Stephen Hawking

Stephen W. Hawking is a physicist theorist and English cosmologist, born on January 8th, 1942 in Oxford.

Its principal work is related to the physical relativist, with the Espace-temps. The world famous of S. Hawking is due at the same time to the quality of its research and its body handicap (he suffers from amyotrophic side Sclérose).

The Astéroïde (7672) Hawking was named in its honor.

Biography

The Hawking young person is not particularly brilliant at the school, but its taste for physical sciences leads it to the Université of Oxford, a place of relative trouble from where it leaves with the honors. The Université of Cambridge is a very other world: on a side, Hawking begins its enthralling doctorate there on the General relativity, other, its disease is declared. In spite of this difficulty, the study of the singularities, physical and astronomical concept recent, makes it possible to the researcher to develop various theories, which will lead it Big Bang to the black holes. Initially, Roger Penrose and builds the mathematical structure to him answering the question of a singularity like origin of the Universe. Then, as from the years 1970, Hawking looks further into its research on the local infinite densities, and its studies on the black holes made progress many other fields. Lastly, the Theory of the whole , aiming at unifying the four physical forces, is in the current research center of Hawking. The goal is to show that the Universe can be described by a stable mathematical model, determined by the known physical laws, under the terms of the principle of finished but not limited growth, model to which Hawking gave much credit.

Its heavy handicap could not explain to him only the great success of its research; Hawking sought to popularize its work, and its book a short history of time is one of greatest successes of scientific literature. In 2001, appears its second work, the universe in a shell of nut which popularizes the last state of its reflections, by approaching the supergravity and the supersymmetry, the quantum theory and theory-MR., holography and the duality, the theory of the supercordes and of the p-branes… He also wonders on the possibility of travelling in time and about the existence of multiple universes.

Summary succint of its research

Hawking radiation

Black mini-holes

In 1971, Hawking advances the assumption that the phenomenon of Big Bang would have dispersed in the space of the black mini-holes of a mass from approximately 10 9 ton S and of the size of a Proton as well as more massive black holes and size of a mountain. Black holes as massive as ten Million S of solar masses could also reside at the center of the Galaxie S, which would explain the intense energy emitted by the Radiogalaxie S and the Quasar S.

Entropy of the black holes

See also: Entropy of the black holes

But through calculations, he also discovers that by applying the laws of the Quantum physics to the Cosmologie, he can determine the Dimension Singularité S, these “points of density and Courbure of Espace-temps Infini S” predicted by the General relativity and that one cannot treat mathematically. He realizes that the horizon of the events of the black holes (limit under which nothing can escape) cannot decrease when he attracts Matière. If one takes an analogy with the Thermodynamique says it, it is exactly what says the Second law of thermodynamics: “in a System closed, the Entropie (its degree of Disorder) cannot decrease”. Others say more simply than the chaos increases. In a singularity, the thermodynamic Système is completely disordered because the Tenseur of Weyl is dominating, it tends even towards the infinite one, which makes it possible Hawking to conclude that its entropy is maximum. But its fellow-member, Jacob Bekenstein of the Université of Princeton answers him, that it is not a question only of one analogy, the horizon of the events represents the measurement of the entropy of the black hole. He follows an exchange of arguments by articles interposed until Hawking points out to him that if a black hole has an entropy, he thus has also a Température, and if he has a temperature, he must emit a Rayonnement, but that by definition a black hole does not emit anything, no radiation. At this point in time Hawking goes further in its calculations and discovers that a black hole can finally emit a radiation in a constant way. He first of all thinks of having made a guard and miscalculation his work for him: “I feared, says it, that Bekenstein does not discover it, and does not use it as argument to support its own theory”. Finally Hawking convinces it of the exactitude of its result and which one can use the quantum physics to explain the mechanism of radiation which bears its name today. Bekenstein yields there unwillingly, saying that it is “basically exact but in one manner which I did not certainly expect”.

Hawking tackles the question later in the first version of its book Black holes and babies universe with grinds details then removes this passage by saying simply that Jacob Bekenstein made him a “crucial suggestion”. One allots actually the fact to him that he wanted to turn the theory of Berkenstein in derision, “laughing” of the theory of his competitor, treating it of “scandalous”, or “foolish” to increase the value of his results. Even its Reader, Dr. Dennis Sciama finds “his tone scorning vis-a-vis the work of Bekenstein”. Finally all the work of its competitor is forgotten.

The loss of information in a black hole

Holes of worm

The arrow of time and universe without edge

The theory of the inflation

New theory on the black holes

Stephen Hawking is on the front of the scene in July 2004 by presenting a new theory on the black holes which goes against its clean old theory, thus losing a Pari that him and Kip Thorne had made with John Preskill, a physicist of the particles. Classically, one can show that the information which passes by the horizon of a black hole is lost for our universe. This fact is known under the name of Théorème of baldness. The problem with this theorem is that it implies that the black hole emits same radiations whatever what returns there. Thus, if a pure state quantum is thrown in a black hole, a state mixed will come out from it. This goes against the rules of the quantum Mécanique and is known under the name of Paradoxe of lost information black holes.

Hawking had speculated before that the Singularité in the center of the black hole could form a bridge towards a “baby universe” in whom lost information could pass; such theories are very popular in the Science-fiction. But according to the new idea of Hawking, presented to the 17th International Conference on general relativity and the gravitation, the July 21st 2004 with Dublin, the black holes end up transmitting, in a disordered way, the information of all the matter that they avalent.

Having concluded that the information is stored, Hawking concedes that it lost its bet, yielding to Preskill its Encyclopédie. However, Thorne remains dubitative with respect to the demonstration of Hawking and refuses to contribute to the reward.

In July 2005 the advertisement of Hawking gave place to a publication in the review Physical Review and largely discussed in the scientific community.

Anecdotes

Stephen Hawking forever hidden the interest which it carries to the universe of Star Trek . He plays his own part in the prolog of the episode “ Descent, Part I ” of the series Star Trek: The Next Generation, engaged in part of poker with Isaac Newton and Albert Einstein. In the final episode of this same series, the character of Dated is titular pulpit lucasienne, that one even as occupies Hawking with Cambridge, following Newton. He is also amateur of the British series Red Dwarf, which he comments on in particular in documentary devoted to the ten years of this series.

He appears in an episode of the Simpsons in 1999, entitled “the large IQ”, like in the episodes “a large tile for a roof” (season 16) and “Small Dad Christmas super cop” (season 18), and also in an episode of the second season of Futurama . One can also see it in an episode of the series Dilbert .

The series Masters off Science Fiction is presented orally by Stephen Hawking. In the cycle of Hypérion of daN Simmons, the interstellar naves are equipped with engines with thorough Hawking , but which are exceeded a little for the advanced time of the novel. Stephen Hawking prefaced the work: the physics of Star Trek, or how to visit the universe in pyjamas of Lawrence Mr. Krauss.

Lastly, he writes its first book in collaboration with his daughter, Lucy, entitled " George and secrecies of UNIVERS" , in which the last discoveries appear on the Black holes.

Random links: