Though it is impossible to see black holes, most scientists agree that they exist, and that they form when an enormous amount of mass is concentrated in one place. This density creates an intense gravitational field where nothing can get out, not even light (hence the name: black hole). If you use the earth as a point of reference, Professor Strominger says, a rocket must go 11 km per second to break through gravity and escape into outer space. For a black hole, on the other hand, the escape velocity is greater than the speed of light, i.e., 300,000 km per second.
But the contradiction between gravity and electromagnetism has complicated any discourse on black holes for years now. As Stephen Hawking showed in the early 1970s, when you throw quantum mechanics into the equation, particles and light can "boil off" the surface of the black hole. This continues until the hole itself actually disappears, leaving no trace of what was inside. This concept, Strominger says, was "extremely disturbing" to physicists who believe in the principle of determinism - the idea that the laws of physics allow scientists to work backwards and reconstruct the past. Could string theory help explain away this problem?
Professor Strominger says it took 20 years for string theory to advance enough to weigh in on the debate. But its answer bodes well for its future as a unifier of physical laws. Where before, black holes were thought to contain nothing, string theory hypothesizes that they do contain these little strings. And the strings store information in a precise way, which never "vanishes without a trace." By viewing black holes through the lens of string theory, the clash between general relativity and quantum mechanics is resolved. This, says Strominger, is the best indication yet that string theory is a "steppingstone to a better understanding of the fundamental laws which govern the universe around us."