Did physics apply just before the Big Bang?

Physics applied, sure, but not the physics we are acquainted with. There would be a wholly different set of rules that applied when everything existed in a single point - physicists are still honing in on what exactly these rules were. Note, however, that the idea of something happening "before" the Big Bang would be a bit of a misnomer: the Big Bang was when time itself started as well. The newly emerging Membrane Theory is offering some interesting possibilities regarding what was going on before the "Big Bang". If there is any truth to Membrane Theory (and there may be elements of it that help explain some weird things about gravity) then the big bang was the result of the collision of two previously existing universes. The collision doesn't happen as you might imagine. Universes are "membranes" at the quantum level, and alternate universes are all around us all the time.