Speech #3

The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole exhibiting gravitational effects so strong that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it. The boundary of the region from which no escape is possible is called the event horizon. Although the event horizon has an enormous effect on the fate and circumstances of an object crossing it, no locally detectable features appear to be observed. In many ways a black hole acts like an ideal black body, as it reflects no light.