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suntrack2
2007-Aug-22, 05:55 PM
1000 years, this measurement I have taken rudely, but what will be the mass of the black hole in such a situation. whether the black hole will expand too much, or there is a great possibility of forming something another?

01101001
2007-Aug-22, 06:07 PM
1000 years, this measurement I have taken rudely, but what will be the mass of the black hole in such a situation. whether the black hole will expand too much, or there is a great possibility of forming something another?

What is it eating?

If there's nothing nearby to munch, it won't gain any mass, and might loose a little to Hawking radiation.

Edit: Or did you mean to specify some particluar, the black hole. Milky Way center?

NEOWatcher
2007-Aug-22, 06:09 PM
Yeah, Ive got a comment...Huh?

It depends on the starting size of the BH, and how much material is near the BH, and how close that material is.

Theoretically, a BH doesn't even need to grow.

JohnD
2007-Aug-23, 08:43 PM
And if Hawking radiation is real, they lose mass, slow or fastdepending on their size.

J

neilzero
2007-Aug-24, 07:36 AM
A typical ten solar mass black hole gains about one part per million by eating for 1000 years. This is offset by a mass loss of less than one part per trillion due to Hawking radiation. A picosol black hole has proportionally lots more Hawking radiation and could shrink to zero in less than 1000 years. A ten solar mass black hole has ten trillion times the starting mass of a pico sol black hole. I'm shooting from the hip, so please correct my numbers. The existance of black holes with less than one sol of mass has not been varified so there are possibly none. Neil

Cougar
2007-Aug-24, 09:34 PM
what would be the size of black hole after 1000 years? (this measurement I have taken rudely, but) what will be the mass of the black hole in such a situation. whether the black hole will expand too much, or there is a great possibility of forming something another?
As mentioned, black holes come in a variety of masses and sit in a myriad of environments. Assuming it has no more local mass to accrete, and with a little simple algebra, you ought to be able to get an idea of how slowly the size of a black hole will change for any length of time or any size of black hole with the following "total evaporation" formula:

t = 1065(MBH/Msun)3 years

So if a black hole has the same mass as the Sun, it would take over six times the current age of the universe to completely evaporate. If it's more massive than the Sun (which they usually are [if not always]), it would take A LOT LONGER.

neilzero
2007-Aug-25, 01:04 AM
That would make the Universe 10 to the 54th years old. One solar mass black holes or more massive take a very, very, very long time to evaporate by Hawking radiation. The one part per trillon loss in 1000 years that I suggested was way high. Neil

neilzero
2007-Aug-25, 01:14 AM
Using that formula, the one picosol black hole would evaporate in 10 to the 29 th years, so I was way low thinking it might evaporate in less than 1000 years. Neil

neilzero
2007-Aug-25, 01:46 AM
If we can have one thousandth of a picosol black hole, it takes 10 to the 20th years to evaporate.
If we can have one billionth of a picosol black hole, it takes 100 years to evaporate. if I did not make an error. Neil