Busted Bandwagon: The Sociology of BICEP2 Groupthink

It's finally official. Today the online version of the journal Nature (an authoritative source for scientists) has an article headlined “Gravitational Waves Discovery Now Officially Dead.”

In March 2014 the BICEP2 study was released, and it claimed to have found evidence for gravitational waves from the beginning of time. It was a result that would have confirmed the theory of cosmic inflation, a theory about what went on during the universe's first second. In March of that year, cosmologists around the world started crowing about how the discovery of the decade (or even the century) had been made. It was claimed that “smoking gun” evidence for the cosmic inflation theory had been found. For months many scientists and “household name” news sources described the inflated claims of the BICEP2 study as scientific fact.

But now the roof has caved in on this claimed breakthrough. Further analysis by the very large team of Planck scientists has found that the results of the BICEP2 team can plausibly be explained as being the result of ordinary dust and something called gravitational lensing, without imagining that the observations are caused by anything having to do with gravitational waves, the Big Bang, or cosmic inflation.

From the beginning there were lots of reason for suspecting that the BICEP2 study was on very shaky ground. The day after the study was released I released a very skeptical blog post entitled “BICEP2 Study Has Not Confirmed Cosmic Inflation,” pointing out some reasons for doubt. I followed this up in the next month with several other very skeptical blog posts on BICEP2. The reasons I discussed were out there in April 2014, but seemed to be ignored by most cosmologists at that time, who got busy writing lots of scientific papers about the implications of the supposedly historical BICEP2 study.

Now some cosmologists will point their fingers at the scientists of the BICEP2 team, and say, “Their error.” But the blame goes surprisingly wide and deep in this matter. We must also attach blame to the many other cosmologists who jumped the gun, and wrote scientific papers based on the BICEP2 claims, treating them as if they were all-but-proven. You can use this link to find the names of 125 scientific papers that have “BICEP2” in their titles. A great deal of these papers had titles such as “The Blah Blah Blah Theory in Light of BICEP2” or “Blah Blah Blah After BICEP2.” It seems that very many theoretical physicists took a good deal of time to write up papers discussing the profound implications of the BICEP2 study, the main results of which have now been declared “officially dead.”

How can we explain this embarrassing goof? It couldn't have been because our cosmologists are stupid. After all, they write these papers with lots of very hard math. Could it be this snafu occurred because no one warned them that the BICEP2 findings were preliminary, and needed to be confirmed by the Planck team? No, there were plenty of such warnings, and it was clear from the beginning the BICEP2 claims were in conflict with some of the Planck results.

In order to explain this gigantic goof, one needs to consider sociological factors. The group of scientists with one particular specialty is a small subculture subject to bandwagon effects, peer pressure, groupthink, group norms, group taboos, and other sociological influences. Given a proclamation by enough scientists within a field that a particular result is a “stunning breakthrough,” acceptance of that result becomes a group norm. Similarly, once a particular effect or result has been denounced by enough scientists within a field, then a taboo has been established, and rejection of that result becomes a group norm. Once a group norm or group taboo has been established in such a small subculture, it is rather like a buffalo stampede. Running with the herd is very easy, and running against the herd is very difficult. Every subculture imposes punishing sanctions on those within it who defy the group norms and group taboos. 

Peer pressure

For several months, acceptance of the BICEP2 claims was a group norm within the community of cosmologists, and so cosmologists fell in line, and followed the herd. A gigantic bandwagon effect was created. Using many dollars of taxpayers and universities, they wrote up lots of scientific papers that were based on the now-defunct group norm.

What lesson can we learn from this misadventure? One important lesson: make a judgment on the truth of something based on the facts and the evidence, not based merely on whether some consensus has been reached by a small subculture of scientists. That's because such a consensus may be heavily influenced by sociological factors and economic factors within the subculture: herd effects, groupthink, group norms, group taboos, bandwagon effects, and vested interests. Like politicians and judges, scientists like to imagine themselves as impartial judges of truth, judging only on the facts. But scientists are subject to sociological influences just like other people, influences that can decisively affect their pronouncements.