  We analyze Higgs condensate bubble expansion during a first-order electroweak
phase transition in the early Universe. The interaction of particles with the
bubble wall can be accompanied by the emission of multiple soft gauge bosons.
When computed at fixed order in perturbation theory, this process exhibits
large logarithmic enhancements which must be resummed to all orders when the
wall velocity is large. We perform this resummation both analytically and
numerically at leading logarithmic accuracy. The numerical simulation is
achieved by means of a particle shower in the broken phase of the electroweak
theory. The two approaches agree to the 10\% level. For fast-moving walls, we
find the scaling of the thermal pressure exerted against the wall to be $P\sim
\gamma^2T^4$, independent of the particle masses, implying a significantly
slower terminal velocity than previously suggested.
