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Author Topic: What is the Ultimate Fate of a Black Hole  (Read 26101 times)

lyner

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What is the Ultimate Fate of a Black Hole
« Reply #25 on: 22/09/2008 10:00:31 »
Don't forget that a black hole is, essentially, a local phenomenon. However massive it happens to be, it will only affect distant objects in the same way as an equivalent 'not-a-black-hole' in the same place. It is reckoned that we are orbiting a super massive black hole in the centre of our Galaxy. But it's only the total mass which is determining our orbit.
A black hole won't 'suck in' all the material of the Universe because there is too much angular momentum in the region around it to allow this to happen. The attractive force is just not great enough to do more than to keep stuff in orbit around it. (I am referring to distances way beyond any event horizon or any region where GR might come into play - not far, in cosmological terms, actually)
 

Offline deucemoi

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Re: What is the Ultimate Fate of a Black Hole
« Reply #26 on: 14/01/2014 04:52:07 »
"What happens to an isolated black hole then depends on whether the expansion of the universe has taken the microwave background temperature below the temperature of the black hole.  If the universe is cold enough it will evaporate incredibly slowly.  If the background is warmer it will grow slowly until the temperature drops low enough for the hole to start to evaporate."
what does microwave background temperature have to do with something as strong as a black hole?
 

Offline evan_au

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Re: What is the Ultimate Fate of a Black Hole
« Reply #27 on: 15/01/2014 08:42:19 »
If a black hole is near other matter, like an accretion disk, or the center of a galaxy, the black hole will grow through matter falling in, and you can ignore much smaller effects like:
  • Hawking Radiation, which would reduce the mass of a black hole over cosmological timescales. Assuming this effect really exists, the equivalent temperature of a solar-mass black hole is around 0.0000001 degrees absolute. This radiates mass extremely slowly.
  • Photons from the Cosmic Microwave Background radiation falling in. These photons currently have an equivalent temperature around 2.7 degrees absolute, so they carry very little mass. With an accelerating expansion of the universe, this equivalent temperature will reduce, contributing even less mass to the black hole in future.

Assuming that there are no infalling matter particles (eg electrons or protons), no light from stars falling in, and no neutrinos being absorbed by the black hole, the balance between Hawking Radiation and CMB is determined by which has the higher effective temperature - at the moment, the photons from the Cosmic Background radiation have a higher temperature than the Hawking temperature of a solar-mass black hole, so such a black hole will grow, extremely slowly.

Hawking radiation could be significant on very tiny black holes, from the atom-mass black holes that might one day be created in the LHC, up to black holes with the mass of a small asteroid.

See: http://en.wikipedia.org/wiki/Black_hole#Evaporation
 

Offline syhprum

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Re: What is the Ultimate Fate of a Black Hole
« Reply #28 on: 15/01/2014 10:40:00 »
http://www.livescience.com/27811-creating-mini-black-holes.html

"Still, conventional physics suggest it would take a quadrillion, or a million-billion, times more energy to form a microscopic black hole than the Large Hadron Collider is capable of, so even a third of that is beyond human reach. Scenarios based on extra dimensions could have black holes form at a lower energy, "but they make no concrete predictions on what it should be,"

I don't think we should worry too much !




 

Online Ethos_

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Re: What is the Ultimate Fate of a Black Hole
« Reply #29 on: 15/01/2014 16:31:52 »

BTW, it seems the general fate of a black hole is to be speculated about endlessly by physicists.
And to that endless debate, I'll add my own tidbit.

The mass/energy that falls into the black hole passes from our Brane to one of the adjacent branes that lie one either side of ours. We still recognize the influence of gravity because gravitational forces can pass unimpeded between those branes.

Or own big bang was such a passage creating our universe from a supermassive black hole in the brane lying next to ours.

To clarify: Like so many other speculations, this is just one in a multitude of others that may never be proven. Nevertheless, I think M theory is one of the best speculations defining the unexplainable.
« Last Edit: 15/01/2014 16:36:19 by Ethos_ »
 

Offline MrVat7

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Re: What is the Ultimate Fate of a Black Hole
« Reply #30 on: 23/01/2014 10:16:53 »
Black hole will eventually eat more and more matter to increase it's mass and then split into two.
 

Online Ethos_

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Re: What is the Ultimate Fate of a Black Hole
« Reply #31 on: 23/01/2014 16:41:22 »
Black hole will eventually eat more and more matter to increase it's mass and then split into two.
Never heard that explanation before. Where did you get your information and can you explain why a black hole should ever split into as you have suggested? According to general consensus, black holes will continue to grow as long as they have local matter upon which to feed. Nowhere have I ever read that black holes would divide or split into multiple parts. If you have a link to any information regarding this assertion, I would like for you to post it here so we could read about it.
 

Offline Mad Mark

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Re: What is the Ultimate Fate of a Black Hole
« Reply #32 on: 23/01/2014 22:26:36 »
What is the nature of a black hole without any space time outside the event horizon?
Is that how you make one go pop?
 

Offline yor_on

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Re: What is the Ultimate Fate of a Black Hole
« Reply #33 on: 24/01/2014 10:06:44 »
As long as we agree on what direction gravity has inside matter, which should be to some sort of a center, it seems most probable that a black hole won't split into two. To get it to split you need to introduce some 'force', able to split it, as for example tidal forces, overwhelming the gravitational 'infinite force' inside that event horizon, splitting it. That should then be a analogue to the idea of greater and smaller infinities, acting upon each other. So you need to make the angular momentum of a black hole infinite, relative the infinity of directional gravity described inside the event horizon. And if you really want to insist on it, making the angular momentum of a greater infinity :) to get to one infinity ripping another infinity apart :)

I know there is a theorem of lesser and greater infinity's, and that it seems logically sound, or mathematically as it is. But in a one to one correspondence, lifting out the 'bits', it then must end in a lesser infinity disappearing before a greater. Which to my eyes make for a definition in where a infinity has an end, either making a one to one correspondence meaningless as a foundation for describing a infinity, or making the ideas of infinity meaningless, as we always can introduce a greater infinity, then using a one to one correspondence to kill of the lesser, lifting 'bits' out.

Either way, using a one to one correspondence my way, it should never end, no matter what size of infinity you define. If you want there to exist infinity's? Defining it that way there is no way to define a magnitude of 'force' to a infinity, because if there was, there would be no infinity's.
 

Offline yor_on

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Re: What is the Ultimate Fate of a Black Hole
« Reply #34 on: 24/01/2014 10:18:17 »
There is a way around it though. the one assuming there is no end to any infinity, lifting out 'bits' in a one to one correspondence, from two infinity's of different magnitude. You then need to assume that as soon as we get to a definition of a infinity, the sum of its parts stop having a meaning. If you assume this, then there can't be any meaningful definition of greater and smaller infinity's. Which makes the mathematics into a dog biting its tail.
=

Or should that be a cat? :)
Ouch.
« Last Edit: 24/01/2014 10:22:27 by yor_on »
 

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Re: What is the Ultimate Fate of a Black Hole
« Reply #34 on: 24/01/2014 10:18:17 »

 

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