Smoking Gun Evidence for Cosmic Inflation: A Misfire
The exciting discovery earlier this year of evidence for Cosmic Inflation looks to have been contaminated by the gas and dust in our own galaxy.
Sometimes theoretical discoveries are made or evidence is uncovered that refines and expands our knowledge of the universe in some fundamental way. Nothing, Absolutely…Nothing, allows that to happen like science does. Science delivers the goods as they say. These advances however are always potentially provisional. There’s always assumptions that could be wrong or unconsidered frames of reference or new powerful evidence that could change things. Of course, many of our most cherished scientific theories are supported not with just a mountain of evidence but continents of high quality evidence. Evolution is the canonical example of this. Its broad strokes are so well established that (to paraphrase Stephen J Gould) it would be fucking asinine not to proceed as if we were 100% certain.
Sometimes discoveries that support our theories achieve high levels of confidence relatively quickly. This happened early on 2014 with one of the biggest scientific announcements of the year.
Cosmologists had found the smoking gun for Cosmic Inflation.
Cosmic Inflation is a bizarre theory in that it proposes that right after the big bang, the universe expanded to an incredible degree very quickly. In one undecillionth of a second (10 to the -36th), a patch of the newborn universe expanded exponentially from one billion times smaller than a proton to that of a golf ball. that’s a relative volume increase of 10 to the 80th power. Trust me, you don’t come across anything to the 80th power very often.
This theory didn’t have much solid evidence to back it up but it did do one thing extraordinarily well. It explained away several incredibly annoying characteristics of the universe that simply didn’t make any sense. This includes the fact that the temperature of our universe is very uniform and its shape is very flat.
Over the years though it’s been very frustrating that we didn’t have more solid evidence for inflation. That’s why the scientific community and enthusiasts the world over were so overjoyed at the announcement by scientists that a device called BICEP2 had uncovered evidence that inflation really happened.
In a big nutshell, this is their discovery:
It is thought that inflation would have caused gravitational waves that would have left an imprint on the first light produced after the big bang called the Cosmic Microwave Background Radiation (CMB). This imprint would consist of a specific type of twisted light called B-Mode Polarization. Light consists of self-perpetuating and alternating magnetic and electric fields at right angles to each other. Normally, they are oriented randomly around the direction of movement but certain processes and materials (like polarized sunglasses) can polarize the light changing this randomness making it identical or giving it a specific pattern.
This apparent gravitational-wave-induced B-Mode polarization is exactly what the scientists claimed that they found. The chain of deduction then proceeds like this:
Twisted light found in the CMB was likely caused by the gravitational waves which were created by cosmic inflation (which happened right after the big bang which happened after….who the hell knows).
Hence the twisted light is evidence that inflation is a real thing that happened.
The scientists and engineers were pretty damn certain of this conclusion. Too certain it seems. They even said they calculated a confidence level between 5 and 7 sigma. That means that the odds of this result being a random occurrence was 1 in two million. Typically, 5 sigma is considered the gold standard in science but one of the gold standards of the scientific process is peer review and they got their asses peer-reviewed off.
A team of scientists called the Planck Collaboration (love that name) did an in-depth study and they found out that the patch of sky the original study looked at has an unusually large amount of gas and dust in our galaxy that contaminated the results. This dust emits twisted polarized light that is the same as the twisted CMB light. The collaboration also identified other deficiencies in the experimental design such as a reliance on one frequency of light.
This is very disappointing but that’s science baby and that’s what makes it so special. Feedback and criticism from peers is expected and integral to the process to either hone your theory, modify it, or even completely discard it.
The bottom line in all this then is that the measurements were in fact solid but the claim that it was evidence of cosmic inflation was premature before outside vetting and verification especially given the facts and deficiencies uncovered by the collaboration.
The next step is that the two teams will combine all their data and it may even be possible that they’ll still be able to tease out evidence of inflation. If that’s the case then the argument for its existence will be much stronger and most likely worthy of a Nobel prize in my opinion. We may know before the end of the year. If it turns out that the entire signal was due to the gas and dust then (crap) the scientists would likely need a dedicated satellite mission to get even more sensitive data. After that we’ll see where the evidence leads.
And that’s one of the key differences between science and an ideology. Often people can’t help but get so emotionally invested in their beliefs that they unknowingly commit a host of logical fallacies and go down the rabbit hole of pathological thinking in order to maintain their cherished beliefs. Science is designed to short-circuit these human failings and even if we make discoveries that turn out to be wrong, it’s only because science is working that we know it’s wrong in the first place.