Tuesday, November 25, 2008

There are more ways of being wrong...Part 2


The distances of the planets from the Sun has been a source of fascination since Copernicus. Johannes Kepler's was the first to look for a rule that explained the relative distances. In his first major astronomical work, The Cosmographic Mystery, he came up with a scheme of inscribing and circumscribing within spheres the five regular Platonic polyhedra to account for the distances of the six known planets -- Mercury, Venus, Earth, Mars, Jupiter, and Saturn. And, indeed, he found a nesting of the polyhedra that matched the known distances of the planets pretty well. Voila!

Had he stumbled upon the Creator's plan of creation, as he fervently believed? The disovery of Uranus in 1781 put paid to his scheme. By then astronomer's had come up with another mathematical rule for the distances of the six known planets, known as the Titus-Bode Law, which had the futher advantage of predicting a planet close to where Uranus was subsequently found. The Titus-Bode rule also precicted a planet between Mars and Jupiter where there apparently wasn't one, but when Ceres, the largest object in the asteroid belt, was found in 1801 at approximately the right distance from the Sun the Titus-Bode Law began to look pretty good. Alas, the discovery of Neptune and then Pluto proved the rule inadequate.

Most astronomers now believe the early success of the Titus-Bode Law was a coincidence. There are currently theories that explain the origin of planetary systems -- gravitation, conservation of angular momentum, etc. -- and computer simulations generate systems similar to our own, but they also allow for a degree of apparent randomness. Other planetary systems will certainly contain planets of different sizes and spacings.

Kepler's nested polyhedra and the Titus-Bode Law were schemes to anticipate nature, and, as such, were prone to failure. Francis Bacon put it this way: truth "is extracted...not only out of the secret closets of the mind, but out of the very entrails of Nature." We call it, loosely, the scientific method. It involves the "closets of the mind," certainly; no way to avoid that. But it also involves interrogating nature in a way that forces a maximally unambiguous response, which means mathematical reasoning, quantitative measurement, and reproducible experiment. As Hume told us, reason alone is a dead-end road on the journey to truth. The anticipation of nature is a fraud.