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Digix
2008-Oct-22, 07:44 PM
Seem that Hawking radiation relies on black hole ability to break symmetry or mater-antimatter because result is pure mater annihilation.

As I know currently there are no known facts or at least plausible theories how that can happen. So why Hawking radiation is so easily accepted?

SagoSans
2008-Oct-22, 08:34 PM
Seem that Hawking radiation relies on black hole ability to break symmetry or mater-antimatter because result is pure mater annihilation.


No. Hawking radiation relies on "vacuum fluctuations": particle and anti-particle pairs are created in vacuum (not only near black holes), exist for a limited time and disappear again ("virtual particles"). When this happens near the event horizon of a black hole, there's a chance that one is sucked into the black hole and it's partner gets away and becomes a "real" particle. The stream of escaping particles is what's called "Hawking radiation". No symmetry is broken.

A thread in the PhysOrgForum (http://www.physforum.com/index.php?act=ST&f=9&t=6603) has a picture, just scroll down a bit. You can view a larger image if you right-click on it and select "View Image" (or however that works with your browser) - I didn't want to hot-link it.

timb
2008-Oct-22, 09:08 PM
No. Hawking radiation relies on "vacuum fluctuations": particle and anti-particle pairs are created in vacuum (not only near black holes), exist for a limited time and disappear again ("virtual particles"). When this happens near the event horizon of a black hole, there's a chance that one is sucked into the black hole and it's partner gets away and becomes a "real" particle. The stream of escaping particles is what's called "Hawking radiation". No symmetry is broken.

A thread in the PhysOrgForum (http://www.physforum.com/index.php?act=ST&f=9&t=6603) has a picture, just scroll down a bit. You can view a larger image if you right-click on it and select "View Image" (or however that works with your browser) - I didn't want to hot-link it.

How is no symmetry broken? X kg of matter go into the black hole at formation and X kg of matter and X kg of antimatter come out (let's ignore photons etc) as Hawking radiation. That thread you linked to seems to have every sort of crank theory about BHs.

SagoSans
2008-Oct-22, 09:12 PM
How is no symmetry broken? X kg of matter go into the black hole at formation and X kg of matter and X kg of antimatter come out (let's ignore photons etc) as Hawking radiation. That thread you linked to seems to have every sort of crank theory about BHs.

There's as much outcoming matter as outcoming antimatter. I've linked the thread for the image only.

Of course the process is a bit more complex and involves quantum tunneling, but I hope you get the gist.

SagoSans
2008-Oct-22, 09:35 PM
How is no symmetry broken? X kg of matter go into the black hole at formation and X kg of matter and X kg of antimatter come out (let's ignore photons etc) as Hawking radiation.

After re-reading your response I want to add some additional info:

The infalling particles have negative energie with respect to an observer far away and balance the outgoing Hawking radiation.

Here's Klaus Kiefer: Towards a Full Quantum Theory of Black Holes (http://xxx.lanl.gov/abs/gr-qc/9803049) from arXiv with a lot of gory details.

The "balancing" negative energie flux into the black hole is described on page 5.

timb
2008-Oct-22, 09:51 PM
After re-reading your response I want to add some additional info:

The infalling particles have negative energie with respect to an observer far away and balance the outgoing Hawking radiation.

Here's Klaus Kiefer: Towards a Full Quantum Theory of Black Holes (http://xxx.lanl.gov/abs/gr-qc/9803049) from arXiv with a lot of gory details.

The "balancing" negative energie flux into the black hole is described on page 5.

Thank you for your replies but neither of them addresses my point.

SagoSans
2008-Oct-22, 10:17 PM
Thank you for your replies but neither of them addresses my point.

Sorry for that. :cry:

(1) Matter/anti-matter
I think this should be clear.

(2) Enegry conservation
The outgoing Hawking radiation is energy. The energy "is paid" for by the black hole in form of lost mass.
E.g. 1kg of mass (=energy) is radiated away from the black hole but at the same time the black hole loses 1kg of mass. Nothing lost (as long as Hawking is right :) )

Digix
2008-Oct-22, 10:49 PM
Symetry is broken because we can imagine black hole as black box which performs such action:

you throw some baryonic crap inside and get photons.
so symmetry is broken, matter is converted to photons.
how that is done we don't care. Only end result matters.
mater ->blackhole-> photons

in case if you say that negative energy falls inside of black hole, then it still need to break symmetry, because how do you expect cancellation of negative photon and normal positive electron that fell inside?

We can make assumption that these do not cancel each other and black hole will still lose energy, but in the end there will be naked singularity with zero energy, zero gravity, which is made of incredible amount of positive and negative energy that cant cancel each other. I expect this thing to blow up and break energy conservation law in that case.

grant hutchison
2008-Oct-22, 11:28 PM
Black holes generate extreme environments which seem likely to generate Grand Unification conditions, where we would expect this sort of symmetry-breaking.
Understanding the physical nature of the singularity is going to require some sort of unification physics, one would guess. Outside the event horizon, the Hawking radiation temperature during the last moment of black hole evaporation will spike into GUT territory. And, perhaps more importantly, an observer lowered gently towards the event horizon and brought to a halt just above it will find a bath of Unruh radiation, the temperature of which tends to infinity as the event horizon is approached. Since Hawking radiation can be treated as the gravitationally redshifted remnant of this intense radiation, it's again maybe not surprising that we can drop baryons in and get photons, or leptons, or whatever, out.

Grant Hutchison

Digix
2008-Oct-23, 01:11 AM
Black holes generate extreme environments which seem likely to generate Grand Unification conditions, where we would expect this sort of symmetry-breaking.


Of course that is not impossible but still there is no theoretical proof that such symmetry breaking can happen.
So hawking radiation is based on some speculation.
Isn't that useless? how can you create strong theories that are based on completely unproven facts?
I think it would be more reasonable to make that grand unification theory before rushing with "absolutely correct" derivatives that come from unproven stuff.

Also if any way for symmetry breaking is possible it must be meaning of existence for humanity, because ability to break mater antimatter symmetry is equal to procession half of God powers.
Imagine that all matter around becomes usable energy source.

cjameshuff
2008-Oct-23, 01:20 AM
Of course that is not impossible but still there is no theoretical proof that such symmetry breaking can happen.

CP symmetry violation has not only been predicted by theory, it has been observed, and the amount of matter seen in the universe indicates larger violations exist, though the fact we haven't seen them indicates they'll be at fairly high energies. It does not seem likely it'd lead to matter annihilation energy sources any time soon...

Digix
2008-Oct-23, 01:47 AM
CP symmetry violation has not only been predicted by theory, it has been observed, and the amount of matter seen in the universe indicates larger violations exist, though the fact we haven't seen them indicates they'll be at fairly high energies. It does not seem likely it'd lead to matter annihilation energy sources any time soon...

however that also does not give any reason to think that it also can happen inside of black hole, because beginning of universe is so much different from everything we know that usual physic laws are almost useless.
And small black hole is still somehow different from rudimentary universe. because something was different there for sure

The strangest thing then is that hawking cared to make that useless theory, but nobody ever cared to even suggest ability to make power source in that way.

lets say that LHC could produce black holes that can evaporate, that means we already have some kind of future energy source prototype. All world would be excited with such possibility. Unlimited energy source forever practically same as perpetual motion device.
finally interstellar and intergalactic travels are possible you can practically reshape entire universe according to your own will.

timb
2008-Oct-23, 04:21 AM
however that also does not give any reason to think that it also can happen inside of black hole, because beginning of universe is so much different from everything we know that usual physic laws are almost useless.
And small black hole is still somehow different from rudimentary universe. because something was different there for sure

The strangest thing then is that hawking cared to make that useless theory, but nobody ever cared to even suggest ability to make power source in that way.


ehem (http://www.bautforum.com/questions-answers/79459-hawking-radiation-2.html#post1335337)...


lets say that LHC could produce black holes that can evaporate, that means we already have some kind of future energy source prototype. All world would be excited with such possibility. Unlimited energy source forever practically same as perpetual motion device.
finally interstellar and intergalactic travels are possible you can practically reshape entire universe according to your own will.

The main problem I see is the complete infeasibility of creating blackholes in the required mass range.

Digix
2008-Oct-23, 05:35 AM
Mass does not matter much, as long as you can create any black hole of any size it will do job at some degree.
of course big mass black holes allow you to feed them with the stream of particles and so you can use them as photon engine for spaceship.
if black hole is too small you will not be able to feed it fast enough to disallow evaporation.

but still that is just one of the options, maybe black holes are unnecessarily at all. If symmetry is breakable maybe it can be broken in other way.
----------------------

I just had a new idea.
If everybody finally agree that black holes can break symmetry maybe they also can break conservation of charge?
what if we drop lots of positive ions into black hole and make it charged?
if it can break symmetry then hell knows what will happen to the particles that fall inside. i dont see why it cant convert electron into positron or quark into antiquark we still have no idea what is charge and what is actual charge carrier . if conditions are so exotic beyond reach of any logic, then everything may be possible. it may be able to destroy charge carriers or change polarity.

afterall if you drop some proton into black hole and it becomes something without name without volume then why that entity should still conserve its charge?

Is there any reason to think that breaking symmetry is possible while breaking charge conservation is not?

JTankers
2008-Oct-23, 01:00 PM
Black hole do not radiate by definition. They do not allow electro-magnetic radiation to escape, including magnetism, that is common sense, black holes are neutral at the event horizon.[1].

Steven Hawking's conjecture is that he does not know how energy escapes, he just suspects it would (he is wrong). Negative Energy, time reversal and faster than light tunneling[2] are figments of Steven Hawking's imagination. Physicists figured this out[4][5] but it is very inconvenient to admit he was wrong[5].

[1] www.wissensnavigator.com/documents/OTTOROESSLERMINIBLACKHOLE.pdf Abraham-Solution to Schwarzschild Metric Implies That CERN Miniblack Holes Pose a Planetary Risk, Prof. Dr. Otto Rossler (2008)
[2] http://projecteuclid.org/DPubS/Repository/1.0/Disseminate?view=body&id=pdf_1&handle=euclid.cmp/1103899181, Particle Creation by Black Holes, S. W. Hawking (12 Apr 1975)
[3] xxx.lanl.gov/abs/gr-qc/0304042 Do black holes radiate?. Dr. Adam Helfer (2003)
[4] arxiv.org/abs/gr-qc/0607137, On the existence of black hole evaporationyet again, Prof. VA Belinski (2006)
[5] http://www.lhcfacts.org/?p=72 CERN’s Dr. Ellis tells only half of the story (2008)

Digix
2008-Oct-23, 01:49 PM
JTankers, I also think all that negative energy and time reversal nonsenses are just bluff, but for mathematician thre is no problem to count imaginary chicken if he gets somehow correct results.
anyway, tunneling is still possible way to escape, imagine if this is relatively small diameter black hole and it has lots of coffined photons inside, it is not even impossible that black hole will be smaller that wavelength of some photons. such ones will escape almost instantly.

same with electron, if you have micro black hole they also can tunnel out, and if you apply some force you can remove tunneled electron away.

same thing as usual thermionic emission. when cathode and anode are very close electrons can cross insulator like there is nothing. even if they have not even remotely enough energy to leave metal.

cjameshuff
2008-Oct-23, 02:05 PM
however that also does not give any reason to think that it also can happen inside of black hole, because beginning of universe is so much different from everything we know that usual physic laws are almost useless.
And small black hole is still somehow different from rudimentary universe. because something was different there for sure

"Something was different"?

We know it's possible to break the symmetry, we've observed it being broken, so "it's impossible to break the symmetry" is not a valid argument. Yes, a black hole is rather different from the big bang, but it is closer than most other things, and it's perfectly reasonable to expect some of the same effects to show up.



lets say that LHC could produce black holes that can evaporate, that means we already have some kind of future energy source prototype. All world would be excited with such possibility. Unlimited energy source forever practically same as perpetual motion device.

...are you trying to use the fact that you've never heard of black holes being proposed as power sources as proof that they can't be used as such?

It's not a new idea, it's one I've seen many times...Earth by David Brin comes to mind as one instance where it was the basis of the book's plot. It hasn't been proposed for a real-world power source due to the difficulty of producing black holes (the LHC is expected to fall far short) and the terrible inefficiencies involved in the most plausible ways for doing so. Say you manage to make a 22000 proton mass (20 TeV) black hole...2 proton masses of that came from input matter, the rest came from input energy in accelerating those protons to collision. If losses in accelerating the protons are greater than 0.009%, all you have is a very energy intensive way of disposing of excess protons.

Digix
2008-Oct-23, 03:51 PM
"Something was different"?

We know it's possible to break the symmetry, we've observed it being broken, so "it's impossible to break the symmetry" is not a valid argument. Yes, a black hole is rather different from the big bang, but it is closer than most other things, and it's perfectly reasonable to expect some of the same effects to show up.
not so fast, we also observed breaking of energy conservation law too in that case.
and again it is reasonable to expect broken symmetry, but you are required to mention that before proposing idea about black hole radiation.
since they are highly dependable on each other

and symmetry breaking also requires some explanation what happens to the particles, how they are converted. For example how we can make Positron from proton. what happens to charge. Lots of interesting questions arise


...are you trying to use the fact that you've never heard of black holes being proposed as power sources as proof that they can't be used as such?

ok I understand that now, process is just to slow and hard to perform to be usable
but in the far future, with the help of nanotecnology it may become somehow usable.

JTankers
2008-Oct-24, 01:39 AM
JTankers, I also think all that negative energy and time reversal nonsenses are just bluff, but for mathematician thre is no problem to count imaginary chicken if he gets somehow correct results.

Fair enough, but I'm not aware of a good argument that black hole evaporation should be assumed to be the "correct result". No evaporation or reverse HR (growth from quantum effects) appears to be the more probable result.

Besides that, I can't imagine someone wanting to create a black hole on Earth just to see what would happen. How is that different from the guy that bought a surplus solid fuel rocket, welded it to his car and set it off to see what would happen? (He died, Darwin Awards 2005).

Jeff Root
2008-Oct-24, 08:46 AM
Black holes generate extreme environments which seem likely to
generate Grand Unification conditions, where we would expect this
sort of symmetry-breaking.
I'm not aware of anything that I would call "symmetry-breaking"
in Hawking radiation. If there is, could you describe it for me?

-- Jeff, in Minneapolis

cjameshuff
2008-Oct-24, 02:37 PM
I'm not aware of anything that I would call "symmetry-breaking"
in Hawking radiation. If there is, could you describe it for me?

It effectively reverses baryogenesis, violating CP symmetry. You start with matter, get photons back, which if converted back to matter give exactly (well, almost exactly) equal amounts of antimatter. I'm not sure about charge conservation...it seems that once the mass of a charged black hole dropped enough (relative to its charge), it would be able to push the like-charged half of a particle/antiparticle pair just above the event horizon to infinity, neutralizing its charge and conserving charge overall, but this hasn't been mentioned in any reliable description of Hawking radiation that I've seen.

But...we know this symmetry can be broken, so using it as evidence of the absurdity of Hawking radiation seems...unconvincing.

Digix
2008-Oct-24, 03:24 PM
Fair enough, but I'm not aware of a good argument that black hole evaporation should be assumed to be the "correct result". No evaporation or reverse HR (growth from quantum effects) appears to be the more probable result.

Besides that, I can't imagine someone wanting to create a black hole on Earth just to see what would happen. How is that different from the guy that bought a surplus solid fuel rocket, welded it to his car and set it off to see what would happen? (He died, Darwin Awards 2005).

if you imagine some kind of microblackhole you may be able to understand.
black hole singularity is basically very hot "lava" because everything falls and provides enormous energy to that.
so any hot black body radiates all spectrum of EM waves.
and here we jyst use analogy with tunneling mode of semiconductors.

Yes, black hole does not allow to escape, same like insulator does not allow to pass electrons, but they still easily pass it if insulator is very thin
so with black hole same will happen as in normal tunnel diode because that no escape region is thin.

also same is valid with blackhole growth, electrons and protons need to get inside and that is quite improbable id crossection is small electrons will just orbit around tunnel through it or just escape instantly.

after all particles are not points but cloud like entities.

Cougar
2008-Oct-24, 03:50 PM
Yes, a black hole is rather different from the big bang, but it is closer than most other things, and it's perfectly reasonable to expect some of the same effects to show up.
not so fast, we also observed breaking of energy conservation law too in that case.
We "observed" no such thing. In fact, the gravitational potential energy and the mass energy may very well balance precisely, making our universe the "ultimate free lunch," as Alan Guth put it, which requires no violation of conservation laws.


...and again it is reasonable to expect broken symmetry, but you are required to mention that before proposing idea about black hole radiation. since they are highly dependable on each other...

Symmetry - yes, a very important concept in physics, but I fail to see any importance to the point you're trying to make. When water freezes, symmetry is broken. So what? This is merely an analogy to help understand the profound symmetry breaking in the very early universe, where the four forces sequentially broke off from their prior unified state as the expanding universe cooled below certain threshold temperatures. Similarly, the hypothesized black hole conversion of mass to energy is likewise a mere analogy of the four-force symmetry breaking that is of keen interest to physicists.

Digix
2008-Oct-24, 05:56 PM
We "observed" no such thing. In fact, the gravitational potential energy and the mass energy may very well balance precisely, making our universe the "ultimate free lunch," as Alan Guth put it, which requires no violation of conservation laws.
ok, but why such extremely important thing is so neglected
I was unable to find anything amiut that energy balance, and basically since all here are relativists, they talk about space time only, in that case it is hard to balance spacetime dilution with rest mass.
since logically our mass is positive energy, then I don't see any way to make it free lunch without something negative.



Symmetry - yes, a very important concept in physics, but I fail to see any importance to the point you're trying to make. When water freezes, symmetry is broken. So what? This is merely an analogy to help understand the profound symmetry breaking in the very early universe, where the four forces sequentially broke off from their prior unified state as the expanding universe cooled below certain threshold temperatures. Similarly, the hypothesized black hole conversion of mass to energy is likewise a mere analogy of the four-force symmetry breaking that is of keen interest to physicists.

for hawking radiation to be possible symmetry must be broken so before you postulate that radiation you must at least guess it.
you cant just say some statment that contradicts with some insignificant part of physic and then say oh well, I guess that will work out somehow.
if these are separate, then just imagine what will happen if hawking radiation is true but back hole does not break symmetry?
I believe that is also possible.

none of hawking radiation explanations involve symmetry breaking and neither the prof of its existence takes it into account.

I dont say that hawking radiation is complete nonsense, but it must always come with mentioning of symmetry breakage.
because as you saw here bunch of people even do not suspect such important thing.

Grey
2008-Oct-24, 07:01 PM
Digix, what I think you're describing is the information paradox (http://en.wikipedia.org/wiki/Black_hole_information_paradox) associated with the "black holes have no hair" (http://en.wikipedia.org/wiki/No_hair_theorem) idea. That is, you throw in some baryons, but once they're inside the black hole, all the information about them (like how many there were) is lost forever. Hawking made a bet that this was the case, but in 2004, he actually conceded (http://en.wikipedia.org/wiki/Thorne-Hawking-Preskill_bet) that bet. Essentially, Hawking now believes that black holes "have hair" after all, and if you throw in a bunch of baryons, you'll eventually get that same number of baryons back out by the time the black hole finally evaporates. Not everyone agrees with that idea (in particular, Kip Thorne, who was also in on the bet, remains unconvinced). You can read Hawking's paper about the issue in detail here (http://arxiv.org/abs/hep-th/0507171).

Digix
2008-Oct-24, 07:23 PM
Digix, what I think you're describing is the information paradox (http://en.wikipedia.org/wiki/Black_hole_information_paradox) associated with the "black holes have no hair" (http://en.wikipedia.org/wiki/No_hair_theorem) idea. That is, you throw in some baryons, but once they're inside the black hole, all the information about them (like how many there were) is lost forever. Hawking made a bet that this was the case, but in 2004, he actually conceded (http://en.wikipedia.org/wiki/Thorne-Hawking-Preskill_bet) that bet. Essentially, Hawking now believes that black holes "have hair" after all, and if you throw in a bunch of baryons, you'll eventually get that same number of baryons back out by the time the black hole finally evaporates. Not everyone agrees with that idea (in particular, Kip Thorne, who was also in on the bet, remains unconvinced). You can read Hawking's paper about the issue in detail here (http://arxiv.org/abs/hep-th/0507171).

so you suggest now that black holes do not break symmetry after all?

anyway it still look so strange when someone is trying to use contradicting theories to get proper result.

because if we use quantum mechanic it is clearly obvious that small black hole is completely different from big black hole.
in case of microblackholes anything can enter and leave singularity anytime because of simple tunneling.
and in case of some extremely micro black hole it will not even have stable horizon, because singularity will statistically spend half of time outside of horizon

Grey
2008-Oct-24, 08:05 PM
so you suggest now that black holes do not break symmetry after all?Not quite. I suggest that the experts on black holes, who understand the theories and observations far better than I do, don't agree on the matter. I think most theorists used to agree that information was lost when objects entered a black hole (which can lead to the symmetry breaking you describe: matter with a nonzero baryon number goes in, energy with baryon number zero comes out), although presumably Preskill, who bet against Hawking in the first place, never felt that way. Now Hawking and others don't think that information is lost, while Thorne presumably still thinks it is. Of course, as others have pointed out, we've observed CP violations (netural kaon decay, in 1964), so we already know the symmetry between matter and antimatter is broken in some instances. But there's not necessarily agreement within the mainstream about whether black holes specifically violate that symmetry or not.

Take heart, though. Any time you can find a question where Stephen Hawking and Kip Thorne disagree, that's probably a good sign that you've stumbled on an interesting question. Unfortunately, understanding enough math to know what those two are actually saying about the issue is a bit of a challenge. :)