Blog #2: What Is A Black Hole?

A black hole is a region of space time from which gravity prevents anything, including light, from escaping. The theory of general relativity predicts that a sufficiently compact mass will deform space time to form a black hole. Around a black hole, there is a mathematically defined surface called an event horizon that marks the point of no return. The hole is called black because it all light that hits the horizon can never escape.

The concept of a body mass being that massive that not even light can escape it was put forth by a geologist John Michell in a 1783 paper sent to the Royal Society. At that time work relating to Issac Newton's theory of gravity and the concept of escape velocity were well known.

After the black hole is formed it can continue to grow by absorbing mass by it's surroundings, absorbing stars and merging with other black holes.Supermassive black holes of millions of solar masses may form.There is a general consensus that supermassive black holes exist in the centers of most galaxies.