Richard Feynman, I hardly knew ye :(

I could not have started my day any better, it feels like.

Freeman Dyson, whose essays in the NYRB are always ones I look forward to, has a wonderful piece on Richard Feynman, while reviewing two biographies of that phenomenal thinker as a person (ht).  Dyson, a gifted and  accomplished polymath himself, writes that perhaps "Richard Feynman is rising to the status of superstar" among the worldwide masses of non-physicists, similar to the standing that Albert Einstein and Stephen Hawking have.

I loved Dyson's summary of Feynman's picture of the classical and quantum layers of nature.  It is amazing how these gifted folks are able to narrate complex scientific ideas to those of us whose intellectual abilities are way, way down the ladder.  Dyson writes:

Feynman’s picture of the world starts from the idea that the world has two layers, a classical layer and a quantum layer. Classical means that things are ordinary. Quantum means that things are weird. We live in the classical layer. All the things that we can see and touch and measure, such as bricks and people and energies, are classical. We see them with classical devices such as eyes and cameras, and we measure them with classical instruments such as thermometers and clocks. The pictures that Feynman invented to describe the world are classical pictures of objects moving in the classical layer. Each picture represents a possible history of the classical layer. But the real world of atoms and particles is not classical. Atoms and particles appear in Feynman’s pictures as classical objects, but they actually obey quite different laws. They obey the quantum laws that Feynman showed us how to describe by using his pictures. The world of atoms belongs to the quantum layer, which we cannot touch directly.
The primary difference between the classical layer and the quantum layer is that the classical layer deals with facts and the quantum layer deals with probabilities. In situations where classical laws are valid, we can predict the future by observing the past. In situations where quantum laws are valid, we can observe the past but we cannot predict the future. In the quantum layer, events are unpredictable. The Feynman pictures only allow us to calculate the probabilities that various alternative futures may happen.
The quantum layer is related to the classical layer in two ways. First, the state of the quantum layer is what is called “a sum-over-histories,” that is, a combination of every possible history of the classical layer leading up to that state. Each possible classical history is given a quantum amplitude. The quantum amplitude, otherwise known as a wave function, is a number defining the contribution of that classical history to that quantum state. Second, the quantum amplitude is obtained from the picture of that classical history by following a simple set of rules. The rules are pictorial, translating the picture directly into a number. The difficult part of the calculation is to add up the sum-over-histories correctly. The great achievement of Feynman was to show that this sum-over-histories view of the quantum world reproduces all the known results of quantum theory, and allows an exact description of quantum processes in situations where earlier versions of quantum theory had broken down.

It was neat to read this especially because a couple of weeks ago I read the interview with Leonard Susskind, whose string theory ideas attempted to provide a unified theory of physics and nature.  Too bad that Scientific American has this behind a subscriber wall!

Dyson's essay comes at a time when we are marking another important milestone in science and technology that also, in a way, introduced Feynman in a big way to the American public and the world--his work with the committee that inquired into the causes for the space shuttle Challenger to explode moments after liftoff.  Here we are having witnessed the final launch of the spaceshuttle, and after Atllantis returns, the space shuttle program will end.  Feynman's simple demonstration of the failure of the "O-ring" when exposed to icy conditions is legendary.  Dyson writes that Feynman was critical of the political culture at NASA that vastly overestimated the safety and success of the spaceshuttle.

The second opportunity to educate the public concerned the culture of NASA. Feynman wrote an account of the cultural situation as he saw it, with the fatal division of the NASA administration into two noncommunicating cultures, engineers and managers. The political dogma of the managers, declaring risks to be a thousand times smaller than the technical facts would indicate, was the cultural cause of the disaster. The political dogma arose from a long history of public statements by political leaders that the Shuttle was safe and reliable. Feynman ended his account with the famous declaration: “For a successful technology, reality must take precedence over public relations, for nature cannot be fooled.”

A profound statement that "nature cannot be fooled."  It is not merely about physics, of course.

I was a first year graduate student at USC when Feynman died.  Shift the time-line a tad, I would have had enjoyed a talk of his at Caltech. But then time flows only in one direction and "nature cannot be fooled."