B Violation in the Hot Standard Model

I explain, as simply and pedagogically as I can, recent arguments that the high-temperature baryon number violation rate depends on the electroweak coupling as \Gamma = # \alpha_\w^5 T^4 (up to higher order corrections). This is in contrast to the form \Gamma = # \alpha_\w^4 T^4 that has historically been assumed in discussions of electroweak baryogenesis. I will give a general analysis of the time scale for non-perturbative gauge field fluctuations in hot non-Abelian plasmas.