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(Sorry, couldn't resist the title)

An article on Physics Today brings news that there is a new record for largest black hole (not) seen in space, some 300 million light-years away. It hints at something in the last sentence:

Also, because of their unusually large mass, they may have evolved differently from smaller black holes.

Could a significant proportion of the mass of the universe be bound up in primordial black holes, which are still moving away from each other with their incredible momenta, warping spacetime as they go?

I can't quite square this with the near-universal red-shift, however; if it was the action of black holes dragging us away from other galaxies, we would see some galaxies drawn towards these black holes with blue-shift instead.

And yet... the peculiarities of spacetime around black holes could account for hyperinflation, couldn't they? If the universe began as one or many black holes, then there would need to be some sort of abnormal physics going on to separate them in the first place.

The joys of ignorance.

Thinking about CMB, there would be some sign in that that there were these black holes, unless they were so numerous that the distribution was nearly uniform.

What do you think?

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300 million miles is 26 light minutes, or about 3 astronomical units. That would be well within the solar system, and would cause lots of problems for us. Did you mean light-years? –  Colin K Dec 7 '11 at 18:28

1 Answer 1

Black holes, or any other matter, cannot account for any cosmological expansion, because space is flat on the largest distance scales. A black hole doesn't gravitate any more than matter, so any question you have about black holes can be reformulated using ordinary matter of the same mass instead, where the answer is obvious.

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space-time is not flat, (properly taken) space slices are. But the long scale space-time geometry has a constant curvature given by $\Lambda$ –  lurscher Apr 27 '12 at 19:04
also, a spacetime filled with equally spaced black holes shall not be asymptotically flat –  Alexey Bobrick Apr 27 '12 at 22:00
@lurscher: I see, sorry about that. I meant space. Of course you are right, I fixed it. –  Ron Maimon Apr 28 '12 at 2:29
@AlexeyBobrick: This is irrelevant--- the equally spaced black holes are the same as any dust of matter. The result can be long-range flat if the universe is expanding critically with dust matter. –  Ron Maimon Apr 28 '12 at 2:30
@Ron: It was relevant before your edit :) One black hole in a flat spacetime is asymptotically flat, as you said. That doesn't say much about the asymptotic properties of a spacetime filled with an infinite number of blackholes, it is RW instead, as you correctly say. –  Alexey Bobrick Apr 28 '12 at 11:00

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