What Really Put The ‘Bang’ In The Big Bang?
So what is it that put the “bang” in the hot Big Bang? It’s the end of inflation. There is a state prior to the start of the hot Big Bang that set it up and provided it with the initial conditions of being spatially flat, the same energy density everywhere, always below a certain threshold temperature, and uniform with quantum fluctuations superimposed atop it on all scales.
When this inflationary state ended, the process of cosmic reheating transformed that energy — which had previously been inherent to the fabric of space itself — into particles, antiparticles and radiation. That transition is what put the “bang” in the hot Big Bang, and led to the birth of the observable Universe as we know it. The details of this were first worked out in the 1980s, back when inflation was just a theoretical idea, and have been confirmed by observations taken in the 1990s, 2000s, and 2010s. For decades, scientists have known what put the “bang” in the Big Bang. At last, now the general public can share in that knowledge, too.
Last week, a story came out that claimed to discover what put the “bang” in the Big Bang. Only, the actual study talked about what occurs in a conflagration or an explosion, which is completely unrelated to anything that occurs in the earliest moments of the hot, dense state that kicked off our Universe as we know it. Fortunately, we don’t have to wonder about what put the “bang” in the Big Bang; this is something scientists have known for decades.