Six Easy Pieces: Essentials of Physics Explained by its Most Brilliant Teacher – Richard Feynman

Thoughts: Six Easy Pieces came recommended by Simon Clark as a good introduction to the field of physics. A slim volume, this book was a bit hit-and-miss for me: some sections I found fascinating, while others were dry. One of the most striking aspects of this book, as pointed out in one of its several prefaces, is Feynman’s knack for finding really elegant and insightful analogies for the phenomena he discusses. If you’re interested in physics, or possibly also pedagogy, Six Easy Pieces may be worth your time.

(The notes below are not a summary of the book, but rather raw notes - whatever I thought, at the time, might be worth remembering.)

Feynman, Richard P. 1995. Six Easy Pieces: Essentials of Physics Explained by its Most Brilliant Teacher. Basic.

Special Preface

• xx: Feynman’s advice for how do decide on a pedagogical approach: “First figure out why you want the students to learn the subject and what you want them to know, and the method will result more or less by common sense.”
• xx-xxi: “Once, during a public lecture, he was trying to explain why one must not verify an idea using the same data that suggested the idea in the first place. Seeming to wander off the subject, Feynman began talking about license plates. ‘You know, the most amazing thing happened to me tonight. I was coming here, on the way to the lecture, and I came in through the parking lot. And you won’t believe what happened. I saw a car parked with the license plate ARW 357. Can you imagine? Of all the millions of license plates in the state, what was the chance that I would see this particular one tonight? Amazing!’”
• xxiii: Six Easy Pieces was excerpted from the full collection of his Caltech lectures: The Feynman Lectures on Physics

Feynman’s Preface

• xxix: quoting Gibbon: “The power of instruction is seldom of much efficacy except in those happy dispositions where it is almost superfluous.”

1: Atoms in Motion

• 2: when we do experiments, can give us hints at the laws by which the universe operates (think esp. unexpected results). But Feynman points out that “also needed is imagination to create from these hints the great generalizations” that can later be tested by more experiments.
• 4: Feynman suggests that, if all accumulated human knowledge was lost except for one statement/idea, the single idea that would convey the most information would be the atomic hypothesis: “all things are made up of atoms—little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another.”
• 10: Absolute zero is temperature at which particles move as little as possible, not the temperature at which particles don’t move at all (if they didn’t move at all, it would violate Heisenberg’s uncertainty principle)
  • by way of illustration, he notes that even at absolute zero, helium does not freeze (unless it is pressurized)
• 12: when a liquid evaporates, it is because specific individual particles at the edge of the liquid have a high enough speed to escape the bonds that hold the liquid together. This is why liquids cool as they evaporate: if the particles that break free from the liquid are the ones with a higher-than-average speed, then the average speed of the particles that remain (i.e. the temperature) necessarily drops.

2: Basic Physics

• 34: why don’t the electrons in an atom fall into the nucleus? if they did, we would know their precision precisely. But based on the uncertainty principle, they must then have a very high (and very uncertain) momentum, i.e. a very large amount of kinetic energy, which would cause them to break free from the nucleus
  • (presumably, the particles in the nucleus have a similarly high momentum, but since they are so much heavier than electrons, this translates into a much lower speed than electrons would have)

3: The Relation of Physics to Other Sciences

4: Conservation of Energy

5: The Theory of Gravitation

• 110: Some have noted that the ratio between the forces of electromagnetic repulsion between two electrons and gravitational attraction between two electrons have the ratio of ~ 10e24 : 1, and the ratio between the age of the universe and the time it takes for a photon to travel the diameter of a proton is also ~10e24 : 1. Could these both, then, be related (and have the laws of the universe, thus, changed over time)?
  • j: I wonder how this speculation has held up to experimentation since Feynman’s day…

6: Quantum Behavior

• 132-133: we see interference patterns in the behavior of individual particles (e.g. in the double slit experiment) - why don’t we see them on the macro level? It turns out that they do exist for macroscopic entities, but that the peaks and troughs of the distribution are so numerous and so close together that they are indistinguishable from a simple probability distribution like a bell curve