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Brandon Carter
Brandon Carter, (born 1942) is an Australian theoretical physics, theoretical physicist who explores the properties of black holes, and was the first to name and employ the anthropic principle in its contemporary form. He is a researcher at the Meudon campus of the Laboratoire Univers et Théories, part of the French CNRS. Biography Carter studied at the University of Cambridge under Dennis William Sciama, Dennis Sciama. He found the exact solution of the geodesic equations for the Kerr–Newman metric, Kerr/Newman electrovacuum solution, and the Analytic continuation, maximal analytic extension of this solution. In the process, he discovered the extraordinary Carter constant, ''fourth constant of motion'' and the Killing–Yano tensor. Together with Werner Israel and Stephen Hawking, he proved partially the no-hair theorem in general relativity, stating that all stationary black holes are completely characterized by mass, charge (physics), charge, and angular momentum. In 19 ... [...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] |
Werner Israel
Werner Israel, (October 4, 1931 – May 18, 2022) was a theoretical physicist known for his contributions to gravitational theory, and especially to the understanding of black holes. Biography Israel was born in Berlin, Germany in 1931. His family fled Nazi Germany in 1936 and settled in Cape Town, South Africa, where he was raised. He was interested in astronomy and cosmology from a young age. For four years, when his parents were seriously ill, Israel and his brother lived in an orphanage. Israel received his B.Sc. and M.Sc. from the University of Cape Town, and his Ph.D. from Trinity College, Dublin, under the direction of John Synge. In 1958, Israel accepted a faculty position at the University of Alberta in Edmonton, where he remained as professor until his retirement in 1996. Following his retirement, Israel was Adjunct Professor of Physics and Astronomy at the University of Victoria in Victoria, British Columbia. He remained active in research ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
21st-century Australian Physicists
File:1st century collage.png, From top left, clockwise: Jesus is crucified by Roman authorities in Judaea (17th century painting). Four different men ( Galba, Otho, Vitellius, and Vespasian) claim the title of Emperor within the span of a year; The Great Fire of Rome (18th-century painting) sees the destruction of two-thirds of the city, precipitating the empire's first persecution against Christians, who are blamed for the disaster; The Roman Colosseum is built and holds its inaugural games; Roman forces besiege Jerusalem during the First Jewish–Roman War (19th-century painting); The Trưng sisters lead a rebellion against the Chinese Han dynasty (anachronistic depiction); Boudica, queen of the British Iceni leads a rebellion against Rome (19th-century statue); Knife-shaped coin of the Xin dynasty., 335px rect 30 30 737 1077 Crucifixion of Jesus rect 767 30 1815 1077 Year of the Four Emperors rect 1846 30 3223 1077 Great Fire of Rome rect 30 1108 1106 2155 Boudic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1942 Births
The Uppsala Conflict Data Program project estimates this to be the deadliest year in human history in terms of conflict deaths, placing the death toll at 4.62 million. However, the Correlates of War estimates that the prior year, 1941, was the deadliest such year. Death toll estimates for both 1941 and 1942 range from 2.28 to 7.71 million each. Events Below, the events of World War II have the "WWII" prefix. January * January 1 – WWII: The Declaration by United Nations is signed by China, the United Kingdom, the United States, the Soviet Union, and 22 other nations, in which they agree "not to make any separate peace with the Axis powers". * January 5 – WWII: Two prisoners, British officer Airey Neave and Dutch officer Anthony Luteyn, escape from Colditz Castle in Germany. After travelling for three days, they reach the Swiss border. * January 7 – WWII: ** Battle of Slim River: Japanese forces of the 5th Division (Imperial Japanese Army), 5th Division, sup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Star
A neutron star is the gravitationally collapsed Stellar core, core of a massive supergiant star. It results from the supernova explosion of a stellar evolution#Massive star, massive star—combined with gravitational collapse—that compresses the core past white dwarf star density to that of Atomic nucleus, atomic nuclei. Surpassed only by black holes, neutron stars are the second smallest and densest known class of stellar objects. Neutron stars have a radius on the order of and a mass of about . Stars that collapse into neutron stars have a total mass of between 10 and 25 solar masses (), or possibly more for those that are especially rich in Metallicity, elements heavier than hydrogen and helium. Once formed, neutron stars no longer actively generate heat and cool over time, but they may still evolve further through Stellar collision, collisions or Accretion (astrophysics), accretion. Most of the basic models for these objects imply that they are composed almost entirely o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tidal Disruption Event
A tidal disruption event (TDE) is a time-domain astronomy, transient astronomical source produced when a star passes so close to a supermassive black hole (SMBH) that it is pulled apart by the black hole's tidal force. The star undergoes spaghettification, producing a tidal stream (astrophysics), tidal stream of material that loops around the black hole. Some portion of the stellar material is captured into orbit, forming an accretion disk around the black hole, which emits electromagnetic radiation. In a small fraction of TDEs, a relativistic jet is also produced. As the material in the disk is gradually consumed by the black hole, the TDE fades over several months or years. TDEs were predicted in the 1970s and first observed in the 1990s. Over a hundred have since been observed, with detections at optical, infrared, radio and X-ray wavelengths. Sometimes a star can survive the encounter with an SMBH, leaving a remnant; those events are termed partial TDEs. History TDEs were f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jean-Pierre Luminet
Jean-Pierre Luminet (born 3 June 1951) is a French astrophysicist, specializing in black holes and cosmology. He is an emeritus research director at the CNRS ( Centre national de la recherche scientifique). Luminet is a member of the Laboratoire d'Astrophysique de Marseille (LAM) and Laboratoire Univers et Théories (LUTH) of the Paris-Meudon Observatory, and is a visiting scientist at the Centre de Physique Théorique (CPT) in Marseilles. He is also a writer and poet. Luminet has been awarded several prizes on account of his work in pure science and science communication, including the Georges Lemaître Prize (1999) in recognition of his work in cosmology. In November 2021, he received the UNESCO Kalinga Prize for the Popularization of Science. He serves on the editorial board of ''Inference: The International Review of Science''. The asteroid 5523 Luminet, discovered in 1991 at Palomar Observatory, was named after him. Luminet has published fifteen science books, seven ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Momentum
Angular momentum (sometimes called moment of momentum or rotational momentum) is the rotational analog of Momentum, linear momentum. It is an important physical quantity because it is a Conservation law, conserved quantity – the total angular momentum of a closed system remains constant. Angular momentum has both a direction (geometry), direction and a magnitude, and both are conserved. Bicycle and motorcycle dynamics, Bicycles and motorcycles, flying discs, Rifling, rifled bullets, and gyroscopes owe their useful properties to conservation of angular momentum. Conservation of angular momentum is also why hurricanes form spirals and neutron stars have high rotational rates. In general, conservation limits the possible motion of a system, but it does not uniquely determine it. The three-dimensional angular momentum for a point particle is classically represented as a pseudovector , the cross product of the particle's position vector (relative to some origin) and its mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charge (physics)
In physics, a charge is any of many different quantities, such as the electric charge in electromagnetism or the color charge in quantum chromodynamics. Charges correspond to the time-invariant generators of a symmetry group, and specifically, to the generators that commute with the Hamiltonian. Charges are often denoted by Q, and so the invariance of the charge corresponds to the vanishing commutator ,H0, where H is the Hamiltonian. Thus, charges are associated with conserved quantum numbers; these are the eigenvalues of the generator Q. A "charge" can also refer to a point-shaped object with an electric charge and a position, such as in the method of image charges. Abstract definition Abstractly, a charge is any generator of a continuous symmetry of the physical system under study. When a physical system has a symmetry of some sort, Noether's theorem implies the existence of a conserved current. The thing that "flows" in the current is the "charge"; the charge is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass
Mass is an Intrinsic and extrinsic properties, intrinsic property of a physical body, body. It was traditionally believed to be related to the physical quantity, quantity of matter in a body, until the discovery of the atom and particle physics. It was found that different atoms and different elementary particle, elementary particles, theoretically with the same amount of matter, have nonetheless different masses. Mass in modern physics has multiple Mass in special relativity, definitions which are conceptually distinct, but physically equivalent. Mass can be experimentally defined as a measure (mathematics), measure of the body's inertia, meaning the resistance to acceleration (change of velocity) when a net force is applied. The object's mass also determines the Force, strength of its gravitational attraction to other bodies. The SI base unit of mass is the kilogram (kg). In physics, mass is Mass versus weight, not the same as weight, even though mass is often determined by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Hole
A black hole is a massive, compact astronomical object so dense that its gravity prevents anything from escaping, even light. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass will form a black hole. The boundary (topology), boundary of no escape is called the event horizon. A black hole has a great effect on the fate and circumstances of an object crossing it, but has no locally detectable features according to general relativity. 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 thermal radiation, the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is of the Orders of magnitude (temperature), 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
