Richard P. Feynman — ‘The Character of Physical Law’

‘A’ hates his mother. The reason is, of course, because she did not caress him or love him enough when he was a child. But if you investigate you find out that as a matter of fact she did love him very much, and everything was alright. Well then, it was because she was over-indulgent when he was a child! By having a vague theory it is possible to get either result. The cure for this one is the following. If it were possible to state exactly, ahead of time, how much love is not enough, and how much love is over-indulgent, then there would be a perfectly legitimate theory against which you could make tests. It is usually said when this is pointed out, ‘When you are dealing with psychological matters things can’t be defined so precisely’. Yes, but then you cannot claim to know anything about it.

The person who recommended this book did so at least partly, I suspect, because of this attitude. He has amusingly little tolerance for psychology, and less for history: they’re bullshit, because they’re made up, or not sufficiently provable, just as the cause of ‘A’’s hatred isn’t in Feynman’s scenario above (though he is attacking vagueness, not psychology as a whole). Usually I would have just as little tolerance for someone who writes things like ‘the reason is, of course, because’*, but this is a fascinating book of lectures, and the speed at which it powers along in this occasionally ungrammatical vein is really helpful if you’ve never read a science book before and all of a sudden here is quantum physics. It’s something of a high wire act, breaking down extremely complicated ideas into explanations and analogies which make sense to the non-specialist reader. There are very few equations, and there is plenty of repetition of key concepts that you might have forgotten from earlier on: if he is developing a concept, he doesn’t assume you remember what it was, which is a help if you hadn’t quite grasped the previous explanation. For example:

This is called the principle of relativity, that uniform motion in a straight line is relative, and that we can look at any phenomenon from either point of view and cannot say which one is standing still and which one is moving.

And:

If we are unable, by any experiment, to see a difference in the physical laws whether we are moving or not, then if the conservation of charge were not local only a certain kind of man would see it work right, namely the guy who is standing still, in an absolute sense. But such a thing is impossible according to Einstein’s relativity principle, and therefore it is impossible to have non-local conservation of charge.

It’s a little unfair to quote these things out of context, precisely because they do work by accumulation. Feynman elucidates gravity, angular momentum, relativity, the laws of conservation and symmetry, winding up with the movement of electrons as both particles and waves, and a discussion of how physics might develop in the future (he’s talking in 1965, so there’s no Higgs Boson, but CERN exists, and he does talk about discoveries happening through high energy collisions). There are some dazzling asides, like his explanation of how carbon can form in a star, when the only other elements present are hydrogen and helium, and how this happy accident is likely to be the cause of life as we know it. He also explains how it is that there are two tides for every one rotation of the earth, and how it might be possible to communicate with aliens in terms of physics: he can discuss dimensions, because he relates them to hydrogen atoms, but because of anti-matter he doesn’t have a way of distinguishing left from right. It also turns out that he doesn’t hate psychology or history after all:

all the sciences, and not just the sciences but all the efforts of intellectual kinds, are an endeavour to see the connections of the hierarchies, to connect beauty to history, to connect history to man’s psychology, man’s psychology to the working of the brain, the brain to the neural impulse, the neural impulse to the chemistry, and so forth, up and down, both ways. And today we cannot, and it is no use making believe that we can, draw carefully a line all the way from one end of this thing to the other, because we have only just begun to see that there is this relative hierarchy.

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* Actually it seems that the lectures were never written, only transcribed, which makes this more forgivable.

Open Culture has the whole lecture series online.