
Everyone's heard of Hans Christian Andersen, the Danish author of classic children's stories like "The Little Mermaid" and "The Ugly Duckling." But if you were wondering about the significance of today's Google logo, you probably don't know that today is the 232nd birthday of another Hans Christian, a physicist who changed the way we see electricity and magnetism.

Children still read fairy tales by Andersen; although they were written over a century ago, they haven't lost their appeal. Neither has Ørsted's simple experiment; I remember it from one of my first science classes. With a wire, a battery, and a compass, you can reenact Ørsted's discovery. And if you can't be bothered, you can visit Florida State University's online java applet lab, with less risk of shocking yourself.

Ørsted was rewarded for his discovery by immortality in the form of a park in Copenhagen that bears his name. Physicists also gave units for magnetic field strength his name, but the oersted died out in the fifties when the SI system replaced the old CGS system, based on the centimeter, gram, and second. (Now we base things on meters, kilograms, and seconds, although there is no SI equivalent of the oersted.) Luckily, his name was resurrected again when the Danes launched their first satellite in 1999. Appropriately enough, Ørsted's mission was to precisely map earth's magnetic field.
Given that Ørsted's been dead two centuries, I don't mind bringing up this alternative version of the story of the physicist's accidental discovery, which comes from the UCLA physics department Web site:
Often during his lectures at the University of Copenhagen H. C. Oersted had demonstrated the non-existence of a connection between electricity and magnetism. He would place a compass needle near to and at right angles to a current carrying wire to show that there was no effect of one on the other. After one of the lectures a student asked, "but, Professor Oersted, what would happen if the compass needle was placed parallel to the current carrying wire?" Oersted said, "Well, let's see," and went down in the history of physics; the student's name is forgotten.

Initially, I thought that Google graphic was supposed to be a bomb. I figured it had something to do with Squeaky Fromme, but it seemed out of character for Google.
ReplyDelete(Continuation from the previous comment)Thanks for the explanation, BTW.
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