Hawking Admits to Mistake

A few weeks ago at the International Conference of General Relativity and Gravitation, Stephen Hawking admitted he was wrong. The story begins back in 1916, after Einstein published his general theory of relativity. Karl Schwarzschild used Einstein's field equation to compute the possibility of a singularity -- a point where Einstein's beautiful space-time no longer makes any sense, and an outcome of Einstein's field equation that Einstein fiercely resisted up to his death in 1955 (Schwarzschild himself died a few months after working this out). A singularity forms from the collapse of star under its own gravitation -- the idea is that gravity is so overwhelming, that it sucks all the mass of the star into an infinitesimally small area -- gravity's intensity is so great that not even light escapes from it.

The term 'black hole' wouldn't coined until the 1960s by physicist John Wheeler. In the 1970s, Hawking came along and made a prediction that made perfect sense, but in effect, destroyed black holes -- proving that they shouldn't exist. One of the predictions of quantum electrodynamics, first proposed by Paul Dirac, is that the 'empty' universe is not really empty, but is in fact seething with virtual particles -- virtual, because while they are very much real, they exist for such a short period of time, that might as well not exist at all. Virtual particles pop in and out of existence all the time -- they come in pairs -- a particle and its anti-particle equivalent -- their existence as a pair, created from nothing, doesn't violate the laws of nature, because as a pair, they are in effect nothing -- and because they exist as a particle-anti-particle pair, they guarantee that they will annihilate each other and cease to exist.

Hawking's supposition was, what happens if virtual particles appear at the event horizon of a black hole? His mathematics predicted something remarkable would happen. One particle would be trapped by the event horizon and be sucked into the black hole, while the other could escape as thermal radiation. This is a problem. The nature of the cosmos requires a balance -- that's why virtual particles annihilate each other. In this scenario, they don't -- or they could, in which case, for a balance to occur, the black hole would need to lose mass equivalent to the mass of the escaping particle. Fine. Except another tenet of quantum physics says that information can't be destroyed -- and by destroying mass within a black hole, information would be destroyed. Hawking continued this line of thinking to the end. If virtual particle pairs are constantly popping into existence, then half of the pairs would be escaping from black holes, causing black holes to lose mass over time -- essentially, there shouldn't be black holes because they should all evaporate! That's the problem.

Hawking had made a bet with John Preskill -- Preskill felt something was wrong with Hawking's supposition that created the problem -- its just for 30-years, no one could figure it out. Hawking apparently did this year. He reworked his math, and came to a different conclusion -- apparently, 30-years ago, he was wrong. (There are more quandaries similar to this -- for instance, we see the effects of a black hole's gravity, and according to quantum mechanics, gravity is mitigated by the graviton particle -- but if nothing can escape from a black hole, gravitons shouldn't be able to -- so in effect, black holes by their very nature, should eventually stop being black. [Yes, it's a circular argument, and I ain't smart enough to do it justice, so I'll leave it at that.])