“Jacob Bekenstein found… in 1971 that every black hole must have an entropy proportional to the area of its horizon… Stephen Hawking then refined this by showing that the constant of proportionality must be… exactly one quarter. …entropy is supposed to correspond to a measure of information …Loop quantum gravity… [gives] a detailed description of the microscopic structure of a black hole. …a horizon can have, for each quantized unit of area, a finite number of states. Counting them, we get exactly Bekenstein's result…”

— Lee Smolin

"Loop Quantum Gravity," The New Humanists: Science at the Edge (2003)

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Lee Smolin 52

American cosmologist 1955

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“We show that it is natural to introduce the concept of black-hole entropy as the measure of information about a black-hole interior which is inaccessible to an exterior observer. Considerations of simplicity and consistency, and dimensional arguments indicate that the black-hole entropy is equal to the ratio of the black-hole area to the square of the Planck length times a dimensionless constant of order unity. A different approach making use of the specific properties of Kerr black holes and of concepts from information theory leads to the same conclusion, and suggests a definite value for the constant.”

Jacob Bekenstein (1947–2015) Mexican-Israeli physicist

[Black Holes and Entropy, Phys. Rev. D, 7, 8, 2333–2346, 15 April 1973, 10.1103/PhysRevD.7.2333]

“The black hole information paradox is probably the most important issue for fundamental physics today. If we cannot understand its resolution, then we cannot understand how quantum theory and gravity work together. Yet very few people seem to understand how robust the original Hawking arguments are and what exactly it would take to resolve the problem.”

Samir D. Mathur Indian physicist

Mathur, Samir D. "What exactly is the information paradox? http://books.google.com/books?id=RfDUXYSSyA0C&pg=PA3." In Physics of Black Holes, pp. 3–48. Springer, Berlin, Heidelberg, 2009. (quote from p. 3)

“I'm sorry to disappoint science fiction fans, but if information is preserved, there is no possibility of using black holes to travel to other universes. If you jump into a black hole, your mass energy will be returned to our universe but in a mangled form which contains the information about what you were like but in a state where it can not be easily recognized. It is like burning an encyclopedia. Information is not lost, if one keeps the smoke and the ashes. But it is difficult to read. In practice, it would be too difficult to re-build a macroscopic object like an encyclopedia that fell inside a black hole from information in the radiation, but the information preserving result is important for microscopic processes involving virtual black holes.”

Stephen Hawking (1942–2018) British theoretical physicist, cosmologist, and author

"Information Loss in Black Holes" http://arxiv.org/abs/hep-th/0507171 (July 2005)

“A black hole is the ultimate manifestation of a region of strong gravity. The pull of gravity in a black hole is so strong that even light cannot escape from it and time stands still.”

Jayant Narlikar (1938) Indian physicist

Source: Jayant Narlikar Black Holes http://books.google.com/books?id=8qi55iSSeiwC, National Book Trust, India, 1 January 2006

“In a previous paper we showed that a static (nonrotating) black hole cannot be endowed with exterior scalar-meson or massive vector-meson fields. Here we show that the same is true for massive spin-2 meson fields. We also extend the above results to the case of a rotating stationary black hole. We conclude from our results that a black hole in its final (static or stationary) state cannot interact with the exterior world via the strong interactions which are mediated by meson fields such as the π (scalar), ρ (vector), and ƒ (spin-2). A direct consequence of this is the impossibility of determining the baryon number of the black hole by means of exterior measurements alone. This results in the transcendence of the law of baryon-number conservation as originally predicted by Wheeler.”

Jacob Bekenstein (1947–2015) Mexican-Israeli physicist

[Nonexistence of baryon number for black holes. II, Physical Review D, 5, 10, 15 May 1972, 2403–2412, 10.1103/PhysRevD.5.2403]

“Is the reader feeling confused about the status of the black hole information paradox and black holes in general? So am I!”

John Moffat book Reinventing Gravity

Source: Reinventing Gravity (2008), Chapter 5, Conventional Black Holes, p. 87

“Black holes set a limitation on the number of species of elementary particles—quarks, leptons, neutrinos—which may exist. And black holes lead to a fundamental limitation on the rate at which information can be transferred for given message energy by any communication system.”

Jacob Bekenstein (1947–2015) Mexican-Israeli physicist

[Black holes and everyday physics, General relativity and gravitation, 14, 4, April 1982, 355–359, 10.1007/BF00756269]

“What we hear about eternal inflation or the string landscape, seems somehow unavoidably to lead to some kind of multiverse. However, it seems to me there is a fundamental problem there. Once of course you have the multiverse, then you can start playing around and try to find probability or getting to the anthropic principle, or whatever. But the point is that the picture is essentially a classical one, and it is difficult to see that if you have many universes, coming essentially with an inflationary state, that there would not be plenty of horizons in this. Now the quantum mechanics of horizons is, I think, perfectly not understood. The simplest example is the black hole, where after all nobody knows really if the problem lies in the singularity or if it lies really already in the horizon.”

François Englert (1932) Belgian theoretical physicist

as quoted in: [Gross, David; Henneaux, Marc; Sevrin, Alexander, eds., The Theory of the Quantum World: Proceedings of the 25th Solvay Conference on Physics, Brussels, Belgium 19-22 October 2011, World Scientific, 2013, 309, https://books.google.com/books/about/The_Theory_of_the_Quantum_World.html?id=0o-6CgAAQBAJ&pg=PA309]

“The BEH mechanism operates within the context of gauge theories. Despite the fact that grand unification schemes reach scales comparable to the Planck scale, there was, a priori, no indication that Yang-Mills fields offer any insight into quantum gravity. The only approach to quantum gravity that had some success, in particular in the context of a quantum interpretation of the black hole entropies, are the superstring theory approaches and the possible merging of the five perturbative approaches (Type IIA, IIB, Type I and the two heterotic strings) into an elusive M-theory whose classical limit would be 11-dimensional supergravity.”

François Englert (1932) Belgian theoretical physicist

page 19 of [2002, A brief course in spontaneous symmetry breaking ii. modern times: The BEH mechanism, arXiv preprint hep-th/0203097, https://arxiv.org/pdf/hep-th/0203097.pdf]

“It is the duty of all troops and police in my command to adopt the severest measures. Every act of violence committed by partisans must be punished immediately. Reports submitted must also give details of countermeasures taken. Wherever there is evidence of a considerable number of partisan groups a proportion of the male population of the area will be arrested, and in the event of an act of violence being committed these men will be shot.”

Albert Kesselring (1885–1960) German Luftwaffe Generalfeldmarschall during World War II

June 20, 1944. Quoted in "Mussolini: The Last 600 Days of Il Duce" - Page 131 - by Ray Moseley - History - 2004.

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