A Brief History of Strings
The subject arose in the late sixties in an attempt to describe strong
Supersymmetric strings -- or superstrings -- were discovered in 1971.
In 1974, after realizing that superstring theories inevitably predict
gravitons, the goal of research was changed to Einstein's old dream of
In the first superstring revolution (1984-1985) we learned there were
five consistent superstring theories:
I, IIA, IIB, HO, HE
of which requires 10 dimensions, with 9 space and one time.