Today I went out for a haircut and came back with a book. I got the haircut ok, but walking back I stumbled across Bells Books, one of those lovely musty second hand bookstores. I emerged with A Sourcebook in Astronomy 1900-1950, in which Harlow Shapley collected original articles by all the right people – Ed Hubble, Annie Cannon, Tommy Gold, Albert Einstein, Abbe Lemaitre and many others, as well as many others you won’t have heard of. I guess I was in the mood for the history of astronomy. My teacher and good colleague Mary Bruck died in December, and I just finished her excellent book on Mary Agnes Clerke.
Carrying my lucky find, I remembered a discussion I had in the Kings Buildings branch of Blackwells last year. The shop had big piles of Course Textbooks but very little else. The guy on the till explained how Amazon was killing real bookshops – why walk to the store, not knowing if they will have the book you want, when you know you can order it from your living room ? We’re not talking about the latest Dan Brown. We are talking about unnusual books, just the right book. The giant warehouse wins when you are hunting in the long tail. But we miss those magical hours wandering the bookshelves, browsing. Wandering the shelves is more than just entertaining; it maximises serendipity. As the man in Blackwells said to me, three times out of four, the book we buy is the one next door to the one we came in to look for.
Scientific progress can be like this too. You are hunting for one thing and find another. There are several famous examples in modern astronomy. One is the building of the Jodrell Bank telescope to look for meteor showers, only to find persistent radio sources, which would turn to be the most powerful objects in the Universe. Another is Giacconi’s rocket shot of 1962, funded to look for solar X-rays reflected from the moon; instead it found Sco X-1 and the X-ray background. I have heard some X-ray astronomy old timers say that Giacconi always wanted to find something new and unexpected; the lunar fluorescence thing was just a funding excuse. It took another twenty eight years before X-ray astronomers really did detect the Moon.
Here is the picture, taken by ROSAT in June 1990. This is such a cool picture. Not only can you see the sunlit side of the Moon, but the other half is dark, because it blocks the cosmic background. You can just see that the sky shines in X-rays coming from behind the Moon.
Sometimes the Snark is a Boojum after all. Decades of struggling to measure the expected deceleration of the universe, which would tell us its mean density, and finally the supernovae show us something entirely new – dark energy – and the universe becomes a more mysterious place.
I wonder what unexpected corner we will turn down next ?