Джеймс Глик - Genius - The Life and Science of Richard Feynman

1. Historical Development of Physical Science 2. Present Status of Physical Science

3. Kinematics: The Study of Motion

4. The Laws of Dynamics

5. Application of the Laws of Motion: Momentum and Energy

6. Elasticity and Simple Harmonic Motion

7. Dynamics of Rigid Bodies

8. Statics of Rigid Bodies

and so on, until in its final weeks the course would reach 26. Atoms and Molecules

in time to touch upon Nuclear Physics and Astrophysics.

Caltech was stil using a generation-old text by its own luminary, Robert Mil ikan, that remained soundly mired in the physics of the eighteenth and nineteenth centuries.

Feynman began with atoms, because that was where his own understanding of the world began—not the world of quantum mechanics but the quotidian world of floating clouds and colors shimmering in oily water. Moments after nearly two hundred freshmen entered the hal for his first lecture in the fal of 1961, they heard these words from the grinning physicist striding back and forth upon the stage: So, what is our over-al picture of the world?

If, in some cataclysm, al of scientific knowledge were to be destroyed, and only one sentence passed on to the next generation of creatures, what statement

would contain the most information in the fewest words? I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to cal it) that all things are made 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. In that one sentence, you wil see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied.

Imagine a drop of water, he said. He took them on a tour inward through the length scales, magnifying the drop until it was forty feet across, then fifteen miles across, then 250

times larger stil , until the teeming molecules came into view, each with a pair of hydrogen atoms stuck like round arms upon a larger oxygen atom. He discussed the contrary forces holding the molecules together and forcing them apart. He described heat as atoms in motion …

pressure … expansion … steam. He described ice, with its molecules held in a rigid crystal ine array. He described the surface of water in air, absorbing oxygen and nitrogen and giving off vapor, and he immediately raised issues of equilibrium and disequilibrium. Instead of Aristotle and Galileo, instead of levers and projectiles, he was building a tangible sense of how atoms create the substances around us and why substances behave as they do. Solution and precipitation, fire and odor—he kept moving, displaying the

atomic hypothesis not as a reductive end point but as a road toward complexity.

If water—which is nothing but these little blobs, mile upon mile of the same thing over the earth—can form waves and foam, and make rushing noises and strange patterns as it runs over cement; if al of this, al the life of a stream of water, can be nothing but a pile of atoms, how much more is possible? … Is it possible that the “thing” walking back and forth in front of you, talking to you, is a great glob of these atoms in a very complex arrangement … ? When we say we are a pile of atoms, we do not mean we are merely a pile of atoms, because a pile of atoms which is not repeated from one to the other might wel have the possibilities which you see before you in the mirror.

He found that he was working harder than at any time since the atomic bomb project. Teaching was only one of his goals. He realized also that he wished to organize his whole embracing knowledge of physics, to turn it end over end until he could find al the interconnections that were usual y, he believed, left as loose ends. He felt as though he were making a map. In fact, for a while he considered actual y trying to draw one, a diagram—a “Guide to the Perplexed,” as he put it.

A team of Caltech physics professors and graduate students scrambled to keep up, week after week, designing problem sets and supplementary material, as his

guide to the perplexed took shape. They met with him at lunch after each lecture to piece together what Feynman had spun from as little as a single sheet of cryptic notes.

Despite the homespun lyricism of his voice, the stress on ideas rather than technique, he was moving quickly, and his fel ow physicists had to work to keep up with some of his leaps.

As every physics course recapitulated the subject’s history, so did Feynman’s, but instead of surveying the Sumerians or the Greeks he chose—in his second lecture

—to sum up “Physics before 1920.” Less than a half-hour later he was on to a quick tour of quantum physics and then the nuclei and the strange particles according to Gel -Mann and Nishijima. This was what many students wanted to hear. Yet he did not want to leave them with the easy sense that here, at the microlevels, lay the most fundamental laws or the deepest unanswered questions. He described another problem, crossing the artificial boundaries that divide scientific disciplines, “not the problem of finding new fundamental particles, but something left over from a long time ago.”

It is the analysis of circulating or turbulent fluids . If we watch the evolution of a star, there comes a point where we can deduce that it is going to start convection, and thereafter we can no longer deduce what should happen… . We cannot analyze the weather. We do not know the patterns of motions that there should be inside the earth.

No one knew how to derive this chaos from the first principles of atomic forces or fluid flow. Simple fluid problems were for textbooks, he told the freshmen.

What we real y cannot do is deal with actual, wet water running through a pipe. That is the central problem which we ought to solve some day.

Feynman designed his lectures as self-contained dramas. He never wanted to end by saying, “Wel , the hour is up, we wil continue this discussion next time …” He timed his diagrams and equations to fil the sliding two-tier blackboard so definitively that an image of the final chalk tableau seemed to have been in his head from the start. He chose grand themes with tentacles that spread into every corner of science: Conservation of Energy; Time and Distance; Probability … Before a month was out he introduced the deep and timely issue of symmetry in physical laws. His approach to the conservation of energy was revealing. This principle was never far from the consciousness of a working theoretical physicist, yet most textbooks let it arise in passing, toward the end of chapters on mechanical energy or thermodynamics. First they would note that mechanical energy is not conserved, since friction inevitably drains it away. Not until the Einsteinian equivalence of matter and energy does the principle ful y come into its own.

Feynman took the conservation of energy as a starting

point for discussing conservation laws in general (as a result, his syl abus managed to introduce the conservation of charge, baryons, and leptons weeks before reaching the subject of speed, distance, and acceleration). He put forward an ingenious analogy. Imagine, he said, a child with twenty-eight blocks. At the end of every day, his mother counts them. She discovers a fundamental law, the conservation of blocks: there are always twenty-eight.

One day she sees only twenty-seven, but careful investigation reveals one under the rug. Another day she finds twenty-six—but a window is open, and two are outside. Then she finds twenty-five—but there is a box in the room, and upon weighing the box and weighing individual blocks she surmises that three blocks are inside.