Hawking Radiation

Saiph · Jun 20, 2007

both particles are indeed real (I thought I stated that a bit more clearly...my mistake). Both particles have real, positive mass. AFAIK, no particle/object with negative mass has been detected. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

mrcurious · Jun 21, 2007

Another, yet similar, way to explain the black hole's loss of mass is that the particle that gets sucked into the black hole gains a negative mass and thus the mass of the black hole decreases... That statement comes is part of the original post. But.....you are saying Both particles have real, positive mass. AFAIK, no particle/object with negative mass has been detected. I'm confused.....

derekmcd · Jun 21, 2007

Hawking radiation is best explained with math to understand what is really happening. I'd love to explain it via math, but math at that level is completely beyond my comprehension. So, I'll give it a whirl with words. Saiph is correct in stating that no known particles have negative mass or energy for that matter. When 'negative energy' is used, it is simply a descriptive tool and not physical in nature. Particles/anti-particles are only opposite in charge or spin of the particle. Virtual particles are so named because they do not survive long enough to be observed. They are only allowed via the Heisenberg Uncertainty Principal. When they are created in a vacuum, it would seem they 'borrow' energy from that system but return it promptly upon annihilation so as to not violate any laws. Now... when this happens near the event horizon of a black hole, sometimes one of the particles gets boosted away from it's anti-particle. The particle boosted away becomes real and observable containing mass or energy as it was not destroyed by being annihilated. That mass had to come from somewhere. It actually doesn't come from the black hole itself as the pair was created outside the event horizon. The way I understand it is that the other particle that falls into the black hole is still a 'virtual' particle that, upon entering the black hole, carries with it a void or vacuum (from the original creation of the pair) that must now be filled (because the pair did not annihilate each other and return the energy it borrowed). So the event horizon literally shrinks to fill that void of energy. The energy contained in the new particle boosted away has to be accounted for, though... If the event horizon shrinks (implying loss of mass) and a new particle is created (the radiation), the real question is how does the energy from within the event horizon get to the particle if they were created outside the event horizone? Quantum tunnel <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

alokmohan · Jun 21, 2007

A very unusual thread with so many learned men on Hawking radiation.Kindly explain what is Hawking radiation.Is it byprouct of exploding black hole?

yevaud · Jun 21, 2007

Derek just did explain it. Re-read the explanation above. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

mrcurious · Jun 21, 2007

Saiph is correct in stating that no known particles have negative mass or energy for that matter. When 'negative energy' is used, it is simply a descriptive tool and not physical in nature. Particles/anti-particles are only opposite in charge or spin of the particle. That clears up a lot. Now... when this happens near the event horizon of a black hole, sometimes one of the particles gets boosted away from it's anti-particle. The particle boosted away becomes real and observable containing mass or energy as it was not destroyed by being annihilated. I with you so far.... That mass had to come from somewhere. It actually doesn't come from the black hole itself as the pair was created outside the event horizon. The way I understand it is that the other particle that falls into the black hole is still a 'virtual' particle that, upon entering the black hole, carries with it a void or vacuum (from the original creation of the pair) that must now be filled (because the pair did not annihilate each other and return the energy it borrowed). So the event horizon literally shrinks to fill that void of energy. The vacuum needs to gain the energy that was lost during the absence of particle pair collisions. The event horizon supplies this energy and thus shrinks. BUT........what happens to the other particle? What happens to the other particle that fell into the black hole? Is this where the information paradox comes in? Because hawking radiation says nothing about the particle that fell into the hole. It only describes the result of particle pairs not annihilating and what happens to the event horizon when its gives up some energy to fill the void in the vacuum. Don't we still have one more particle to account for?

Saiph · Jun 21, 2007

well, it's gone into the black hole...and we can't tell much about it. It's mass, charge and spin get added to the BH. However there is still a net loss in the exchange. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

alokmohan · Jun 22, 2007

Can you tell me if there are twoterms absolute horizon and apparent horizon.Which we are discussing at present?

mrcurious · Jun 22, 2007

well, it's gone into the black hole...and we can't tell much about it. It's mass, charge and spin get added to the BH. However there is still a net loss in the exchange. OK, so then my inital assumtion about the infalling particle is correct, its lost and we dont know anything about it. Are there any speculations on what happens to it? Also, adding the mass of the infalling particle, doesn't add mass to the black hole?

dragon04 · Jun 22, 2007

Nobody has ever explained to me to my satisfaction one thing. Physics utterly states that it requires a specific amount of imploded mass to cause a black hole. If a black hole loses mass via Hawking Radiation or any other vehicle, how can a black hole "evaporate" into nothingness rather than simply re-enter the Universe as the densest observable neutron star out there? I'll willingly admit my ignorance and lack of formal education, but it seems that the tiniest fraction of mass vs. density determines what is or is not a BH. Once a BH loses that mass vs. density, how can it possibly defy the very "laws" that define it and mysteriously evaporate? <div class="Discussion_UserSignature"> "2012.. Year of the Dragon!! Get on the Dragon Wagon!". </div>

derekmcd · Jun 22, 2007

A neutron star's collapse is halted by the outward pressure of degenerate matter. Given enough mass, the gravitational colapse will overwhelm all outward pressures. The matter within a black hole is 'beyond' degenerate and nothing can ever overcome these forces. It simply shrinks, thus maintaining the proper ratio of mass and density. <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

mrcurious · Jun 22, 2007

If electron degeneracy causes neutrons, neutron degenercy causes quark degeneracy and then finally quark degeneracy leads to the black hole. (Quark degeneray is highly speculative) http://en.wikipedia.org/wiki/Degenerate_matter Is it possible that a black hole produces degenerate matter in the form of dark matter? I don't believe its a concidence that dark matter is more concentrated in the center of galaxies where supermassive black holes exist. Inside the black hole the tidal forces could strip a particle to down to whatever its most fundametal level. At which point that particle or string would go through a phase transition into dark matter. QM states that the singularity of a black hole can't exist and that only a very large mass inside a very small space is there. Considering the infinitesimal space that would exist at the center of the black hole and the mass inside that space, if that mass could exert degenerate pressure because the mass of particles has no where else to go then I would think that this mass could go through an additional phase transition into dark matter.

dragon04 · Jun 22, 2007

Thank you. Thank you, thank you, thank you. <div class="Discussion_UserSignature"> "2012.. Year of the Dragon!! Get on the Dragon Wagon!". </div>

derekmcd · Jun 22, 2007

"Is it possible that a black hole produces degenerate matter in the form of dark matter?" I guess, by definition alone, black holes ARE dark matter. But, black holes are not abundant enough to account for the observations about galaxies. Dark matter doesn't really need to be some form of exotic matter. Dark matter is only dark because we can't see it. It doesn't radiate or reflect anything that our instruments can detect as of yet. We are getting better at observing the effects of dark matter, but can not detect it directly. Same with black holes. <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

derekmcd · Jun 22, 2007

Your welcome. repeat, repeat, repeat <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

nexium · Jun 22, 2007

I'm not sure I know, but let me give it a try. We don't think black holes ever explode unless their mass falls below about one ton. Most of the virtual particles are electrons or protons with rather rare more massive particles such as an iron or oxygen nuclius. It takes a million times a milion times a million years for a solar mass black hole to shrink to one ton and that assumes the black hole ate nothing but virtual particles all that time. We can safely assume that nearly all solar mass and more black holes are slowly gaining mass faster than they are losing mass by Hawkings radiation. We have not found any black holes with less mass than one solar mass. Neil

mrcurious · Jun 23, 2007

Dark matter doesn't really need to be some form of exotic matter. It doesn't need to be....It could be a lot of things. I only present it as an idea. Then I went looking on the web and found these: http://www.iop.org/EJ/article/0264-9381/18/4/101/q104l1.html http://flux.aps.org/meetings/YR01/APR01/abs/S2390008.html http://eproceedings.worldscinet.com/9789812701862/9789812701862_0001.html I gotta get this article.. http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v500n2/37089/37089.html I present these links only to consider what dark matter could be and how they may be linked to black holes. I really never gave that idea much thought. When I read the your posting about degenerate matter, I finally could make a connection between the two, SMBH & dark matter. Dark matter is only dark because we can't see it Your right, dark matter is only "dark" because we can't see it. We can't see it because it doesn't radiate light, nor does it absorb it. The reason for exotic matter is not because its "dark." Its exotic because we don't know of any matter with these properties. Something that has mass, yet it is invisible. Gases behave like this, except gases can reflect light. Also how would any gas get to be billions to trillions of solar masses. Its hard for me to accept dark matter as anything, but some form of exotic matter.

alokmohan · Jun 26, 2007

Scientists are aware of dark matter for last fifty years.Neutrino and brown dwarf ar two of many candidates.Exotic matter is different ,it is virtual particle.We have no idea of what type of beast it may be.

alokmohan · Jun 28, 2007

It dates back to Zwicky

alokmohan · Jun 30, 2007

If two black holes collide ,we may have explosion only then.system loses mass.

alokmohan · Jul 1, 2007

I like to point out that when two black holes collide sum of their surface energy becomes more than two together.This is because it loses energy.So ultimately it explodes.We are taking discussion to another line. I want you know about two terms ,absolute horizon and apparent horizon.

nojocujo · Jul 7, 2007

The problem is that the event horizon is relative to a specific system GR and particle antiparticle or pair production is relative to to a different system QED. Hawking radiation is an attempt to bring the two together but until there is a quantum gravity theory which can't exist at the quantum level since it so waek in a flat spacetime. As far a hawking radiation and the net loss in energy........ There is no net loss in energy at the event horizon in pair prodution. you have the gravitational energy density of the gravitational well which also encompasses the gravitational well but the bh is a closed system but a subset of the gravitational well. It is the gravitational energy density of the whole system that in fact creates the pair production. So the bh gains mass and energy in the gain of the particle or antiparticle. The event horizon represents what energy level?? I can look it up but what level translated to the QGP level of 10 TEv-16. The combination of temperature or energy and the gravitayional energy density equaling 10 TEV -16 should result in a GRB and possibly XRF's as the degeneracy pressure is exceeded and a further implosion results. I do think that if the temperature of a bh which BTW should be cooled to the equivalent of a bose einstein condensate at the QGP level due to pair production and symetry breaking. Imagine yourself on the surface of a bh but it is intensely bright but a hint of quark rain.

nojocujo · Jul 7, 2007

Sorry for the double posting.

alokmohan · Jul 7, 2007

Why double posting.Any way there are two horizons one absolute horizon ,another apparent horizon.

nojocujo · Jul 8, 2007

I agree that there are two significant horizons but I don't know if we agree as to what they represent....I don't know if I would limit myself to just two though. Can you explain?

Hawking Radiation

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