In chapter 3, Feynman describes the relationship between physics and the other branches of science, namely, chemistry, biology, astronomy, geology, and psychology, which can all be described in terms of physics. As Feynman himself says towards the end of the chapter, “in order for physics to be useful to other sciences in a theoretical way, the science in question must supply a description of the object in a physicist’s language.” In other words, to what extent can we reduce other fields of science to interactions between atoms? Feynman does not ask this question condescendingly, but rather continues providing motivation for his lectures. Why care that everything is made of atoms? Because with that knowledge, we can understand the cosmos, from how our own bodies function to each sun in the universe. What really comes across in this lecture is the beauty Feynman sees in the phenomena that we understand and describe with physics, which he hopes to pass on to his students and reader.
Several themes emerge from Feynman’s answer. First, we see just how much overlap there is between fields of knowledge. It becomes clear how arbitrary and artificial the boundaries between disciplines are. Chemistry at its most basic, theoretical level is quantum physics, and in its turn organic chemistry encroaches on the territory of biology. Unsolved problems in various disciplines are, at heart, the same physical process. Feynman describes an age old mechanics problem that has yet to be solved: that of turbulent flow. If we can’t accurately describe what happens when water flows turbulently down a pipe, then we naturally have problems knowing exactly what happens when convection currents (turbulent flow) begin inside a star and the star is a few million years from exploding, or even how those currents work geologically, within the earth or in the atmosphere in the form of weather. These lead us to the other themes in this chapter: the complexity of describing and predicting phenomena, and just how little we know as a result. In previous chapters Feynman has already described how the nature of quantum mechanics prevents us from predicting how very tiny particles will behave. Often the best we can do is to look at the behavior of the aggregate, such as in the shared branch of chemistry and physics called statistical mechanics.
Feynman spends much more words examining biology than on any of the other disciplines. This is the one part of the chapter where he loses focus, describing a lot of biological concepts without ever relating all of them back to physics, which is his goal. While interesting, it is easy to get lost in his descriptions of enzymes, proteins, and DNA. He ends his survey of the role of physics in the other sciences with a brief description of the challenges in psychology. He is careful to differentiate between the science of psychology, and psychoanalysis, which he likens to witch doctoring. While useful, the witch doctor’s knowledge is not science. Instead, he asks, how can physics help us to understand how the brain works? Here, we see Feynman’s long-time frustration with science instruction, which often fails to adequately lay a foundation for students’ knowledge—in this case, what is and is not science.
Physics diverges from other disciplines in what Feynman calls the “historical question”: how did this get to be the way that it is? Biology has the theory of evolution, and astronomy has the big bang. But as far as we know, the “rules of the game”, the physical laws of our existence that physicists constantly seek closer and closer approximations of, are unchanging. We can ask why those rules exist, and while Feynman does not explicitly answer it, he would probably say that the ultimate “why” for the mechanics of our existence is beyond the scope of experimentation, and therefore beyond that of science. What we can say, is that our knowledge of physics has given us a glimpse into the inner workings of the universe. Perhaps the historical aspect of “natural philosophy” is simply how our relationship with nature has evolved. Science, with physics at its base, has led humans not onlt to understand the mechanics of our world but also to realize just how little we know.
Feynman aims to explore the role of physics in our understanding of the world, and thus provide a motivation for its study. In what would ostensibly be the material for a single lecture, he does it fairly well. In a footnote, Feynman freely admits that he is not giving each subject its due, continuing with a rebuttal to the stereotype of science as cold and utilitarian:
How much each sentence in this brief story contains… Poets say science takes away from the beauty of the stars—mere gobs of gas atoms. Nothing is ‘mere.’[…] stuck on this carousel my little eye can catch one-million-year-old light […] far more marvelous is the truth than any artists of the past imagined!
The beauty Feynman saw in science is certainly one of his inspirations, and it is clear that he hopes to inspire the same wonder in his students. In the last paragraph of the chapter, he sardonically agrees with the poets he mocks, by adapting the line “The whole universe is in a glass of wine.” Feynman’s point is that we can see, beyond the wine itself, all the phenomena underlying the universe: the wine evaporates, the yeast ferments alcohol from sugars, the reflections of light off the glass: the dance of atoms. Through physics, we understand these phenomena and gain a glimpse at the inner workings of the universe, a glimpse of which poets and mystics of ages past could only dream.
As much as Feynman deprecates poets, he himself possesses the poetic ability to make the “ordinary” seem extraordinary. Perhaps that is the problem with our view of science today: we have come to view these phenomena, and our understanding of them, as mundane. Feynman’s writing reveals them as anything but mundane and restores their magic to them. At the very least, Feynman clarifies that our knowledge of the world is not as fragmented as our usual instruction might lead us to think, and that for all we have discovered, we have lit only a candle in the darkness– or maybe a few lamps, depending on your degree of optimism.