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How will the universe end ?

by Abidal Sala
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Abidal Sala
#1
Feb6-12, 02:58 AM
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If we proposed that the universe is expanding forever, will black holes eventually get rid of all ordinary matter? and what remains of the universe is just dark matter and dark energy ?
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Cantstandit
#2
Feb6-12, 05:12 AM
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If there is a black hole in the center of a galaxy, then it will probably suck the galaxy into it eventually, but I don't know if every galaxy has to have black hole in its center, or if it's not possible for a body to have stable orbit around such black hole.

Dark matter and dark energy are not necessarily actual matter and energy. These are just placeholder names for phenomena that we don't yet understand that look *like* it were matter and energy at work, that we can't see. It could turn out that it's not an additional matter, but that our equations were wrong, or that we were looking in wrong place/wrong way.
Ryan_m_b
#3
Feb6-12, 06:04 AM
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There are multiple ideas as to the ultimate fate of the universe such as the heat death.
Quote Quote by jadeturners View Post
I am not looking forward to witnessing the end of the universe. It's just so horrible.
Considering the time scales involved are on the order of 10100 years (ten thousand, trillion, trillion trillion, trillion, trillion, trillion, trillion, trillion times greater than the current age of the universe) I doubt anyone will be around to see it.

salvestrom
#4
Feb6-12, 01:52 PM
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How will the universe end ?

Quote Quote by Cantstandit View Post
If there is a black hole in the center of a galaxy, then it will probably suck the galaxy into it eventually, but I don't know if every galaxy has to have black hole in its center, or if it's not possible for a body to have stable orbit around such black hole.

Dark matter and dark energy are not necessarily actual matter and energy. These are just placeholder names for phenomena that we don't yet understand that look *like* it were matter and energy at work, that we can't see. It could turn out that it's not an additional matter, but that our equations were wrong, or that we were looking in wrong place/wrong way.
Sean M Carroll stated (in a talk on cosmology) that all matter would end up in blackholes. I had previously ventured this opinion on these boards and was told 'no, that won't happen'. I currently have no idea who's right. This seems like a good thread to hammer it out.
Ryan_m_b
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Feb6-12, 01:57 PM
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Quote Quote by salvestrom View Post
Sean M Carroll stated (in a talk on cosmology) that all matter would end up in blackholes. I had previously ventured this opinion on these boards and was told 'no, that won't happen'. I currently have no idea who's right. This seems like a good thread to hammer it out.
Why would you think it would? Note that black holes do not "suck". The gravity of a black hole is no different to the gravity of anything else, if the sun suddenly became a black hole it would make absolutely no difference to Earth's orbit (though it would get quite cold). To say that all matter will end up in black holes is to imply that over deep time all matter will at some point come into contact with a black hole. Without clear maths showing the probability of that it is an unfounded assertion especially considering the vanishingly small volume of the universe occupied by black holes.

See this section of the link I provided above.
salvestrom
#6
Feb6-12, 02:32 PM
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Quote Quote by Ryan_m_b View Post
Why would you think it would? Note that black holes do not "suck". The gravity of a black hole is no different to the gravity of anything else, if the sun suddenly became a black hole it would make absolutely no difference to Earth's orbit (though it would get quite cold). To say that all matter will end up in black holes is to imply that over deep time all matter will at some point come into contact with a black hole. Without clear maths showing the probability of that it is an unfounded assertion especially considering the vanishingly small volume of the universe occupied by black holes.

See this section of the link I provided above.
Why I would think so isn't relevant. I was already shot down. The actual question is why did Sean M Carroll say it would.

EDiT: I actually read that link. It says 1-10% of a galaxy's content will end up in the blackhole. The rest will be flung out into empty space and decay into photons.
Haelfix
#7
Feb6-12, 02:59 PM
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There is a blackhole era, where most matter in galaxies will be concentrated (the rest will have decayed into photons and/or be ejected)

See

http://en.wikipedia.org/wiki/Future_...nding_universe

But eventually they too will decay away via Hawking radiation.

What happens after that point is a real puzzle. The approximations used in statistical mechanics start to break down when you deal with length and timescales of that magnitude, and all sorts of exotic effects start to become possible!
Drakkith
#8
Feb6-12, 04:46 PM
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Wouldn't orbital energy be radiated away over huge timescales by gravity waves?
Haelfix
#9
Feb6-12, 07:33 PM
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There are several effects at play. Stellar winds, accretion rate's of matter etc. But over long timescales black holes mostly grow until the CMB cools sufficiently at which point Hawking radiation will dominate.
ynot1
#10
Feb11-12, 08:26 AM
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Quote Quote by Haelfix View Post
There is a blackhole era, where most matter in galaxies will be concentrated (the rest will have decayed into photons and/or be ejected)

See

http://en.wikipedia.org/wiki/Future_...nding_universe

But eventually they too will decay away via Hawking radiation.

What happens after that point is a real puzzle. The approximations used in statistical mechanics start to break down when you deal with length and timescales of that magnitude, and all sorts of exotic effects start to become possible!
As I see it electrical charges are stripped out of their atoms and ejected from black holes as high energy cosmic rays. The ultimate fate of the universe is charged particles and radiation. I suspect gravitational fields separate oppositely charged particles until the electrostatic forces overcome gravitational forces. Charged particles come together and annihilate, causing the quark-gluon plasma to be formed and another big bang.
Chronos
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Feb12-12, 01:20 AM
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While most mass may eventually reside in black holes, it is unlikely all of it has this destiny. Even an extraordinarily thin gruel of matter dispersed throughout space creates havoc with most bounce models - unless you are willing to settle for gazillion of years between bounces.
Drakkith
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Feb12-12, 01:40 AM
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Quote Quote by ynot1 View Post
As I see it electrical charges are stripped out of their atoms and ejected from black holes as high energy cosmic rays. The ultimate fate of the universe is charged particles and radiation. I suspect gravitational fields separate oppositely charged particles until the electrostatic forces overcome gravitational forces. Charged particles come together and annihilate, causing the quark-gluon plasma to be formed and another big bang.
I'm sorry, none of this makes any sense.
phinds
#13
Feb12-12, 03:15 AM
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Quote Quote by ynot1 View Post
As I see it electrical charges are stripped out of their atoms and ejected from black holes as high energy cosmic rays. The ultimate fate of the universe is charged particles and radiation. I suspect gravitational fields separate oppositely charged particles until the electrostatic forces overcome gravitational forces. Charged particles come together and annihilate, causing the quark-gluon plasma to be formed and another big bang.
"As I see it" and "I suspect" are not helpful arguments and your statements are utter nonsense. Read some physics.
ynot1
#14
Feb12-12, 06:38 AM
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Quote Quote by phinds View Post
"As I see it" and "I suspect" are not helpful arguments and your statements are utter nonsense. Read some physics.
I'm not a lawyer. I'm not here to litigate. I'm here to propose what I view as a most plausible scenario. You might try reading up on Van de Graf generators. Imagine an outer shell of positrons and an inner shell of electrons. Do you understand electrostatic attraction between unlike charges? What would happen in that case?
ynot1
#15
Feb12-12, 04:42 PM
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Quote Quote by phinds View Post
Now THERE'S something you and I can agree on (although not the "we" part). You are dealing not just in speculation but in unsubstantiated speculation that is absurd. A Van deGraff generator as a model of a black hole??? REALLY???

Look, I'm coming across as rude in this and that's not actually my intent. It's just that I see your proposals as having no relation to actual physics except that you have mashed up some buzz words that are used in physics.

I mean take the thought

"gravitational fields separate oppositely charged particles"


I was not aware that charge has any effect on gravitational attraction. Do you have any references for this?
The Van de Graff generator is used as an analogy of the universe after the black holes have long gone. Sorry for the confusion.

Certainly charge has no affect on gravitational attraction. Only matter. Charged particles do have mass, I believe. And gravity has effect on mass. I'm suggesting gravity has an attractive force on matter and a repulsive force on antimatter. Positrons, being I believe antimatter, would then be repelled by gravity. Electrons, of course, attracted. So as long as gravity is around it will separate positrons and electrons. I know it's is a bit indirect. Difficult to understand I guess. But I wouldn't waste time looking for any references about charge having any effect on gravitational attraction. Could be though. I just never thought about it I guess.
ynot1
#16
Feb12-12, 05:34 PM
P: 90
Quote Quote by Ryan_m_b View Post
Why would you think it would? Note that black holes do not "suck". The gravity of a black hole is no different to the gravity of anything else, if the sun suddenly became a black hole it would make absolutely no difference to Earth's orbit (though it would get quite cold). To say that all matter will end up in black holes is to imply that over deep time all matter will at some point come into contact with a black hole. Without clear maths showing the probability of that it is an unfounded assertion especially considering the vanishingly small volume of the universe occupied by black holes.

See this section of the link I provided above.
I understand even the proton decays, but before that time it would most likely be recycled by a black hole.
Drakkith
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Feb12-12, 06:54 PM
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Quote Quote by ynot1 View Post
Certainly charge has no affect on gravitational attraction. Only matter. Charged particles do have mass, I believe. And gravity has effect on mass. I'm suggesting gravity has an attractive force on matter and a repulsive force on antimatter. Positrons, being I believe antimatter, would then be repelled by gravity. Electrons, of course, attracted. So as long as gravity is around it will separate positrons and electrons. I know it's is a bit indirect. Difficult to understand I guess. But I wouldn't waste time looking for any references about charge having any effect on gravitational attraction. Could be though. I just never thought about it I guess.
The current view of science is that both matter and antimatter follow the same laws regarding gravity. It is "possible" that antimatter would be repelled, but by possible I mean that we simply haven't tested it conclusively yet.
phinds
#18
Feb12-12, 08:51 PM
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Quote Quote by ynot1 View Post
I understand even the proton decays, but before that time it would most likely be recycled by a black hole.
WHY? Where do you get this nonsense?


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