The discussion centers on the limiting mass at the final stages of black hole evaporation, specifically whether it approaches the Planck mass or if a remnant is left behind. Current theories suggest three possibilities: complete evaporation, retention of a Planck mass remnant, or an exotic outcome. The conversation highlights the lack of a definitive theory of quantum gravity, which hampers understanding of Hawking radiation and its implications, including the trans-Planckian problem related to photon tracing at the event horizon.
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We don't have a definite answer to this question because we don't have a theory of quantum gravity. Possible answers which have been proposed in the literature are:dsaun777 said:As Hawking radiation does away with black holes in the eons of time it takes to evaporate, what is the limiting mass at the final stages of the black hole evaporation? Is it Planck mass? or some fractional mass of the initial BH?
TbhkB=hc3/GM8π. Temperature is the average of the kinetic energy of Hawking radiation. What are the limits of frequencies for the Hawking radiation? I hear there is a problem with trans-Planckian wavelengths when you trace back a "photon" to the horizon of the black hole. Has this issue been resolved where energy divergences happen near the horizon?PeterDonis said:We don't have a definite answer to this question because we don't have a theory of quantum gravity. Possible answers which have been proposed in the literature are:
(1) The hole evaporates completely; nothing is left behind.
(2) A remnant of something like the Planck mass is left behind.
(3) Something more exotic happens.
This is a heuristic belief currently, yes, but we have no microphysical model of how Hawking radiation is emitted to back it up, because, as I said, we don't have a theory of quantum gravity.dsaun777 said:Temperature is the average of the kinetic energy of Hawking radiation.
We don't know. That's one of the open questions we have yet to get a definite answer for.dsaun777 said:What are the limits of frequencies for the Hawking radiation?
"I hear" is not a valid reference. Do you have one?dsaun777 said:I hear there is a problem with trans-Planckian wavelengths when you trace back a "photon" to the horizon of the black hole.
"Evading the Trans-Planckian problem..."PeterDonis said:This is a heuristic belief currently, yes, but we have no microphysical model of how Hawking radiation is emitted to back it up, because, as I said, we don't have a theory of quantum gravity.We don't know. That's one of the open questions we have yet to get a definite answer for."I hear" is not a valid reference. Do you have one?
Yes, this is one speculative resolution. But it's speculative, as all proposals in this area are, because we have no evidence in this regime and won't get any any time soon.dsaun777 said:Addresses the problem
Is all of theoretical physics at this point a race to come forward with a testable prediction that can confirm any "quantum gravitation" theory? Eric Weinstein may be onto something in his recent rants about physics. His arguments are a bit dramatic and even wrong in some instances though. To put his thoughts simply, he does not support the direction of physics and string theory because it lacks anything testable.PeterDonis said:Yes, this is one speculative resolution. But it's speculative, as all proposals in this area are, because we have no evidence in this regime and won't get any any time soon.
Not at all. There is plenty going on other than that. Also, we have no prospect of getting any test of quantum aspects of gravity any time soon; we would have to be able to probe the Planck scale regime and that is many orders of magnitude away from our experimental capability.dsaun777 said:Is all of theoretical physics at this point a race to come forward with a testable prediction that can confirm any "quantum gravitation" theory?
I share his misgivings about string theory, but there is a lot of work going on in physics other than string theory.dsaun777 said:he does not support the direction of physics and string theory because it lacks anything testable.