Tuesday, March 25, 2014

BICEP2: reasons to be sceptical, part 1

As the dust begins to settle following the amazing announcement of the discovery of gravitational waves by the BICEP2 experiment, physicists around the world are taking stock and scrutinizing the results.

What I wanted to do today is to possibly contribute to that by gathering together all the main points of concern and reasons to be sceptical of the BICEP result. This is partly for my own purposes, since writing things down helps to clarify my thoughts. I will divide these concerns into three main categories, addressing the following questions:
  • how certain can we be that BICEP2 observed a real B-mode signal?
  • how certain can we be that this B-mode signal is cosmological in origin, i.e. that it is due to gravitational waves rather than something less exciting?
  • how certain can we be that these gravitational waves were caused by inflation?