Who lives in the Universe besides humans?

The universe is a big place. A place where among millions of other planets we find planet Earth.

Planet earth is at the edge of the Milky Way galaxy. But Milky Way is not the only galaxy in The Universe. Moreover, we do not know even a small part of our galaxy, and do not know anything about the universe, about his majesty and complexity.   Therefore we can divide The Universe into two parts: one that we know it,

What are the black holes?

Among other things, general relativity theory of Albert Einstein predicted the existence of one of the strangest cosmic phenomena - black holes. Recent hypothesis suggests that our galaxy is in the midst of a massive black hole. Why are these holes "black"?
It is known that mass distorts space. We also know that the path of light is affected by gravity. We also know that Einstein's theory of general relativity predicts the existence of one of the strangest objects imagined by physicists - black holes.