It might be thought that particles with no charge, half-integer spin, and very little mass could not really be that complicated. Yet it has taken 70 years to discover that they had any mass at all, and in the process the objects with well-defined mass were found not to have well-defined flavor and vice versa. It is the first clear upset for the venerable Standard Model. Exactly what the mass is still remains unknown. Created in abundance in the big bang, neutrinos were once prime suspects for the dark matter in the universe. They are not massive enough for that, we now know, but they could still have played an important role in shaping the large-scale structure of the universe. Step by step, physics is closing in on the neutrino mass, and the talk will be a status report on the search and its future.

Argonne Physics Division Colloquium Schedule