Symmetries and the search for physics beyond the standard model

Beginning with an introduction to its significance, we briefly review the status of our knowledge of the strangeness content of the nucleon, both experimental and theoretical. We then recall how the success of the corresponding experimental program at JLab led to an unanticipated improvement in the precision with which we constrain the possible existence of parity violating lepton-quark interactions beyond the Standard Model. This leads naturally to the consideration of the major outstanding discrepancy in the evolution of sin2θW. In particular, we explain how the nuclear modification of parton distributions, combined with charge symmetry violation eliminate this discrepancy.