Collins and Pinch conclude that sometimes a "classic confrontation between theory and experiment" can make us question practically every assumption. But why then, do we take our assumptions, our scientific beliefs to be ok, most of the time? After all, the answer does not lie in recalcitrant nature.

It was, and is, generally believed that stars get their energy from nuclear fusion reactions. Our theory of atomic physics is applied in astrophysics to get a theory of stellar evolution. The theory of stellar evolution plays an important role in astronomy, and it is highly successful. However, in the 1960s, no one had ever directly observed nuclear fusion in a star. The fusion is buried deep in the middle of a star, and the light, for example, the star produces takes millions of years to make it to the surface, and by then it has been shaken and stirred so much that it bears little evidence of the fusion reaction.

Neutrinos, however, can pass through anything practically unobstructed. Unlike the light, the neutrinos produced by the fusion reaction take 8 minutes to get to the earth. Thus, one can observe the fusion reaction directly by observing the neutrinos.

Davis had made a neutrino detector just because he could. He tried detecting the neutrinos from a nuclear reactor unsuccessfully. A theoretician explained that they were the wrong kind of neutrinos. When someone realized that Davis's detector should be able to detect solar neutrinos, he was back in business. Problem: he needs a really big one, and it is expensive. In order to get it built, he needs evidence that he'll be able to detect the neutrinos and so he needs a good estimate of how many and what kind of neutrinos come from the sun. The estimate of how many neutrinos climbs, and reaches a maximum right about when Davis gets funding.

When the experiment is finally run, Davis detects no neutrinos. That isn't possible, and so what he reports is that there are no more than ... neutrinos. He improves the detector and checks it by shooting in some neutrinos. He still gets far too few neutrinos. He "wastes" a lot of time ruling out every single thing that might have caused him to miss neutrinos that anyone suggests. Though there are many suggestions about what Davis did wrong, he persists so effectively that his results continue to be taken seriously, at least in the sense that people keep finding more possible mistakes. In addition, estimates of the neutrino flux drop precipitously and keep going down. Finally, a theoretician says that Davis is right, and relatively soon after even Davis's supporters agree.

All hell breaks loose: people propose that the sun is not heated by fusion, that neutrinos oscillate between the three different kinds, that the core of the sun is cooler than had been thought because of mixing, that there are more heavy elements in the core of the sun than had been thought. And so on. Duhem would have been thrilled.

The example does not show what Collins and Pinch claim, though it does show that there is a larger social component to science than might have been generally expected. In addition, it is a useful corrective to an obvious misinterpretation of Kuhn: not every failed experiment just gets dismissed as an anomaly, even within normal science.

-- ShaughanLavine - 05 May 2009