Donald Knuth on the Presentation of Quantum Mechanics

Today is the 70th birthday of the famous computer scientist Donald Knuth and out on the web there are lots of blog posts about him.  A good one to start with is this by Scott Aaronson. From it I take the following two Knuth quotes on quantum mechanics:

Several years ago, I chanced to open Paul Dirac’s famous book on the subject and I was surprised to find out that Dirac was not only an extremely good writer but also that his book was not totally impossible to understand. The biggest surprise, however — actually a shock — was to learn that the things he talks about in that book were completely different from anything I had ever read in Scientific American or in any other popular account of the subject. Apparently when physicists talk to physicists, they talk about linear transformations of generalized Hilbert spaces over the complex numbers; observable quantities are eigenvalues and eigenfunctions of Hermitian linear operators. But when physicists talk to the general public they don’t dare mention such esoteric things, so they speak instead about particles and spins and such, which are much less than half the story. No wonder I could never really understand the popular articles.

...

The extra detail that gets suppressed when quantum mechanics gets popularized amounts to the fact that, according to quantum mechanics, the universe actually consists of much more data than could ever be observed.