So anyway, Feynman, yadda yadda, isn't it cool that they knew precisely what it was that they didn't know, and then found it?
Next comes the question, precisely how does the order of the ... units determine the arrangement of the amino acids in the protein? This is the central unsolved problem in biology today.
Then we get to geology. Whoa.
The phenomenon of volcanoes is really not understood. What makes an earthquake is, ultimately, not understood. It is understood that if something is pushing something else, it snaps and will slide--that is all right. But what pushes, and why? The theory is that there are currents inside the earth--circulating currents, due to the difference in temperature inside and outside--which, in their motion, push the surface slightly. Thus if there are two opposite circulations next to each other, the matter will collect in the region where they meet and make belts of mountains which are in unhappy stressed conditions, and so produce volcanoes and earthquakes.
It's that beautiful moment just before a paradigm shift. I had no idea that plate tectonics was so recent! If I recall correctly, we were learning it as gospel truth when I was in elementary school in the '80s. Yes, I know that this static view of science is just the way that elementary school science is generally taught (since most elementary school teachers are as uncomfortable with science as most Americans, and thus teach it the same way as social studies, reading the book and answering questions at the end of the chapter), but I figured it took longer for new discoveries to percolate down to the 5th grade curriculum. Ka mashma lan.
Feynman distinguishes between physics and astronomy/geology/biology, because the latter are dealing with historical questions (evolution, star formation, formation of the earth), whereas physics is not. Until cosmology and the Big Bang came along!
And that's it for the overview. Chapter 4 is on conservation of energy, and from here on out, the content stops being dated, except for quaint units like pounds and feet, and other things that I'm going to point out because it's fun. Starting the study of physics with the conservation of energy, and deriving the formula for gravitational potential energy before defining mass, force, work, etc., are very cool. He stops just short of using the word "torque", but it appears that the concept of torque can be derived from conservation of energy! I'm using that in my class in the fall.
What's the deal with the word "heat"? It refers to the transfer of thermal energy, and using "heat" to refer to a type of energy is deprecated. Wikipedia calls it a "common misconception". But Feynman does it! Is this a shift in the word's usage between 1963 and the present (making the common misconception quite understandable), or did Feynman goof?
In 1963, a second is still defined as 1/86400 of an average day, and a meter is the distance between two scratches on a bar of platinum-iridium alloy. So cute!