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Topic: Stephen Hawking thread (Read 225 times) previous topic - next topic

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  • Pingu
Stephen Hawking thread
I have a Darwin-debased mind.

Re: Stephen Hawking thread
Reply #1
This is probably a good time to mention that he is dead.

  • Pingu
Re: Stephen Hawking thread
Reply #2
Sorry, I forgot to say.
I have a Darwin-debased mind.

Re: Stephen Hawking thread
Reply #3
Love is like a magic penny
 if you hold it tight you won't have any
if you give it away you'll have so many
they'll be rolling all over the floor

  • el jefe
  • asleep till 2020 or 2024
Re: Stephen Hawking thread
Reply #4
as I understand it, he (and Jakob bekenstein) have done some of the most salient work on quantum gravity, in coming up with semiclassical models of blackhole radiation.  like all QG work, it's untested and probably won't be for a long time, but the proposal is modest enough and the reasoning solid enough that most people take it seriously as a thing that stands a good chance of being real.

background:  general relativity (describes spacetime and says gravity is a warping of it) and the 2nd law of thermodynamics (roughly says things tend to get more disorganized and uniform over time) seem to be in conflict, at least in spirit, on the question of what happens at the edge of a black hole.  GR says matter, energy, and information which pass the event horizon can never escape.  but the clustering of mass, energy, and information that leads to is in tension with the 2LoT.

iiuc, bekenstein said that if you postulate that 2LoT wins the contest, then it follows that black holes radiate, and he deduced properties of that radiation.  it's a macroscopic argument.

iiuc, hawking came up with a complementary microscopic argument which provides a model of what such radiation might actually consist of.  he did QED on a schwarzschild spacetime, and showed that there are some virtual electron - positron pairs where one will be caught by the black hole and the other will escape (at least temporarily).  a virtual pair  aren't supposed to survive because (insert qft that I don't understand yet), but trapping one in the black hole and freeing the other forces them both to survive.  somehow you end up having to choose between violating mass-energy conservation and stealing mass-energy from the black hole to provide some to the newly created virtual-turned-legit particle that escapes to infinity.  in that way the black hole should radiate.

  • el jefe
  • asleep till 2020 or 2024
Re: Stephen Hawking thread
Reply #5
and now cold one can tell us what really happens