A recent article in the New York Times highlights the ongoing debate among theoretical cosmologists about what happens when you enter a black hole, the so-called “Firewall Paradox”. At stake are some of the basic tenets of modern science, in particular Einstein’s general theory of relativity, the theory of gravity, on which our understanding of the Universe is based.
The traditional view holds that an astronaut falling into a black hole would not be physically aware of crossing the point of no return, known as the event horizon. (Of course, he or she will inevitably be crushed by the monstrous gravitational forces…)
In 1974, British cosmologist Stephen Hawking theorized, using general relativity and quantum theory (the laws which govern behaviors on the smallest, subatomic scales) that black holes, could leak particles and radiation back into space. This in itself generated a 30-year debate, and a famous wager with Caltech physicist John Preskill, on whether such escaping particles would carry some quantum information with them or not. In 2004, Hawking conceded that such information could survive.
A group of researchers at the University of California, Santa Barbara studying how information escapes a black hole’s clutches have presented the “Firewall Paradox”: that having information flowing out of a black hole is incompatible with having an otherwise smooth space-time at its boundary, i.e. the traditional event horizon. Instead there would be a discontinuity in the vacuum that would manifest itself as energetic particles — a literal “firewall” — lurking just inside the black hole.
If the firewall argument proves to be correct, one of three ideas that lie at the heart of modern physics, must be wrong. Either information can be lost in a black hole after all; Einstein’s principle of equivalence is wrong; or quantum field theory, which describes how elementary particles and forces interact, is wrong and needs fixing.
To find out more about possible solutions to this problem, read Dennis Overbye’s full New York Times article here.