Six Easy Pieces: Essentials of Physics Explained by Its Most Brilliant Teacher

by Richard P. Feynman

Science is a people-driven activity like all human endeavor, and just as subject to fashion and whim.

Feynman was a theoretical physicist par excellence.

Feynman himself did much to cultivate his distinctive persona. Although reluctant to put pen to paper, he was voluble in conversation, and loved to tell stories about his ideas and escapades.

The Feynman Lectures on Physics were a huge success,

Feynman’s pedagogical technique was simple. A summation of his teaching philosophy was found among his papers in the Caltech archives, in a note he had scribbled to himself while in Brazil in 1952: 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.

The lectures here are not in any way meant to be a survey course, but are very serious. I thought to address them to the most intelligent in the class and to make sure, if possible, that even the most intelligent student was unable to completely encompass everything that was in the lectures—by

There is no natural way to group them as “molecules of salt.”

A process in which the rearrangement of the atomic partners occurs is what we call a chemical reaction. The other processes so far described are called physical processes,

there is nothing that living things do that cannot be understood from the point of view that they are made of atoms acting according to the laws of physics.

Curiosity demands that we ask questions, that we try to put things together and try to understand this multitude of aspects as perhaps resulting from the action of a relatively small number of elemental things and forces acting in an infinite variety of combinations.

Observation, reason, and experiment make up what we call the scientific method.

So, without being able to follow the details, we can always check our idea about the bishop’s motion by finding out whether it is always on a red square. Of course it will be, for a long time, until all of a sudden we find that it is on a black square

From the point of view of basic physics, the most interesting phenomena are of course in the new places, the places where the rules do not work—not the places where they do work! That is the way in which we discover new rules.

While we may not be able to tell why Alekhine moves this particular piece, perhaps we can roughly understand that he is gathering his pieces around the king to protect it, more or less, since that is the sensible thing to do in the circumstances.

Before 1920, our world picture was something like this: The “stage” on which the universe goes is the three-dimensional space of geometry, as described by Euclid, and things change in a medium called time.

There are waves of excess density, where too many particles have collected, and so as they rush off they push up piles of particles farther out, and so on. This wave of excess density is sound.

one cannot know both where something is and how fast it is moving.

the nucleus is very small. An atom has a diameter of about 10—8 cm.

(Remember that when a crystal is cooled to absolute zero, we said that the atoms do not stop moving, they still jiggle. Why? If they stopped moving, we would know where they were and that they had zero motion, and that is against the uncertainty principle. We cannot know where they are and how fast they are moving, so they must be continually wiggling in there!)

it is not possible to predict exactly what will happen in any circumstance.

nature, as we understand it today, behaves in such a way that it is fundamentally impossible to make a precise prediction of exactly what will happen in a given experiment. This is a horrible thing; in fact, philosophers have said before that one of the fundamental requisites of science is that whenever you set up the same conditions, the same thing must happen. This is simply not true; it is not a fundamental condition of science. The fact is that the same thing does not happen, that we can find only an average, statistically, as to what happens.

the sole test of the validity of any idea is experiment.

That new particle is called a photon. The new view of the interaction of electrons and photons that is electromagnetic theory, but with everything quantum-mechanically correct, is called quantum electrodynamics.

the neutrons and protons are called baryons,

One of the amino acids, called proline, is not really an amino acid, but imino acid.

Yes! Physics has given up. We do not know how to predict what would happen in a given circumstance, and we believe now that it is impossible, that the only thing that can be predicted is the probability of different events. It