BICEP2 Collaboration –the Hot Air Merchants from the South Pole
It is a little suspicious when a discovery is declared worth a Nobel Prize the very same day of the discovery by the discoverers. The BICEP2 claim that gravitational waves have been found was breaking news this week.
Let us have brief a look at gravitational wave detection—since the 1960s, this has always been a tricky business. Its history is beautifully described in Gravity’s Shadow by Harry Collins—this is probably the field with the highest number of retracted claims. Huge efforts were undertaken to prove the existence of gravitational waves directly, but all big sience experiments such as LIGO have been unable to confirm gravitational waves to this day. One may even wonder why none of the various anomalous signals were interpreted as gravitational waves in the meantime.
Ultimately, this is a merit of the very clear methodology and definition of the wave signal in laboratory experiments—it must show up in different places at fixed times, determined by the wave velocity c. This difficulty can hardly be appreciated highly enough—it is an almost unsourmountable barrier for artifacts to be falsely declared as signals. Unfortunately, the cosmic microwave background does not contain such a barrier.
One persisting problem is, as a speaker at the conference “The first billion years” (Garching, 2005) already put it in a nutshell: “The limit of background measurement is foreground.” A considerable amount of filtering and modeling is included in the analysis, rendering it gradually more prone to artifacts. (One would wish the entire anaylsis to be publicly available and transparent.)
This is already a huge problem for the tiny polarization signal seen at the time of the formation of the cosmic microwave background (CMB), assumed to be 380,000 years after the Big Bang, but it renders ridiculous the claims about the first seconds of the universe. How could such subtle information survive in a sizzling hot soup for almost half a million years?
In addition, the signal declared as evidence for gravitational waves, the “B-Mode polarization,” is utterly banal—polarization is (practically) a vector field and every vector field can be decomposed into “div” and “curl” parts. Cosmologists now claim that they cannot explain the origin of the curl part, but so what? Why gravitational waves? A pile of theoretical assumptions enters through the back door of this so-called observation. Hundreds of unknowns, artifacts, or dirt effects could cause such a “B-mode polarization.” To call this ‘direct observation’ (much more indirect as the already inconclusive evidence from the Taylor-Hulse pulsar) is audacious, to put it mildly.
To further the hype, they added the preposterous claim that those gravitational waves constitute evidence for the theory of inflation, an obviously nonsensical assertion that should leap to the eye of any sane researcher. How could an effect of the first 10-32 seconds be tracked over 50 orders of magnitude, to 380,000 years? Utterly absurd.
However, we live in a period in which the borders of science and fairy tale stories are blurring. Laura Mersini-Houghton, in all seriousness, has claimed that a “cold spot” in the CMB chart is evidence for the multiverse. MIT cosmologist Max Tegmark has recently published a book with ridiculous speculations, but he is nevertheless respected for his work on the CMB. I prefer to view it the other way around: whoever spreads such obvious baloney will hardly engage in serious science elsewhere.
The analysis of the CMB, since Penzias and Wilson, gradually became a more complicated issue and is now running for the most intransparent astrophysical business, much alike particle physics. It becomes increasingly harder to separate the hard facts from the tea leaves; thus, I would like to mention the work of Pierre-Marie Robitaille, who is even more skeptical about the CMB than I am. So much nonsense being published about the CMB makes me increasingly suspicious about its very foundations.
