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Oppenheimer–Snyder Model
In general relativity, the Oppenheimer–Snyder model is a solution to the Einstein field equations based on the Schwarzschild metric describing the collapse of an object of extreme mass into a black hole. It is named after physicists J. Robert Oppenheimer and Hartland Snyder, who published it in 1939. During the collapse of a star to a black hole the geometry on the outside of the sphere is the Schwarzschild geometry. However the geometry inside is, curiously enough, the same Robertson-Walker geometry as in the rest of the observable universe. History Albert Einstein, who had developed his theory of general relativity in 1915, initially denied the possibility of black holes, even though they were a genuine implication of the Schwarzschild metric, obtained by Karl Schwarzschild in 1916, the first known non-trivial exact solution to Einstein's field equations. In 1939, Einstein published "On a Stationary System with Spherical Symmetry Consisting of Many Gravitating Masses" in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Relativity
General relativity, also known as the general theory of relativity, and as Einstein's theory of gravity, is the differential geometry, geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics. General theory of relativity, relativity generalizes special relativity and refines Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time in physics, time, or four-dimensional spacetime. In particular, the ''curvature of spacetime'' is directly related to the energy and momentum of whatever is present, including matter and radiation. The relation is specified by the Einstein field equations, a system of second-order partial differential equations. Newton's law of universal gravitation, which describes gravity in classical mechanics, can be seen as a prediction of general relativity for the almost flat spacetime geometry around stationary mass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lev Landau
Lev Davidovich Landau (; 22 January 1908 – 1 April 1968) was a Soviet physicist who made fundamental contributions to many areas of theoretical physics. He was considered as one of the last scientists who were universally well-versed and made seminal contributions to all branches of physics. He is credited with laying the foundations of twentieth century condensed matter physics, and is also considered arguably the greatest Soviet theoretical physicist. His accomplishments include the independent co-discovery of the density matrix method in quantum mechanics (alongside John von Neumann), the quantum mechanical theory of diamagnetism, the theory of superfluidity, the theory of second-order phase transitions, invention of order parameter technique, the Ginzburg–Landau theory of superconductivity, the theory of Fermi liquids, the explanation of Landau damping in plasma physics, the Landau pole in quantum electrodynamics, the two-component theory of neutrinos, and Landau's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cygnus X-1
Cygnus X-1 (abbreviated Cyg X-1) is a galactic X-ray source in the constellation Cygnus and was the first such source widely accepted to be a black hole. It was discovered in 1964 during a rocket flight and is one of the strongest X-ray sources detectable from Earth, producing a peak X-ray flux density of (). It remains among the most studied astronomical objects in its class. The compact object is now estimated to have a mass about 21.2 times the mass of the Sun and has been shown to be too small to be any known kind of normal star or other likely object besides a black hole. If so, the radius of its event horizon has "as upper bound to the linear dimension of the source region" of occasional X-ray bursts lasting only for about 1 ms. Cygnus X-1 belongs to a high-mass X-ray binary system, located about 7,000 light-years away, that includes a blue supergiant variable star designated HDE 226868, which it orbits at about 0.2 AU, or 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulsar
A pulsar (''pulsating star, on the model of quasar'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its Poles of astronomical bodies#Magnetic poles, magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Earth (similar to the way a lighthouse can be seen only when the light is pointed in the direction of an observer), and is responsible for the pulsed appearance of emission. Neutron stars are very density, dense and have short, regular rotational Period (physics), periods. This produces a very precise interval between pulses that ranges from milliseconds to seconds for an individual pulsar. Pulsars are one of the candidates for the source of ultra-high-energy cosmic rays (see also centrifugal mechanism of acceleration). Pulsars’ highly regular pulses make them very useful tools for astronomers. For example, observations of a pulsar in a PSR B1913+16, binary neutron star system were use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Telescope
A radio telescope is a specialized antenna (radio), antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the radio frequency portion of the electromagnetic spectrum, just as optical telescopes are used to make observations in the visible light, visible portion of the spectrum in traditional optical astronomy. Unlike optical telescopes, radio telescopes can be used in the daytime as well as at night. Since astronomical radio sources such as planets, stars, nebulas and galaxy, galaxies are very far away, the radio waves coming from them are extremely weak, so radio telescopes require very large antennas to collect enough radio energy to study them, and extremely sensitive receiving equipment. Radio telescopes are typically large Parabolic antenna, parabolic ("dish") antennas similar to those employed in tracking and communicating with satellites an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lawrence Livermore National Laboratory
Lawrence Livermore National Laboratory (LLNL) is a Federally funded research and development centers, federally funded research and development center in Livermore, California, United States. Originally established in 1952, the laboratory now is sponsored by the United States Department of Energy and administered privately by Lawrence Livermore National Security, LLC. The lab was originally established as the University of California Radiation Laboratory, Livermore Branch in 1952 in response to the detonation of the Soviet Union's first atomic bomb during the Cold War. It later became autonomous in 1971 and was designated a national laboratory in 1981. Lawrence Livermore Lab is primarily funded by the United States Department of Energy, U.S. Department of Energy and it is managed Privately held company, privately and operated by Lawrence Livermore National Security, LLC (a Public-private partnerships in the United States, partnership of the University of California, Bechtel, BW ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stirling Colgate
Stirling Auchincloss Colgate (; November 14, 1925 – December 1, 2013) was an American nuclear physicist at the Los Alamos National Laboratory and a professor emeritus of physics at the New Mexico Institute of Mining and Technology from 1965 to 1974, of which he also served its president. A scion of the Colgate toothpaste family, he was America's premier diagnostics scientist on thermonuclear weapons during the early years at the Lawrence Livermore National Laboratory in California, and later in Los Alamos National Laboratory (LANL). While much of his involvement with physics is still highly classified, he made many contributions in the open literature including physics education and astrophysics, specifically studying plasma physics. Early life and education Colgate was born in New York City in 1925, to Henry Auchincloss and Jeanette Thurber (née Pruyn) Colgate. He attended Los Alamos Ranch School until 1942 when a military delegation along with input from Robert Oppenheime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward Teller
Edward Teller (; January 15, 1908 – September 9, 2003) was a Hungarian and American Theoretical physics, theoretical physicist and chemical engineer who is known colloquially as "the father of the hydrogen bomb" and one of the creators of the History of the Teller–Ulam design, Teller–Ulam design based on Stanisław Ulam's design. He had a volatile personality, and was "driven by his megaton ambitions, had a Messiah complex, messianic complex, and displayed autocratic behavior." A thermonuclear design he devised was an Alarm Clock model bomb with a yield of 1000 MT (1 GT of TNT) and he proposed delivering it by boat or submarine. It would be capable of incinerating a continent. Born in Austria-Hungary in 1908, Teller emigrated to the US in the 1930s, one of the many so-called The Martians (scientists), "Martians", a group of Hungarian scientist émigrés. He made numerous contributions to Nuclear physics, nuclear and molecular physics, spectroscopy, and Surface science, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freeman Dyson
Freeman John Dyson (15 December 1923 – 28 February 2020) was a British-American theoretical physics, theoretical physicist and mathematician known for his works in quantum field theory, astrophysics, random matrix, random matrices, mathematical formulation of quantum mechanics, condensed matter physics, nuclear physics, and nuclear engineering, engineering. He was professor emeritus in the Institute for Advanced Study in Princeton, New Jersey, Princeton and a member of the board of sponsors of the ''Bulletin of the Atomic Scientists''. Dyson originated several concepts that bear his name, such as Dyson's transform, a fundamental technique in additive number theory, which he developed as part of his proof of Mann's theorem; the Dyson tree, a hypothetical genetic engineering, genetically engineered plant capable of growing in a comet; the Dyson series, a Perturbation theory (quantum mechanics), perturbative series where each term is represented by Feynman diagrams; the Dys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kip Thorne
Kip Stephen Thorne (born June 1, 1940) is an American theoretical physicist and writer known for his contributions in gravitational physics and astrophysics. Along with Rainer Weiss and Barry C. Barish, he was awarded the 2017 Nobel Prize in Physics for his contributions to the LIGO detector and the observation of gravitational waves. A longtime friend and colleague of Stephen Hawking and Carl Sagan, he was the Richard P. Feynman Professor of Theoretical Physics at the California Institute of Technology (Caltech) until 2009 and speaks of the astrophysical implications of the general theory of relativity. He continues to do scientific research and scientific consulting, a notable example of which was for the Christopher Nolan film '' Interstellar''. Life and career Thorne was born on June 1, 1940, in Logan, Utah. His father, D. Wynne Thorne (1908–1979), was a professor of soil chemistry at Utah State University, and his mother, Alison (née Comish; 1914–2004), was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Business Insider
''Business Insider'' (stylized in all caps: BUSINESS INSIDER; known from 2021 to 2023 as INSIDER) is a New York City–based multinational financial and business news website founded in 2007. Since 2015, a majority stake in ''Business Insider''s parent company Insider Inc. has been owned by the international publishing house Axel Springer. It operates several international editions, including one in the United Kingdom. ''Insider'' publishes original reporting and aggregates material from other outlets. it maintained a liberal policy on the use of anonymous sources. It has also published native advertising and granted sponsors editorial control of its content. The outlet has been nominated for several awards, but has also been criticized for using factually incorrect clickbait headlines to attract viewership. In 2015, Axel Springer SE acquired 88 percent of the stake in Insider Inc. for $343 million (€306 million), implying a total valuation of $442 million. From ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tolman–Oppenheimer–Volkoff Limit
The Tolman–Oppenheimer–Volkoff limit (or TOV limit) is an upper bound to the mass of cold, non-rotating neutron stars, analogous to the Chandrasekhar limit for white dwarf stars. Stars more massive than the TOV limit collapse into a black hole. The original calculation in 1939, which neglected complications such as nuclear forces between neutrons, placed this limit at approximately 0.7 solar masses (). Later, more refined analyses have resulted in larger values. Theoretical work in 1996 placed the limit at approximately 1.5 to 3.0 , corresponding to an original stellar mass of 15 to 20 ; additional work in the same year gave a more precise range of 2.2 to 2.9 . Data from GW170817, the first gravitational wave observation attributed to merging neutron stars (thought to have collapsed into a black hole within a few seconds after merging) placed the limit in the range of 2.01 to 2.17 . In the case of a rigidly spinning neutron star, meaning that different levels in the interio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
