A black hole occurs when a star collapses. It burns up all its fuel and becomes so dense and heavy that it no longer glows or shines or gives off any light. Its gravity is so intense that light cannot escape from the mass. It is very small because of its compact construction. It is also highly magnetic and everything that gets close to it is sucked into it. In the middle of the black hole everything stops.
I am sure that Stephen Hawking would provide a much better description of the black hole than I can. This is about all I know about it, but I have experienced black holes. My husband was in the hospital for a long time several years ago. He was very ill and he was getting worse every day. Everyday I was drawn deeper into the black hole of his illness. They ran tests and tried all kinds of treatments, but he still got worse.
The power of that black hole was slowing time and no light light was coming through. The edge of the black hole is called the event horizon. That is the place where you cannot get away from the deep magnetic draw of the dense center. I could feel the black hole claiming me.
After about three weeks, they discovered what was wrong with him. Then other things took over and he still got worse. The black hole would not let go. Medical science finally got it right and the analogy fell apart. He left the hospital.
There are other things that act like a black hole. Depression fits the model. When everything in your life is drawing you into the blackness that no light can penetrate and no power can untangle, remember the black hole. Avoid the event horizon because the deeper you allow yourself to sink into its depths, the harder it is to retreat, and it is invisible to everyone else. Nobody but you knows it's there.