Thursday, 26 April 2007

Tea for Two

Those crazy Spanish academics in Barcelona have figured out why green tea is good for you. Apparently, it's because of "an extremely narrow adiabatic potential-energy profile corresponding to the hydrogen abstraction by the peroxyl radical," which is much as I always expected. I once took part in a study at UCL into the benefits of black tea, which included being made to do stressful tasks while someone measured my cortisol levels. I had to drink some rather unpleasant fruit tea for 10 weeks, and no coffee, no chocolate, no cranberries. Still, I was well paid and contributed more to science in those 10 weeks than the previous three years (during which I completed my PhD in tea studies).

The Dormouse in Alice's Adventures in Wonderland was occasionally woken by the Mad Hatter by having hot tea poured on its nose. While this is cruel and unusual, the real point that Carroll was making is a reference to a Biblical story. Lewis Carroll was the pen-name of the Reverend Charles Dodgson, sometime vicar of Daresbury. A favourite sermon topic of his was an account of when then prophet Elijah was wandering in the desert, near starvation, he prayed to God. The next day, some ravens bought him some meat to eat, under God's command, and a dormouse bought him tea to wash it down with, as is every Englishman's right. By the way, Dodgson's middle name was "Lutwidge" which is anglicized via Latin as "Lewis", while "Charles" becomes... Carroll. Hence the pen-name. Rather more impressive than the usual porn-name generator.

Thursday, 12 April 2007

I can sing a rainbow

Aristotle believed that rainbows were made up of just three colours: red, green and violet. He said that sometimes, you can also see yellow, but this is just "due to contrast for the red is whitened by its juxtaposition with green." He was sadly unaware of refraction and so tried to explain rainbows purely in terms of reflection, which is tricky. Does a cloud look like a gigantic ball of mirrors to you? Ibn al-Haitham introduced the idea of refraction (along with camera obscura, possibly) and totally re-invented optics towards what we know today. He way cool. Isaac Newton was convinced there were seven colours in the rainbow, so he made up the name "indigo" for one of them.

In fact, we can see around seven million colours in the rainbow, though we don't yet have names for all of them. A UN-sponsored project, headquartered in Sweden, is collating every colour name used in every language spoken (and as many extinct languages as can be analysed). The aim is to come up with a definitive list of all 7 million visible shades.

Monday, 2 April 2007

Irradiating bathers

Seurat's rightly-famous painting "The Bathers" has many interesting features, including the use of irradiation. That is to say that if a light object is placed on a darker background, then it appears even lighter. So certain light objects (e.g. the bathers' skin) are enhanced by darkening their backgrounds (e.g. the water) in a way that is a) totally artificial and b) very pleasing. This has been known for centuries, and is an example of simultaneous brightness contrast. The eye is not trying to tell us exactly how the world is, but only allowing us to behave usefully in the world.

Irradiation also refers to bombarding objects with radio waves (such as gamma or x-rays), typically in order to sterilise food. When anthrax was sent through the US mail repeatedly a few years back, the postal service started routinely irradiating parcels and letters. This led indirectly to the bankruptcy of at least three mail-order cheese companies, whose products were irradiated to the extent that the mould in the blue-cheeses was killed, along with widespread problems regarding magenetic tapes, photographic films and slides becoming corrupted.