Far-out neutrinos

Neutrino telescopes, proposed and under construction, should map out the neutrino sky, analogous to the way the electromagnetic sky has been mapped for centuries. Like light and unlike cosmic-rays, the neutrinos will point back to their sources. Unlike light, the neutrinos are not attenuated at high energies and so will allow us to see farther into space, and deeper into sources. We illustrate with specific examples the promise which neutrino astronomy at energies from a TeV to a ZeV holds to study astrophysics and particle physics. For astrophysics we focus on three 'almost guaranteed' neutrino fluxes. For particle physics, we focus on what can be learned from cosmic neutrino flavor identification