The Universe Before Time

What Was There Before the Big Bang? The Leading Scientific Theories Explained Ask what happened before the Big Bang and physics runs into one of its deepest problems. The conventional Big Bang model describes an extraordinarily hot, dense early Universe expanding and cooling roughly 13.8 billion years ago, but it does not by itself tell us whether that state represented the absolute beginning of reality. That distinction matters. Modern cosmologists can reconstruct much of the Universe's history with remarkable precision, yet the closer they approach the first fractions of a second, the less certain conventional physics becomes. Somewhere beyond that frontier may lie an earlier universe, a quantum state with no ordinary time, a period of eternal inflation, a cosmic contraction followed by a bounce — or something for which current physics does not yet have the language.