I don’t have my copy of The Elegant Universe with me, so I can’t quote, but this morning I read about how string theory has went from, in the 1980s, being boldly claimed by a small number of string theorists to be a theory of everything (and dismissed by many physics heavyweights), to gaining wider and wider acceptance during the following decade – despite not having been verified by experiments. In later years, some progresses have been made, but it seems that it still is more of a hypothesis than a theory. (I guess that the fact that many scientists believe in it, indeed makes it a theory, though.)

Why is this interesting? Well, to me it suggests that there’s a good dosage of intuition, gut feelings, or whatever, involved. It seems, from reading Brian Greene’s book, that many physicists feel that the ultimate theory of the universe would be elegant, symmetric, et cetera – and as it seems that string theory is very so (as indicated by the book’s title), perhaps this is why so many believe in it?