I'm more fascinated by how small a black hole can be, theoretically. I don't know the exact number, but they can be pretty small like the size of a penny right? Correct me if I'm wrong. And the smallest known black hole, so far, is only a few km in diameter.
You're right. Black holes can theoretically be any size, so long as matter is compressed to a density sufficient that the object's escape velocity exceeds the speed of light. If Earth were compressed to 1.76 cm (slightly smaller than a dime in fact) it would form a black hole of said size. The trouble is, the forces needed to induce such a cataclysmic implosion come from massive dying stars, which only yield black holes of several solar masses or greater.
However, in the early universe, pressures were so high that slight inhomogeneities in the distribution of matter could have created regions of space with densities sufficient to create black holes. These could be any size, though black holes weighing less 10^11 kg would have evaporated by now due to Hawking radiation. For comparison, a stellar black hole of 5 solar masses (5x10^31 kg) would take 10^69 years to evaporate. Primordial black holes the mass of asteroids are also candidates for dark matter. Their microscopic size and lack of individual gravitational influence would render them virtually undetectable. A high speed black hole of this sort could pass through Earth with hardly any trace.
I have no idea, but that sounds pretty wild that they found one only a few km wide! It's interesting to think about the consequences of even being near a black hole the size of a penny. It'd be chaos if it were nearby.
Not as far as I understood, no. Black holes do not suddenly start sucking all matter into them; they have the same gravity as the stars from which they resulted from.
If you compress a penny down to a black hole, it will still have the same mass and the same gravitational pull as the penny had before. (i.e.: not very much)
Oh wow, I didn't know that. I figured it would do exactly what you said it wouldn't, that it'd start sucking everything up. Interesting! Thanks for letting me know!
I'm more fascinated by how small a black hole can be, theoretically. I don't know the exact number, but they can be pretty small like the size of a penny right? Correct me if I'm wrong. And the smallest known black hole, so far, is only a few km in diameter.
You're right. Black holes can theoretically be any size, so long as matter is compressed to a density sufficient that the object's escape velocity exceeds the speed of light. If Earth were compressed to 1.76 cm (slightly smaller than a dime in fact) it would form a black hole of said size. The trouble is, the forces needed to induce such a cataclysmic implosion come from massive dying stars, which only yield black holes of several solar masses or greater. However, in the early universe, pressures were so high that slight inhomogeneities in the distribution of matter could have created regions of space with densities sufficient to create black holes. These could be any size, though black holes weighing less 10^11 kg would have evaporated by now due to Hawking radiation. For comparison, a stellar black hole of 5 solar masses (5x10^31 kg) would take 10^69 years to evaporate. Primordial black holes the mass of asteroids are also candidates for dark matter. Their microscopic size and lack of individual gravitational influence would render them virtually undetectable. A high speed black hole of this sort could pass through Earth with hardly any trace.
I have no idea, but that sounds pretty wild that they found one only a few km wide! It's interesting to think about the consequences of even being near a black hole the size of a penny. It'd be chaos if it were nearby.
Not as far as I understood, no. Black holes do not suddenly start sucking all matter into them; they have the same gravity as the stars from which they resulted from.
If you compress a penny down to a black hole, it will still have the same mass and the same gravitational pull as the penny had before. (i.e.: not very much)
Oh wow, I didn't know that. I figured it would do exactly what you said it wouldn't, that it'd start sucking everything up. Interesting! Thanks for letting me know!
More Info: https://www.nasa.gov/topics/universe/features/smallest_blackhole.html
Thanks, that was a nice read! Fifteen miles across is tiny when you think of black holes.