Computational complexity of vacua and near-vacua in field and string theory

We demonstrate that the problems of finding stable or metastable vacua in a low energy effective field theory requires solving nested nondeterministically polynomial (NP)-hard and co-NP-hard problems, while the problem of finding near-vacua can be solved in polynomial (P) time. Multiple problems relevant for computing effective potential contributions from string theory are shown to be instances of NP-hard problems. If P≠NP, the hardness of finding string vacua is exponential in the number of scalar fields. Cosmological implications, including for rolling solutions, are discussed in light of a recently proposed measure.