It’s Nobel Prize month and once again I like to highlight the science prizes because of how little mainstream news coverage they get. I don’t think there’s anything too surprising this year except that some people wondered why there’s been no acknowledgment of the mRNA technology that has powered many of the vaccines used to fight the ongoing pandemic. That’s silly of course given the time scales of how the Nobel Prize committee works such that it takes a while for a discovery to be deemed important enough to merit an award.

I suppose the most headline grabbing prize this year is the one for physics because it’s being described as being an award for climate change research. It’s more complicated than that of course as it is really about methods to describe and predict the behavior of large, complex systems with a lot of chaos and the planet’s climate is the best possible use case for such methods. This story begins in the 1960s with Syukuro Manabe for linking increased levels of carbon dioxide in the atmosphere with higher temperatures and developed the first models of the Earth’s climate.

Some ten years later Klaus Hasselmann showed that local weather despite being chaotic and unpredictable could lead to reliable long-term predictions of the climate as a whole. Then in the 1980s Giorgio Parisi, studying complex materials such as spin glass such as a matrix of copper atoms that also contain scatted iron atoms and hence have complicated magnetic orientations, devised mathematical ideas to understand this complexity. Naturally these are also applicable to other fields including climate science.

Hopefully most people still reading this already know what catalysts are and why they are essential in chemical reactions to turn one type of molecule into another. It was thought however that catalysts fall into two types: enzymes, which are large, complicated protein molecules, and transition metals, the elements in the middle of the periodic table. Benjamin List and David MacMillan, working independently but towards the same ends, discovered an entirely new type of catalysts now called organocatalysts, for which they have been awarded the prize for chemistry.

These are relatively small organic molecules that don’t include metal. The latter is a desirable trait because metal compounds are frequently toxic and metal-based catalysts don’t distinguish between different mirror-image versions of molecules and as these have different effects, drugmakers usually want only one specific version. Since about 2000 when these discoveries were made, organocatalysts have become widely used in many industrial processes.

The prize for medicine may not seem so exciting but it is a natural extension of the realization that our senses work through incredibly specialized organs and channels and we still don’t know all of them, including elementary ones like how we sense temperature. David Julius beginning in the 1990s studied capsaicin, the active ingredient that makes chili peppers hot, and worked out which protein in heat-receptor cells are sensitive to capsaicin. In doing so, he discovered the ion channel protein now called TRV1 and worked out it is triggered when heat rises to painful levels. This led to other discoveries of other temperature sensing receptors including work by both Julius and Ardem Patapoutian to use menthol to identify cold sensitive receptors.

Patapoutian also found touch sensitive receptors, beginning with Piezo1 which is actually found in organs like the bladder. This sensitivity to mechanical pressure is what causes people to feel the need to urinate. Through its similarity to Piezo1, he also found Piezo2 which is responsible for our more familiar sense of touch and proprioception, which lets us know the position and movement of our body.

Unlike the physical sciences, it is extremely difficult to perform experiments in the social sciences or economics. David Card however realized that one could identify natural experiments such as when the state of New Jersey passed a minimum wage law in 1992 but nearby Pennsylvania didn’t. Reasoning that the two states are similar enough, Pennsylvania could serve as the control group to work out the effects of the minimum wage law. This seems obvious today but apparently it was quite novel back then.

Often however such differences between two groups aren’t so neat as that, and it may be necessary to tease them out in clever ways. Joshua Angrist was one of those who realized that the date of birth of each school student makes a small but measurable difference in how much schooling that student gets in the US. Effectively those were born earlier in the year gets slightly less schooling than one born late in the year. This makes it possible to work how the length of schooling a person receives impacts lifetime earnings. Guido Imbens is also included as one of the winners for working out the theoretical framework to analyze the causal relationships in these empirical phenomena.