Question: how do you get information about black holes?

Alexander Burke answered on 3 Mar 2018:

This is a really good question. It’s very hard to get information about black holes in general. A black hole is a region in space where nothing, not even light, can escape its gravity. Black holes are very hard to observe because they are invisible. If light cannot escape a black hole then how can the light from the black hole reach us? If the light doesn’t reach us then we can’t observe them by eye.
The best way to observe black holes is to observe how they affect their surrounding areas. For example, if there are a large number of stars travelling around a black spot where the black spot is sucking up gas and other stuff, then that black spot is likely a black hole. We can also observe black holes by seeing them collide with other black holes. When two black holes collide, they warp space and that warped space essentially travels outwards towards us at the speed of light. It’s amazing how we can now detect these sorts of things! On September the 14th, 2015, we detected the collision of two black holes by observing the “gravitational waves” emitted from them. These gravitational waves are the warped space I was describing above.
To summarise. We can observe black holes by their effect on stuff around them. We can also detect black holes from how they warp space and time around them when they collide with other black holes.