What is the Smallest Possible Size of a Black Hole?

In summary: So, no, there is no direct proof for the existence of an event horizon. However, the concept of an event horizon is necessary in order to make sense of the dynamics of a black hole.Yes. If it didn't, it wouldn't be a black hole.
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what is the smallest possible size of a black hole?
 
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I'm taking it you mean the centre-singularity? I heard it could be as small as an atom, or something called Planck length...

Wondered this myself as well.
 
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A black hole the mass of the sun is about 3 km in radius (Schwarzschild radius or radius of the event horizon), and the radius is directly proportional to the mass. If you can compress matter to a high enough density you can theoretically make a black hole arbitrarily small, but practically there is no known way to create black holes except in the collapse of massive stars. The smallest black hole that we know of is about 5 solar masses, so about 15 km in radius. There is a hypothesis that smaller black holes could have been created during the very early phase of the big bang, but these have never been seen.
 
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phyzguy said:
A black hole the mass of the sun is about 3 km in radius (Schwarzschild radius or radius of the event horizon), and the radius is directly proportional to the mass. If you can compress matter to a high enough density you can theoretically make a black hole arbitrarily small, but practically there is no known way to create black holes except in the collapse of massive stars. The smallest black hole that we know of is about 5 solar masses, so about 15 km in radius. There is a hypothesis that smaller black holes could have been created during the very early phase of the big bang, but these have never been seen.

I have wondered in the past if there would have been black holes from the early phase of the big bang, it definitely seems possible.

One question. Is it true that the larger stars with more mass will become smaller black holes as they will collapse further under their own pressure? Or does it not work like that? I don't know much about physics so excuse any questions that might be stupid haha
 
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CallumBoson said:
One question. Is it true that the larger stars with more mass will become smaller black holes as they will collapse further under their own pressure? Or does it not work like that? I don't know much about physics so excuse any questions that might be stupid haha

No. The Schwarzschild radius of a black hole is directly proportional to the mass, so the larger the mass, the larger the black hole.
 
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phyzguy said:
No. The Schwarzschild radius of a black hole is directly proportional to the mass, so the larger the mass, the larger the black hole.

Thank you for clearing that up
 
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will the 15 km black hole also have 'event horizon'?
 
  • #8
jayaramas said:
will the 15 km black hole also have 'event horizon'?

Yes. If it didn't, it wouldn't be a black hole.
 
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are we having proof for the existence of event horizon ? or can we explain a black hole without the concept of event horizon?
 
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The smallest possible black hole would weigh a Planck mass [which is actually pretty enormous compared to other Planck units]. It's event horizon would be a Planck length. It is believed such a tiny black hole would evaporate via Hawking radiation in about a Planck time.
 

What is the smallest possible size of a black hole?

The smallest possible size of a black hole is known as the Planck scale, which is approximately 1.6 x 10^-35 meters.

How is the size of a black hole determined?

The size of a black hole is determined by its event horizon, which is the point of no return where the gravitational pull is so strong that not even light can escape.

Can black holes be smaller than the Planck scale?

No, according to current theories, the Planck scale is the smallest possible size that a black hole can have. Anything smaller would violate fundamental laws of physics.

Do all black holes have the same size?

No, the size of a black hole can vary depending on its mass. The more massive a black hole is, the larger its event horizon will be.

Can black holes ever shrink in size?

While black holes can grow in size by consuming matter, they cannot shrink in size. This is because the event horizon can only expand and never contract.

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