Based on our current understanding of physics, what would be the consequences of a 2 particle collision, (for argument's sake say an electron-positron collision), each with roughly half the energy of the universe (~1.9×1081 GeV/c2 i think)? How would this differ from our picture of the big bang? My current understanding, mostly through guesswork, is that a great many exotic particles/antiparticles would be created, eventually over time breaking down into more familiar particles. This particle cloud would expand in at a great rate, possibly with areas higher in density collecting by gravitational attraction. This, to my mind, sounds similar to the big bang, but a) with much more antimatter and b) already existing in space-time, not forming it as a consequence. I have a very limited knowledge of quantum field theories and general relativity, i was hoping someone with more insight could amend/add to my understanding. Just to be clear: a) I am not proposing this as a theory for the origin of the universe, I am just curious what the difference would be. b) I assume that our knowledge of physics is not expected to hold at these energies, i was just wondering what the consequences would be if they did.