A black hole is a region of spacetime where gravity is so strong that nothing, including light and other electromagnetic waves, is capable of possessing enough energy to escape it. Einstein's theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The 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 it 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 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.
The weak and the strong cosmic censorship hypotheses are two mathematical conjectures about the structure of gravitational singularities arising in general relativity.
The holographic principle is a property of string theories and a supposed property of quantum gravity that states that the description of a volume of space can be thought of as encoded on a lower-dimensional boundary to the region — such as a light-like boundary like a gravitational horizon. First proposed by Gerard 't Hooft, it was given a precise string theoretic interpretation by Leonard Susskind, who combined his ideas with previous ones of 't Hooft and Charles Thorn. Leonard Susskind said, "The three-dimensional world of ordinary experience––the universe filled with galaxies, stars, planets, houses, boulders, and people––is a hologram, an image of reality coded on a distant two-dimensional surface." As pointed out by Raphael Bousso, Thorn observed in 1978 that string theory admits a lower-dimensional description in which gravity emerges from it in what would now be called a holographic way. The prime example of holography is the AdS/CFT correspondence.
A Brief History of Time: From the Big Bang to Black Holes is a book on theoretical cosmology by English physicist Stephen Hawking. It was first published in 1988. Hawking wrote the book for readers who had no prior knowledge of physics.
Hawking radiation is the theoretical thermal black-body radiation released outside a black hole's event horizon. This is counterintuitive because once ordinary electromagnetic radiation is inside the event horizon, it cannot escape. It is named after the physicist Stephen Hawking, who developed a theoretical argument for its existence in 1974. Hawking radiation is predicted to be extremely faint and is many orders of magnitude below the current best telescopes' detecting ability.
Richard Siegmund Lindzen is an American atmospheric physicist known for his work in the dynamics of the middle atmosphere, atmospheric tides, and ozone photochemistry. He is the author of more than 200 scientific papers. From 1972 to 1982, he served as the Gordon McKay Professor of Dynamic Meteorology at Harvard University. In 1983, he was appointed as the Alfred P. Sloan Professor of Meteorology at the Massachusetts Institute of Technology, where he would remain until his retirement in 2013. Lindzen has disputed the scientific consensus on climate change and criticizes what he has called "climate alarmism".
Yakov Borisovich Zeldovich, also known as YaB, D.N. was a leading Soviet physicist of Belarusian origin, who is known for his prolific contributions in physical cosmology, physics of thermonuclear reactions, combustion, and hydrodynamical phenomena.
In theoretical physics, the anti-de Sitter/conformal field theory correspondence is a conjectured relationship between two kinds of physical theories. On one side are anti-de Sitter spaces (AdS) that are used in theories of quantum gravity, formulated in terms of string theory or M-theory. On the other side of the correspondence are conformal field theories (CFT) that are quantum field theories, including theories similar to the Yang–Mills theories that describe elementary particles.
The chronology protection conjecture is a hypothesis first proposed by Stephen Hawking that laws of physics beyond those of standard general relativity prevent time travel on all but microscopic scales - even when the latter theory states that it should be possible. The permissibility of time travel is represented mathematically by the existence of closed timelike curves in some solutions to the field equations of general relativity. The chronology protection conjecture should be distinguished from chronological censorship under which every closed timelike curve passes through an event horizon, which might prevent an observer from detecting the causal violation.
Micro black holes, also called mini black holes or quantum mechanical black holes, are hypothetical tiny black holes, for which quantum mechanical effects play an important role. The concept that black holes may exist that are smaller than stellar mass was introduced in 1971 by Stephen Hawking.
The black hole information paradox is a paradox that appears when the predictions of quantum mechanics and general relativity are combined. The theory of general relativity predicts the existence of black holes that are regions of spacetime from which nothing—not even light—can escape. In the 1970s, Stephen Hawking applied the semiclassical approach of quantum field theory in curved spacetime to such systems and found that an isolated black hole would emit a form of radiation. He also argued that the detailed form of the radiation would be independent of the initial state of the black hole, and depend only on its mass, electric charge and angular momentum.
John Phillip Preskill is an American theoretical physicist and the Richard P. Feynman Professor of Theoretical Physics at the California Institute of Technology, where he is also the director of the Institute for Quantum Information and Matter.
Fuzzballs are hypothetical objects in superstring theory, intended to provide a fully quantum description of the black holes predicted by general relativity.
The Thorne–Hawking–Preskill bet was a public bet on the outcome of the black hole information paradox made in 1997 by physics theorists Kip Thorne and Stephen Hawking on the one side, and John Preskill on the other, according to the document they signed 6 February 1997, as shown in Hawking's 2001 book The Universe in a Nutshell.
James Douglas Annan is a scientist involved in climate prediction. He was a member of the Global Warming Research Program at Frontier Research Centre for Global Change which is associated with the Earth Simulator in Japan. In 2014 he left Japan, returning to the United Kingdom as a co-founder of Blue Skies Research.
The iris hypothesis was a hypothesis proposed by Richard Lindzen and colleagues in 2001 that suggested increased sea surface temperature in the tropics would result in reduced cirrus clouds and thus more infrared radiation leakage from Earth's atmosphere. His study of observed changes in cloud coverage and modeled effects on infrared radiation released to space as a result seemed to support the hypothesis. This suggested infrared radiation leakage was hypothesized to be a negative feedback in which an initial warming would result in an overall cooling of the surface.
Stephen William Hawking was an English theoretical physicist, cosmologist, and author who was director of research at the Centre for Theoretical Cosmology at the University of Cambridge. Between 1979 and 2009, he was the Lucasian Professor of Mathematics at Cambridge, widely viewed as one of the most prestigious academic posts in the world.
Blackbird is an experimental wind-powered vehicle, built in 2010 to demonstrate that it is possible for such a vehicle to go directly downwind faster than the wind. Blackbird employs a rotor connected to the wheels and does not have a motor, battery or flywheel. It was constructed by Rick Cavallaro and John Borton of Sportvision, sponsored by Google and Joby Energy in association with the San Jose State University aeronautics department.
Black Hole War: My Battle with Stephen Hawking to Make the World Safe for Quantum Mechanics is a 2008 popular science book by American theoretical physicist Leonard Susskind. The book covers the black hole information paradox, and the related scientific dispute between Stephen Hawking and Susskind. Susskind is known for his work on string theory and wrote a previous popular science book, The Cosmic Landscape, in 2005.
