Thread: Can Hawkings Radiation really happen?

How can a particle cross the EH in real time ( from the perspective of an external observer)? If it cant then HR is not possible.

Hawking radiation is exactly that -- radiation. (simplistically) The radiation doesn't cross the event horizon. What happens is that a quantum fluctuation allows a particle inside the event horizon to temporarily cross the horizon, emit the radiation, and then cross back. You have to understand that GR is a purely classical theory and there have to be quantum modifications of GR results. The fluctuation that allows the (virtual) particle to cross over and then back is typical of quantum fluctuations in many physical processes.

Originally Posted by PhysicsNard

Hawking radiation is exactly that -- radiation. (simplistically) The radiation doesn't cross the event horizon. What happens is that a quantum fluctuation allows a particle inside the event horizon to temporarily cross the horizon, emit the radiation, and then cross back. You have to understand that GR is a purely classical theory and there have to be quantum modifications of GR results. The fluctuation that allows the (virtual) particle to cross over and then back is typical of quantum fluctuations in many physical processes.

mmmm ... so it crosses the EH? but then it must travel at faster than the speed of light to escape right?

no, I agree; Hawking radiation doesn't happen, but I think it is a good analogy for what really happens, ie in terms of rate of evaporation etc.


I think the buzz word, in the future will be 'pre-Hawking radiation', which is what I've read about, but there isn't much information about it on the net.


I would bet that the equations for Hawking radiation and pre-Hawking radiation would be similar if not the same.

I've heard other explanations, not necessarily better. If the virtual particle emerges outside the event horizon, 0.99c is sufficient to escape if the direction is optimum. Likely most of the particles that escape are recaptured by the black hole in a day or less, so the net grams that escapes is tiny, and almost independent of the mass of the black hole = Super massive black holes recapture most of the escapes eventually, while solar mass black holes, if any, need to recapture in hours as later recapture is very low probability.
Even though the distant observer can't see the escape because time is frozen for the distant observer, the distant observer can observe the effects of the mass loss, except the mass loss is much too small for today's technology. We may never know for sure. I'm guessing. Does an electron that will be recaptured a million times a million = 10E12 years later subtract from the net mass loss? Most black holes likely capture more mass than they evaporate so the mass of typical black holes is increasing, very slowly. Neil

Hawking Radiation is based on a faulty model (see Introduction to Quantum-Geometry Dynamics, Particle Classifiation and Cosmology and On the Singularity of the Nature of Light and the Heisenberg Uncertainty Principle. All available for download in PDF format here.

Hawking radiation in 30 seconds:

1) empty space is full of particle--anti-particle pairs that are constantly being created and annihilated.
2) If a black hole exists, then sometimes, one of these particles will be swallowed by the hole and the other will not.
3) If the particle can annihilate a "particle" that is part of the singularity, then the singularity loses mass.

The problem is this: what is the net effect of the virtual particles on the "singularity"? Since no one can say for certain what the singularity "is", and we do not have the computational power to calculate the time-evolution of a realistic black hole, it is pretty much up for grabs until someone observes Hawking radiation from a black hole.

At one time, there was a simplistic calculation linking the occurrence of "gamma ray bursts" to the explosion of extremal black holes.... Since that time, GRBs have been linked to other phenomena. If this is the case, why are we not seeing extremal black hole "explosions"?