This morning's previous post pictured the cover
of a book titled "The Mystery of the Quantum World."
That title, together with Peter Woit's post on Hawking
yesterday, suggests a review of the phrase "M -theory."
See remarks on that topic in the October 1998
Notices of the American Mathematical Society :
"The richer theory, which has as limiting cases
the five string theories studied in the last generation,
has come to be called M -theory, where M stands for
magic, mystery, or matrix, according to taste."
— "Magic, Mystery, and Matrix," by Edward Witten
See also, in this journal, a post mentioning Hawking's
vulgarized M -theory book The Grand Design , as well
as a post of January 9, 2012, titled "M Theory."
Of Witten's three alternative meanings for M , I prefer "matrix."