Neutrino transport from stars to supernovae and neutron-star mergers

In this talk neutrino transport in astrophysical environments is discussed. Neutrinos, because of their feeble interactions, can transport energy and entropy over long distances inside and away from stars to supernovae and neutron-star mergers. Depending on the environment, neutrino transport may be governed by either matter-enhance neutrino oscillations or collective neutrino oscillations. Collective oscillations, which result from neutrino-neutrino interactions, entangle the neutrinos. Impact of the collective neutrino oscillations on nucleosynthesis is explored.