Thursday June 3, 2004
Â· You won’t be surprised that I get a lot of critical email. This is very embarrassing, but it’s best that I put my hands up and admit it: last week, I was wrong. In my defence, I am a very angry man, but that’s no excuse for getting in a huff and throwing out pejorative statements like “blood is not magnetic” because, as reader Mark van Ments – who may be the pickiest scientist in the world – points out, blood does, like all objects, exhibit diamagnetism (see Letters, page 10). Thanks Mark. What I meant to say is: blood is not ferro-magnetic. Diamagnetism was first thought through 150 years ago: the electrons orbiting an atom, being charged, are going to readjust their orbits when you stick them in a strong magnetic field, as you might expect. But in doing so, they then create their own magnetic field. To be fair [coughs] the effect is so weak that the rest of the world is roughly one billion times less magnetic than a lump of iron but yes, hands up, that doesn’t mean it’s not significant. And, let’s not be in any doubt, the most significant application of diamagnetism research is to allow mankind, and specifically me, to fly, unaided, like Superman.
Â· People have been levitating chunks of diamagnetic superconductor for years: that’s a bit easier, what with superconductors (unlike me) being specifically designed to let electrons roam around in them unhindered. But I don’t want to fly like Superman through liquid nitrogen; I want to do it where it’s safe to wear my Y-fronts over my corduroy trousers. Objects other than superconductors proved marginally trickier, but in 1991 Beaugnon and Tournier levitated water, and were soon followed by others who levitated liquid hydrogen and frogs’ eggs.
Â· But most promising is the work of Berry and Geim, who in 1997 levitated practically everything they could get their hands on, from hazelnuts and pieces of pizza to frogs and a mouse. Watching the video of a frog hovering in mid-air is a humbling and weirdly tranquil experience. For the anti-vivisectionists among you there is a film of a levitating strawberry. The basic small levitation set-up, of superconducting magnet with room temperature core, only costs about $100,000. To levitate yourself, you will need a special racetrack magnet of about 40 Tesla in the back garden, a socket in your home capable of providing around 1GW of continuous power consumption, and an extension cable with a 5 million amp fuse. Don’t forget it’s my birthday soon.