A great post on Dark Matter over at Cosmic Variance by Sean Carroll. It’s also an interesting case study in science in the media, and the problem of the catchy headline.
The most interesting part for me was Sean’s case for MOND being ugly. To my mind, this is enough to rule out MOND even if it explained the data as well as dark matter. It’s more than just Ockham’s razor – nature has taught us to look not just for simplicity, but for elegance and beauty. General relativity, for example, perhaps isn’t particularly simple, but it is beautiful. Beauty in mathematics is one thing, but one of the great pleasures of physics is to bask in the thought: “I can’t believe that this actually describes the universe!”
Beauty in physical theories is such a difficult thing to define, especially to non-physicists. But in this case, MOND has clearly been dealt the wrong end of the ugly stick.