More on BICEP2 and the inflationary universe story from Sean Carrol

Sean Carroll at Preposterous Universe:

Here I am at an extremely stimulating meeting on gravity and quantum spacetime in Santa Barbara, but I skipped yesterday’s afternoon session to talk on the PBS News Hour about the new inflation results:

There’s a great parallel (if the BICEP2 result holds up!) between Monday’s evidence for inflation and the Higgs discovery back in 2012. When talking about the Higgs, I like to point out the extraordinary nature of the accomplishment of those physicists (Anderson, Englert, Brout, Higgs, Guralnik, Hagen, Kibble) who came up with the idea back in the early 1960′s. They were thinking about a fairly general question: how can you make forces of nature (like the nuclear forces) that don’t obey an inverse square law, but instead only stretch over a short distance? They weren’t lucky enough to have specific, detailed experimental guidance; just some basic principles and an ambitious goal. And they (independently!) proposed a radical idea: empty space is suffused with an invisible energy field that affects the behavior of other fields in space in a profound way. A crazy-sounding idea, and one that was largely ignored for quite a while. Gradually physicists realized that it was actually quite promising, and we spent billions of dollars and many thousands of scientist-years of effort to test the idea. Finally, almost half a century later, a tiny bump on a couple of plots showed they were right.

The inflation story is similar. Alan Guth was thinking about some very general features of the universe: the absence of monopoles, the overall smoothness and flatness. And he proposed an audacious idea: in its very earliest moments, the universe was driven by the potential energy of some quantum field to expand at an accelerated rate, smoothing things out and diluting unwanted relics like monopoles. Unlike the Higgs idea, inflation caught on quite quickly, and people soon realized that it helped explain the origin of density perturbations and (potentially) gravitational-wave fluctuations.

More here.