Wikipedia:Today's featured article/June 22, 2015

In physics, M-theory is a unification of what were originally thought to be five distinct versions of superstring theory. The possibility of such a theory was first conjectured by Edward Witten (pictured) at a string theory conference at the University of Southern California in 1995, initiating a flurry of research activity known as the second superstring revolution. Work by several physicists showed that the original five theories could be related by transformations called S-duality and T-duality. Witten's conjecture drew on these dualities and on a field theory called eleven-dimensional supergravity. Some physicists believe that a complete formulation of M-theory could provide a framework for developing a unified theory of all the fundamental forces of nature. Current directions of research in the theory include matrix theory and gauge/gravity duality. According to Witten, the M in M-theory can stand for "magic", "mystery", or "membrane" according to taste, and the true meaning of the title should be decided when a more fundamental formulation of the theory is known.