You've heard of the Big Bang theory, which holds that the universe exploded from a single tiny point and is still expanding outwards, stretching and moving beyond its point of origin. But what if the Big Bang was actually preceded by a Big Splat?
Take two universes, smack them together, and you have the beginnings of the so-called ekpyrotic (Greek for conflagration) scenario, brought to life in 2001 by several physicists. In this scenario, the universe is cyclical, periodically repeating similar events. Multidimensional universes smash into each other, starting universes anew, but without the inflation and expansion of the Big Bang.
As with so many models, the ekpyrotic model relies on assumptions about mechanisms that make the universe work. But for most modern scientists, this model relies and far too many assumptions and subsequent complexities (Google "ghost condensate" if you dare) that render the whole model interesting but highly unlikely.
The simplest explanations are often the most promising. And the measurements and theories behind the Big Bang are still the best understanding we have of our universe's genesis.