Diamagnetics was discovered by Michael Faraday in 1846, but no one at the time thought that it could lead to any appreciable effects. William Thomson (Lord Kelvin), referring to levitation as the problem of "Mohamet's coffin," had this to say: "It will
obably be impossible ever to observe this phenomenon, on account of the difficulty of getting a magnet strong enough, and a diamagnetic substance sufficiently light, as the [magnetic] forces are excessively feeble."
Fields strong enough to lift diamagnetic materials became available during the mid-20th century. In 1939, Werner Braunbeck levitated small beads of graphite in a vertical electromagnet. Graphite has the largest ratio c /r known for diamagnetics (8x10-5
m3/g); today, this experiment can be repeated using just a strong permanent magnet, such as one made of neodymium, iron and boron. Leaving aside superconductors (which are ideal diamagnetics), first......
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