- #1
kokain
- 51
- 0
Is there a limit on the mass of a black hole? How big can it get?
Theoretically? Nope. They can get as big as they want to. In practice one has to be careful. You can't have a black hole which has twice the mass of the universe right?kokain said:Is there a limit on the mass of a black hole? How big can it get?
Forget twice - it was a mere example where I chose a number at random. All I was saying is that you can't make a black hole as big as you want if you're lacking the material to make it. However nobody knows how much mass there is in the universe.kokain said:Why twice the mass? Why not exactly equal to the mass of the universe? Where would it get anymore mass?
No but the lower limit is more interesting. Nothing in theory as far as I know imposes a lower limit on black holes but that doesn't mean that any low mass black holes exist. It is a question of how could low mass black holes come into existence. Apparently many physicist think that a lot of black holes were formed early in the history of the universe, perhaps at the same time when the rest of matter came into existence. Hawking radiation means that smaller black holes would have a shorter life span but only in isolation. Black holes are likely to become the centers of gathering masses like galaxies and star clusters, where they tend to gain more mass. So are there small black holes in isolation out there somewhere, left over from the beginning? Is there any physical event that can create small black holes?kokain said:Is there a limit on the mass of a black hole? How big can it get?
Speculations about quantum gravity suggest the lower limit would probably be on the order of the Planck mass, about 10^-8 kilograms (close to the mass of a flea), in which case the black hole's radius would be around the Planck length.mitchellmckain said:No but the lower limit is more interesting. Nothing in theory as far as I know imposes a lower limit on black holes but that doesn't mean that any low mass black holes exist.
The universe is not believed to be a black hole, because black holes have a singularity at the end of time (not the beginning of time). The universe is *probably* not a time-reversed black hole (a white hole) either.jimmysnyder said:The universe is a black hole. That's why light can't escape from it. The mass of the black hole is 1 in universal units.
Well, not by some maybe, but by others? Thanks for the link. I always knew that the "universe is a black hole" thing was strained. I just didn't realize how taut it was.pervect said:The universe is not believed to be a black hole,
The Black Hole is derived from the singular situation 2GM>rc2to the spherically symmetric Schwarzschild solution. The cosmological solution is a different case and it would be inappropriate to confuse the two.jimmysnyder said:Well, not by some maybe, but by others? Thanks for the link. I always knew that the "universe is a black hole" thing was strained. I just didn't realize how taut it was.Originally Posted by pervect
The universe is not believed to be a black hole,
There is no scientific basis for such an assumption. Why would you think this would be true? For example; suppose there is a star which collpases into a black hole. At a distance from the star there will be no observed changes in the gravitational field. None! The only thing that changes is the star itself in the the size decreases so much that you can get closer and closer to the original center. Eventually you'd get so close to the center that you'd cross the event horizon and be swallowed up. But there are no changes in the gravitational field at distances which are greater than the original stars radius.kokain said:I question how large they can be because everything will eventually be consumed by a black hole.
A black hole is a region in space where the gravitational pull is so strong that nothing, including light, can escape from it. This creates a dark, invisible object that is surrounded by an event horizon, which is the point of no return for anything that enters the black hole.
Black holes are formed when a massive star runs out of fuel and collapses under its own gravity. This causes the core of the star to become extremely dense and compact, creating a black hole.
The size of a black hole is determined by its mass. Theoretically, a black hole can get infinitely large, as long as it continues to consume matter and grow in mass. However, the largest known black holes are around 10 billion times the mass of the sun.
Scientists use various methods to measure the mass of a black hole, such as observing the effects of its gravity on nearby objects or studying the motion of stars and gas around the black hole. They can also measure the size of the event horizon and use that to calculate the mass.
Yes, there are three main types of black holes: stellar, intermediate, and supermassive. Stellar black holes are the smallest and are formed from the collapse of a single massive star. Intermediate black holes have a mass between that of stellar and supermassive black holes. Supermassive black holes are the largest and are found at the center of most galaxies, including our own Milky Way.