Paul Steinhardt - Time to Take the ‘Big Bang’ out of the Big Bang Theory? (May 5, 2021)

A wide range of empirical evidence supports the notion that the universe has been expanding and cooling for the last 14 billion years. However, the idea that it began with a bang is pure speculation based on extrapolating back in time, assuming equations remain valid under conditions far beyond where they have been tested. In this talk, Paul Steinhardt will explain why it may be time to jettison the Big Bang. Namely, a series of recent advances strongly suggest that the only way to describe the remarkable homogeneity and isotropy observed on large scales may be if the universe first underwent a period of ultra-slow contraction. In that case, it is essential to replace the bang with a ‘bounce’ — a smooth transition from contraction to a dense, hot universe that proceeds to expand and cool. Among possible implications is a novel kind of cyclic theory of cosmic evolution. More details: https://www.simonsfoundation.org/even...