The Universe got a little more amazing today. Thirty years ago, the theory of cosmic inflation was proposed. The idea is that, for about one billion billion billion billionth of a second, the universe expanded faster than the speed of light.
The inflationary theory explained a lot of things, such as the remarkable smoothness of the universe. And it had some interesting implications, such as the potential existence of other universes, perhaps with different laws of physics. But a scientific hypothesis isn’t really a theory until it has made a successful prediction.
That happened today:
Inflationary models predict that other marks were left on the Universe, and one of these is that as the Universe underwent rapid expansion, it would create ripples in the fabric of space-time called gravitational waves. These are literally small expansions and contractions of space itself, like a wave traveling down a Slinky. We know these exist—we see their effects in astronomy, and two astronomers won a Nobel Prize in 1993 for finding an example of gravitational waves—but seeing them coming from the inflationary period of the Universe is incredibly difficult.
We don’t see the waves themselves, but we can detect the effect they had on light coming from the early Universe. The waves would polarize the light, in a sense aligning the waves of light in certain ways. There are many different ways light can be polarized, but gravitational waves left over from inflation would do so in a very specific way (called B mode polarization, which twists and curls the direction of the polarization; see the image at the top of this post). Finding this kind of polarization in the light leftover from the fires of the Big Bang would be clear evidence of gravitational waves… and it was precisely this type of polarization that was finally detected by a telescope called BICEP2 (Background Imaging of Cosmic Extragalactic Polarization), located in Antarctica.
You should read Phil’s entire post. You should also watch this video of Andrei Linde, the father of inflation theory, getting the news that he was right.
Here’s the thing. BICEP2 closed shop two years ago. According to one source, they’ve have this result for three years but have spent those years making absolutely sure they were right. The patience involved in that relentless checking is amazing.
We live in a great time. First Higgs and now Linde vindicated by observations.