About 10 picoseconds after the beginning of the Universe, the Higgs field turned on. In extensions of the Standard Model of particle physics, this could have been a first order phase transition, with the spontaneously nucleated bubbles of the Higgs phase expanding and colliding at relativistic speeds. I will discuss how sound waves from colliding bubbles generate gravitational radiation, prospects for observing the radiation at the future space-based gravitational wave detector LI! SA, and outline how LISA complements the LHC as a probe of physics beyond the Standard Model