Written by: Stephen Hsu
Primary Source: Information Processing
Theoretical physicist John Hopfield, inventor of the Hopfield neural network, on the differences between physics and biology. Hopfield migrated into biology after making important contributions in condensed matter theory. At Caltech, Hopfield co-taught a famous course with Carver Mead and Richard Feynman on the physics of computation.
(Phys. Biol. 11 053002 doi:10.1088/1478-3975/11/5/053002)
Abstract: ‘I didn’t really think of this as moving into biology, but rather as exploring another venue in which to do physics.’ John Hopfield provides a personal perspective on working on the border between physical and biological sciences.
… With two parents who were physicists, I grew up with the view that science was about understanding quantitatively how things worked, not about collecting details and categorizing observations. Their view, though not so explicitly stated, was certainly that of Rutherford: ‘all science is either physics or stamp collecting.’ So, when selecting science as a career, I never considered working in biology and ultimately chose solid state physics research.
… I attended my first biology conference in the summer of 1970 at a small meeting with the world’s experts on the hemoglobin molecule. It was held at the Villa Serbelloni in Bellagio, in sumptuous surroundings verging on decadence as I had never seen for physics meetings. One of the senior biochemists took me aside to explain to me why I had no place in biology. As he said, gentlemen did not interpret other gentlemen’s data, and preferably worked on different organisms. If you wish to interpret data, you must get your own. Only the experimentalist himself knows which of the data points are reliable, and so only he should interpret them. Moreover, if you insist on interpreting other people’s data, they will not publish their best data. Biology is very complicated, and any theory with mathematics is such an oversimplification that it is essentially wrong and thus useless. And so on… On closer examination, this diatribe chiefly describes differences between the physics and biology paradigms (at the time at least) for engaging in science. Physics papers use data points with error bars; biology papers lacked them. Physics was based on the quantitative replication of experiments in different laboratories; biology broadened its fact collecting by devaluing replication. Physics education emphasized being able to look at a physical system and express it in mathematical terms. Mathematical theory had great predictive power in physics, but very little in biology. As a result, mathematics is considered the language of the physics paradigm, a language in which most biologists could remain illiterate. Time has passed, but there is still an enormous difference in the biology and physics paradigms for working in science. Advice? Stick to the physics paradigm, for it brings refreshing attitudes and a different choice of problems to the interface. And have a thick skin. …