Can a black hole overeat?
Asked by
ETpro (
34605)
April 16th, 2012
Do the largest black holes in the Universe just continue to grow forever or is it possible that they eventually reach a critical mass and explode in an event smaller than, but similar to the Big Bang?
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13 Answers
I don’t know, lets go ask Beyonce ;¬}
I have a physicist buddy who knows this stuff pretty well, I’ll ask him and respond when I hear from him.
Straight from the physicist’s mouth Grow forever. There is no theoretical limit to a black-hole’s size or mass. Unlike, say, a white dwarf that has a mass limit of 1.4 solar masses (the “Chandresekhar limit”). Now, that could be a limitation in our understanding of the phenomena…it’s not like we’ll ever be able to study a black hole in great detail up close and in person. However, it has yet to be observed, and the current theory doesn’t support a limit, so it’ll probably grow forever. In fact, there are “super-massive” black holes at the center of galaxies (including our own).
@tedd, @ETpro For the purposes of this question we are going to focus on the type of black hole you find in outerspace and exclude the type you find in nappy headed hoes. The answer is that there isn’t a physical law which limits the amount of matter/mass that they might contain but in practice there is a limit. The universe is likely becoming less dense as time passes (same amount of matter and energy in a larger space as universe expends) so the rate a black hole can take in matter decreases with time as the universe becomes more sparse. Also, black holes slowly lose matter with time and are said to evaporate (even if presently they are undergoing a net gain). This happens when a pair of virtual particles pop into existence and one falls into the black hole and the other escapes it. An outside observer sees the black hole as losing mass. This is called Hawking Radiation. Since the rate at which black holes take in matter is decreasing but Hawking Radiation isn’t decreasing eventually all black holes will totally evaporate given a LONG period of time.
As others have said, black holes just grow and do a great job of it. At one time, there was some serious science support a Big Bounce: Essentially all matter would get eaten by all the black holes which, in turn, would get eaten by bigger black holes. Eventually, all matter would be condensed into a single black hole. Then, somehow, that would explode and create a new Universe.
Now, we are probably on what I choose to call the Big Black. As the expansion of the Universe continues, the rate of expansion is increasing. At some point, you’ll look out at the night sky and not see other stars/galaxies. This is not happening next week obviously.
Since Hawkings paper that ‘black holes have hairs’ it is assumed that – speaking in billions and billions of aeons, black holes will evaporate. “From WikiP, For a black hole of one solar mass ( = 1.98892 × 1030 kg), we get an evaporation time of 2.098 × 1067 years—much longer than the current age of the universe at 13.73 ± 0.12×109 years.” http://en.wikipedia.org/wiki/Hawking_radiation
Other fun things to happen: There might be a drop in the vacuum energy in one part of the Universe. It would expand and destroy our Universe at the speed of light. Likewise, we could have a new Universe, potentially with different fundamental constants, pop up somewhere in ours. Again, we get destroyed. These are the things that keep me up at night. ;)
My understanding is that blackholes will evaporate after they have consumed everything within reach of its gravitational influence.
@Bill1939 As I understand it, they lose matter all the time but in unimaginably small amounts.
@ucme I can’t do that. If I got close enough to ask, I’d surely beg to eat hers.
@tedd Thanks for checking with your buddy.
@fluthercensors Welcome to Fluther. I’m delighted to see someone with some knowledge of astrophysics join. Too bad there is so little solace in the fact that the biggest black hole out there isn’t going to devour everything. That being because we escape that fate only through heat death. Oh well, at least I’ve plenty of time to plan what do do after that occurs.
@ro_in_motion Not much comfort there either. So the evaporate, but only after thare is nothing left to eat. WAY after there is nothing left to eat. Check those equations. I think they lack a power of ten multiplier, and the stated multipliers are actually powers of 10.
@Bill1939 & @ro_in_motion Yes, WAY after…
@ETpro Careful, you may fall in & be gone for days.
@ucme That’s EXACTLY what would happen. I can feel the tug of the event horizon even from this distance.
Larry Fishburne will be awfully jealous.
@ETpro You’re right – wikipedia copied text doesn’t survive the trip to Fluther. I was too confident that modern technology had solved ‘exponentiation cut and paste’ issues. ;)
The link gives them correctly.
Fluther’s limited set of the 2004 implementation of Textile is NOT modern technology. Not by Web standards, anyway. Personally, I wish they supported XHTML markup and just puked out any invalid code or unclosed tags. :-)
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