Almost all we know about the universe is derived from the
observation of photons. As astronomers have developed
instruments to exploit new regions of the electromagnetic
spectrum, from radio waves to gamma rays, fascinating new
objects have been revealed. At very high energies, however, the
universe itself becomes opaque to photons, making astronomy
difficult. Many observed phenomena, such as Gamma Ray Bursts,
are poorly understood. Other objects which must exist, like the
sources of the high energy cosmic rays, have not yet been
identified. Neutrinos offer a useful alternative to photons as
astronomical messenger particles. Over the last two decades,
neutrinos from astrophysical sources have proved useful for both
astrophysics and particle physics. The IceCube neutrino
telescope, under construction at the South Pole, will give us a
new window on the universe at TeV energies and above. It will
also permit us to address topics in particle physics such as
extra dimensions, supersymmetry, dark matter, neutrino o