# The Naked Scientists Forum

### Author Topic: What's the minimum mass to form a black hole?  (Read 1625 times)

#### jccc

• Hero Member
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##### What's the minimum mass to form a black hole?
« on: 31/07/2014 07:14:00 »
We know the value of C, can we calculate the minimum mass? Searched like 1 to 3 solar mass is enough, don't get it.

How's possible any mini black hole exist?
« Last Edit: 31/07/2014 08:12:59 by jccc »

#### PmbPhy

• Neilep Level Member
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##### Re: What's the minimum mass to form a black hole?
« Reply #1 on: 31/07/2014 10:27:12 »
We know the value of C, can we calculate the minimum mass? Searched like 1 to 3 solar mass is enough, don't get it.

How's possible any mini black hole exist?
There's no minimum since all that is required is that all the mass be confined within a certain region of space. All that's required is that the mass be greater than the Planck mass. Theoretically there are micro black holes aka primordial black holes that have been around since the big bang
http://en.wikipedia.org/wiki/Micro_black_hole

#### JP

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##### Re: What's the minimum mass to form a black hole?
« Reply #2 on: 31/07/2014 17:13:37 »
We know the value of C, can we calculate the minimum mass? Searched like 1 to 3 solar mass is enough, don't get it.

How's possible any mini black hole exist?
There's no minimum since all that is required is that all the mass be confined within a certain region of space. All that's required is that the mass be greater than the Planck mass. Theoretically there are micro black holes aka primordial black holes that have been around since the big bang
http://en.wikipedia.org/wiki/Micro_black_hole

Pete's correct.  The reason we don't see small stars forming black holes is that as he says, you need to put enough mass in a small volume to create a black hole.  For smallish stars (below ~3 solar masses), the gravity of the star itself is not strong enough to compress mass to the level needed for a black hole to form.  For large stars, gravity is strong enough to do this.

Of course, if gravitational collapse of a star isn't the mechanism to make a black hole, you can make a smaller one, such as the primordial black holes.

#### The Naked Scientists Forum

##### Re: What's the minimum mass to form a black hole?
« Reply #2 on: 31/07/2014 17:13:37 »