Is string theory looked on with derision by physicists, or is it viewed as a valid theory?
Yes. As I understand it, many physicists are impressed with the mathematical elegance of string theory, and the way that many inconsistencies in our understanding of the Universe get resolved by string theory. However, string theory has not (yet) produced a testable observational prediction, where scientists can fire up their colliders, look at the results, and say “Yes, this indicates that string theory is likely true”. To many scientists, the lack of testable predictions means that string theory is not science in the strictest sense.
I would not use the word “derision”. “Although string theory is an outgrowth of physics, some contend that string theory’s current untestable status means that it should be classified as more of a mathematical framework for building models as opposed to a physical theory. For a theory to be physics, it must be corroborated empirically, through experiment or observation, but few avenues for such contact with experiment have been claimed. – Is string theory falsifiable? Following the appearance of two books claiming string theory is a failure, a hot media debate evolved in 2007. “For more than a generation, physicists have been chasing a will-o’-the-wisp called string theory. The beginning of this chase marked the end of what had been three-quarters of a century of progress. Dozens of string-theory conferences have been held, hundreds of new Ph.D.s have been minted, and thousands of papers have been written. Yet, for all this activity, not a single new testable prediction has been made,
Yes. There are still many cosmologists and others who are very skeptical, although string theory is looking more and more like an acceptable theory. The problem with acceptance of string theory is that it’s all mathematics and almost no experimental verification at this point. That gives most physicists the willies! Heh!
