We do not know how to formulate string theory nor do we know its underlying principles. Surprisingly, this fact does not stop us from making progress.
Nathan SeibergThis is a rather unusual situation in physics. We perform approximate calculations which are valid only in some regime and this gives us the exact answer. This is a theorist's heaven- exact results with approximate methods.
Nathan SeibergI am almost certain that space and time are illusions. These are primitive notions that will be replaced by something more sophisticated.
Nathan SeibergWhat will the greatest experiment discover? I have no idea!, maybe nothing!, If we won't check, we will never know. In science there is never a guarantee of success. If you understood this last sentence, then you understood the most important message of this lecture.
Nathan SeibergNewton's theory is not 'not right', it just does not cover all distances. Contrary to popular belief, theories in science are not proven wrong, they are just replaced by more complete and convenient theories. To sound provocative, even the geocentric theory was never "proven" wrong, it is just not as convenient as the heliocentric theory, since it requires endless epicycles.
Nathan Seiberg