Sunday, July 6, 2014

More doubts about big bang gravity wave

Quanta Mag tells doubts about BICEP2:
Most of them were careful to point out that the revolutionary claim from the scientists involved in the experiment, which used the BICEP2 telescope (for Background Imaging of Cosmic Extragalactic Polarization, second generation), must be confirmed by additional experiments that could rule out alternative explanations. But because BICEP2’s very technical paper asserted that the possibility of the gravitational-wave signal being false was very low, the discovery seemed like a done deal to most people.

But not to David Spergel. Spergel earned his stripes in astrophysics as a team member on the Wilkinson Microwave Anisotropy Probe (WMAP), a radio telescope that launched into orbit in 2001. ...

QUANTA MAGAZINE: You are a leading critic of the BICEP2 team’s claim to have discovered the existence of primordial gravitational waves. Why?

DAVID SPERGEL: The BICEP2 astrophysicists should have been more cautious. The evidence they have reported fails to convince me that the signal they interpret as being caused by gravitational waves is not, in fact, caused by galactic dust.
So maybe they saw a shock wave from the biggest event in the history of the universe. Or maybe they just saw dust. No one can be sure.
Why didn’t they use the raw Planck data?

Planck’s raw data will not be made public until the end of the year.

Did you ask the BICEP2 scientists for access to their data?

Yes, but they declined to release it, saying that their data is not calibrated.

Is it common practice to hold onto such data?

It’s fine to keep raw data secret until it is properly calibrated by scientists who understand the limitations of the instrument that collected the data. But if you are willing to publish a paper based upon your data, then you should make that data public.
That is a little fishy. When scientists hold press conferences, and start divvying up the Nobel prizes, they ought to be willing to share their data with peers for analysis.

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