The scientific goals of this new branch of science are manifold and go far beyond pure astronomical interests. Besides pure astrophysical problems such as the search for the sources of the cosmic radiation, the mystery concerning their acceleration, the study of binary systems, pulsars and distant active galactic nuclei, we address questions ranging from modern particle physics to cosmology, such as neutrino oscillations and reactions, the search for particular forms of dark matter and even topics concerning the earth sciences, such as neutrino tomography of the earth to determine its internal structure.

The fact that this multitude of seemingly very different problems can be treated with one and the same instrument is partly a consequence of modern cosmology, which closely links microcosm and macrocosm. On the other hand, it must be realized that in comparison to a common optical telescope, a neutrino telescope is a highly complex particle detector that can handle several tasks simultaneously.

For reasons of simplicity we will confine the following discussion mostly to the search of the sources of the cosmic radiation.