Science, Scientism, the Speed of Light and more.

This week, Stephen Hawking was awarded the Copley Medal, and the BBC took the opportunity to broadcast the Today Show direct from the Royal Society, in what seemed to me a fairly amateurish production. Professor Peter Coles reprised his usual and welcome role as an anti-Hawking-hype nay-sayer. Another commentator (sorry, I’ve forgotten whom) made the crucial point that Newton, Einstein and Maxwell really invented entire new disciplines of physics with reverberations in almost everything we physicists do. In contrast, Hawking’s most famous work, on black hole radiation and quantum cosmology, consolidated existing strands (and is no less brilliant for that).

Much of the rest of the show felt like it was being broadcast from Heatheringfarnborough Village Hall with a strangely patronizing John Humphries leading on an incoherent and somewhat reactionary audience. The low point to me was a supposed discussion between the equally-exasperating Bryan Appleyard and Lewis Wolpert. Appleyard sets up the straw man of “scientism”, the idea that we scientists think that all questions have scientific answers, and for his part Wolpert manages to fall into the rhetorical trap. (I agree with almost everything Wolpert, like Richard Dawkins, says. I just wish they each would learn to say it in a less annoying way.)

Appleyard correctly points out that trying to ask scientific questions about, say, the pursuit of stem cell research or abortion, involves a category error: whether a lump of cells is “a human being” is not a question that has a scientific answer, since there is no well-specified scientific definition of the rather fuzzy concept of “human being”.

Perhaps coincidentally, BBC4’s In Our Time featured a discussion of the Speed of Light. (I will resist calling it “illuminating”…). John Barrow made an excellent analogy between a light wave and a crime wave. In a sound wave, particles are moving closer together or further apart; in a water wave they are mostly moving up and down. But a light wave, rather, is a wave of quantum-mechanical information which changes the probabilities that receptors in our eyes, or CCD chips in our cameras, will interact with the incoming photons.

Jocelyn Bell Burnell discussed the infamous “twin paradox” of relativity — but she didn’t actually explain why it’s a paradox! Consider a pair of twins, and send one out on a very fast spaceship, moving near the speed of light. If that twin turns around and comes back to earth, she’ll find that she’s much older than the sister she left behind. Why? Relativity states that moving clocks run slow, so the moving twin ages more slowly than the earthbound twin. But it’s not yet a paradox — that comes in when we remember that relativity also says that motion at a constant velocity is completely relative. That is, while the twins are moving away from one another, the space traveller would equally well say that her earthbound sister’s clocks are running slow compared to hers! But (here’s the paradox) if the situations are symmetric, how come the outcome is different? Why is the travelling twin older? The answer is that the situation isn’t really symmetric between the twins at all: the moving twin had to accelerate her spaceship with respect to the earth when she leaves, again when she turns around, and then finally when she returns, accelerations that the stay-at-home twin doesn’t undergo.

Finally, my review of Davies’ Goldilocks Enigma has made it to the top of the “Arts & Letters Daily” aggregator (look for “cosmic evolution”). Thanks to those of you who’ve read it and sent me comments; please feel encouraged to post them here for others to read.

Update: Bryan Appleyard elucidates a slightly more nuanced position in the comments.