Colloquia

Most of us have looked at the spectacular pictures taken by the Hubble Space Telescope. Galaxies, nebulae, super novae -- but there is something peculiar about these images. Where ever we look in space we only see matter. No significant quantities of anti-matter have been found. Since we believe equal amounts of matter and anti-matter have been produced originally we must conclude that there is an asymmetry between particle and anti-particle decays. In the laboratory, however, nature always seems to obey the particle - antiparticle symmetry with one known exception. Almost 40 years ago a small difference has been found in the neutral kaon system. But the nature of this system made it extremely difficult for both theorists and experimentalists to extract a clear picture of this effect. For years there has been great hope in the particle physics community that a large matter - antimatter asymmetry can be observed in a new system - the weak decays of massive B mesons. The past decade has seen a vigorous experimental effort to produce the large quantities of B mesons required to discover the cause of this asymmetry. Particle accelerators have been upgraded and new detectors were constructed. As we enter the Golden Age of B physics nearly a billion B meson decays have been recorded by these experiments. I will review some of the old questions that have been answered and discuss some of the new puzzles that have been uncovered.