Richard Feynman's sister Joan's advice to him: "Imagine you're a student again"

Richard and Joan at the beach

Richard Feynman might have been the most famous Feynman of the twentieth century, but his younger sister Joan - who turned 90 a few days ago -  was no slouch. At a time when it was difficult for women to enter and thrive in science, she became a noted astrophysicist in her own right, investigating stellar nucleosynthesis and the aurora among other topics. By all accounts the two also enjoyed a warm relationship, with Richard encouraging Joan's scientific interests from an early age.

There was one time however when it was Joan who gave Richard a very valuable piece of advice for solving a thorny scientific problem, and not only did it serve him well throughout his future career, but it's also one that all of us can really benefit from. In the 1950s, during the heyday of particle physics, Feynman was at a conference in Rochester where there was word of a profoundly deep potential discovery - so-called 'parity violation'. Parity violation means that left and right are not the same, a fact that seems to go against very fundamental physical laws: for instance, in chemistry there is no a priori reason why the parity or 'handedness' of amino acids should be left instead of right, and most researchers think that the only reason we have left handed amino acids is because of an initial accident that then got perpetuated. And yet there were some unstable particles whose decay into simpler ones seemed to violate parity.

At the conference Feynman read a paper by Chen Ning Yang and Tsung Dao Lee, two Chinese-American physicists who had theoretically showed that parity could be violated in certain ways. At that point in time Feynman was in the middle of a kind of scientific slump. He had made his most famous, Nobel Prize winning discovery - the reformulation of quantum electrodynamics - about ten years earlier, and was looking for fresh scientific questions to ponder. Parity violation seemed exactly like the kind of bold and potentially revolutionary problem that would benefit from an unconventional mind like this. But he felt stuck. At that point Joan came to his rescue. As he writes in his memoirs,

“During the conference I was staying with my sister in Syracuse. I brought the paper home and said to her, “I can’t understand these things that Lee and Yang are saying. It’s all so complicated.”

“No,” she said, “what you mean is not that you can’t understand it, but that you didn’t invent it. You didn’t figure it out your own way, from hearing the clue. What you should do is imagine you’re a student again, and take this paper upstairs, read every line of it, and check the equations. Then you’ll understand it very easily.”

I took her advice, and checked through the whole thing, and found it to be very obvious and simple. I had been afraid to read it, thinking it was too difficult.”

And this was sound advice indeed. Feynman thought hard about parity violation, and along with his 'frenemy' Murray Gell-Mann came up with a theory of beta decay that was one of his most significant contributions to physics (it would be the only paper the two would jointly co-author). He got out of his scientific slump and went on to invent a startlingly original theory of superfluidity. But Joan's advice - for which he deeply thanked her later - was pivotal in getting him started on this path.

The advice may seem obvious, and yet it's something that we often forget once we graduate from college or graduate school and progress in our scientific careers. One of my college professors once offered another related piece of advice: "Nothing's difficult, only unfamiliar". When we are students we are used to actually studying difficult topics and walking through them line by line (perhaps because it's required for the final exam, but nonetheless!). Later somehow we seem to lose the zeal and inclination for sustained, serious study of the kind that we did as eager college students. 

What Joan was telling Richard that it's only prolonged attacks on tough subject material that can yield insights. When you don't invent something - and that applies to most things - you do have to go back to basics and try to understand it from scratch. That approach of taking everything apart and understanding it from a fresh perspective played right into the Feynman playbook; it was what had enabled him to reinvent quantum mechanics. When it came to parity violation the strategy clearly worked for him. And there is no reason why it should not work for lesser mortals. We didn't invent many things, but we can understand most things.