-leading content that positions their brand at the cutting edge of trends. Discover more at consulting.wired.co.uk. © 2026 Condé Nast. All rights reserved. WIRED may earn a portion of sales from products that are purchased through our site as part of our Affiliate Partnerships with retailers. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of Condé Nast. Ad Choices |
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[SOURCE: https://www.mako.co.il/finances-law] | [TOKENS: 1276] |
כסף משפט הפלירטוטים באינטרנט עלו לבעל עשרות אלפי דולרביה"ד הרבני קבע: הבעל יישא במלוא כתובת אשתו "אב לנערים שעובדים לא צריך לשלם מזונות"אין אפשרות לחייב אבות במזונות לילדים מעל 18 הלקח המשפטי מהסיפור של מתן בלוגם צעירים ובריאים עלולים לאבד כשירות ברגע גם צעירים ובריאים עלולים לאבד כשירות ברגע התקבלה בקשת החברה לדחות על הסף ערעור אגף השיקום במשרד הביטחון סירב למתן ההכרה העסקת עובדים זרים: הרפורמה שאחרי המלחמהעורך דין מסביר מה השתנה מאז אוקטובר 2023 "יש קייס לתביעה"?: הבוט שמנבא פסקי דיןכלי AI חדש מציג הסתברות הצלחה בבית המשפט הסיבה שאסור להמתין עם עריכת ייפוי כוח מתמשךמה קורה כשמאבדים כשירות בלי מסמך מסודר? קרן הפנסיה המשיכה לשלם לה בטעות כך תתמודדו פיננסית במציאות כאוטית בעלה חתם בשמה על המסמכים ללא ידיעתה השניים קיבלו שישית בלבד מהעמלה המגיעה להם חנות שהושכרה מאז 1989 בדיירות מוגנת נמכרה בעידן של חוזים מבוססי AI וניגודי עניינים התקבלה גרסתו שמעד בבניין המדרגות המשותף סגן מנהל מחלקה ב"מרכנתיל" חטף כדור בחנייתו בית המשפט קבע כי הורי המנוחה יזכו בכספים ביה"ד הרבני קבע: הבעל יישא במלוא כתובת אשתו אין אפשרות לחייב אבות במזונות לילדים מעל 18 ביה"ד הרבני שוכנע שהבעל בגד באשתו צעיר שנתפס עם עשרות אקדחים טען שלא ידע עליהם השופטת התקשתה להאמין והתוצאה הייתה זיכוי למרות התחכום הרב, השופט הקל בעונשו בן ה-18 גרם ברשלנות למות צעירה על אופנוע התביעה דרשה להשית מאסר, ולו בעבודות שירות שתי שנות הפסילה שקיבל מהוות עונש מינימום |
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[SOURCE: https://www.theverge.com/laptops] | [TOKENS: 777] |
Laptops It’s my turn to graciously host one of our Verge subscriber-exclusive AMAs. Join me in the comments here at 11AM PT / 2PM ET, and feel free to get your question(s) in early. Ask me about laptops, laptop reviews, photography or whatever else we can geek-out over together. I review laptops for The Verge, ask me anything 7 Verge Score This pricey laptop has got sleek no-frills looks and Strix Halo strengths on lock. HP has started offering subscriptions to rent its laptops, including its Victus and Omen gaming laptops ranging from $50 per month up to $129 per month, PC Gamer reports. There’s no option to own the laptop that you’re subscribed to, but HP will let you trade it in for an upgrade every year. 8 Verge Score Asus made all the right tweaks, and the new Panther Lake chip delivers. The first chip of Intel’s 18A process is speedy, even on battery power. And it’s a solid option for 1080p gaming. I worked exclusively on a pre-production Asus Zenbook A16 with a Snapdragon X2 processor throughout CES, and I came away impressed. Smart lights that know where they’re placed in a room, wild designs for next-gen routers, and a glowing inedible donut. Rollable laptops, twice-folding phones, and a ‘longevity station.’ This is the CES tech we come back for. AMD’s Strix Halo is a big, pricey chip with the best integrated graphics we’ve ever seen. The Asus TUF is the brand’s budget-friendly gaming line. So how “affordable” will Asus’s new TUF Gaming A14 laptop with Strix Halo be? We don’t know yet, because Asus hasn’t finalized pricing. But I look forward to testing this TUF. *To be clear, this was with Intel’s XeSS upscaling, at 1080p resolution, with 4x frame gen — the actual framerate was a quarter of that. But the beefiest integrated GPU in Intel’s new Panther Lake chips never let the true framerate dip below 40fps, even unplugged, with settings that looked and felt good enough for single-player games. After 2020’s pricey first effort, Asus is trying the Zephyrus Duo formula again. But this time, it’s added extra space that could make its two-screen laptop setup worthwhile. Here’s Antonio with a closer look at the new Duo. The 2026 Vivobook S14, S15, and S16, announced today at CES, pair a familiar design with new processors, including the Qualcomm Snapdragon X2 Elite, along with updated Intel Core Ultra Series 2 and AMD Ryzen AI 300 Series options. According to Asus, the Snapdragon-powered S16 boasts 25 hours of battery life. Acer is announcing a new Nitro V 16 AI entry-level gaming laptop with AMD’s new Gorgon Point chips. Announced at CES with a handful of other Acer laptops, the Nitro is meant to offer a budget-friendly-ish price for AMD’s new chip and Nvidia GPUs — from the RTX 5050 to RTX 5070. It’s expected in Q2, but pricing isn’t finalized. Dell reversed course on its confusing naming scheme from 2025, but some of it’s intact — with new tweaks. The returning XPS laptops are still joined by entry-level vanilla “Dell” models. Enterprise-focused Dell Pro laptops are now topped by Dell Pro Precision models instead of the Apple-y sounding Pro Max. Perfect? No. Better? Much. Pagination Most Popular The Verge Daily A free daily digest of the news that matters most. This is the title for the native ad © 2026 Vox Media, LLC. All Rights Reserved |
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[SOURCE: https://en.wikipedia.org/wiki/Indian_Ocean_coastal_belt] | [TOKENS: 448] |
Contents Indian Ocean coastal belt The Indian Ocean coastal belt is one of the nine recognised biomes of South Africa. They are described in terms of their vegetation and climatic variations. Location and description The Indian Ocean coastal belt is a region of coastal dunes and coastal grassy plains in KwaZuluNatal and the Eastern Cape, from sea level to an altitude of about 600 m. Mean annual rainfall ranges from 819 to 1,272 mm, and falls throughout the year, peaking in summer. The mean annual temperature ranges from 19.1 °C near the Mbhashe River in the southwest to 22 °C in the north east near the Mozambican border, with hot summers and mild, frost-free winters. The belt is about 800 km long and narrow, with a maximum width of about 35 km in the north to less than 10 km in parts of the wild coast, and the total area is relatively small. The relief of the region varies between flat in Maputaland, rolling hills with deeply incised valleys between Richards Bay and Port Edward in KwaZulu-Natal and further south as far as the Great Kei River mouth. The Pondoland coast and other areas with sandstone geology have elevated plateaus with deep gorges. Flora The dominant forest cover is interrupted by areas of grassland, with part of the belt comprising dense savanna vegetation, with scattered areas of forest and grassland. Most of the coastal belt outside the remaining patches of forest has been changed considerably. The following vegetation units have been identified: Fauna Economic value The region provides water supplies and fodder for livestock grazing. Threats and preservation The biome is fairly well protected relative to the other South African biomes in that about 45% of the 20-year target is protected. Climate change impacts Three scenarios have been modeled for climate change impacts on the South African biomes. The low risk scenario suggests a possible increase in area for this biome, with warm, moist conditions expanding southwest along the coast, and extending further inland, but the intermediate and high risk models show a possibility of less water availability and parts of the biome shifting to a savanna climate. See also References Further reading |
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[SOURCE: https://en.wikipedia.org/wiki/Are.na] | [TOKENS: 602] |
Contents Are.na Are.na is an online social networking community and creative research platform founded by Charles Broskoski, Daniel Pianetti, Chris Barley, and Chris Sherron. Are.na was built as a successor to hypertext projects like Ted Nelson's Xanadu, and as an ad-free alternative to social networks like Facebook, forgoing "likes," "favorites," or "shares" in its design. Are.na allows users to compile uploaded and web-clipped "blocks" into different "channels," and has been described as a "vehicle for conscious Internet browsing," "playlists, but for ideas," and a "toolkit for assembling new worlds." Features and community Are.na is popular amongst designers, artists, and architects including Cory Arcangel, Michael Bell-Smith, Margaret Lee, Laurel Schwulst, Emily Segal, Mindy Seu, Martine Syms, Allan Yu, and others who publicly cite Are.na as a tool in their creative process. Are.na's blog, written and curated by Meg Miller, includes essays about Are.na's research and publishing tools as well as noteworthy or "featured" user channels. Are.na-specific terms include: Revenue model Are.na is free to peruse but finances itself by upselling premium accounts with the ability to upload an unlimited number of private blocks. It also sells branded apparel on its store. Unlike Pinterest, Are.na does not finance itself through advertising or user data collection. History Co-founder Charles Broskoski began working for Rhizome's John Michael Boling and Sapient Corporation's Stuart Moore in the early 2010s, coding prototypes of a platform which would containerize knowledge into "informational building blocks." Soon after, Broskoski brought artist Damon Zucconi and K-HOLE's Dena Yago onto the project. Broskoski, Yago, and Zucconi eventually split off to found Are.na, soon joined by co-founder Chris Sherron (also of K-HOLE) and Dan Brewster. Broskoski set out to build an open-ended community tool, with Ted Nelson's Computer Lib/Dream Machines and hypertext project Xanadu as major influences on Are.na's founding and design. Collaborations In 2015, Are.na worked with the Guggenheim Museum on the Åzone Futures Market. The museum's first online exhibition, curated by Troy Conrad Therrien, Åzone Futures Market allowed visitors to the site to invest cåin, a digital currency, in different technology-driven visions of the future. Two years later, Are.na partnered with the Chicago Architecture Biennial, building out their blog alongside ArchDaily, Archinect, and Architizer. Are.na has also partnered with the Manhattan Museum of Arts and Design, New Inc. incubator, the Vilém Flusser archives, and artists Carson Salter and David Hilmer Rex. See also References External links |
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[SOURCE: https://en.wikipedia.org/wiki/Transjordan_(region)] | [TOKENS: 2941] |
Contents Transjordan (region) Transjordan, also known as the East Bank or the Transjordanian Highlands (Arabic: شرق الأردن, romanized: Sharq al ʾUrdun, lit. 'East of the Jordan'), is the part of the Southern Levant east of the Jordan River, mostly contained in present-day Jordan. The region, known as Transjordan, was controlled by numerous powers throughout history. During the early modern period, the region of Transjordan was included under the jurisdiction of Ottoman Syrian provinces. After the Great Arab Revolt against Ottoman rule during the 1910s, the Emirate of Transjordan was established in 1921 by Hashemite Emir Abdullah, and the emirate became a British protectorate. In 1946, the emirate achieved independence from the British and in 1949 the country changed its name to the "Hashemite Kingdom of Jordan", after the Jordanian annexation of the West Bank following the 1948 Arab–Israeli War. Name The prefix trans- is Latin and means "across" or beyond, and so "Transjordan" refers to the land on the other side of the Jordan River. The equivalent term for the west side is the Cisjordan – literally, "on this side of the [River] Jordan". Both terms reflect the biblical perspective, as different regions were seen when looked at from the Holy Land. The Tanakh's Hebrew: בעבר הַיַּרְדֵּן מִזְרָח הַשֶּׁמֶשׁ, romanized: bʿēḇer hayyardēn mizrāḥ haššemeš, lit. 'beyond the Jordan towards the sunrise', is translated in the Septuagint to Ancient Greek: πέραν τοῦ Ιορδάνου,, romanized: translit. péran toú Iordánou,, lit. 'beyond the Jordan', which was then translated to Latin: trans Iordanen, lit. 'beyond the Jordan' in the Vulgate. However, some authors give the Hebrew: עבר הירדן, romanized: ʿēḇer hayyardēn, lit. 'beyond the Jordan', as the basis for Transjordan, which is also the Modern Hebrew usage. Whereas the term "East" as in "towards the sunrise" is used in Arabic: شرق الأردن, romanized: Sharq al ʾUrdun, lit. 'East of the Jordan'. History The Shasu were Semitic-speaking cattle nomads in the Levant from the late Bronze Age to the Early Iron Age. In a 15th-century BCE list of enemies inscribed on column bases at the temple of Soleb built by Amenhotep III, six groups of Shasu are noted; the Shasu of S'rr, the Shasu of Rbn, the Shasu of Sm't, the Shasu of Wrbr, the Shasu of Yhw, and the Shasu of Pysps. Some scholars link the Israelites and the worship of a deity named Yahweh with the Shasu. The Egyptian geographical term Retjenu is traditionally identified as an area covering Sinai and Canaan south of Lebanon, with the regions of Amurru and Apu to the north. As such, parts of Canaan and southwestern Syria became tributary to the pharaohs of ancient Egypt before the Late Bronze Age collapse. When Canaanite confederacies centered on Megiddo and Kadesh came under the control of the New Kingdom of Egypt. However, the empire's control was sporadic, and not strong enough to prevent frequent local rebellions and inter-city conflict. During the Late Bronze Age collapse the Amorites of Syria disappeared after being displaced or absorbed by a new wave of semi-nomadic West Semitic-speaking peoples known collectively as the Ahlamu. Over time, the Arameans emerged as the dominant tribe amongst the Ahlamu;[citation needed] with the destruction of the Hittites and the decline of Assyria in the late 11th century BCE, they gained control over much of Syria and Transjordan. The regions they inhabited became known as Aram (Aramea) and Eber-Nari. The Book of Numbers (chapter 32) tells how the tribes of Reuben and Gad came to Moses to ask if they could settle in the Transjordan. Moses is dubious, but the two tribes promise to join in the conquest of the land, so Moses grants them this region to live in. The Tribe of Manasseh is not mentioned until verse 33. David Jobling suggests that this is because Manasseh settled in the land that previously belonged to Og north of the Zarqa, while Reuben and Gad settled Sihon's land, which lay south of the Zarqa. Since Og's territory was not on the route to Canaan, it was "more naturally part of the Promised Land", and so the Manassites' status is less problematic than that of the Reubenites or Gadites. In Joshua 1, Joshua affirms Moses' decision and urges the men of the two-and-a-half tribes to help in the conquest, which they are willing to do. In Joshua 22, the Transjordanian tribes returned and built a massive altar called the Witness by the Jordan River. This causes the "whole congregation of the Israelites" to prepare for war. They first sent a delegation to the Transjordanians, accusing them of making God angry and suggesting their land may be unclean. In response to this, the Transjordanians said that the altar is not for offerings, but is only a "witness". The western tribes were satisfied and return home. Assis argues that the unusual dimensions of the altar suggest that it "was not meant for sacrificial use", but was, in fact, "meant to attract the attention of the other tribes" and provoke a reaction. Per the settlement of the Israelite tribes east of the Jordan, Burton MacDonald notes; There are various traditions behind the Books of Numbers, Deuteronomy, Joshua, Judges, and 1 Chronicles' assignment of tribal territories and towns to Reuben, Gad, and the half-tribe of Manasseh. Some of these traditions provide only an idealized picture of Israelite possessions east of the Jordan; others are no more than vague generalizations. Num 21.21–35, for example, says only that the land the people occupied extended from Wadi Arnon to Wadi Jabbok, the boundary of the Amorites. There is some ambiguity about the status of the Transjordan in the mind of the biblical writers. Horst Seebass argues that in Numbers "one finds awareness of Transjordan as being holy to YHWH." He argues for this based on the presence of the Cities of Refuge there, and because land taken in a holy war is always holy. Richard Hess, on the other hand, asserts that "the Transjordanian tribes were not in the land of promise." Moshe Weinfeld argues that in the Book of Joshua, the Jordan is portrayed as "a barrier to the promised land", but in Deuteronomy 1:7 and 11:24, the Transjordan is an "integral part of the promised land." Unlike the other tribal allotments in Joshua, the Transjordanian territory was not divided by lot. Jacob Milgrom suggests that it is assigned by Moses rather than by God. Lori Rowlett argues that in the Book of Joshua, the Transjordanian tribes function as the inverse of the Gibeonites (mentioned in Joshua 9). Whereas the former have the right ethnicity, but wrong geographical location, the latter have the wrong ethnicity, but are "within the boundary of the 'pure' geographical location." According to Genesis, (19:37–38), Ammon and Moab were born to Lot and Lot's younger and elder daughters, respectively, in the aftermath of the destruction of Sodom and Gomorrah. The Bible refers to both the Ammonites and Moabites as the "children of Lot". Throughout the Bible, the Ammonites and Israelites are portrayed as mutual antagonists. During the Exodus, the Israelites were prohibited by the Ammonites from passing through their lands (Deuteronomy 23:4). In the Book of Judges, the Ammonites work with Eglon, king of the Moabites against Israel. Attacks by the Ammonites on Israelite communities east of the Jordan were the impetus behind the unification of the tribes under Saul (1 Samuel 11:1–15). According to both Books of Kings (14:21–31) and Books of Chronicles (12:13), Naamah was an Ammonite. She was the only wife of King Solomon to be mentioned by name in the Tanakh as having borne a child. She was the mother of Solomon's successor, Rehoboam. The Ammonites presented a serious problem to the Pharisees because many marriages with Ammonite (and Moabite) wives had taken place in the days of Nehemiah (Nehemiah 13:23). The men had married women of the various nations without conversion, which made the children not Jewish. The legitimacy of David's claim to royalty was disputed on account of his descent from Ruth, the Moabite. King David spent time in the Transjordan after he had fled from the rebellion of his son Absalom (2 Samuel 17–19). The Decapolis is named from its ten cities enumerated by Pliny the Elder (23–79). What Pliny calls Decapolis, Ptolemy (c. 100–c. 170) calls Cœle-Syria. Ptolemy does not use the term "Transjordan", but rather the periphrasis "across the Jordan". And he enumerates the cities; Cosmas, Libias, Callirhoe, Gazorus, Epicaeros—as being in this district—east of the Jordan, that Josephus et al. called Perea. Jerash was a prominent central community for the surrounding region during the Neolithic period and was also inhabited during the Bronze Age. Ancient Greek inscriptions from the city, and the literary works of Iamblichus and the Etymologicum Magnum indicate that the city was founded as "Gerasa" by Alexander the Great or his general Perdiccas, for the purpose of settling retired Macedonian soldiers (γῆρας—gēras—means "old age" in Ancient Greek). It was a city of the Decapolis, and is one of the most important and best preserved Ancient Roman cities in the Near East. The Nabataeans' trading network was centered on strings of oases that they controlled. The Nabataean kingdom reached its territorial zenith during the reign of Aretas III (87-62 BCE), when it encompassed parts of the territory of modern Jordan, Syria, Saudi Arabia, Egypt and Israel. Bosra is located in a geographical area called the Hauran plateau. The soil of this volcanic plateau made it a fertile region for the cultivation of domesticated cereals during the Neolithic Agricultural Revolution. The city was noted in Egyptian documents of the 14th century BCE, and was situated on the trade routes where caravans brought spices from India and the Far East across the eastern desert while other caravans brought myrrh and frankincense from the south. The region of Hauran then called "Auranitis" came under the control of the Nabataean kingdom. And the city of Bosra then called "Bostra" became the northern capital of the kingdom while its southern capital was Petra. After Pompey's military conquest of Syria, Judaea, and Transjordan. Control of the city was later transferred to Herod the Great and his heirs until 106 CE, when Bosra was incorporated into the new Roman province of Arabia Petraea. The Herodian kingdom of Judaea was a client state of the Roman Republic from 37 BCE, and included Samaria and Perea. And when Herod died in 4 BCE, the kingdom was divided among his sons into the Herodian Tetrarchy. Provincia Arabia Petraea or simply Arabia, was a frontier province of the Roman Empire beginning in the 2nd century. It consisted of the former Nabataean kingdom in the southern Levant, Sinai Peninsula, and northwestern Arabian peninsula. The Lordship of Oultrejordain (Old French for "beyond the Jordan"), also called the Lordship of Montreal, otherwise Transjordan, was part of the Crusader Kingdom of Jerusalem. Trade routes Roman roads The King's Highway was a trade route of vital importance to the ancient Near East. It began in Egypt and stretched across the Sinai Peninsula to Aqaba. From there it turned northward across Transjordan, leading to Damascus and the Euphrates River. During the Roman period the road was called Via Regia (Orient). Emperor Trajan rebuilt and renamed it Via Traiana Nova (viz. Via Traiana Roma), under which name it served as a military and trade road along the fortified Limes Arabicus. The Incense Route comprised a network of major ancient land and sea trading routes linking the Mediterranean world with Eastern and Southern sources of incense, spices and other luxury goods, stretching from Mediterranean ports across the Levant and Egypt through Northeastern Africa and Arabia to India and beyond. The incense land trade from South Arabia to the Mediterranean flourished between roughly the 7th century BCE to the 2nd century CE. Though not essentially connected to a trade-route, Transjordan maintained its relative importance once it gained a status of independence from Ottoman Rule in the 1920s due to its close geographical and historical connection to Damascus. Maps See also References External links |
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[SOURCE: https://www.mako.co.il/ninemonth] | [TOKENS: 779] |
תשעה חודשים שנים חלמו להיות הורים - ואז הם פגשו את שמרית"הרגשתי שאני עוזרת להם להפוך להיות משפחה" הסיפור המטורף של לימור: לא הבנתי שאני יולדת "תוך 20 דקות התינוקת היתה כבר בחוץ" לידה שקטה משפיעה על אימהות גם אחרי 40 שנה "האימהות יותר מכווננות לילדים שלהן" למה הורים כל כך פוחדים מבדיקות גנטיות? סקר: זוגות מוותרים על בדיקות לפני ההיריון עברה 19 הפלות ב-17 שנההמסע המטורף של א' להורות אלה השמות הכי פופולאריים בישראל בשנת 2024 ומה השם שהורים פחות רצו אחרי ה-7.10? "רציתי משפחה גדולה וידעתי שאצטרך ללדת מהר" איך נשאות BRCA משפיעה על תכנון המשפחה? "ניתאי עזר לנו להבין שאסור לעולם להתייאש" סיפור הלידה המטורף של יסמין מחקר: הסיכון החדש בהשמנת יתר לפני ההיריון "עלולות להיווצר בעיות בההתפתחות הנוירולוגית" נורית ילדה לבדה את בתה בסלון, כשבתה בחדר לידבמד"א לא ראו מעולם דבר כזה הייתם קוראים ככה לבת שלכם? הבנים שמקבלים שמות של בנות – ולהפך |
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[SOURCE: https://en.wikipedia.org/wiki/Mughr_al-Khayt] | [TOKENS: 114] |
Contents Mughr al-Khayt Mughr al-Khayt was a Palestinian Arab village in the Safad Subdistrict. It was depopulated during the 1947–1948 Civil War in Mandatory Palestine on May 2, 1948, by the Palmach's First Battalion of Operation Yiftach. It was located 4.5 km northeast of Safad. In 1945 it had a population of 490 Muslims. References Bibliography External links This geography of Palestine article is a stub. You can help Wikipedia by adding missing information. |
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[SOURCE: https://en.wikipedia.org/wiki/Gamma_ray] | [TOKENS: 6830] |
Contents Gamma ray A gamma ray, also known as gamma radiation (symbol γ), is a penetrating form of electromagnetic radiation arising from high-energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. Lower energy gamma radiation overlaps the upper end of X-ray radiation; they are distinguished by their different origins. Gamma ray photons have photon energy at the lower end from 10keV to 10,000 keV; ultra-high-energy gamma rays have energies over 1011 keV.: 12 Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays based on their relatively strong penetration of matter; in 1900, he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power. Gamma rays from radioactive decay are in the energy range from ten kiloelectronvolts (keV) to 10 megaelectronvolts (MeV), corresponding to the typical energy levels in nuclei with reasonably long lifetimes. The energy spectrum of gamma rays can be used to identify the decaying radionuclides using gamma spectroscopy. Very-high-energy gamma rays in the 100–1000 teraelectronvolt (TeV) range have been observed from astronomical sources such as the Cygnus X-3 microquasar. Natural sources of gamma rays originating on Earth are mostly a result of radioactive decay and secondary radiation from atmospheric interactions with cosmic ray particles. However, there are other rare natural sources, such as terrestrial gamma-ray flashes, which produce gamma rays from electron action upon the nucleus. Notable artificial sources of gamma rays include fission, such as that which occurs in nuclear reactors, and high energy physics experiments, such as neutral pion decay and nuclear fusion. The energy ranges of gamma rays and X-rays overlap in the electromagnetic spectrum, so the terminology for these electromagnetic waves varies between scientific disciplines. In some fields of physics, they are distinguished by their origin: gamma rays are created by nuclear decay while X-rays originate outside the nucleus. In astrophysics, gamma rays are conventionally defined as having photon energies above 100 keV and are the subject of gamma-ray astronomy, while radiation below 100 keV is classified as X-rays and is the subject of X-ray astronomy. Gamma rays are ionizing radiation and are thus hazardous to life. They can cause DNA mutations, cancer and tumors, and at high doses burns and radiation sickness. Due to their high penetration power, they can damage bone marrow and internal organs. Unlike alpha and beta rays, they easily pass through many common materials and thus pose a formidable radiation protection challenge, requiring shielding made from dense materials such as lead or concrete. On Earth, the magnetosphere protects life from most types of lethal cosmic radiation other than gamma rays. History of discovery The first gamma ray source to be discovered was the radioactive decay process called gamma decay. In this type of decay, an excited nucleus emits a gamma ray almost immediately upon formation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, while studying radiation emitted from radium. Villard knew that his described radiation was more powerful than previously described types of rays from radium, which included beta rays, first noted as "radioactivity" by Henri Becquerel in 1896, and alpha rays, discovered as a less penetrating form of radiation by Rutherford, in 1899. However, Villard did not consider naming them as a different fundamental type. Later, in 1903, Villard's radiation was recognized as being of a type fundamentally different from previously named rays by Ernest Rutherford, who named Villard's rays "gamma rays" by analogy with the beta and alpha rays that Rutherford had differentiated in 1899. The "rays" emitted by radioactive elements were named in order of their power to penetrate various materials, using the first three letters of the Greek alphabet: alpha rays as the least penetrating, followed by beta rays, followed by gamma rays as the most penetrating. Rutherford also noted that gamma rays were not deflected (or at least, not easily deflected) by a magnetic field, another property making them unlike alpha and beta rays. Gamma rays were first thought to be particles with mass, like alpha and beta rays. Rutherford initially believed that they might be extremely fast beta particles, but their failure to be deflected by a magnetic field indicated that they had no charge. In 1914, gamma rays were observed to be reflected from crystal surfaces, proving that they were electromagnetic radiation. Rutherford and his co-worker Edward Andrade measured the wavelengths of gamma rays from radium, and found they were similar to X-rays, but with shorter wavelengths and thus, higher frequency. This was eventually recognized as giving them more energy per photon, as soon as the latter term became generally accepted. A gamma decay was then understood to usually emit a gamma photon. Sources Natural sources of gamma rays on Earth include gamma decay from naturally occurring radioisotopes such as potassium-40, and also as a secondary radiation from various atmospheric interactions with cosmic ray particles. Natural terrestrial sources that produce gamma rays include lightning strikes and terrestrial gamma-ray flashes, which produce high energy emissions from natural high-energy voltages. Gamma rays are produced by a number of astronomical processes in which very high-energy electrons are produced. Such electrons produce secondary gamma rays by the mechanisms of bremsstrahlung, inverse Compton scattering and synchrotron radiation. A large fraction of such astronomical gamma rays are screened by Earth's atmosphere. Notable artificial sources of gamma rays include fission, such as occurs in nuclear reactors, as well as high energy physics experiments, such as neutral pion decay and nuclear fusion. A sample of gamma ray-emitting material that is used for irradiating or imaging is known as a gamma source. It is also called a radioactive source, isotope source, or radiation source, though these more general terms also apply to alpha and beta-emitting devices. Gamma sources are usually sealed to prevent radioactive contamination, and transported in heavy shielding. Gamma rays are produced during gamma decay, which normally occurs after other forms of decay occur, such as alpha or beta decay. A radioactive nucleus can decay by the emission of an α or β particle. The daughter nucleus that results is usually left in an excited state. It can then decay to a lower energy state by emitting a gamma ray photon, in a process called gamma decay. The emission of a gamma ray from an excited nucleus typically requires only 10−12 seconds. Gamma decay may also follow nuclear reactions such as neutron capture, nuclear fission, or nuclear fusion. Gamma decay is also a mode of relaxation of many excited states of atomic nuclei following other types of radioactive decay, such as beta decay, so long as these states possess the necessary component of nuclear spin. When high-energy gamma rays, electrons, or protons bombard materials, the excited atoms emit characteristic "secondary" gamma rays, which are products of the creation of excited nuclear states in the bombarded atoms. Such transitions, a form of nuclear gamma fluorescence, form a topic in nuclear physics called gamma spectroscopy. Formation of fluorescent gamma rays are a rapid subtype of radioactive gamma decay. In certain cases, the excited nuclear state that follows the emission of a beta particle or other type of excitation, may be more stable than average, and is termed a metastable excited state, if its decay takes (at least) 100 to 1000 times longer than the average 10−12 seconds. Such relatively long-lived excited nuclei are termed nuclear isomers, and their decays are termed isomeric transitions. Such nuclei have half-lifes that are more easily measurable, and rare nuclear isomers are able to stay in their excited state for minutes, hours, days, or occasionally far longer, before emitting a gamma ray. The process of isomeric transition is therefore similar to any gamma emission, but differs in that it involves the intermediate metastable excited state(s) of the nuclei. Metastable states are often characterized by high nuclear spin, requiring a change in spin of several units or more with gamma decay, instead of a single unit transition that occurs in only 10−12 seconds. The rate of gamma decay is also slowed when the energy of excitation of the nucleus is small. An emitted gamma ray from any type of excited state may transfer its energy directly to any electrons, but most probably to one of the K shell electrons of the atom, causing it to be ejected from that atom, in a process generally termed the photoelectric effect (external gamma rays and ultraviolet rays may also cause this effect). The photoelectric effect should not be confused with the internal conversion process, in which a gamma ray photon is not produced as an intermediate particle (rather, a "virtual gamma ray" may be thought to mediate the process). One example of gamma ray production due to radionuclide decay is the decay scheme for cobalt-60, as illustrated in the accompanying diagram. First, 60Co decays to excited 60Ni by beta decay emission of an electron of 0.31 MeV. Then the excited 60Ni decays to the ground state (see nuclear shell model) by emitting gamma rays in succession of 1.17 MeV followed by 1.33 MeV. This path is followed 99.88% of the time: Another example is the alpha decay of 241Am to form 237Np; which is followed by gamma emission. In some cases, the gamma emission spectrum of the daughter nucleus is quite simple, (e.g. 60Co/60Ni) while in other cases, such as with (241Am/237Np and 192Ir/192Pt), the gamma emission spectrum is complex, revealing that a series of nuclear energy levels exist. Gamma rays are produced in many processes of particle physics. Typically, gamma rays are the products of neutral systems which decay through electromagnetic interactions (rather than a weak or strong interaction). For example, in an electron–positron annihilation, the usual products are two gamma ray photons. If the annihilating electron and positron are at rest, each of the resulting gamma rays has an energy of ~ 511 keV and frequency of ~ 1.24×1020 Hz. Conversely, gamma rays above 1022 keV can interact with nuclei via pair production of an electron and positron. Similarly, a neutral pion most often decays into two photons. Many other hadrons and massive bosons also decay electromagnetically. High energy physics experiments, such as the Large Hadron Collider, accordingly employ substantial radiation shielding. Because subatomic particles mostly have far shorter wavelengths than atomic nuclei, particle physics gamma rays are generally several orders of magnitude more energetic than nuclear decay gamma rays. Since gamma rays are at the top of the electromagnetic spectrum in terms of energy, all extremely high-energy photons are gamma rays; for example, a photon having the Planck energy would be a gamma ray. A few gamma rays in astronomy are known to arise from gamma decay (see discussion of SN1987A), but most do not. Photons from astrophysical sources that carry energy in the gamma radiation range are often explicitly called gamma-radiation. In addition to nuclear emissions, they are often produced by sub-atomic particle and particle-photon interactions. Those include electron-positron annihilation, neutral pion decay, bremsstrahlung, inverse Compton scattering, and synchrotron radiation. In October 2017, scientists from various European universities proposed a means for sources of GeV photons using lasers as exciters through a controlled interplay between the cascade and anomalous radiative trapping. Thunderstorms can produce a brief pulse of gamma radiation called a terrestrial gamma-ray flash. These gamma rays are thought to be produced by high intensity static electric fields accelerating electrons, which then produce gamma rays by bremsstrahlung as they collide with and are slowed by atoms in the atmosphere. Gamma rays up to 100 MeV can be emitted by terrestrial thunderstorms, and were discovered by space-borne observatories. This raises the possibility of health risks to passengers and crew on aircraft flying in or near thunderclouds. The most effusive solar flares emit across the entire EM spectrum, including γ-rays. The first confident observation occurred in 1972. Extraterrestrial, high energy gamma rays include the gamma ray background produced when cosmic rays (either high speed electrons or protons) collide with ordinary matter, producing pair-production gamma rays at 511 keV. Alternatively, bremsstrahlung are produced at energies of tens of MeV or more when cosmic ray electrons interact with nuclei of sufficiently high atomic number (see gamma ray image of the Moon near the end of this article, for illustration). The gamma ray sky (see illustration at right) is dominated by the more common and longer-term production of gamma rays that emanate from pulsars within the Milky Way. Sources from the rest of the sky are mostly quasars. Pulsars are thought to be neutron stars with magnetic fields that produce focused beams of radiation, and are far less energetic, more common, and much nearer sources (typically seen only in our own galaxy) than are quasars or the rarer gamma-ray burst sources of gamma rays. Pulsars have relatively long-lived magnetic fields that produce focused beams of relativistic speed charged particles, which emit gamma rays (bremsstrahlung) when those strike gas or dust in their nearby medium, and are decelerated. This is a similar mechanism to the production of high-energy photons in megavoltage radiation therapy machines (see bremsstrahlung). Inverse Compton scattering, in which charged particles (usually electrons) impart energy to low-energy photons boosting them to higher energy photons. Such impacts of photons on relativistic charged particle beams is another possible mechanism of gamma ray production. Neutron stars with a very high magnetic field (magnetars), thought to produce astronomical soft gamma repeaters, are another relatively long-lived star-powered source of gamma radiation. More powerful gamma rays from very distant quasars and closer active galaxies are thought to have a gamma ray production source similar to a particle accelerator. High energy electrons produced by the quasar, and subjected to inverse Compton scattering, synchrotron radiation, or bremsstrahlung, are the likely source of the gamma rays from those objects. It is thought that a supermassive black hole at the center of such galaxies provides the power source that intermittently destroys stars and focuses the resulting charged particles into beams that emerge from their rotational poles. When those beams interact with gas, dust, and lower energy photons they produce X-rays and gamma rays. These sources are known to fluctuate with durations of a few weeks, suggesting their relatively small size (less than a few light-weeks across). Such sources of gamma and X-rays are the most commonly visible high intensity sources outside the Milky Way galaxy. They shine not in bursts (see illustration), but relatively continuously when viewed with gamma ray telescopes. The power of a typical quasar is about 1040 watts, a small fraction of which is gamma radiation. Much of the rest is emitted as electromagnetic waves of all frequencies, including radio waves. The most intense sources of gamma rays are also the most intense sources of any type of electromagnetic radiation presently known. They are the "long duration burst" sources of gamma rays in astronomy ("long" in this context, meaning a few tens of seconds), and they are rare compared with the sources discussed above. By contrast, "short" gamma-ray bursts of two seconds or less, which are not associated with supernovae, are thought to produce gamma rays during the collision of pairs of neutron stars, or a neutron star and a black hole. The so-called long-duration gamma-ray bursts produce a total energy output of about 1044 joules (as much energy as the Sun will produce in its entire life-time) but in a period of only 20 to 40 seconds. Gamma rays are approximately 50% of the total energy output. The leading hypotheses for the mechanism of production of these highest-known intensity beams of radiation, are inverse Compton scattering and synchrotron radiation from high-energy charged particles. These processes occur as relativistic charged particles leave the region of the event horizon of a newly formed black hole created during supernova explosion. The beam of particles moving at relativistic speeds are focused for a few tens of seconds by the magnetic field of the exploding hypernova. The fusion explosion of the hypernova drives the energetics of the process. If the narrowly directed beam happens to be pointed toward the Earth, it shines at gamma ray frequencies with such intensity, that it can be detected even at distances of up to 10 billion light years, which is close to the edge of the visible universe. Properties Due to their penetrating nature, gamma rays require large amounts of shielding mass to reduce them to levels which are not harmful to living cells, in contrast to alpha particles, which can be stopped by paper or skin, and beta particles, which can be shielded by thin aluminium. Gamma rays are best absorbed by materials with high atomic numbers (Z) and high density, which contribute to the total stopping power. Because of this, a lead (high Z) shield is 20–30% better as a gamma shield than an equal mass of a low-Z shielding material, such as aluminium, concrete, water, or soil; lead's major advantage is not in lower weight, but rather its compactness due to its higher density. Protective clothing, goggles and respirators can protect from internal contact with or ingestion of alpha or beta emitting particles, but provide no protection from gamma radiation from external sources. The higher the energy of the gamma rays, the thicker the shielding made from the same shielding material is required. Materials for shielding gamma rays are typically measured by the thickness required to reduce the intensity of the gamma rays by one half (the half-value layer or HVL). For example, gamma rays that require 1 cm (0.4 inch) of lead to reduce their intensity by 50% will also have their intensity reduced in half by 4.1 cm of granite rock, 6 cm (2.5 inches) of concrete, or 9 cm (3.5 inches) of packed soil. However, the mass of this much concrete or soil is only 20–30% greater than that of lead with the same absorption capability. Depleted uranium is sometimes used for shielding in portable gamma ray sources, due to the smaller half-value layer when compared to lead (around 0.6 times the thickness for common gamma ray sources, i.e. Iridium-192 and Cobalt-60) and cheaper cost compared to tungsten. In a nuclear power plant, shielding can be provided by steel and concrete in the pressure and particle containment vessel, while water provides a radiation shielding of fuel rods during storage or transport into the reactor core. The loss of water or removal of a "hot" fuel assembly into the air would result in much higher radiation levels than when kept under water. When a gamma ray passes through matter, the probability for absorption is proportional to the thickness of the layer, the density of the material, and the absorption cross section of the material. The total absorption shows an exponential decrease of intensity with distance from the incident surface: where x is the thickness of the material from the incident surface, μ= nσ is the absorption coefficient, measured in cm−1, n the number of atoms per cm3 of the material (atomic density) and σ the absorption cross section in cm2.: 280 As it passes through matter, gamma radiation ionizes via several different processes: The secondary electrons (and/or positrons) produced in any of these three processes frequently have enough energy to produce much ionization themselves. High-energy (from 80 GeV to ~10 TeV) gamma rays arriving from far-distant quasars are used to estimate the extragalactic background light in the universe: The highest-energy rays interact more readily with the background light photons and thus the density of the background light may be estimated by analyzing the incoming gamma ray spectra. Gamma spectroscopy is the study of the energetic transitions in atomic nuclei, which are generally associated with the absorption or emission of gamma rays. As in optical spectroscopy (see Franck–Condon effect) the absorption of gamma rays by a nucleus is especially likely (i.e., peaks in a "resonance") when the energy of the gamma ray is the same as that of an energy transition in the nucleus. In the case of gamma rays, such a resonance is seen in the technique of Mössbauer spectroscopy. In the Mössbauer effect the narrow resonance absorption for nuclear gamma absorption can be successfully attained by physically immobilizing atomic nuclei in a crystal. The immobilization of nuclei at both ends of a gamma resonance interaction is required so that no gamma energy is lost to the kinetic energy of recoiling nuclei at either the emitting or absorbing end of a gamma transition. Such loss of energy causes gamma ray resonance absorption to fail. However, when emitted gamma rays carry essentially all of the energy of the atomic nuclear de-excitation that produces them, this energy is also sufficient to excite the same energy state in a second immobilized nucleus of the same type. Applications Gamma rays provide information about some of the most energetic phenomena in the universe; however, they are largely absorbed by the Earth's atmosphere. Instruments aboard high-altitude balloons and satellites missions, such as the Fermi Gamma-ray Space Telescope, provide our only view of the universe in gamma rays. Gamma-induced molecular changes can also be used to alter the properties of semi-precious stones, and is often used to change white topaz into blue topaz. Non-contact industrial sensors commonly use sources of gamma radiation in refining, mining, chemicals, food, soaps and detergents, and pulp and paper industries, for the measurement of levels, density, and thicknesses. Gamma-ray sensors are also used for measuring the fluid levels in water and oil industries. Typically, these use Co-60 or Cs-137 isotopes as the radiation source. In the US, gamma ray detectors are beginning to be used as part of the Container Security Initiative (CSI). These machines are advertised to be able to scan 30 containers per hour. Gamma radiation is often used to kill living organisms, in a process called irradiation. Applications of this include the sterilization of medical equipment (as an alternative to autoclaves or chemical means), the removal of decay-causing bacteria from many foods and the prevention of the sprouting of fruit and vegetables to maintain freshness and flavor. Despite their cancer-causing properties, gamma rays are also used to treat some types of cancer, since the rays also kill cancer cells. In the procedure called gamma-knife surgery, multiple concentrated beams of gamma rays are directed to the growth in order to kill the cancerous cells. The beams are aimed from different angles to concentrate the radiation on the growth while minimizing damage to surrounding tissues. Gamma rays are also used for diagnostic purposes in nuclear medicine in imaging techniques. A number of different gamma-emitting radioisotopes are used. For example, in a PET scan a radiolabeled sugar called fluorodeoxyglucose emits positrons that are annihilated by electrons, producing pairs of gamma rays that highlight cancer as the cancer often has a higher metabolic rate than the surrounding tissues. The most common gamma emitter used in medical applications is the nuclear isomer technetium-99m which emits gamma rays in the same energy range as diagnostic X-rays. When this radionuclide tracer is administered to a patient, a gamma camera can be used to form an image of the radioisotope's distribution by detecting the gamma radiation emitted (see also SPECT). Depending on which molecule has been labeled with the tracer, such techniques can be employed to diagnose a wide range of conditions (for example, the spread of cancer to the bones via bone scan). Health effects Gamma rays cause damage at a cellular level and are penetrating, causing diffuse damage throughout the body. However, they are less ionising than alpha or beta particles, which are less penetrating.[citation needed] Low levels of gamma rays cause a stochastic health risk, which for radiation dose assessment is defined as the probability of cancer induction and genetic damage. The International Commission on Radiological Protection says "In the low dose range, below about 100 mSv, it is scientifically plausible to assume that the incidence of cancer or heritable effects will rise in direct proportion to an increase in the equivalent dose in the relevant organs and tissues": 51 (The unit mSv is milli-Seivert). High doses produce deterministic effects, which is the severity of acute tissue damage that is certain to happen. These effects are compared to the physical quantity absorbed dose measured by the unit gray (Gy).: 61 When gamma radiation breaks DNA molecules, a cell may be able to repair the damaged genetic material, within limits. However, a study of Rothkamm and Lobrich concerning X-ray radiation has shown that this repair process works well after high-dose exposure but is much slower in the case of a low-dose exposure. Studies have shown low-dose gamma radiation may be enough to cause cancer. In a study of mice, they were given human-relevant low-dose gamma radiation, with genotoxic effects 45 days after continuous low-dose gamma radiation, with significant increases of chromosomal damage, DNA lesions and phenotypic mutations in blood cells of irradiated animals, covering the three types of genotoxic activity. Another study studied the effects of acute ionizing gamma radiation in rats, up to 10 Gy, and who ended up showing acute oxidative protein damage, DNA damage, cardiac troponin T carbonylation, and long-term cardiomyopathy. Natural gamma radiation in the United Kingdom of accounts for about 13% of the average radiation dose. Natural exposure to gamma rays is about 1 to 2 mSv per year, and the average total amount of radiation received in one year per inhabitant in the USA is 3.6 mSv. There might be a small increase in the dose around small particles of depleted uranium should these enter the human body from spent munitions, caused by increased effects of natural gamma radiation. By comparison, the radiation dose from chest radiography (about 0.06 mSv) is a fraction of the annual naturally occurring background radiation dose. A chest CT delivers 5 to 8 mSv. A whole-body PET/CT scan can deliver 14 to 32 mSv depending on the protocol. The dose from fluoroscopy of the stomach is much higher, approximately 50 mSv (14 times the annual background). An acute full-body equivalent single exposure dose of 1 Sv (1000 mSv), or 1 Gy, will cause mild symptoms of acute radiation sickness, such as nausea and vomiting; and a dose of 2.0–3.5 Sv (2.0–3.5 Gy) causes more severe symptoms (i.e. nausea, diarrhea, hair loss, hemorrhaging, and inability to fight infections), and will cause death in a sizable number of cases—about 10% to 35% without medical treatment. A dose of 3–5 Sv (3–5 Gy) is considered approximately the LD50 (or the lethal dose for 50% of exposed population) for an acute exposure to radiation even with standard medical treatment. A dose higher than 5 Sv (5 Gy) brings an increasing chance of death above 50%. Above 7.5–10 Sv (7.5–10 Gy) to the entire body, even extraordinary treatment, such as bone-marrow transplants, will not prevent the death of the individual exposed (see radiation poisoning). (Doses much larger than this may, however, be delivered to selected parts of the body in the course of radiation therapy.) For low-dose exposure, for example among nuclear workers, who receive an average yearly radiation dose of 19 mSv,[clarification needed] the risk of dying from cancer (excluding leukemia) increases by 2 percent. For a dose of 100 mSv, the risk increase is 10 percent. By comparison, risk of dying from cancer was increased by 32 percent for the survivors of the atomic bombing of Hiroshima and Nagasaki. Units of measurement and exposure The following table shows radiation quantities in SI and non-SI units: The measure of the ionizing effect of gamma and X-rays in dry air is called the exposure, for which a legacy unit, the röntgen, was used from 1928. This has been replaced by kerma, now mainly used for instrument calibration purposes but not for received dose effect. The effect of gamma and other ionizing radiation on living tissue is more closely related to the amount of energy deposited in tissue rather than the ionisation of air, and replacement radiometric units and quantities for radiation protection have been defined and developed from 1953 onwards. These are: Distinction from X-rays The conventional distinction between X-rays and gamma rays has changed over time. Originally, the electromagnetic radiation emitted by X-ray tubes almost invariably had a longer wavelength than the radiation (gamma rays) emitted by radioactive nuclei. Older literature distinguished between X and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10−11 m, defined as gamma rays. Since the energy of photons is proportional to their frequency and inversely proportional to wavelength, this past distinction between X-rays and gamma rays can also be thought of in terms of its energy, with gamma rays considered to be higher energy electromagnetic radiation than are X-rays. However, since current artificial sources are now able to duplicate any electromagnetic radiation that originates in the nucleus, as well as far higher energies, the wavelengths characteristic of radioactive gamma ray sources vs. other types now completely overlap. Thus, gamma rays are now usually distinguished by their origin: X-rays are emitted by definition by electrons outside the nucleus, while gamma rays are emitted by the nucleus. Exceptions to this convention occur in astronomy, where gamma decay is seen in the afterglow of certain supernovas, but radiation from high energy processes known to involve other radiation sources than radioactive decay is still classed as gamma radiation. For example, modern high-energy X-rays produced by linear accelerators for megavoltage treatment in cancer often have higher energy (4 to 25 MeV) than do most classical gamma rays produced by nuclear gamma decay. One of the most common gamma ray emitting isotopes used in diagnostic nuclear medicine, technetium-99m, produces gamma radiation of the same energy (140 keV) as that produced by diagnostic X-ray machines, but of significantly lower energy than therapeutic photons from linear particle accelerators. In the medical community today, the convention that radiation produced by nuclear decay is the only type referred to as "gamma" radiation is still respected. Due to this broad overlap in energy ranges, in physics the two types of electromagnetic radiation are now often defined by their origin: X-rays are emitted by electrons (either in orbitals outside of the nucleus, or while being accelerated to produce bremsstrahlung-type radiation), while gamma rays are emitted by the nucleus or by means of other particle decays or annihilation events. There is no lower limit to the energy of photons produced by nuclear reactions, and thus ultraviolet or lower energy photons produced by these processes would also be defined as "gamma rays" (indeed, this happens for the isomeric transition of the extremely low-energy isomer 229mTh). The only naming-convention that is still universally respected is the rule that electromagnetic radiation that is known to be of atomic nuclear origin is always referred to as "gamma rays", and never as X-rays. However, in physics and astronomy, the converse convention (that all gamma rays are considered to be of nuclear origin) is frequently violated. In astronomy, higher energy gamma and X-rays are defined by energy, since the processes that produce them may be uncertain and photon energy, not origin, determines the required astronomical detectors needed. High-energy photons occur in nature that are known to be produced by processes other than nuclear decay but are still referred to as gamma radiation. An example is "gamma rays" from lightning discharges at 10 to 20 MeV, and known to be produced by the bremsstrahlung mechanism. Another example is gamma-ray bursts, now known to be produced from processes too powerful to involve simple collections of atoms undergoing radioactive decay. This is part and parcel of the general realization that many gamma rays produced in astronomical processes result not from radioactive decay or particle annihilation, but rather in non-radioactive processes similar to X-rays.[clarification needed] Although the gamma rays of astronomy often come from non-radioactive events, a few gamma rays in astronomy are specifically known to originate from gamma decay of nuclei (as demonstrated by their spectra and emission half-life). A classic example is that of supernova SN 1987A, which emits an "afterglow" of gamma-ray photons from the decay of newly made radioactive nickel-56 and cobalt-56. Most gamma rays in astronomy, however, arise by other mechanisms. See also Explanatory notes References External links |
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[SOURCE: https://www.ynet.co.il/economy/category/8315] | [TOKENS: 254] |
נדל״ן> פונו, חזרו ושוב פונו: הדרמה הבלתי נגמרת בפרויקט הפינוי בינוי ביבנה לקראת סיום עיר ההייטק ועיר האגרו-טק: אושרה התוכנית האסטרטגית לנגב המערבי מהפכה נשית: בית המשפט סלל את הדרך להבאת עובדות בניין לישראל 2026: מחירי השכירות ממשיכים לעלות – וההיצע צנח ב-8% |
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[SOURCE: https://www.theverge.com/phones] | [TOKENS: 742] |
Phones CEO Carl Pei had previously teased the date in a playful response to Apple’s recently announced event on the 4th, but now it’s official. With no Phone 4 this year, the 4A, and likely 4A Pro, should be Nothing’s biggest releases in 2026. Phone manufacturers are throwing everything they have at long-distance lenses in order to stand out. Redmagic’s new 11 Air just launched in China. Sounds thin and light, right? Well, sort of — at 8mm thick and 207g it’s smaller than Redmagic’s liquid-cooled 11 Pro, but a far cry from the 5.6mm, 165g iPhone Air. Still, not bad for a phone with a 7,000mAh battery and built-in fan. Smart lights that know where they’re placed in a room, wild designs for next-gen routers, and a glowing inedible donut. Rollable laptops, twice-folding phones, and a ‘longevity station.’ This is the CES tech we come back for. 7 Verge Score The company’s best phone camera yet can compete with anything around. Realme is once again an Oppo subbrand in a bid to save money. Both were once brands under the Chinese consumer hardware behemoth BBK Electronics, which was also responsible for brands like Vivo, OnePlus, and a few more. But BBK consciously uncoupled a few years ago to avoid regulator scrutiny, creating a myriad of legal entities that occasionally shared supply chains, R&D efforts, and even marketing teams. [Reuters] Soccer’s governing body isn’t at its most popular right now, from price gouging complaints to allegedly breaking its own rules giving a “peace prize” to Donald Trump. But hey, it’s a World Cup year, so you can’t blame it for trying its luck with this branded version of last year’s regular Motorola Razr. The Verge’s Dominic Preston got a look at a static prototype of the phone this week, but unlike Boston Dynamics’ Spot robots, the phone’s fancy camera didn’t move. In case you missed the announcement for the Robot Phone and its gimbal camera (which is apparently intelligent), check out this video for a recap of what we know so far. I only got to see (and not touch) a prototype, and the fold-out gimbal camera wasn’t operational. So it’s strictly TBC what the Robot Phone will actually do, but Honor did tell me this is no concept: after the full launch at MWC next month it will go on sale — but only in China. There’s been a surprising development. This China-only Android phone is the first to include the feature, along with just about every other type of cooling tech, including fans, a heatsink, and a vapor chamber, all topped by the blue liquid cooling system. According to iFixit, however, all that cooling didn’t make up for the RedMagic 11 Pro’s limited repair options. One of Google’s new Android updates is the beta for Call Reason, which allows callers to flag that it’s urgent. Sounds smart, but if you’re below the age of 40, “urgent” might be the only type of call you ever make. mekalos: Sorry but if literally anyone I know is calling me instead of texting, it’s already urgent. Get the day’s best comment and more in my free newsletter, The Verge Daily. Pagination Most Popular The Verge Daily A free daily digest of the news that matters most. This is the title for the native ad © 2026 Vox Media, LLC. All Rights Reserved |
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[SOURCE: https://en.wikipedia.org/wiki/Black_hole#cite_note-260] | [TOKENS: 13839] |
Contents Black hole A black hole is an astronomical body so compact that its gravity prevents anything, including light, from escaping. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass will form a black hole. The boundary of no escape is called the event horizon. In general relativity, a black hole's event horizon seals an object's fate but produces no locally detectable change when crossed. General relativity also predicts that every black hole should have a central singularity, where the curvature of spacetime is infinite. In many ways, a black hole acts like an ideal black body, as it reflects no light. Quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is of the order of billionths of a kelvin for stellar black holes, making it essentially impossible to observe directly. Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. In 1916, Karl Schwarzschild found the first modern solution of general relativity that would characterise a black hole. Due to his influential research, the Schwarzschild metric is named after him. David Finkelstein, in 1958, first interpreted Schwarzschild's model as a region of space from which nothing can escape. Black holes were long considered a mathematical curiosity; it was not until the 1960s that theoretical work showed they were a generic prediction of general relativity. The first black hole known was Cygnus X-1, identified by several researchers independently in 1971. Black holes typically form when massive stars collapse at the end of their life cycle. After a black hole has formed, it can grow by absorbing mass from its surroundings. Supermassive black holes of millions of solar masses may form by absorbing other stars and merging with other black holes, or via direct collapse of gas clouds. There is consensus that supermassive black holes exist in the centres of most galaxies. The presence of a black hole can be inferred through its interaction with other matter and with electromagnetic radiation such as visible light. Matter falling toward a black hole can form an accretion disk of infalling plasma, heated by friction and emitting light. In extreme cases, this creates a quasar, some of the brightest objects in the universe. Merging black holes can also be detected by observation of the gravitational waves they emit. If other stars are orbiting a black hole, their orbits can be used to determine the black hole's mass and location. Such observations can be used to exclude possible alternatives such as neutron stars. In this way, astronomers have identified numerous stellar black hole candidates in binary systems and established that the radio source known as Sagittarius A*, at the core of the Milky Way galaxy, contains a supermassive black hole of about 4.3 million solar masses. History The idea of a body so massive that even light could not escape was first proposed in the late 18th century by English astronomer and clergyman John Michell and independently by French scientist Pierre-Simon Laplace. Both scholars proposed very large stars in contrast to the modern concept of an extremely dense object. Michell's idea, in a short part of a letter published in 1784, calculated that a star with the same density but 500 times the radius of the sun would not let any emitted light escape; the surface escape velocity would exceed the speed of light.: 122 Michell correctly hypothesized that such supermassive but non-radiating bodies might be detectable through their gravitational effects on nearby visible bodies. In 1796, Laplace mentioned that a star could be invisible if it were sufficiently large while speculating on the origin of the Solar System in his book Exposition du Système du Monde. Franz Xaver von Zach asked Laplace for a mathematical analysis, which Laplace provided and published in a journal edited by von Zach. In 1905, Albert Einstein showed that the laws of electromagnetism would be invariant under a Lorentz transformation: they would be identical for observers travelling at different velocities relative to each other. This discovery became known as the principle of special relativity. Although the laws of mechanics had already been shown to be invariant, gravity remained yet to be included.: 19 In 1907, Einstein published a paper proposing his equivalence principle, the hypothesis that inertial mass and gravitational mass have a common cause. Using the principle, Einstein predicted the redshift and half of the lensing effect of gravity on light; the full prediction of gravitational lensing required development of general relativity.: 19 By 1915, Einstein refined these ideas into his general theory of relativity, which explained how matter affects spacetime, which in turn affects the motion of other matter. This formed the basis for black hole physics. Only a few months after Einstein published the field equations describing general relativity, astrophysicist Karl Schwarzschild set out to apply the idea to stars. He assumed spherical symmetry with no spin and found a solution to Einstein's equations.: 124 A few months after Schwarzschild, Johannes Droste, a student of Hendrik Lorentz, independently gave the same solution. At a certain radius from the center of the mass, the Schwarzschild solution became singular, meaning that some of the terms in the Einstein equations became infinite. The nature of this radius, which later became known as the Schwarzschild radius, was not understood at the time. Many physicists of the early 20th century were skeptical of the existence of black holes. In a 1926 popular science book, Arthur Eddington critiqued the idea of a star with mass compressed to its Schwarzschild radius as a flaw in the then-poorly-understood theory of general relativity.: 134 In 1939, Einstein himself used his theory of general relativity in an attempt to prove that black holes were impossible. His work relied on increasing pressure or increasing centrifugal force balancing the force of gravity so that the object would not collapse beyond its Schwarzschild radius. He missed the possibility that implosion would drive the system below this critical value.: 135 By the 1920s, astronomers had classified a number of white dwarf stars as too cool and dense to be explained by the gradual cooling of ordinary stars. In 1926, Ralph Fowler showed that quantum-mechanical degeneracy pressure was larger than thermal pressure at these densities.: 145 In 1931, Subrahmanyan Chandrasekhar calculated that a non-rotating body of electron-degenerate matter below a certain limiting mass is stable, and by 1934 he showed that this explained the catalog of white dwarf stars.: 151 When Chandrasekhar announced his results, Eddington pointed out that stars above this limit would radiate until they were sufficiently dense to prevent light from exiting, a conclusion he considered absurd. Eddington and, later, Lev Landau argued that some yet unknown mechanism would stop the collapse. In the 1930s, Fritz Zwicky and Walter Baade studied stellar novae, focusing on exceptionally bright ones they called supernovae. Zwicky promoted the idea that supernovae produced stars with the density of atomic nuclei—neutron stars—but this idea was largely ignored.: 171 In 1939, based on Chandrasekhar's reasoning, J. Robert Oppenheimer and George Volkoff predicted that neutron stars below a certain mass limit, later called the Tolman–Oppenheimer–Volkoff limit, would be stable due to neutron degeneracy pressure. Above that limit, they reasoned that either their model would not apply or that gravitational contraction would not stop.: 380 John Archibald Wheeler and two of his students resolved questions about the model behind the Tolman–Oppenheimer–Volkoff (TOV) limit. Harrison and Wheeler developed the equations of state relating density to pressure for cold matter all the way through electron degeneracy and neutron degeneracy. Masami Wakano and Wheeler then used the equations to compute the equilibrium curve for stars, relating mass to circumference. They found no additional features that would invalidate the TOV limit. This meant that the only thing that could prevent black holes from forming was a dynamic process ejecting sufficient mass from a star as it cooled.: 205 The modern concept of black holes was formulated by Robert Oppenheimer and his student Hartland Snyder in 1939.: 80 In the paper, Oppenheimer and Snyder solved Einstein's equations of general relativity for an idealized imploding star, in a model later called the Oppenheimer–Snyder model, then described the results from far outside the star. The implosion starts as one might expect: the star material rapidly collapses inward. However, as the density of the star increases, gravitational time dilation increases and the collapse, viewed from afar, seems to slow down further and further until the star reaches its Schwarzschild radius, where it appears frozen in time.: 217 In 1958, David Finkelstein identified the Schwarzschild surface as an event horizon, calling it "a perfect unidirectional membrane: causal influences can cross it in only one direction". In this sense, events that occur inside of the black hole cannot affect events that occur outside of the black hole. Finkelstein created a new reference frame to include the point of view of infalling observers.: 103 Finkelstein's new frame of reference allowed events at the surface of an imploding star to be related to events far away. By 1962 the two points of view were reconciled, convincing many skeptics that implosion into a black hole made physical sense.: 226 The era from the mid-1960s to the mid-1970s was the "golden age of black hole research", when general relativity and black holes became mainstream subjects of research.: 258 In this period, more general black hole solutions were found. In 1963, Roy Kerr found the exact solution for a rotating black hole. Two years later, Ezra Newman found the cylindrically symmetric solution for a black hole that is both rotating and electrically charged. In 1967, Werner Israel found that the Schwarzschild solution was the only possible solution for a nonspinning, uncharged black hole, meaning that a Schwarzschild black hole would be defined by its mass alone. Similar identities were later found for Reissner-Nordstrom and Kerr black holes, defined only by their mass and their charge or spin respectively. Together, these findings became known as the no-hair theorem, which states that a stationary black hole is completely described by the three parameters of the Kerr–Newman metric: mass, angular momentum, and electric charge. At first, it was suspected that the strange mathematical singularities found in each of the black hole solutions only appeared due to the assumption that a black hole would be perfectly spherically symmetric, and therefore the singularities would not appear in generic situations where black holes would not necessarily be symmetric. This view was held in particular by Vladimir Belinski, Isaak Khalatnikov, and Evgeny Lifshitz, who tried to prove that no singularities appear in generic solutions, although they would later reverse their positions. However, in 1965, Roger Penrose proved that general relativity without quantum mechanics requires that singularities appear in all black holes. Astronomical observations also made great strides during this era. In 1967, Antony Hewish and Jocelyn Bell Burnell discovered pulsars and by 1969, these were shown to be rapidly rotating neutron stars. Until that time, neutron stars, like black holes, were regarded as just theoretical curiosities, but the discovery of pulsars showed their physical relevance and spurred a further interest in all types of compact objects that might be formed by gravitational collapse. Based on observations in Greenwich and Toronto in the early 1970s, Cygnus X-1, a galactic X-ray source discovered in 1964, became the first astronomical object commonly accepted to be a black hole. Work by James Bardeen, Jacob Bekenstein, Carter, and Hawking in the early 1970s led to the formulation of black hole thermodynamics. These laws describe the behaviour of a black hole in close analogy to the laws of thermodynamics by relating mass to energy, area to entropy, and surface gravity to temperature. The analogy was completed: 442 when Hawking, in 1974, showed that quantum field theory implies that black holes should radiate like a black body with a temperature proportional to the surface gravity of the black hole, predicting the effect now known as Hawking radiation. While Cygnus X-1, a stellar-mass black hole, was generally accepted by the scientific community as a black hole by the end of 1973, it would be decades before a supermassive black hole would gain the same broad recognition. Although, as early as the 1960s, physicists such as Donald Lynden-Bell and Martin Rees had suggested that powerful quasars in the center of galaxies were powered by accreting supermassive black holes, little observational proof existed at the time. However, the Hubble Space Telescope, launched decades later, found that supermassive black holes were not only present in these active galactic nuclei, but that supermassive black holes in the center of galaxies were ubiquitous: Almost every galaxy had a supermassive black hole at its center, many of which were quiescent. In 1999, David Merritt proposed the M–sigma relation, which related the dispersion of the velocity of matter in the center bulge of a galaxy to the mass of the supermassive black hole at its core. Subsequent studies confirmed this correlation. Around the same time, based on telescope observations of the velocities of stars at the center of the Milky Way galaxy, independent work groups led by Andrea Ghez and Reinhard Genzel concluded that the compact radio source in the center of the galaxy, Sagittarius A*, was likely a supermassive black hole. On 11 February 2016, the LIGO Scientific Collaboration and Virgo Collaboration announced the first direct detection of gravitational waves, named GW150914, representing the first observation of a black hole merger. At the time of the merger, the black holes were approximately 1.4 billion light-years away from Earth and had masses of 30 and 35 solar masses.: 6 In 2017, Rainer Weiss, Kip Thorne, and Barry Barish, who had spearheaded the project, were awarded the Nobel Prize in Physics for their work. Since the initial discovery in 2015, hundreds more gravitational waves have been observed by LIGO and another interferometer, Virgo. On 10 April 2019, the first direct image of a black hole and its vicinity was published, following observations made by the Event Horizon Telescope (EHT) in 2017 of the supermassive black hole in Messier 87's galactic centre. In 2022, the Event Horizon Telescope collaboration released an image of the black hole in the center of the Milky Way galaxy, Sagittarius A*; The data had been collected in 2017. In 2020, the Nobel Prize in Physics was awarded for work on black holes. Andrea Ghez and Reinhard Genzel shared one-half for their discovery that Sagittarius A* is a supermassive black hole. Penrose received the other half for his work showing that the mathematics of general relativity requires the formation of black holes. Cosmologists lamented that Hawking's extensive theoretical work on black holes would not be honored since he died in 2018. In December 1967, a student reportedly suggested the phrase black hole at a lecture by John Wheeler; Wheeler adopted the term for its brevity and "advertising value", and Wheeler's stature in the field ensured it quickly caught on, leading some to credit Wheeler with coining the phrase. However, the term was used by others around that time. Science writer Marcia Bartusiak traces the term black hole to physicist Robert H. Dicke, who in the early 1960s reportedly compared the phenomenon to the Black Hole of Calcutta, notorious as a prison where people entered but never left alive. The term was used in print by Life and Science News magazines in 1963, and by science journalist Ann Ewing in her article "'Black Holes' in Space", dated 18 January 1964, which was a report on a meeting of the American Association for the Advancement of Science held in Cleveland, Ohio. Definition A black hole is generally defined as a region of spacetime from which no information-carrying signals or objects can escape. However, verifying an object as a black hole by this definition would require waiting for an infinite time and at an infinite distance from the black hole to verify that indeed, nothing has escaped, and thus cannot be used to identify a physical black hole. Broadly, physicists do not have a precisely-agreed-upon definition of a black hole. Among astrophysicists, a black hole is a compact object with a mass larger than four solar masses. A black hole may also be defined as a reservoir of information: 142 or a region where space is falling inwards faster than the speed of light. Properties The no-hair theorem postulates that, once it achieves a stable condition after formation, a black hole has only three independent physical properties: mass, electric charge, and angular momentum; the black hole is otherwise featureless. If the conjecture is true, any two black holes that share the same values for these properties, or parameters, are indistinguishable from one another. The degree to which the conjecture is true for real black holes is currently an unsolved problem. The simplest static black holes have mass but neither electric charge nor angular momentum. According to Birkhoff's theorem, these Schwarzschild black holes are the only vacuum solution that is spherically symmetric. Solutions describing more general black holes also exist. Non-rotating charged black holes are described by the Reissner–Nordström metric, while the Kerr metric describes a non-charged rotating black hole. The most general stationary black hole solution known is the Kerr–Newman metric, which describes a black hole with both charge and angular momentum. The simplest static black holes have mass but neither electric charge nor angular momentum. Contrary to the popular notion of a black hole "sucking in everything" in its surroundings, from far away, the external gravitational field of a black hole is identical to that of any other body of the same mass. While a black hole can theoretically have any positive mass, the charge and angular momentum are constrained by the mass. The total electric charge Q and the total angular momentum J are expected to satisfy the inequality Q 2 4 π ϵ 0 + c 2 J 2 G M 2 ≤ G M 2 {\displaystyle {\frac {Q^{2}}{4\pi \epsilon _{0}}}+{\frac {c^{2}J^{2}}{GM^{2}}}\leq GM^{2}} for a black hole of mass M. Black holes with the maximum possible charge or spin satisfying this inequality are called extremal black holes. Solutions of Einstein's equations that violate this inequality exist, but they do not possess an event horizon. These are so-called naked singularities that can be observed from the outside. Because these singularities make the universe inherently unpredictable, many physicists believe they could not exist. The weak cosmic censorship hypothesis, proposed by Sir Roger Penrose, rules out the formation of such singularities, when they are created through the gravitational collapse of realistic matter. However, this theory has not yet been proven, and some physicists believe that naked singularities could exist. It is also unknown whether black holes could even become extremal, forming naked singularities, since natural processes counteract increasing spin and charge when a black hole becomes near-extremal. The total mass of a black hole can be estimated by analyzing the motion of objects near the black hole, such as stars or gas. All black holes spin, often fast—One supermassive black hole, GRS 1915+105 has been estimated to spin at over 1,000 revolutions per second. The Milky Way's central black hole Sagittarius A* rotates at about 90% of the maximum rate. The spin rate can be inferred from measurements of atomic spectral lines in the X-ray range. As gas near the black hole plunges inward, high energy X-ray emission from electron-positron pairs illuminates the gas further out, appearing red-shifted due to relativistic effects. Depending on the spin of the black hole, this plunge happens at different radii from the hole, with different degrees of redshift. Astronomers can use the gap between the x-ray emission of the outer disk and the redshifted emission from plunging material to determine the spin of the black hole. A newer way to estimate spin is based on the temperature of gasses accreting onto the black hole. The method requires an independent measurement of the black hole mass and inclination angle of the accretion disk followed by computer modeling. Gravitational waves from coalescing binary black holes can also provide the spin of both progenitor black holes and the merged hole, but such events are rare. A spinning black hole has angular momentum. The supermassive black hole in the center of the Messier 87 (M87) galaxy appears to have an angular momentum very close to the maximum theoretical value. That uncharged limit is J ≤ G M 2 c , {\displaystyle J\leq {\frac {GM^{2}}{c}},} allowing definition of a dimensionless spin magnitude such that 0 ≤ c J G M 2 ≤ 1. {\displaystyle 0\leq {\frac {cJ}{GM^{2}}}\leq 1.} Most black holes are believed to have an approximately neutral charge. For example, Michal Zajaček, Arman Tursunov, Andreas Eckart, and Silke Britzen found the electric charge of Sagittarius A* to be at least ten orders of magnitude below the theoretical maximum. A charged black hole repels other like charges just like any other charged object. If a black hole were to become charged, particles with an opposite sign of charge would be pulled in by the extra electromagnetic force, while particles with the same sign of charge would be repelled, neutralizing the black hole. This effect may not be as strong if the black hole is also spinning. The presence of charge can reduce the diameter of the black hole by up to 38%. The charge Q for a nonspinning black hole is bounded by Q ≤ G M , {\displaystyle Q\leq {\sqrt {G}}M,} where G is the gravitational constant and M is the black hole's mass. Classification Black holes can have a wide range of masses. The minimum mass of a black hole formed by stellar gravitational collapse is governed by the maximum mass of a neutron star and is believed to be approximately two-to-four solar masses. However, theoretical primordial black holes, believed to have formed soon after the Big Bang, could be far smaller, with masses as little as 10−5 grams at formation. These very small black holes are sometimes called micro black holes. Black holes formed by stellar collapse are called stellar black holes. Estimates of their maximum mass at formation vary, but generally range from 10 to 100 solar masses, with higher estimates for black holes progenated by low-metallicity stars. The mass of a black hole formed via a supernova has a lower bound: If the progenitor star is too small, the collapse may be stopped by the degeneracy pressure of the star's constituents, allowing the condensation of matter into an exotic denser state. Degeneracy pressure occurs from the Pauli exclusion principle—Particles will resist being in the same place as each other. Smaller progenitor stars, with masses less than about 8 M☉, will be held together by the degeneracy pressure of electrons and will become a white dwarf. For more massive progenitor stars, electron degeneracy pressure is no longer strong enough to resist the force of gravity and the star will be held together by neutron degeneracy pressure, which can occur at much higher densities, forming a neutron star. If the star is still too massive, even neutron degeneracy pressure will not be able to resist the force of gravity and the star will collapse into a black hole.: 5.8 Stellar black holes can also gain mass via accretion of nearby matter, often from a companion object such as a star. Black holes that are larger than stellar black holes but smaller than supermassive black holes are called intermediate-mass black holes, with masses of approximately 102 to 105 solar masses. These black holes seem to be rarer than their stellar and supermassive counterparts, with relatively few candidates having been observed. Physicists have speculated that such black holes may form from collisions in globular and star clusters or at the center of low-mass galaxies. They may also form as the result of mergers of smaller black holes, with several LIGO observations finding merged black holes within the 110-350 solar mass range. The black holes with the largest masses are called supermassive black holes, with masses more than 106 times that of the Sun. These black holes are believed to exist at the centers of almost every large galaxy, including the Milky Way. Some scientists have proposed a subcategory of even larger black holes, called ultramassive black holes, with masses greater than 109-1010 solar masses. Theoretical models predict that the accretion disc that feeds black holes will be unstable once a black hole reaches 50-100 billion times the mass of the Sun, setting a rough upper limit to black hole mass. Structure While black holes are conceptually invisible sinks of all matter and light, in astronomical settings, their enormous gravity alters the motion of surrounding objects and pulls nearby gas inwards at near-light speed, making the area around black holes the brightest objects in the universe. Some black holes have relativistic jets—thin streams of plasma travelling away from the black hole at more than one-tenth of the speed of light. A small faction of the matter falling towards the black hole gets accelerated away along the hole rotation axis. These jets can extend as far as millions of parsecs from the black hole itself. Black holes of any mass can have jets. However, they are typically observed around spinning black holes with strongly-magnetized accretion disks. Relativistic jets were more common in the early universe, when galaxies and their corresponding supermassive black holes were rapidly gaining mass. All black holes with jets also have an accretion disk, but the jets are usually brighter than the disk. Quasars, typically found in other galaxies, are believed to be supermassive black holes with jets; microquasars are believed to be stellar-mass objects with jets, typically observed in the Milky Way. The mechanism of formation of jets is not yet known, but several options have been proposed. One method proposed to fuel these jets is the Blandford-Znajek process, which suggests that the dragging of magnetic field lines by a black hole's rotation could launch jets of matter into space. The Penrose process, which involves extraction of a black hole's rotational energy, has also been proposed as a potential mechanism of jet propulsion. Due to conservation of angular momentum, gas falling into the gravitational well created by a massive object will typically form a disk-like structure around the object.: 242 As the disk's angular momentum is transferred outward due to internal processes, its matter falls farther inward, converting its gravitational energy into heat and releasing a large flux of x-rays. The temperature of these disks can range from thousands to millions of Kelvin, and temperatures can differ throughout a single accretion disk. Accretion disks can also emit in other parts of the electromagnetic spectrum, depending on the disk's turbulence and magnetization and the black hole's mass and angular momentum. Accretion disks can be defined as geometrically thin or geometrically thick. Geometrically thin disks are mostly confined to the black hole's equatorial plane and have a well-defined edge at the innermost stable circular orbit (ISCO), while geometrically thick disks are supported by internal pressure and temperature and can extend inside the ISCO. Disks with high rates of electron scattering and absorption, appearing bright and opaque, are called optically thick; optically thin disks are more translucent and produce fainter images when viewed from afar. Accretion disks of black holes accreting beyond the Eddington limit are often referred to as polish donuts due to their thick, toroidal shape that resembles that of a donut. Quasar accretion disks are expected to usually appear blue in color. The disk for a stellar black hole, on the other hand, would likely look orange, yellow, or red, with its inner regions being the brightest. Theoretical research suggests that the hotter a disk is, the bluer it should be, although this is not always supported by observations of real astronomical objects. Accretion disk colors may also be altered by the Doppler effect, with the part of the disk travelling towards an observer appearing bluer and brighter and the part of the disk travelling away from the observer appearing redder and dimmer. In Newtonian gravity, test particles can stably orbit at arbitrary distances from a central object. In general relativity, however, there exists a smallest possible radius for which a massive particle can orbit stably. Any infinitesimal inward perturbations to this orbit will lead to the particle spiraling into the black hole, and any outward perturbations will, depending on the energy, cause the particle to spiral in, move to a stable orbit further from the black hole, or escape to infinity. This orbit is called the innermost stable circular orbit, or ISCO. The location of the ISCO depends on the spin of the black hole and the spin of the particle itself. In the case of a Schwarzschild black hole (spin zero) and a particle without spin, the location of the ISCO is: r I S C O = 3 r s = 6 G M c 2 , {\displaystyle r_{\rm {ISCO}}=3\,r_{\text{s}}={\frac {6\,GM}{c^{2}}},} where r I S C O {\displaystyle r_{\rm {_{ISCO}}}} is the radius of the ISCO, r s {\displaystyle r_{\text{s}}} is the Schwarzschild radius of the black hole, G {\displaystyle G} is the gravitational constant, and c {\displaystyle c} is the speed of light. The radius of this orbit changes slightly based on particle spin. For charged black holes, the ISCO moves inwards. For spinning black holes, the ISCO is moved inwards for particles orbiting in the same direction that the black hole is spinning (prograde) and outwards for particles orbiting in the opposite direction (retrograde). For example, the ISCO for a particle orbiting retrograde can be as far out as about 9 r s {\displaystyle 9r_{\text{s}}} , while the ISCO for a particle orbiting prograde can be as close as at the event horizon itself. The photon sphere is a spherical boundary for which photons moving on tangents to that sphere are bent completely around the black hole, possibly orbiting multiple times. Light rays with impact parameters less than the radius of the photon sphere enter the black hole. For Schwarzschild black holes, the photon sphere has a radius 1.5 times the Schwarzschild radius; the radius for non-Schwarzschild black holes is at least 1.5 times the radius of the event horizon. When viewed from a great distance, the photon sphere creates an observable black hole shadow. Since no light emerges from within the black hole, this shadow is the limit for possible observations.: 152 The shadow of colliding black holes should have characteristic warped shapes, allowing scientists to detect black holes that are about to merge. While light can still escape from the photon sphere, any light that crosses the photon sphere on an inbound trajectory will be captured by the black hole. Therefore, any light that reaches an outside observer from the photon sphere must have been emitted by objects between the photon sphere and the event horizon. Light emitted towards the photon sphere may also curve around the black hole and return to the emitter. For a rotating, uncharged black hole, the radius of the photon sphere depends on the spin parameter and whether the photon is orbiting prograde or retrograde. For a photon orbiting prograde, the photon sphere will be 1-3 Schwarzschild radii from the center of the black hole, while for a photon orbiting retrograde, the photon sphere will be between 3-5 Schwarzschild radii from the center of the black hole. The exact location of the photon sphere depends on the magnitude of the black hole's rotation. For a charged, nonrotating black hole, there will only be one photon sphere, and the radius of the photon sphere will decrease for increasing black hole charge. For non-extremal, charged, rotating black holes, there will always be two photon spheres, with the exact radii depending on the parameters of the black hole. Near a rotating black hole, spacetime rotates similar to a vortex. The rotating spacetime will drag any matter and light into rotation around the spinning black hole. This effect of general relativity, called frame dragging, gets stronger closer to the spinning mass. The region of spacetime in which it is impossible to stay still is called the ergosphere. The ergosphere of a black hole is a volume bounded by the black hole's event horizon and the ergosurface, which coincides with the event horizon at the poles but bulges out from it around the equator. Matter and radiation can escape from the ergosphere. Through the Penrose process, objects can emerge from the ergosphere with more energy than they entered with. The extra energy is taken from the rotational energy of the black hole, slowing down the rotation of the black hole.: 268 A variation of the Penrose process in the presence of strong magnetic fields, the Blandford–Znajek process, is considered a likely mechanism for the enormous luminosity and relativistic jets of quasars and other active galactic nuclei. The observable region of spacetime around a black hole closest to its event horizon is called the plunging region. In this area it is no longer possible for free falling matter to follow circular orbits or stop a final descent into the black hole. Instead, it will rapidly plunge toward the black hole at close to the speed of light, growing increasingly hot and producing a characteristic, detectable thermal emission. However, light and radiation emitted from this region can still escape from the black hole's gravitational pull. For a nonspinning, uncharged black hole, the radius of the event horizon, or Schwarzschild radius, is proportional to the mass, M, through r s = 2 G M c 2 ≈ 2.95 M M ⊙ k m , {\displaystyle r_{\mathrm {s} }={\frac {2GM}{c^{2}}}\approx 2.95\,{\frac {M}{M_{\odot }}}~\mathrm {km,} } where rs is the Schwarzschild radius and M☉ is the mass of the Sun.: 124 For a black hole with nonzero spin or electric charge, the radius is smaller,[Note 1] until an extremal black hole could have an event horizon close to r + = G M c 2 , {\displaystyle r_{\mathrm {+} }={\frac {GM}{c^{2}}},} half the radius of a nonspinning, uncharged black hole of the same mass. Since the volume within the Schwarzschild radius increase with the cube of the radius, average density of a black hole inside its Schwarzschild radius is inversely proportional to the square of its mass: supermassive black holes are much less dense than stellar black holes. The average density of a 108 M☉ black hole is comparable to that of water. The defining feature of a black hole is the existence of an event horizon, a boundary in spacetime through which matter and light can pass only inward towards the center of the black hole. Nothing, not even light, can escape from inside the event horizon. The event horizon is referred to as such because if an event occurs within the boundary, information from that event cannot reach or affect an outside observer, making it impossible to determine whether such an event occurred.: 179 For non-rotating black holes, the geometry of the event horizon is precisely spherical, while for rotating black holes, the event horizon is oblate. To a distant observer, a clock near a black hole would appear to tick more slowly than one further from the black hole.: 217 This effect, known as gravitational time dilation, would also cause an object falling into a black hole to appear to slow as it approached the event horizon, never quite reaching the horizon from the perspective of an outside observer.: 218 All processes on this object would appear to slow down, and any light emitted by the object to appear redder and dimmer, an effect known as gravitational redshift. An object falling from half of a Schwarzschild radius above the event horizon would fade away until it could no longer be seen, disappearing from view within one hundredth of a second. It would also appear to flatten onto the black hole, joining all other material that had ever fallen into the hole. On the other hand, an observer falling into a black hole would not notice any of these effects as they cross the event horizon. Their own clocks appear to them to tick normally, and they cross the event horizon after a finite time without noting any singular behaviour. In general relativity, it is impossible to determine the location of the event horizon from local observations, due to Einstein's equivalence principle.: 222 Black holes that are rotating and/or charged have an inner horizon, often called the Cauchy horizon, inside of the black hole. The inner horizon is divided up into two segments: an ingoing section and an outgoing section. At the ingoing section of the Cauchy horizon, radiation and matter that fall into the black hole would build up at the horizon, causing the curvature of spacetime to go to infinity. This would cause an observer falling in to experience tidal forces. This phenomenon is often called mass inflation, since it is associated with a parameter dictating the black hole's internal mass growing exponentially, and the buildup of tidal forces is called the mass-inflation singularity or Cauchy horizon singularity. Some physicists have argued that in realistic black holes, accretion and Hawking radiation would stop mass inflation from occurring. At the outgoing section of the inner horizon, infalling radiation would backscatter off of the black hole's spacetime curvature and travel outward, building up at the outgoing Cauchy horizon. This would cause an infalling observer to experience a gravitational shock wave and tidal forces as the spacetime curvature at the horizon grew to infinity. This buildup of tidal forces is called the shock singularity. Both of these singularities are weak, meaning that an object crossing them would only be deformed a finite amount by tidal forces, even though the spacetime curvature would still be infinite at the singularity. This is as opposed to a strong singularity, where an object hitting the singularity would be stretched and squeezed by an infinite amount. They are also null singularities, meaning that a photon could travel parallel to the them without ever being intercepted. Ignoring quantum effects, every black hole has a singularity inside, points where the curvature of spacetime becomes infinite, and geodesics terminate within a finite proper time.: 205 For a non-rotating black hole, this region takes the shape of a single point; for a rotating black hole it is smeared out to form a ring singularity that lies in the plane of rotation.: 264 In both cases, the singular region has zero volume. All of the mass of the black hole ends up in the singularity.: 252 Since the singularity has nonzero mass in an infinitely small space, it can be thought of as having infinite density. Observers falling into a Schwarzschild black hole (i.e., non-rotating and not charged) cannot avoid being carried into the singularity once they cross the event horizon. As they fall further into the black hole, they will be torn apart by the growing tidal forces in a process sometimes referred to as spaghettification or the noodle effect. Eventually, they will reach the singularity and be crushed into an infinitely small point.: 182 However any perturbations, such as those caused by matter or radiation falling in, would cause space to oscillate chaotically near the singularity. Any matter falling in would experience intense tidal forces rapidly changing in direction, all while being compressed into an increasingly small volume. Alternative forms of general relativity, including addition of some quatum effects, can lead to regular, or nonsingular, black holes without singularities. For example, the fuzzball model, based on string theory, states that black holes are actually made up of quantum microstates and need not have a singularity or an event horizon. The theory of loop quantum gravity proposes that the curvature and density at the center of a black hole is large, but not infinite. Formation Black holes are formed by gravitational collapse of massive stars, either by direct collapse or during a supernova explosion in a process called fallback. Black holes can result from the merger of two neutron stars or a neutron star and a black hole. Other more speculative mechanisms include primordial black holes created from density fluctuations in the early universe, the collapse of dark stars, a hypothetical object powered by annihilation of dark matter, or from hypothetical self-interacting dark matter. Gravitational collapse occurs when an object's internal pressure is insufficient to resist the object's own gravity. At the end of a star's life, it will run out of hydrogen to fuse, and will start fusing more and more massive elements, until it gets to iron. Since the fusion of elements heavier than iron would require more energy than it would release, nuclear fusion ceases. If the iron core of the star is too massive, the star will no longer be able to support itself and will undergo gravitational collapse. While most of the energy released during gravitational collapse is emitted very quickly, an outside observer does not actually see the end of this process. Even though the collapse takes a finite amount of time from the reference frame of infalling matter, a distant observer would see the infalling material slow and halt just above the event horizon, due to gravitational time dilation. Light from the collapsing material takes longer and longer to reach the observer, with the delay growing to infinity as the emitting material reaches the event horizon. Thus the external observer never sees the formation of the event horizon; instead, the collapsing material seems to become dimmer and increasingly red-shifted, eventually fading away. Observations of quasars at redshift z ∼ 7 {\displaystyle z\sim 7} , less than a billion years after the Big Bang, has led to investigations of other ways to form black holes. The accretion process to build supermassive black holes has a limiting rate of mass accumulation and a billion years is not enough time to reach quasar status. One suggestion is direct collapse of nearly pure hydrogen gas (low metalicity) clouds characteristic of the young universe, forming a supermassive star which collapses into a black hole. It has been suggested that seed black holes with typical masses of ~105 M☉ could have formed in this way which then could grow to ~109 M☉. However, the very large amount of gas required for direct collapse is not typically stable to fragmentation to form multiple stars. Thus another approach suggests massive star formation followed by collisions that seed massive black holes which ultimately merge to create a quasar.: 85 A neutron star in a common envelope with a regular star can accrete sufficient material to collapse to a black hole or two neutron stars can merge. These avenues for the formation of black holes are considered relatively rare. In the current epoch of the universe, conditions needed to form black holes are rare and are mostly only found in stars. However, in the early universe, conditions may have allowed for black hole formations via other means. Fluctuations of spacetime soon after the Big Bang may have formed areas that were denser then their surroundings. Initially, these regions would not have been compact enough to form a black hole, but eventually, the curvature of spacetime in the regions become large enough to cause them to collapse into a black hole. Different models for the early universe vary widely in their predictions of the scale of these fluctuations. Various models predict the creation of primordial black holes ranging from a Planck mass (~2.2×10−8 kg) to hundreds of thousands of solar masses. Primordial black holes with masses less than 1015 g would have evaporated by now due to Hawking radiation. Despite the early universe being extremely dense, it did not re-collapse into a black hole during the Big Bang, since the universe was expanding rapidly and did not have the gravitational differential necessary for black hole formation. Models for the gravitational collapse of objects of relatively constant size, such as stars, do not necessarily apply in the same way to rapidly expanding space such as the Big Bang. In principle, black holes could be formed in high-energy particle collisions that achieve sufficient density, although no such events have been detected. These hypothetical micro black holes, which could form from the collision of cosmic rays and Earth's atmosphere or in particle accelerators like the Large Hadron Collider, would not be able to aggregate additional mass. Instead, they would evaporate in about 10−25 seconds, posing no threat to the Earth. Evolution Black holes can also merge with other objects such as stars or even other black holes. This is thought to have been important, especially in the early growth of supermassive black holes, which could have formed from the aggregation of many smaller objects. The process has also been proposed as the origin of some intermediate-mass black holes. Mergers of supermassive black holes may take a long time: As a binary of supermassive black holes approach each other, most nearby stars are ejected, leaving little for the remaining black holes to gravitationally interact with that would allow them to get closer to each other. This phenomenon has been called the final parsec problem, as the distance at which this happens is usually around one parsec. When a black hole accretes matter, the gas in the inner accretion disk orbits at very high speeds because of its proximity to the black hole. The resulting friction heats the inner disk to temperatures at which it emits vast amounts of electromagnetic radiation (mainly X-rays) detectable by telescopes. By the time the matter of the disk reaches the ISCO, between 5.7% and 42% of its mass will have been converted to energy, depending on the black hole's spin. About 90% of this energy is released within about 20 black hole radii. In many cases, accretion disks are accompanied by relativistic jets that are emitted along the black hole's poles, which carry away much of the energy. The mechanism for the creation of these jets is currently not well understood, in part due to insufficient data. Many of the universe's most energetic phenomena have been attributed to the accretion of matter on black holes. Active galactic nuclei and quasars are believed to be the accretion disks of supermassive black holes. X-ray binaries are generally accepted to be binary systems in which one of the two objects is a compact object accreting matter from its companion. Ultraluminous X-ray sources may be the accretion disks of intermediate-mass black holes. At a certain rate of accretion, the outward radiation pressure will become as strong as the inward gravitational force, and the black hole should unable to accrete any faster. This limit is called the Eddington limit. However, many black holes accrete beyond this rate due to their non-spherical geometry or instabilities in the accretion disk. Accretion beyond the limit is called Super-Eddington accretion and may have been commonplace in the early universe. Stars have been observed to get torn apart by tidal forces in the immediate vicinity of supermassive black holes in galaxy nuclei, in what is known as a tidal disruption event (TDE). Some of the material from the disrupted star forms an accretion disk around the black hole, which emits observable electromagnetic radiation. The correlation between the masses of supermassive black holes in the centres of galaxies with the velocity dispersion and mass of stars in their host bulges suggests that the formation of galaxies and the formation of their central black holes are related. Black hole winds from rapid accretion, particularly when the galaxy itself is still accreting matter, can compress gas nearby, accelerating star formation. However, if the winds become too strong, the black hole may blow nearly all of the gas out of the galaxy, quenching star formation. Black hole jets may also energize nearby cavities of plasma and eject low-entropy gas from out of the galactic core, causing gas in galactic centers to be hotter than expected. If Hawking's theory of black hole radiation is correct, then black holes are expected to shrink and evaporate over time as they lose mass by the emission of photons and other particles. The temperature of this thermal spectrum (Hawking temperature) is proportional to the surface gravity of the black hole, which is inversely proportional to the mass. Hence, large black holes emit less radiation than small black holes.: Ch. 9.6 A stellar black hole of 1 M☉ has a Hawking temperature of 62 nanokelvins. This is far less than the 2.7 K temperature of the cosmic microwave background radiation. Stellar-mass or larger black holes receive more mass from the cosmic microwave background than they emit through Hawking radiation and thus will grow instead of shrinking. To have a Hawking temperature larger than 2.7 K (and be able to evaporate), a black hole would need a mass less than the Moon. Such a black hole would have a diameter of less than a tenth of a millimetre. The Hawking radiation for an astrophysical black hole is predicted to be very weak and would thus be exceedingly difficult to detect from Earth. A possible exception is the burst of gamma rays emitted in the last stage of the evaporation of primordial black holes. Searches for such flashes have proven unsuccessful and provide stringent limits on the possibility of existence of low mass primordial black holes, with modern research predicting that primordial black holes must make up less than a fraction of 10−7 of the universe's total mass. NASA's Fermi Gamma-ray Space Telescope, launched in 2008, has searched for these flashes, but has not yet found any. The properties of a black hole are constrained and interrelated by the theories that predict these properties. When based on general relativity, these relationships are called the laws of black hole mechanics. For a black hole that is not still forming or accreting matter, the zeroth law of black hole mechanics states the black hole's surface gravity is constant across the event horizon. The first law relates changes in the black hole's surface area, angular momentum, and charge to changes in its energy. The second law says the surface area of a black hole never decreases on its own. Finally, the third law says that the surface gravity of a black hole is never zero. These laws are mathematical analogs of the laws of thermodynamics. They are not equivalent, however, because, according to general relativity without quantum mechanics, a black hole can never emit radiation, and thus its temperature must always be zero.: 11 Quantum mechanics predicts that a black hole will continuously emit thermal Hawking radiation, and therefore must always have a nonzero temperature. It also predicts that all black holes have entropy which scales with their surface area. When quantum mechanics is accounted for, the laws of black hole mechanics become equivalent to the classical laws of thermodynamics. However, these conclusions are derived without a complete theory of quantum gravity, although many potential theories do predict black holes having entropy and temperature. Thus, the true quantum nature of black hole thermodynamics continues to be debated.: 29 Observational evidence Millions of black holes with around 30 solar masses derived from stellar collapse are expected to exist in the Milky Way. Even a dwarf galaxy like Draco should have hundreds. Only a few of these have been detected. By nature, black holes do not themselves emit any electromagnetic radiation other than the hypothetical Hawking radiation, so astrophysicists searching for black holes must generally rely on indirect observations. The defining characteristic of a black hole is its event horizon. The horizon itself cannot be imaged, so all other possible explanations for these indirect observations must be considered and eliminated before concluding that a black hole has been observed.: 11 The Event Horizon Telescope (EHT) is a global system of radio telescopes capable of directly observing a black hole shadow. The angular resolution of a telescope is based on its aperture and the wavelengths it is observing. Because the angular diameters of Sagittarius A* and Messier 87* in the sky are very small, a single telescope would need to be about the size of the Earth to clearly distinguish their horizons using radio wavelengths. By combining data from several different radio telescopes around the world, the Event Horizon Telescope creates an effective aperture the diameter size of the Earth. The EHT team used imaging algorithms to compute the most probable image from the data in its observations of Sagittarius A* and M87*. Gravitational-wave interferometry can be used to detect merging black holes and other compact objects. In this method, a laser beam is split down two long arms of a tunnel. The laser beams reflect off of mirrors in the tunnels and converge at the intersection of the arms, cancelling each other out. However, when a gravitational wave passes, it warps spacetime, changing the lengths of the arms themselves. Since each laser beam is now travelling a slightly different distance, they do not cancel out and produce a recognizable signal. Analysis of the signal can give scientists information about what caused the gravitational waves. Since gravitational waves are very weak, gravitational-wave observatories such as LIGO must have arms several kilometers long and carefully control for noise from Earth to be able to detect these gravitational waves. Since the first measurements in 2016, multiple gravitational waves from black holes have been detected and analyzed. The proper motions of stars near the centre of the Milky Way provide strong observational evidence that these stars are orbiting a supermassive black hole. Since 1995, astronomers have tracked the motions of 90 stars orbiting an invisible object coincident with the radio source Sagittarius A*. In 1998, by fitting the motions of the stars to Keplerian orbits, the astronomers were able to infer that Sagittarius A* must be a 2.6×106 M☉ object must be contained within a radius of 0.02 light-years. Since then, one of the stars—called S2—has completed a full orbit. From the orbital data, astronomers were able to refine the calculations of the mass of Sagittarius A* to 4.3×106 M☉, with a radius of less than 0.002 light-years. This upper limit radius is larger than the Schwarzschild radius for the estimated mass, so the combination does not prove Sagittarius A* is a black hole. Nevertheless, these observations strongly suggest that the central object is a supermassive black hole as there are no other plausible scenarios for confining so much invisible mass into such a small volume. Additionally, there is some observational evidence that this object might possess an event horizon, a feature unique to black holes. The Event Horizon Telescope image of Sagittarius A*, released in 2022, provided further confirmation that it is indeed a black hole. X-ray binaries are binary systems that emit a majority of their radiation in the X-ray part of the electromagnetic spectrum. These X-ray emissions result when a compact object accretes matter from an ordinary star. The presence of an ordinary star in such a system provides an opportunity for studying the central object and to determine if it might be a black hole. By measuring the orbital period of the binary, the distance to the binary from Earth, and the mass of the companion star, scientists can estimate the mass of the compact object. The Tolman-Oppenheimer-Volkoff limit (TOV limit) dictates the largest mass a nonrotating neutron star can be, and is estimated to be about two solar masses. While a rotating neutron star can be slightly more massive, if the compact object is much more massive than the TOV limit, it cannot be a neutron star and is generally expected to be a black hole. The first strong candidate for a black hole, Cygnus X-1, was discovered in this way by Charles Thomas Bolton, Louise Webster, and Paul Murdin in 1972. Observations of rotation broadening of the optical star reported in 1986 lead to a compact object mass estimate of 16 solar masses, with 7 solar masses as the lower bound. In 2011, this estimate was updated to 14.1±1.0 M☉ for the black hole and 19.2±1.9 M☉ for the optical stellar companion. X-ray binaries can be categorized as either low-mass or high-mass; This classification is based on the mass of the companion star, not the compact object itself. In a class of X-ray binaries called soft X-ray transients, the companion star is of relatively low mass, allowing for more accurate estimates of the black hole mass. These systems actively emit X-rays for only several months once every 10–50 years. During the period of low X-ray emission, called quiescence, the accretion disk is extremely faint, allowing detailed observation of the companion star. Numerous black hole candidates have been measured by this method. Black holes are also sometimes found in binaries with other compact objects, such as white dwarfs, neutron stars, and other black holes. The centre of nearly every galaxy contains a supermassive black hole. The close observational correlation between the mass of this hole and the velocity dispersion of the host galaxy's bulge, known as the M–sigma relation, strongly suggests a connection between the formation of the black hole and that of the galaxy itself. Astronomers use the term active galaxy to describe galaxies with unusual characteristics, such as unusual spectral line emission and very strong radio emission. Theoretical and observational studies have shown that the high levels of activity in the centers of these galaxies, regions called active galactic nuclei (AGN), may be explained by accretion onto supermassive black holes. These AGN consist of a central black hole that may be millions or billions of times more massive than the Sun, a disk of interstellar gas and dust called an accretion disk, and two jets perpendicular to the accretion disk. Although supermassive black holes are expected to be found in most AGN, only some galaxies' nuclei have been more carefully studied in attempts to both identify and measure the actual masses of the central supermassive black hole candidates. Some of the most notable galaxies with supermassive black hole candidates include the Andromeda Galaxy, Messier 32, Messier 87, the Sombrero Galaxy, and the Milky Way itself. Another way black holes can be detected is through observation of effects caused by their strong gravitational field. One such effect is gravitational lensing: The deformation of spacetime around a massive object causes light rays to be deflected, making objects behind them appear distorted. When the lensing object is a black hole, this effect can be strong enough to create multiple images of a star or other luminous source. However, the distance between the lensed images may be too small for contemporary telescopes to resolve—this phenomenon is called microlensing. Instead of seeing two images of a lensed star, astronomers see the star brighten slightly as the black hole moves towards the line of sight between the star and Earth and then return to its normal luminosity as the black hole moves away. The turn of the millennium saw the first 3 candidate detections of black holes in this way, and in January 2022, astronomers reported the first confirmed detection of a microlensing event from an isolated black hole. This was also the first determination of an isolated black hole mass, 7.1±1.3 M☉. Alternatives While there is a strong case for supermassive black holes, the model for stellar-mass black holes assumes of an upper limit for the mass of a neutron star: objects observed to have more mass are assumed to be black holes. However, the properties of extremely dense matter are poorly understood. New exotic phases of matter could allow other kinds of massive objects. Quark stars would be made up of quark matter and supported by quark degeneracy pressure, a form of degeneracy pressure even stronger than neutron degeneracy pressure. This would halt gravitational collapse at a higher mass than for a neutron star. Even stronger stars called electroweak stars would convert quarks in their cores into leptons, providing additional pressure to stop the star from collapsing. If, as some extensions of the Standard Model posit, quarks and leptons are made up of the even-smaller fundamental particles called preons, a very compact star could be supported by preon degeneracy pressure. While none of these hypothetical models can explain all of the observations of stellar black hole candidates, a Q star is the only alternative which could significantly exceed the mass limit for neutron stars and thus provide an alternative for supermassive black holes.: 12 A few theoretical objects have been conjectured to match observations of astronomical black hole candidates identically or near-identically, but which function via a different mechanism. A dark energy star would convert infalling matter into vacuum energy; This vacuum energy would be much larger than the vacuum energy of outside space, exerting outwards pressure and preventing a singularity from forming. A black star would be gravitationally collapsing slowly enough that quantum effects would keep it just on the cusp of fully collapsing into a black hole. A gravastar would consist of a very thin shell and a dark-energy interior providing outward pressure to stop the collapse into a black hole or formation of a singularity; It could even have another gravastar inside, called a 'nestar'. Open questions According to the no-hair theorem, a black hole is defined by only three parameters: its mass, charge, and angular momentum. This seems to mean that all other information about the matter that went into forming the black hole is lost, as there is no way to determine anything about the black hole from outside other than those three parameters. When black holes were thought to persist forever, this information loss was not problematic, as the information can be thought of as existing inside the black hole. However, black holes slowly evaporate by emitting Hawking radiation. This radiation does not appear to carry any additional information about the matter that formed the black hole, meaning that this information is seemingly gone forever. This is called the black hole information paradox. Theoretical studies analyzing the paradox have led to both further paradoxes and new ideas about the intersection of quantum mechanics and general relativity. While there is no consensus on the resolution of the paradox, work on the problem is expected to be important for a theory of quantum gravity.: 126 Observations of faraway galaxies have found that ultraluminous quasars, powered by supermassive black holes, existed in the early universe as far as redshift z ≥ 7 {\displaystyle z\geq 7} . These black holes have been assumed to be the products of the gravitational collapse of large population III stars. However, these stellar remnants were not massive enough to produce the quasars observed at early times without accreting beyond the Eddington limit, the theoretical maximum rate of black hole accretion. Physicists have suggested a variety of different mechanisms by which these supermassive black holes may have formed. It has been proposed that smaller black holes may have also undergone mergers to produce the observed supermassive black holes. It is also possible that they were seeded by direct-collapse black holes, in which a large cloud of hot gas avoids fragmentation that would lead to multiple stars, due to low angular momentum or heating from a nearby galaxy. Given the right circumstances, a single supermassive star forms and collapses directly into a black hole without undergoing typical stellar evolution. Additionally, these supermassive black holes in the early universe may be high-mass primordial black holes, which could have accreted further matter in the centers of galaxies. Finally, certain mechanisms allow black holes to grow faster than the theoretical Eddington limit, such as dense gas in the accretion disk limiting outward radiation pressure that prevents the black hole from accreting. However, the formation of bipolar jets prevent super-Eddington rates. In fiction Black holes have been portrayed in science fiction in a variety of ways. Even before the advent of the term itself, objects with characteristics of black holes appeared in stories such as the 1928 novel The Skylark of Space with its "black Sun" and the "hole in space" in the 1935 short story Starship Invincible. As black holes grew to public recognition in the 1960s and 1970s, they began to be featured in films as well as novels, such as Disney's The Black Hole. Black holes have also been used in works of the 21st century, such as Christopher Nolan's science fiction epic Interstellar. Authors and screenwriters have exploited the relativistic effects of black holes, particularly gravitational time dilation. For example, Interstellar features a black hole planet with a time dilation factor of over 60,000:1, while the 1977 novel Gateway depicts a spaceship approaching but never crossing the event horizon of a black hole from the perspective of an outside observer due to time dilation effects. Black holes have also been appropriated as wormholes or other methods of faster-than-light travel, such as in the 1974 novel The Forever War, where a network of black holes is used for interstellar travel. Additionally, black holes can feature as hazards to spacefarers and planets: A black hole threatens a deep-space outpost in 1978 short story The Black Hole Passes, and a binary black hole dangerously alters the orbit of a planet in the 2018 Netflix reboot of Lost in Space. Notes References Further reading External links |
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