Physicists have found a long-predicted twist in light from the big bang that represents the first image of ripples in the universe called gravitational waves, researchers announced today. The finding is direct proof of the theory of inflation, the idea that the universe expanded extremely quickly in the first fraction of a nanosecond after it was born. What’s more, the signal is coming through much more strongly than expected, ruling out a large class of inflation models and potentially pointing the way toward new theories of physics, experts say. ...We will have to wait and see whether their is any other good explanation of the data. I have expressed skepticism about a lot of modern theoretical physics, but not that inflation might be at least partly correct. It seems plausible that the early universe was in a false vacuum, and then made a quantum leap to a lower state.
The Background Imaging of Cosmic Extragalactic Polarization 2 (BICEP2) experiment at the South Pole found a pattern called primordial B-mode polarization in the light left over from just after the big bang, known as the cosmic microwave background (CMB). This pattern, basically a curling in the polarization, or orientation, of the light, can be created only by gravitational waves produced by inflation. “It looks like a swirly pattern on the sky,” says Chao-Lin Kuo, a physicist at Stanford University, who designed the BICEP2 detector. “We’ve found the smoking gun evidence for inflation and we’ve also produced the first image of gravitational waves across the sky.”
I have been skeptical about a whole set of ideas associated with inflation, such as string theory, multiverse, eternal inflation, etc.
John Horgan is still skeptical about inflation:
Indeed, inflation, like string theory, has always suffered from what is sometimes called the “Alice’s Restaurant Problem.” Like the diner eulogized in the iconic Arlo Guthrie song, inflation comes in so many different versions that it can give you “anything you want.” In other words, it cannot be falsified, and so–like psychoanalysis, Marxism and other overly flexible hypotheses–it is not really a scientific theory.Considering that inflation seems to mean so many different things to different people, I am waiting to see exactly what was confirmed by the new experiment. We have what appears to be the remnant of a violent event in the early big bang, but I am not sure what all the consequences are yet.
Inflation enthusiasts have claimed vindication before—for example, in 1992, when the COBE satellite produced a detailed map of the cosmic microwave background, the afterglow of the Big Bang; and in the late 1990s, when astrophysicists discovered that the expansion of the universe is accelerating. But neither of these supposed confirmations of inflation held up.
Just two months ago, inflation pioneer Paul Steinhardt wrote on the website Edge.org: “I think a priority for theorists today is to determine if inflation and string theory can be saved from devolving into a Theory of Anything and, if not, seek new ideas to replace them. ...”