Stephen Hawking said he got it wrong

[OpenGL guy]

Since black holes evaporate they are not completely black. According to general relativity the superstrong gravitational field around a black hole constantly creates pairs of particles and anti particles. Sometimes one of the "twins" escapes while the other falls into the black hole.

That's one thing that always bothered me... How can the black hole be evaporating if it is absorbing matter from this process? I mean, one particle escapes and the other is captured... didn't the mass of the black hole just increase by one particle?

 

[Guden Oden]

I'd like to see what the creation of a black hole looks like, as far as we know it now that is.

Ie, we have a supernova that blows up or a neutron star that collapses into a black hole. What exactly would that look like?

 

[Fred]

"That's one thing that always bothered me... How can the black hole be evaporating if it is absorbing matter from this process? I mean, one particle escapes and the other is captured... didn't the mass of the black hole just increase by one particle?"

First off, what happens when there is no more nearby matter to absorb? Eventually the rate of emission will grow much larger than the rate of absorption.

Now, Hawkings process is more or less the following.. Consider a virtual electron-positron pair just outside the event horizon. These quantum fields are totally random fluctuations, however it takes some gravitational energy to actually induce them on mass shell (ie in order to become 'real particles') So one particle escapes and the other is absorbed. You would think this is a net gain of zero for the blackhole (half absorbed, half emitted).. but no, the field around the black hole requires energy to make them seperate, so in essence more than half of the energy of the process is directly lost by the black hole in the process. By Einstein's relation, this results in a net loss of mass of the bh.

Think of it as so.. x amount of gravitional energy is required to seperate the pair. A tiny bit less than x/2 is reabsorbed, the remaining half is emitted, and the little left over energy goes into more particle-pair creation or other fields. Net energy loss x - x/2 ~ x/2.

 

[rotten]

I'd like to see what the creation of a black hole looks like, as far as we know it now that is.

Ie, we have a supernova that blows up or a neutron star that collapses into a black hole. What exactly would that look like?

if u have a deathwish y not try more traditional methods?
like jumpin off a cliff or something...
that way u dnt put in any danger the rest of us...[/code]

 

[K.I.L.E.R]

I'd like to see what the creation of a black hole looks like, as far as we know it now that is.

Ie, we have a supernova that blows up or a neutron star that collapses into a black hole. What exactly would that look like?

My underwear after wearing it for a week?

 

[2senile]

(that will be revealed at a conference next week).

21st, if I recall correctly.

 

[Tahir2]

What happened to the idea of White Holes?

 

[Vadi]

If wormholes existed, there would be white holes at their "exits" and black holes at their "entraces".

 

[gosh]

"Black holes are where God divided by zero"
Steven Wright

 

[Fred]

For anyone interested in an almost accessible to layman talk, here is the transcript of Hawkings talk today.

http://pancake.uchicago.edu/~carroll/hawkingdublin.txt

The full as yet to be published paper will be when the fun starts.

Btw, a bunch of us are really skeptical of this result, for a number of reasons. There are some mathematical problems to begin with, and a few loose assumptions hanging around.