Saturday, August 30, 2014

Do I want molecular biology to turn into physics?

I just read this little Nature News feature about the detection of low-energy neutrinos produced during the fusion reactions that power the Sun. I don't know much nuclear physics, but the article says that fusion in the sun involves the fusion of two hydrogen molecules into deuterium, and the conversion of one proton into a neutron leads to the production of low energy neutrinos, but nobody has been able to detect them because their low energy leads to their signal getting swamped out.

The experiment itself sounds incredible:
The core of the Borexino experiment features a nylon vessel containing 278 tonnes of an ultrapure benzene-like liquid that emits flashes of light when electrons are scattered by neutrinos. The liquid was derived from a crude-oil source nearly devoid of radioactive carbon-14, which can hide the neutrino signal. The detector fluid is surrounded by 889 tonnes of non-scintillating liquid that shields the vessel from spurious radiation emitted by the experiment's 2,212 light detectors.
That is some BIG science! Clearly an experimental triumph.

But it's also a triumph of theory. Theory in physics is so amazing. Can't tell you how many articles about physics have some version of the following line:
While the detection validates well-established stellar fusion theory, future, more sensitive versions of the experiment could look for deviations from the theory that would reveal new physics.
Not only is theory qualitatively right in physics, it's usually provides quantitative predictions with an accuracy that seem utterly preposterous from the perspective of a molecular biologist:
Borexino can measure the flux of low-energy neutrinos with a precision of 10%. Future experiments could bring that down to 1%, providing a demanding test of theoretical predictions and thus potentially uncovering new physics.
For fellow quantitative biologists, it is beyond our wildest fantasies to have strongly predictive theories and models like these. Usually, we're pretty happy if we can get the sign of the prediction correct! That said, there is also something troubling in these articles, which are all the little hints like "more sensitive... could... reveal new physics". I think the operative word is "could". Mostly, it feels like our understanding of many fundamental physical processes is so deep and so accurate that there aren't many surprises left out there (except for that whole dark matter/energy thing...).

I think I'm overall really happy that biology has surprises coming out all the time that make us reconsider our basic understanding of how things work. I do think that molecular biology does suffer a bit from "let's find the latest molecule that breaks the dogma" syndrome instead of focusing more effort on systematizing what we do know, but for the most part, I love the energy that comes from the huge amount of unknowns in the field and the huge challenge that comes with the effort to make molecular biology as predictive physics. Of course, there's no reason to believe a priori that such predictivity is possible. But that's what makes it fun!

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