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 oscillations, and magnetic monopoles.