White holes, black holes


by kernelpenguin
Tags: black, holes, white
kernelpenguin
kernelpenguin is offline
#1
Jul20-04, 10:01 AM
P: 47
Do physicists nowadays accept the possibility of a white hole or not? I heard from someplace that quasars are considered by some to be white holes simply because for a quasar to be as bright as it is and for it to be a supermassive black hole, it would have to consume more matter each year than there could be around it.

I was wondering, if it's the exact opposite of a black hole, shouldn't time speed up near it? And where would this matter come that's flowing out of it all the time?

White holes were considered to be the 'exit points' of black holes, or so I've heard. So I guess the concept was created to deal with the existence of black holes and to get the matter out of them again. But if a black hole emits radiation and finally evaporates, then there's no need for white holes anymore, is there?

Speaking of which, what exactly happens when a black hole has lost enough energy via evaporation that its mass is no longer sufficient for it to be a singularity? Would a sea of very high energy photons stream out of it? Or would there be other particles as well? Could a stellar body of some sort form in its place?

Would such a black hole's end of life explain the very high energy particles that have been observed?
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MiGUi
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#2
Jul20-04, 02:29 PM
P: 183
As I know, white holes are supposed due to simetry in RG equations. As black holes devour energy and matter from space, white holes are supposed to throw high quantities of matter and energy.

But, if something were throwing energy in the universe, I think that we would have some indication of their existence, as we have several candidates to be black holes.

I think that white holes are NOT supposed to be the exit of NOTHING. That's only Sci-Fi, and its only the way to suppose the existence of wormholes.
meteor
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#3
Jul20-04, 05:00 PM
P: 915
I'm sure that you have heard of something called "acoustic black holes" -they trap sound. Well, there's the complement, in analogy with their big brothers, the sonic white holes, they can serve to try to determine if the cosmological white holes really exist
http://arxiv.org/abs/gr-qc/0211069

urtalkinstupid
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#4
Jul20-04, 07:43 PM
P: 261

White holes, black holes


Personally, I deny the existance of black holes. For this arguement, I'll revert my mind to when I did believe of the black hole's existance. Black holes are now said to be a string with the mass of the neutron star it was condensed from. This would in turn make this string quite dense. Well, an object just the opposite of that? White holes are not real, they are just a possible solution to equation:

[tex]E^2=m^2_0c^4+p^2c^2[/tex]

How can the existance of white holes be rational when Einstein himself even doubted the existance of black holes which seemed to be a possibility from his work in physics?
kernelpenguin
kernelpenguin is offline
#5
Jul21-04, 02:42 PM
P: 47
Meteor, no, I haven't heard of sonic black nor white holes. Could you give us a short summary of those two?

Well, let's view white holes as purely theorethical constructs that are possible according to the best theory we have about spacetime. As such, what would be the properties of such a beast?

Would time slow down or speed up near a white hole?
Would a white hole be gravitationally repulsive or attractive?
Where would all this energy come from that the white hole spews out? (Virtual particles materializing because of its repulsive force?) Wouldn't it violate a few rules? Like the simple fact that you can't make something from nothing? (And doesn't the theory which allows white holes take this into account?)
If a black hole consists of too much mass in one place, what would a white hole consist of?

Is there anyone here that thinks quasars could be white holes?
meteor
meteor is offline
#6
Jul22-04, 08:25 PM
P: 915
Meteor, no, I haven't heard of sonic black nor white holes. Could you give us a short summary of those two?
I have read that some scientists, Liberati one of them, believe that is poosible to create acoustic black holes. They create a flow, and then accelerate some portion of it to supersonic velocity, and then this supersonic flow is able to trap sound waves. The event horizon of a cosmological black hole is called in this case "acoustic horizon", and in analogy with Hawking radiation, should also emit things, in this case phonons (the quasiparticle associated with some theories of superconductivity)
Chronos
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#7
Jul23-04, 12:58 AM
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P: 9,182
Doubtful that quasars are white holes. There are other theories [supermassive black holes in proto-galaxies] that are reasonable and consistent with the mathematics we currently understand. Not to say white holes have been ruled out, just that we still have other candidates more worthy and practical to test before resorting to the less probable explanations. The process of science is one of economics. We have very limited resources to work with. Bang for the buck is the driving force. History supports the premise it is better to nibble than gulp.


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