black holes/white holes

[cowman602]

I was doing a bit of thinking and as you know you can not create or destroy matter. So a black hole must go some where. A white hole is theorized to exist for that purpose. But what if a white whole is the equivalent of the big bang? What if every star that collapses and creates a black/white hole starts a new big bang in another universe/dimension? Not sure if this has been thought of yet as I am only in high school but I'm just looking for thoughts on the matter.

[imatfaal]

Cowman - it's been thought of a lot, but no one has a good answer yet.

 

one thing to bear in mind - black holes do not destroy matter, they merely crunch it up very small and take it beyond possible observation and out of our knowledge. BHs actually give back the matter they have absorbed through the emission of Hawking Radiation; but for massive black holes this is a very long process and will not really start to have an effect until the universe is cold and dark in the long distant future (ie only when the black hole is warmer than the vacuum of space).

 

we have no real idea of what happens beyond the event horizon of a black hole - and there is no way we can observe it. The idea you explained, and many others, are great notions and interesting - but until they can produce testable hypotheses observable outside the event horizon they are just nice ideas.

[cowman602]

Thanks for your input

[Andeh]

I think that this problem is called the "black hole information paradox"

 

I've always thought of it like this:

from the perspective of an object falling into a black hole, it would enter the black hole and be destroyed. But from the perspective of an outside observer, the object's motion would slow as it neared the event horizon because of time dilation, and NEVER ACTUALLY REACH THE EVENT HORIZON, in other words, it would not be destroyed. So for all intents and purposes, it's information is not destroyed.

 

 

And imaatfall, I thought that Hawking radiation was caused by virtual particles forming near a blackhole so that one goes into the blackhole and one is released. How does that have to do with "giving back the matter"?

 

 

[MigL]

There is no law that prohibits the destruction of matter!

There is a law that prohibits the destruction of mass/energy, and black holes being good citizens of the universe, dutifully obey this law. They conserve both mass and energy, so there is no need to postulate 'white holes'.

[imatfaal]

I think that this problem is called the "black hole information paradox"

 

I've always thought of it like this:

from the perspective of an object falling into a black hole, it would enter the black hole and be destroyed. But from the perspective of an outside observer, the object's motion would slow as it neared the event horizon because of time dilation, and NEVER ACTUALLY REACH THE EVENT HORIZON, in other words, it would not be destroyed. So for all intents and purposes, it's information is not destroyed.

 

 

And imaatfall, I thought that Hawking radiation was caused by virtual particles forming near a blackhole so that one goes into the blackhole and one is released. How does that have to do with "giving back the matter"?

 

The black hole information paradox is slightly different; that has to do with the loss of information. Heuristically; when a black hole absorbs information-rich matter and emits information-poor radiation, and this process continues till the black hole has evaporated there has been a loss of information which is forbidden. You can read more here

 

What Cowman was asking was what happens to the matter - and did this violate a conservation law, and could the solution be a reciprocal white hole that spewed out matter.

MIGL correctly pointed out that there is no conservation of matter, the conservation is of matter/energy.

 

Blackholes take in matter and energy and remove it from our ken and any possibility of observation - when Bekenstein and Hawking showed that black holes have a temperature and must emit radiation it became clear that the removal of energy and matter from outside the event horizon was not a one way irreversible process. The description of Hawking radiation via one of a virtual particle going one way and the other going into the BH is a little misleading - however the actual explanation is beyond me; however the upshot is that Hawking radiation can be seen as the evaporation of the blackhole (ie any energy radiated is balanced by mass loss).

[cowman602]

see that is why i like science. you think you know a lot then bam! someone blows your mind again. thank you a lot for your guys's input on the subject i feel like i learned a lot

[Dekan]

The black hole information paradox is slightly different; that has to do with the loss of information. Heuristically; when a black hole absorbs information-rich matter and emits information-poor radiation, and this process continues till the black hole has evaporated there has been a loss of information which is forbidden.

 

Could you expand, please, on why loss of information should be forbidden? Surely it happens all the time. For example, suppose you take a printed book. The book might be a physics textbook, or the complete works of Shakespeare, or an atlas, or whatever.

 

Whatever the book is, it contains a lot of information. Then you set fire to the book. When the fire has finished burning, all that's left is a pile of ashes. Plus some smoke and gas, which has escaped into the atmosphere, and become randomly distributed.

 

The fire has, so to speak, absorbed the information-rich book, and emitted information-poor ash and gas.

 

If a fire can do that, why can't a black hole do it too?

[imatfaal]

Could you expand, please, on why loss of information should be forbidden? Surely it happens all the time. For example, suppose you take a printed book. The book might be a physics textbook, or the complete works of Shakespeare, or an atlas, or whatever.

 

Whatever the book is, it contains a lot of information. Then you set fire to the book. When the fire has finished burning, all that's left is a pile of ashes. Plus some smoke and gas, which has escaped into the atmosphere, and become randomly distributed.

 

The fire has, so to speak, absorbed the information-rich book, and emitted information-poor ash and gas.

 

If a fire can do that, why can't a black hole do it too?

 

 

To be honest - I cannot truly understand it, let alone explain it; here is wikipedia's attempt

 

A postulate of quantum mechanics is that complete information about a system is encoded in its wave function, an abstract concept not present in classical physics. The evolution of the wave function is determined by a unitary operator, and unitarity implies that information is conserved in the quantum sense. There are two main principles at work: quantum determinism, and reversibility. Quantum determinism means that given a present wave function, its future changes are uniquely determined by the evolution operator. Reversibility refers to the fact that the evolution operator has an inverse, meaning that the past wave functions are similarly unique. With quantum determinism, reversibility, and a conserved Liouville measure, the von Neumann entropy ought to be conserved, if coarse graining is ignored.

 

 

 

[MigL]

I wold go so far as to say there is no such thing as information conservation, yet. It is a quantum mechanical concept being applied to the 'classical' theory of GR. Only a quantum gravity theory will provide answers.

[DrRocket]

I was doing a bit of thinking and as you know you can not create or destroy matter. So a black hole must go some where. A white hole is theorized to exist for that purpose. But what if a white whole is the equivalent of the big bang? What if every star that collapses and creates a black/white hole starts a new big bang in another universe/dimension? Not sure if this has been thought of yet as I am only in high school but I'm just looking for thoughts on the matter.

 

There are (exotic) white hole solutions to the vfield equations of general relativity. However, there is not the slightest bit of evide4nce that white holes actually exist.

 

Conservation of mass/energy does not in any way imply that black holes must "go somewhere" and in fact that phrase is meaningless.

 

Imagination is good. But in science imagination must be tempered with knowledge of what is already known and the limitations that imposes on potentially valid theories, else what you have is not imagination but just fantasy.

 

I wold go so far as to say there is no such thing as information conservation, yet. It is a quantum mechanical concept being applied to the 'classical' theory of GR. Only a quantum gravity theory will provide answers.

 

Physicists tend to be rather loose when discussing "conservation of information", but a rigorous treatrment seems to be equivalent to stating that the quantum mechanical state function evolves according to a one-parameter family of unitary transformations. A violation of that principle would be a very big deal.

 

The black hole information problem is that under a scenario proposed by Hawking unitarity would appear to be violated. However a way around that has been proposed, and Hawking has conceded a bet that he make with Preskill. Butr, not everyone accepts Hawking's conclusion, including Kip Thorne who is also a party to the bet. Moreover, the "resolution" involves string theory and the AdS/CFTcorrespondence, which itself is an unproved conjecture of Maldecena that dates from about 1997.

 

There is a very one-sided, biased and misleading account of this problem in Leonard Susskind's book The Black Hole War. You may find it enlightening, but be forewarned that you should read it with a lot more than just a grain of salt.

[TheOnlyMaster]

you might find this of interest http://news.nationalgeographic.com/news/2010/04/100409-black-holes-alternate-universe-multiverse-einstein-wormholes/