Black Holes ain't so black...

Renegade 13 · #1 July 22nd, 2004, 04:12 PM

Quote:

Originally posted by Karibu:
The life time of black holes is billions of times as long as our universe is old by now. To make it more understandable, our universe is about 10^10 years old (10 billion years. I know it is about 5 billion years, but I speak of cosmological decades, not exact years, so 10^10 years is fitting).

I thought cosmologists had narrowed the age of the universe down to somewhere between 14 and 15 billion years old.

But perhaps I'm mistaken.

Slick · #2 July 22nd, 2004, 04:30 PM

Actually, the rate at which a black hole evaporates (under Hawking's theory) is related to its mass. The larger the black hole, the slower it evaporates. More accurately, it's related to the surface area of the event horizon (proportional to mass squared or possibly cubed, I don't have the formula in front of me).

Also, there are theories that allow for the creation of black holes by mechanisms other than stellar collapse. These other mechanisms could produce black holes of quite small mass which would have very short lifetimes relative to the age of the universe.

Slick.

[ July 22, 2004, 15:34: Message edited by: Slick ]

spoon · #3 July 22nd, 2004, 04:54 PM

Quote:

Originally posted by Slick:
Also, there are theories that allow for the creation of black holes by mechanisms other than stellar collapse.

...such as when PBW goes down...

Suicide Junkie · #4 July 22nd, 2004, 07:23 PM

Quote:

Originally posted by Slick:
Also, there are theories that allow for the creation of black holes by mechanisms other than stellar collapse. These other mechanisms could produce black holes of quite small mass which would have very short lifetimes relative to the age of the universe.

Slick.

There are also potentially "primordial black holes" which would have been generated about the time of the big bang at a variety of sizes...
As such, they'd evaporate at various times, and might be visible from the burst of radiation as they die.
Too close, and they'd irradiate the solar system killing everything, of course, so there is an upper limit as to how many could be floating around.

Slick · #5 July 22nd, 2004, 08:32 PM

Yes, that is one of the other mechanisms for creation of black holes. Not to scare anyone, but gamma ray observing satellites "see" about 1 huge gamma ray burst per day from varying, but so far safe, distances. The question of what causes these is debated. One postulated source is the "death" of a black hole. If one occurred close to our solar system, we would be fried.

Slick.

narf poit chez BOOM · #6 July 24th, 2004, 06:10 AM

2 million years from now: 'Billy! Stop poking that black hole with a stick! We need that one!'

LonghornXtreme · #7 July 27th, 2004, 03:47 AM

Isn't the only reason that black holes aren't truly black is that at the event horizon, particles are being ripped in two, with one entering the black hole and one being emitted as light? Thats why black holes aren't black?

Don't quote me, I don't know too much about the universe.