Looking up at the GUT / Planck World

The importance of the mass spectroscopy of the superparticles is emphasized. It will be shown that the gauge coupling constants give us information on the GUT-scale mass spectrum once the superparticle masses are known. The gaugino masses will provide us a model-independent test of the grand unification irrespective of the symmetry breaking pattern. The sfermion masses carry the information on the intermediate symmetries, if present. Combining the mass spectrum, we will be able to distinguish among the GUT models, and hopefully supergravity models also. Present Address: Theoretical Physics Group, Lawrence Berkeley Laboratory, University of California, Berkeley, CA 94720.