The black hole firewall is a relatively recent idea. On Wikipedia you can read how it “was proposed in 2012 by Ahmed Almheiri, Donald Marolf, Joseph Polchinski, and James Sully as a possible solution to an apparent inconsistency in black hole complementarity”. Their proposal is known as the AMPS firewall, and the title of their paper is black holes: complementarity or firewalls? They cannot all be true They start by saying “we argue that the following three statements cannot all be true: (i) Hawking radiation is…

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The information paradox

The information paradox was first mooted by Stephen Hawking in 1976. For an introduction to the subject, see Brian Koberlein’s black holes tell no tales or do they? Then see Hawking’s paper on the breakdown of predictability in gravitational collapse. Hawking said information is lost down a black hole because the quantum emission is completely random and uncorrelated. He also said “this means there is no S matrix for the process of black-hole formation and evaporation”. The S-matrix is the scattering matrix which is to do…

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The Hawking papers

You can find a list of Stephen Hawking’s publications on the website. It starts with his 1965 PhD thesis. This is said to have “borrowed from Roger Penrose's theorem which described a 'spacetime singularity' being present in the centre of black holes”. Penrose was one of Hawking’s PhD examiners. Seven out of Hawking’s first ten papers concerned singularities. Singularities and the geometry of spacetime One of Hawking’s early papers was singularities and the geometry of spacetime dating from 1966. At 91 pages it’s curiously long.…

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Black holes

We can trace black holes all the way back to John Michell in 1783. He's the man who devised the torsion balance used by Henry Cavendish to determine the mass of the Earth. Michell was something of an expert on gravity. He talked about “dark stars”, and said this: "if there should really exist in nature any bodies, whose density is not less than that of the sun, and whose diameters are more than 500 times the diameter of the sun, since their light could not…

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