Part 7/9:
This culminated in the realization that all five superstring theories were manifestations of a single overarching framework known as M-theory, introduced by physicist Ed Witten at a string conference in 1995. M-theory, which adds an eleventh dimension, elegantly unified various superstring theories and provided a renewed sense of beauty.
The Impasse of String Theory
Despite this resurgence, string theory now sits in uncertainty. Problems arise from its failure to define M-theory adequately and its reliance on Calabi-Yau manifolds—complex geometries that govern the behavior of strings in extra dimensions. With a staggering number of potential Calabi-Yau configurations—estimated to be around 10^500—pinpointing which corresponds to our universe appears nearly impossible.