Origins of String Theory
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Quick Timeline 5 1921 - Kaluza-Klein Theory 1970 - Birth of string theory 1971 - Supersymmetry 1973 - Quantum Chromodynamics 1974 - Gravitons; advent of string theory as a unified theory 1976 - Supergravity; supersymmetry applied to gravity 1980 - Superstrings; supersymmetry applied to strings 1984 - First Revolution; anomalies are cancelled and string theory goes mainstream 1987 - E8xE8 Heterotic superstring theory that may explain dark matter 1994 - Second Revolution; understanding of how strings are related with dualities 1996 - Black Hole Entropy; microscopic origin for black hole thermodynamics achieved in string theory |
String theory was originally used to attempt to explain the strong nuclear
force. It had an irritating side effect, however. It required the existence
of a particle without mass and two units of spin which didn't fit anywhere
into the strong force. This idea was placed on the back-burner, and in
1971 supersymmetry was applied to strings which incorporated fermions as
well as bosons, thus replacing bosonic string theory The first string revolution occurred in 1984. In this year, Greene and
Schwarz discovered that anomalies in the math behind strings conveniently
cancelled. The immediate result of this was the advancement of five consistent
superstring In 1987, Gross, Harvey, Martinec, and Rohm discovered the E8xE8 Heterotic In 1994, Seiberg and Witten found supersymmetric gauge theories while Hull and Townsend found string dualities (to be discussed in the next section). The second revolution resulted in the realization that the five superstring theories, plus a sixth found later that exists in eleven dimensions, are manifestations of an underlying M-theory that ties them all together 6. |
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