After the lecture, both of us converged on Ovrut from different directions. No one can recall who blurted it out first, but one of us asked, “Can’t these worlds move along the extra dimension? And, if so, is it possible that the big bang is nothing more than a collision between these two worlds?” It became immediately clear that we had been struck with the same vision. Ovrut’s compelling conceptual picture suggested that the big bang might not be the “beginning” of the universe after all, but instead a physically explicable event with a “before” and an “after.” Furthermore, if there was no inflation to spread apart and dilute the … Continue reading Paul J. Steinhardt, Neil Turok