1974, Hawking and Jacob Bekenstein showed that black holes are not actually completely black, but that they should thermally create and emit sub-atomic particles, known today as Hawking radiation, until they eventually exhaust their energy and evaporate. This also resulted in the so-called “Information Paradox” or “Hawking Paradox”, whereby physical information (which roughly means the distinct identity and properties of particles) appears to be completely lost to the universe, in contravention of the accepted laws of physics. Hawking defended this paradox against the arguments of Leonard Susskind and others for thirty years, until famously retracting his claim in 2004. [see 2004 below where he adapts idea of multiverse to explain the disappearance of physical information]
These cutting edge achievements were made despite the increasing paralysis caused by Hawking's ALS. By 1974, he was unable to feed himself or get out of bed, and his speech became so slurred that he could only be understood by people who knew him well. In 1985, he caught pneumonia and had to have a tracheotomy, which left him unable to speak at all, although although a variety of friends and well-wishers collaborated in building him a device that enabled him to write onto a computer with small movements of his body, and then to speak what he had written using a voice synthesizer.
Hawking’s ground-breaking research resulted in considerable fame and celebrity. In 1974, at the age of 32, he was elected as one of the youngest ever Fellows of the Royal Society. He was created a Commander of the Order of the British Empire (CBE) in 1982, and became a Companion of Honour in 1989. He has accumulated twelve honorary degrees, as well as many other awards, medals and prizes, including the Albert Einstein Award, the most prestigious in theoretical physics. He also became well-known among a wider audience, especially after his 1988 international bestselling book “A Brief History of Time”, and its follow ups “The Universe in a Nutshell” (2001) and “A Briefer History of Time” (2005).
He continued lines of research into exploding black holes, string theory, and the birth of black holes in our own galaxy. His work also increasingly indicated the necessity of unifying general relativity and quantum theory in an all-encompassing theory of quantum gravity, a so-called "theory of everything", particularly if we are explain what really happened at the moment of the Big Bang. As early as 1974, his theory of the emission of Hawking radiation from black holes was perhaps one of the first ever examples of a theory which synthesized, at least to some extent, quantum mechanics and general relativity
Among the myriad other scientific investigations pursued by Hawking over the years are the study of quantum cosmology, cosmic inflation, helium production in anisotropic Big Bang universes, "large N" cosmology, the density matrix of the universe, the topology and structure of the universe, baby universes, Yang-Mills instantons and the S matrix, anti-de Sitter space, quantum entanglement and entropy, the nature of space and time and the arrow of time, spacetime foam, string theory, supergravity, Euclidean quantum gravity, the gravitational Hamiltonian, the Brans-Dicke and Hoyle-Narlikar theories of gravitation, gravitational radiation, holography, time symmetry and wormholes.
Never afraid to court controversy, he even began to question the Big Bang theory itself in the 1980s, suggesting that perhaps there never was a start and would be no end, but just change, a constant transition of one "universe" giving way to another through glitches in space-time. He developed his "No Boundary Proposal" in collaboration with the Amercian physicist Jim Hartle. Under classical general relativity, the universe either has to be infinitely old or had to have started at a singularity, but Hawking and Hartle’s proposal raises a third possibility: that the universe is finite but had no initial singularity to produce a boundary. The history of this no-boundary universe in "imaginary time" can perhaps be best envisaged using the analogy of the surface of Earth, with the Big Bang equivalent to Earth’s North Pole, and the size of the universe increasing with imaginary time as you head south toward the equator.
In 2004, he dramatically reversed one of his earlier controversial claims about black holes (that they destroy everything that falls into them and that no information is ever retrieveable from a black hole), claiming new findings that could help solve the so-called “black hole information paradox”. In his new definition of black holes, the event horizon is not so well-delineated and may not completely hide everything within it from the outside, and he has embraced the concept of the multiverse to help explain the conservation of information in black holes.
https://www.physicsoftheuniverse.com...s_hawking.html
Stephen Hawking dead at 76
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Originally Posted by Danke
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