BICEP2: New Evidence Of Cosmic Inflation!
Following on from yesterday’s news, here’s a more detailed analysis of the implications of the BICEP2 result from Matt Straessler’s blog. I certainly agree with the statement highlighted in red in his post:
Until this measurement/discovery is confirmed by another experiment, you should consider it provisional. Although this is too large a signal to be likely to be due to a pure statistical fluke, it could still be due to a mistake or problem, or due to something other than gravitational waves from inflation.
[For your reference if you can’t follow this post: My History of the Universe, and a primer to help you understand what’s going on today.]
I’m still updating this post as more information comes in and as I understand more of what’s in the BICEP2 paper and data. Talking to and listening to experts, I’d describe the mood as cautiously optimistic; some people are worried about certain weird features of the data, while others seem less concerned about them… typical when a new discovery is claimed. I’m disturbed that the media is declaring victory before the scientific community is ready to. That didn’t happen with the Higgs discovery, where the media was, wisely, far more patient.
The Main Data
Here’s BICEP2’s data! The black dots at the bottom of this figure, showing evidence of B-mode polarization both at small scales (“Multipole” >> 100, where it is due to gravitational…
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In the Dark 
March 18, 2014 at 12:08 pm
I think the description of the last plot as a bit inaccurate, running of the spectral index is not how “n_s slowly varies as inflation proceeds” but how n_s varies with k. Or am I missing something?
March 18, 2014 at 12:10 pm
But the variation with scale corresponds to a dependence of the scalar field dynamics on time….