actually there would not have to be an explosion per se. many believe the point from which it expanded was a singularity. I forget which of the light level experts in the area said that black holes would evaproate without new materials coming in. if all the material of the universe was pulled into one sigularity, then there could be no new material added. eventually it would evaporise, meaning that the material would expand from it rapidly. at first there would be no solid or even energy as we know it. In our universe, no matter can travel faster than light speed but would not apply as this was not matter. it would leave the spot at perhaps many times the speed of light. Only after it "congealled" (for lack of better more scientific term) in to energy and matter would it slow down. the material that "congealed first, would be slowed more, or the space around it would not expand as fast (depending on which way you choise to see it).
basically, untill it congealled into something that science can explain, the laws of physics that we know would not apply. Im sure there are laws that would apply to that material, perhaps even some laws identical to the ones that apply to matter and energy that we know. there is even one theory (with little acceptance last i heard) that each time a universe is created by a big crunch followed by a big bang, the laws of physics change.
