
Yesterday, we noted that a big announcement was expected re gravitational waves (Have astronomers picked up echoes of the Big Bang?), expressing the hope for a return to a cosmology based on fact, not on what dope the guy smokes. Well, it’s been made and here are physicist Rob Sheldon’s comments on it:
Okay everybody, the announcement has been made, the speculation was accurate.
BICEP (a telescope at the South Pole), has made careful measurements of the cosmic microwave background radiation (CMB) coming from the Big Bang, and thinks they have a real polarization signal. Just like the blue sky, in which there is a polarization signal that birds can see and use for navigational purposes which you might be able to observe with the right kind of sunglasses, so also the CMB has a tiny tiny bit of polarization in it.
Now the rest of the press release is all speculation, or theory, or whatever you call it when people breathlessly tell you that the sky is falling because something hit them on the head.
One (out of very many) theories holds that the way the CMB can get polarized, is if gravity waves from the original BB are amplified by this idea of “inflation” that expanded the universe by a gazillion times right after it banged. So this observation is being touted as a double-header—the first observation of gravity waves, and the first observation of inflation. We could toss the Easter bunny in there too, at this point it looks like it’s the first observation of all sorts of invisible things.
Now the probability that two unproved theories are confirmed by one observation is close to nil. I don’t know how strongly I can say this, but lightning doesn’t strike twice in the same spot, and these press reports are claiming that.
So what else could this polarization signal in the CMB mean? I’m no expert in these matters, but I happen to know that starlight is also polarized. In the case of starlight, the polarization is caused by scattering off of spinning dust grains in a magnetic field. It would seem to me that the same process that polarizes starlight would work just as well on CMB and it has nothing to do with either gravitational waves or inflationary cosmology. Just plain ordinary dust.
That would be where I put my betting money.
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See also: The Science Fictions series at your fingertips (cosmology).