What Einstein Did Not Know

This public lecture is about 100 years of research on elementary particles and fundamental forces, beginning with the identification of the electron about 1900 and extending to the astonishing discovery of Dark Matter in the late 1900s. I talk about the elementary particle concept; the discoveries of leptons, quarks and force carrying particles; and some of the experimental technology used. I tell of my own research, our discovery of the tau lepton, our long, inconclusive search for fractional charged particles, and my new involvement in astronomical research on Dark Matter. I conclude by looking ahead to old unsolved puzzles and new questions on the fundamental nature of matter and force that face us in the 21st Century.