Energy Flow in the Universe

A brief but broad survey is presented of the flows, forms and large-scale transformations of mass-energy in the universe, spanning a range of about twenty orders of magnitude (m_{Planck}/m_{proton}) in space, time and mass. Forms of energy considered include electromagnetic radiation, magnetic fields, cosmic rays, gravitational energy and gravitational radiation, baryonic matter, dark matter, vacuum energy, and neutrinos; sources considered include vacuum energy and cosmic expansion, fluctuations and gravitational collapse, AGN and quasars, stars, supernovae and gamma ray bursts.