Archive for the 'Cosmology' Category

What happened in the first instants after the Big Bang?

The BICEP2 telescope at the South Pole, designed to look for polarization of light that could be the sign of inflation. [Credit: Steffen Richter]

The BICEP2 telescope at the South Pole, designed to look for polarization of light that could be the sign of inflation. [Credit: Steffen Richter]

One of the biggest science stories of 2014 came out of the BICEP2 cosmic microwave background polarization experiment. Last spring, the BICEP2 researchers announced they had measured something known as B-mode or tensor-mode polarization, a particular twisting of light that is the hallmark of primordial gravitational waves. Those waves in turn would be a strong piece of evidence for inflation: the proposed incredibly rapid expansion of the Universe in the first fraction of a second after the Big Bang.

However, even from the start, there were reasons to doubt the BICEP2 results were exactly what they seemed. First, the size of their signal was much larger than the limits set by earlier observations; second, they had no decent data on cosmic dust, which can imitate or obscure the gravitational wave polarization signal. In recent months, the narrative has switched from “BICEP2 has discovered inflation!” to “BICEP2’s results are all dust!”, but I think both are just as wrong. The real story is still developing, and while it seems likely that dust is the majority of the BICEP2 signal, there might yet be gravitational waves hiding in it. (A particularly interesting idea is that the possible gravitational wave signal in the data could actually rule out inflation, at least in its typical versions.)

I bring this up for two reasons:

  1. I am leading a panel discussion on BICEP2 at the National Association of Science Writers/Committee for the Advancement of Science Writing (NASW/CASW) meeting next Monday. Johns Hopkins cosmologist Marc Kamionkowski, WIRED editor Betsy Mason, and I will discuss the challenges of reporting evolving stories, especially those with strong claims. A publication of no less stature than Nature has endorsed the session!
  2. The following week, I will be teaching an online class on Inflation and the Very Early Universe! In addition to BICEP2, we’ll talk about the odd observational facts that motivated inflation, the current models and problems with inflationary theory, potentially detectable consequences of inflation, and some alternative ideas. Sign up today!
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