You enter a completely new world where things aren't at all what you're used to.

One very important aspect of string theory is definitely testable. That was the prediction of supersymmetry, which emerged from string theory in the early '70s.

I just think too many nice things have happened in string theory for it to be all wrong. Humans do not understand it very well, but I just don't believe there is a big cosmic conspiracy that created this incredible thing that has nothing to do with the real world.

M stands for Magic, Mystery, or Matrixaccording to taste

I wouldn't have thought that a wrong theory should lead us to understand better the ordinary quantum field theories or to have new insights about the quantum states of black holes.

1/r^2 has a nasty singularity at r=0, but it did not bother Newton-the Moon is far enough.

String theory is 21 st century physics that fell accidentally into the 20th century.