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

M stands for Magic, Mystery, or Matrixaccording to taste

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.

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

One of the basic things about a string is that it can vibrate in many different shapes or forms, which gives music its beauty.

But the beauty of Einstein's equations, for example, is just as real to anyone who's experienced it as the beauty of music. We've learned in the 20th century that the equations that work have inner harmony.

There was a long history of speculation that in quantum gravity, unlike Einstein's classical theory, it might be possible for the topology of spacetime to change.