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.

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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.

Manage Your Electronic Environment

Via taw's blog, a couple of electronic devices to help you manage your electronic environment:

Wave Bubble - a mobile phone jammer.  Could be useful for those of us who like to sleep on trains.  Unfortunately this is just a design; you have to build it yourself (and apparently it is not easy).  Limor Fried, the designer, states: "This design is not for sale or available as a kit and never will be due to FCC regulations".  This is obviously why it is small enough hide in a cigarette box.

TV-B-Gone - A universal remote control TV off switch.   The homepage includes a video showing it being used to switch off a TV in a shop window.  This device does seem to be available commercially here (disguised as a key-fob).

Like a Hurricane

From a table of measured velocities in Motion Mountain by Christoph Schiller:

• Wind speed at 12 Beaufort (hurricane):   above 33m/s
• Speed of air in throat when sneezing:  42m/s

Masks

A cabinet of masks and figurines in the Pitt Rivers Museum of anthropology and archaeology in Oxford.  This museum is housed in a poorly-lit back room of the Oxford University Museum of Natural History.  Augustus Henry Lane Fox Pitt Rivers (1827 - 1900) was one of the first archaeologists to stress the importance of collecting and cataloguing all artefacts, not just the beautiful and unusual ones.

What I changed my Mind about in 2007

Over at Edge.org, John Brockman asked over 160 scientists and other intellectuals what they had changed their mind about and why.  Though not explicitly restricted to 2007, some people seem to have interpreted it that way.

My biggest change of mind during 2007 was brought about by reading Stephen Oppenheimer's The Origins of  the British. Before then I had more or less accepted the traditional view that the English people were mainly descended from Anglo-Saxon and Scandinavian immigrants who arrived in the centuries following the departure of the Romans.  However, Oppenheimer describes recent genetic work which indicates that most of the genes in present day English people have been in England since well before the Romans arrived.  Indeed, most of these genes probably came with the first people to recolonize England after the ice sheet retreated around 10,000 years ago. 

Last summer I stood on one of the  Bronze-age burial mounds on the moors above Guisborough and looked out over the town that I, my father and his father had grown up in.   For the first time, it occurred to me that we might actually be related to the people buried in those mounds.