Already the alleged discovery of not only primordial gravitational waves but also the big bang era of inflation (which I discussed in Has the ‘smoking gun’ of the ‘big bang’ been found? and also in this blog, only a little over a week ago) has been questioned in a paper1 by leading cosmologists. This is in a paper, submitted to the preprint archive (arXiv.org) on March 20th, 2014, just three days after the press release (on March 17th) of the “discovery” by the BICEP2 Collaboration team.
On March 25th a press item appeared on phys.org quoting these cosmologists and entitled ‘Cosmologists cast doubt on inflation evidence’, with a storyline saying
Some theorists are advising that we “put the champagne back in the fridge”… at least for now.2
Researchers from the BICEP2 project at the South Pole Telescope had claimed unambiguous evidence of primordial gravitational waves in the cosmic microwave background, the residual rippling of space and time created by the sudden inflation of the Universe a quintillionth quintillionth of a second after the big bang. And there were even whispers of a Nobel prize nomination. The team’s findings were hailed as the best direct evidence yet of cosmic inflation, and even support for the existence of a multiverse—multiple universes outside our own.
The theorists James B. Dent (University of Louisiana at Lafayette), Lawrence M. Krauss (Arizona State University and Mount Stromlo Observatory, ANU) and Harsh Mathur (Case Western Reserve University) question those findings:1
In order to provide compelling evidence, other possible sources of the signal need to be ruled out. While the Inflationary signal remains the best motivated source, the current measurement unfortunately still allows for the possibility [of another cause]
In other words, you cannot make a definitive claim of proof of anything unless you have first ruled out all other possibilities that might cause the same effect. In my article3 I wrote:
In this case it would have to be shown that the evidence could not come from any other possible source or mechanism. This is the problem with cosmology in general.
Cosmology is not science in the usual laboratory repeatable experiment sense. The idea that one could treat the universe as a lab to test your model and obtain definitive outcomes of an experiment belies credibility. The universe is too large, we cannot see all that we need to see, and when we are talking of the putative big bang or events one cannot truly justify ‘seeing’ that which we cannot actually see. We only have the radiation arriving at our telescopes on earth or in orbit in the solar system. The interpretation of that evidence is circumstantial at best. The universe still has much we don’t understand. Why do cosmologists have to make up stuff like inflation, dark matter and dark energy? Simply because we do not understand the universe.
The cosmologists in their paper also state that,
…it is important to demonstrate that other possible sources cannot account for the current BICEP2 data before definitely claiming Inflation has been proved.1
But I would go even further and claim that there is a plethora of other possible sources; some that may be known, and some that have not even been thought of yet. To claim a definitive proof from the cosmos is pure speculation. It is not science.
1. James B. Dent, Lawrence M. Krauss and Harsh Mathur, Killing the Straw Man: Does BICEP Prove Inflation?, http://arxiv.org/pdf/1403.5166v1.pdf
3. John G. Hartnett, Has the ‘smoking gun’ of the ‘big bang’ been found?