I don’t know much about string theory except (1) it attempts to unify two of most successful theories of physics, viz. quantum mechanics and Einstein’s general theory of relativity; (2) it countenances 10 (or is it 11?) dimensions, coiled up in a very tiny portion of spacetime; and (3) asserts that “strings” are the fundamental constituents of all matter, and give rise to the four fundamental forces of nature by unique “vibrations” of those “strings”.
I also know, though, that many physicists have come out and said that String Theory is untestable. But how are we to understand this charge? Some say if it’s not testable it is as good as theological hypotheses, e.g. God exists. I am not so pessimistic. My guess is that String Theory is testable, IN PRINCIPLE, but not IN PRACTICE. That is to say, we can imagine an experiment that, if it gives us the right outcomes, string theory will be either directly or indirectly confirmed. Consider the Ekpyrotic Model in cosmology. There are imaginable experiments that would test this model against the Inflationary Model (aka the Big Bang Theory); the trick is putting it into practice, actually conducting these experiments. The author’s of this model are holding their breaths for future testing, which, if they receive their funds and experimental apparatus, the Big Bang Theory will go against a new kid on the block. The Ekpyrotic Model, interestingly enough, incorporates string theory; that is, string theory is indispensable from use of the Model. Thus, if the Model is confirmed, string theory receives indirect confirmation.
So, maybe I’m missing something. Is String Theory truly untestable in principle, such as God’s existence is argued to be?