Recently scientists succeeded in taking a picture of a black hole. Therefore, I want to write a few lines about this phenomenon.
In a black hole, matter is so highly compressed that even light cannot escape from its vicinity. General relativity treats a black hole as a point, i.e. it has no extension. This is hard to imagine. However, take as an example the electron which is considered as a point particle, although it has a mass at rest.
A black hole is surrounded by an event horizon. Everything that passes it becomes invisible for the world outside. If a matter-antimatter pair is created from the vacuum near the event horizon, a particle may cross it. The other particle seems to come out. This is Hawking radiation.
In particle physics, there are collisions at high energies. Can a black hole be produced in a collider experiment? This question was subject of a court dispute. The physicists bring forward the argument that the cosmic radiation contains particles of much higher energy. Although the cosmic radiation hits the Earth, our world still exists.