Quantum mechanics brought an unexpected fuzziness into physics because of quantum uncertainty, the Heisenberg uncertainty principle. String theory does so again because a point particle is replaced by a string, which is more spread out.
Edward Witten1/r^2 has a nasty singularity at r=0, but it did not bother Newton-the Moon is far enough.
Edward WittenI 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.
Edward WittenI have a much easier time imagining how we would understand the big bang, even though we can't do it yet, than I can imagine understanding consciousness.
Edward Witten