“I know of no other scientist, no other theoretical physicist alive who has a clearer focus on whether our theories and ideas are relevant to the real world. And that’s always what he’s after.” -Neil Turok, on Paul Steinhardt
The inflationary Universe is one of the most revolutionary new ways of looking at the cosmos to come out of the last 40 years of science. Instead of going all the way back to a singularity from which time, space, matter, and energy all emerged, cosmic inflation posits a different state that gave rise to our hot, dense, matter-and-radiation-filled Universe. With energy inherent to space itself, brought about via coupling to a new field known as the inflaton, this exponentially expanding epoch preceded what we presently know as the observable Universe.
Inflation has its attractive features, and can explain many features that are observed to be true. In addition, it has made successful predictions that were borne out, years or even decades later, by detailed observations of the Big Bang’s leftover glow. But there’s a darker side to inflation: the phenomenon of “infinite model-building,” where theorists churn out model after model after model, predicting every imaginable outcome, and therefore, predicting nothing at all.
Although inflation has some incredible features that no other competitor can match, it’s not a theory without its flaws. Sabine Hossenfelder gives us a peek behind the curtain on Starts With A Bang today.