Thursday, June 01, 2006

Black Hole Information Lost Forever? Not Quite, According to String Theory

by Sam Wass (Class of '06)

One of the most intriguing conclusions found by string theory, the proposed “theory of everything” which unifies the four fundamental forces (gravity, electromagnetism, strong nuclear force, weak nuclear force), regards one of the universe’s most bizarre objects: black holes. String theory applied to black holes suggests that black holes do not necessarily lose all of the information of the objects sucked inside of them. This resolves one of the greatest problems in modern physics, called the information paradox. Classical equations stipulated that the end result of a black hole was always the same, regardless of the matter put into it. However, this violates quantum mechanics, because it stipulates that processes must be traceable.

Black holes are one solution to Einstein’s equations of general relativity. They are the remnants of stars so massive that they collapsed in on themselves after their supernova, a massive explosion of a dying star. These bizarre objects have zero volume and infinite density, and are completely described by their electrical charge, angular momentum, and mass. It was long thought that information sucked into a black hole was lost forever, but string theory suggests that this may not be the case at all.

String theory, as its name indicates, suggests that the universe is composed of tiny “strings”, which are extremely small loops of energy. They vibrate in different ways, in very much the same was as a musical string would be plucked, and these different vibrations produce the different particles that science observes. Because of Einstein’s mass/energy equivalent (E=mc^2), the string at lower energies represent the least massive particles, while strings at high energies represent more massive particles.

If string theory is applied to black holes, then the singularity, or center of the black hole where the laws of physics do not apply, does not become so indescribable anymore. String theorists describe the singularity as a large mesh of strings, rather than a point in space. This mesh, or “fuzzball” as it is often called, would become very stretchy as it becomes more massive in order to create a supermassive object like a black hole. Scientists who tested the diameter of a black hole that would be produced using this method found that their answer closely approximated the diameter of classical equations.

If this postulate is correct, then information about the objects sucked into the black hole can be stored inside, and then reemitted via Hawking radiation, which happens when the black hole radiates its mass in the form of small particles. Until the application of string theory to black holes, it was believed that a black hole would destroy any information stored inside it. In order to justify this loss of information, quantum mechanics, the rules that govern the universe at its smallest scales, was thought to break down in black holes. However, the application of string theory shows that information stored in black holes is not lost, if string theory is proven to be correct.


New Scientist, “Hawking Cracks Black Hole Paradox” by Jenny Hogan

“Physics, M-Theory, and Black Holes"

"Information Paradox Solved? If So, Black Holes Are “Fuzzballs”"

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