Rosio Pavoris

I finished The Character of Physical Law by Richard Feynman the other night. It’s pretty short (about 170 pages), being just a collection of seven lectures by Feynman on (surprisingly) the character of physical law.
The only other thing I’ve read by Feynman was The Meaning of It All, which is also a collection of lectures. I wonder if he wrote “proper” books.

Either way, it’s a very interesting read. These lectures took place in 1965, and no doubt some fundamental advances have been made since then (if you want to call string theory an advance, all of that only started in the late ’60s), but it’s general enough that it’s still a relevant and fascinating work.

Feynman talks about a number of things, starting, in the first lecture, with the law of gravitation as an example, going over Kepler, Brahe, Newton, and eventually Einstein, to demonstrate how the law was derived and refined further and further.

In the second lecture, he talks about the relationship between mathematics and physics, noting that physics is a very mathematical field, but that there are some important difference between doing physics and doing mathematics. In mathematics, you derive tons of conclusions from a fixed set of axioms, and in physics, we have a vast amount of conclusions, but nothing to unify it to come up with the central model from which they flow. In Feynman’s own words, we’re doing physics in the way the Babylonians did mathematics, rather than in the way the Greeks did it.

The next few lectures describe some interesting properties which seem to hold across the various laws of physics, including various principles of conservation, various types of symmetry (which, as he explains, is vital to being to derive new laws, through inconsistencies in known ones), and the principle of causality and the arrow of time.

In the sixth lecture, he gets into the basics of quantum mechanics. Probability and uncertainty, the way light (and electrons) behaves variously like particles or like waves (he goes into some detail regarding the double-slit experiment, which I think I’ll go into in a future post; every single popular science work on physics written in the past seventy or so years has explained it, but it’s an interesting and important experiment), &c.

And in the final lecture, he explains how physicists usually go about finding new laws, and more importantly, how he himself does it. It’s worth remembering that Feynman was perhaps the most influential physicist of the second half of the 20th century (and by second half, I mean part of the first half as well).

To sum up, The Character of Physical Law is a fascinating read, even if it shouldn’t really tell you anything new. If anyone but Feynman had written it, it would’ve sucked, but he makes it work.
Also, he spelled “connection” “connexion”, which made me happy.

Next up is Six Easy Pieces, also by Feynman. Apparently it’s supposed to cover much of the same ground, and it certainly seems to have the same preface by Paul Davies, but it looks a bit more advanced.