Feb 02 2015

Gravity Waves and Science Self-Correction

In 2011 scientists tentatively reported that they may have detected neutrinos traveling faster than the speed of light in apparent contradiction to the theory of relativity. By early 2012 the technical error that led to the apparent discovery was revealed.

Also in 2012 scientists reported that, using the Large Hadron Collider, they probably found the Higgs boson, the particle responsible for mass. However they were still not completely sure so they kept testing, and then last year they announced that indeed they did identify the Higgs as predicted by the standard model of particle physics.

In March of 2014, in what was definitely the biggest science news story of the year scientists reported detected gravity waves from the Big Bang, confirming the theory called the “inflationary universe.” The discovery was hailed as a “smoking gun.” Space.com at the time wrote:

If it holds up, the landmark discovery — which also confirms the existence of hypothesized ripples in space-time known as gravitational waves — would give researchers a much better understanding of the Big Bang and its immediate aftermath.

In those four little words, “if it holds up,” lies the essence of science. This is just a sample of recent big science news stories that reveal the process of science – skeptical questioning of all claims and testing those claims against objective evidence.

It seems that the story of possible gravity waves supporting inflationary theory is going the way of FTL neutrinos rather than the Higgs.

Inflationary theory is the notion that in the first fractions of a second after the Big Bang the universe expanded rapidly. This would explain some interesting features about the universe that would otherwise be difficult to explain, including why our universe appears to flat and uniform. Rapid inflation would have had the effect of, to use an analogy frequently offered, taking a crumpled piece of paper and then flattening it out.

It was a nice idea that had useful explanatory power. Scientists, however, are not philosophers, theologians, or metaphysicists. It doesn’t matter how pretty, clean, or useful an idea is. They want to know if it is actually correct. Does it make predictions about how reality behaves, predictions that can be confirmed through observation or experiment? The inflationary theory does make a specific prediction, that early inflation would have caused gravity waves, subtle ripples of gravity that can possibly be detected.

That is what was announced last March – that the BICEP2 experiment using the Keck array to analyze the cosmic microwave background (CMB) revealed the predicted gravity waves.

Almost immediately, however, there were possible problems. Other scientists pointed out that the data could be interpreted as the effect of galactic dust. Fortunately there was another independent set of data from ESA’s Planck satellite, which was just completing a very thorough mapping of the CMB. Those scientists analysing the Planck data came to the conclusion that the features in the CMB interpreted as gravity waves were from galactic dust, not gravity waves from early inflation.

The story wasn’t over yet, though. Now we have two sets of data coming to two different conclusions. The scientists, of course, just want to know the truth, even if it means losing the Nobel Prize for some. So they combined their data and did a new analysis of the combined data. This new analysis revealed…galactic dust.

But the story is not over yet – it never is with science. The new analysis does not rule out gravity waves altogether. It just means that this current data does not prove their existence. It is even possible that there is evidence for even more subtle gravity waves hidden in the data.

There is already a headline that overstates the implications of this new analysis, from CosmosUp.com: Big Disappointment: ‘Cosmic Inflation’ Theory is Wrong. Accuracy in science headlines is important. This headline is simply wrong – the new analysis does not disprove gravity waves, let alone cosmic inflation. It simply shows that the CMB data does not currently show evidence of gravity waves. Sure, this is a blow to cosmic inflation, but the theory is not dead yet.


In my encounters with pseudoscientists, cranks, and conspiracy theorists of every stripe I frequently encounter the claim that scientists are closed minded, they are dogmatic, and they protect their pet theories and the status quo. Nothing could be further from the truth.

These claims are just made up out of whole cloth because they support the crank narrative. It is common to simply assume a subjective opinion that supports one’s narrative. We need to actively fight against this tendency. It is difficult to step back from one’s ideology and look fairly at the evidence to see what it is actually telling us.

I also freely admit that I have a pro-science bias and so I tend to interpret the evidence in a science-friendly manner. I try to be aware of this bias and maintain my objectivity. I often go out of my way to point out that scientists are flawed, they have egos, sometimes they are dogmatic and protective of their pet theories.

But the scientific community is not monolithic. One scientist’s pet theory may be utter nonsense to another scientist. What these recent examples (and countless others) demonstrate is that, at the end of the day, evidence is king. Different teams of scientists looking at different data came to different conclusions. This demonstrates how the scientific community is a check on its members and provides self-correction. In the end they combined their data and came to a consensus.

We see this played out over and over. Different scientists have different theories, and their task is to convince the broader scientific community with evidence.

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