Planck CMB Polarization and BICEP2

The Planck collaboration has released a new measurement of the power spectrum of polarized light from dust. It’s been getting a lot of press because the measurement seems to present a challenge to the earlier (and much-touted) BICEP2 result that claimed to see evidence of primordial gravitational waves in polarized light from the Cosmic Microwave Background (CMB).

Sean Carroll has a summary here. It seems that there is a good chance that BICEP’s measurement was good but their interpretation of it as gravitational waves was not correct. However, a member of the Planck collaboration shows up in the comments to say that Carroll is probably overstating the case that the BICEP2 result was spurious. The two groups are apparently working on a combined result that will hopefully clear up the current confusion over what was actually seen.