Oops. Maybe.
In March, a team of astronomers working with the BICEP2 radio telescope at the South Pole announced an exciting discovery, claiming to have discovered patterns in the cosmic microwave background that would exist if the universe underwent an enormous expansion almost immediately after the Big Bang. This “inflation” is a well-established feature of modern cosmology, and seems to be consistent with all the observational data, but direct evidence for its validity had not yet been seen. If the BICEP2 team’s claims were true, their results provided that direct evidence. But I was relieved to find that in my original post, I had included the obligatory scientist’s word of caution that the claim needed to be confirmed and reviewed. It looks like we’ll need to wait for results from other experiments before we can say that we have that evidence for inflation.
This doesn’t mean that inflation is wrong. It just means that the BICEP2 team’s evidence for it is flawed.
I’m going to leave out an enormous amount of detail and scientific jargon to give the version with which you can impress your friends, neighbors, and casual acquaintances at your next social gathering. The claimed detection was of particular polarization patterns in the cosmic microwave background. (For explanations of these terms, go again to that March Star Struck post.) The problem is that there are other sources of polarization. The BICEP2 team used some preliminary data from another team’s work that hadn’t yet determined how much of the polarization seen came from each of two well-known sources. One of those sources is our own galaxy, whose dust polarizes microwave radiation as well.
The bottom line? We don’t know how much of the polarization announced in March is from the cosmic background radiation (CMB), and how much from our own Milky Way galaxy. The announced CMB polarization may (and may not) be overstated.
There are other teams working in this area, and we may have more definitive results by the end of the year. In the meantime, I hope no one from the BICEP2 team has bought non-refundable tickets to Stockholm.
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