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 absorbs all the light that hits the horizon, reflecting nothing, just
like a perfect black body in thermodynamics.Quantum field theory in curved space time predicts that event horizons emit radiation like a black body with a finite temperature. This temperature is inversely proportional to the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass or greater. |