Wednesday, March 17, 2010

Mooning science

Last year we honored the 150th anniversary of Darwin's Origin of Species (1859), a landmark achievement that changed the direction of science. Technically, we should have celebrated a year earlier, because Darwin and Alfred Wallace deserved joint credit for understanding the nature of evolution in a joint presentation to the Linnean Society in 1858. But never mind, because this year we have a more clearly singular and comparably transformative anniversary to celebrate.

This time it's a 400th anniversary, and the transformation was even more encompassing: it set the stage for all of modern science, even biology.

Do you recognize this picture? It stunned the world!

This was what Galileo saw through his self-made version of a Dutch invention being hawked in Paris as a child's toy: the first telescope. In Galileo's book Sidereus Nuncas (Starry Messenger), he showed that unlike the Truth accepted by everyone from Aristotle's time to Galileo's, the Moon was not a perfect sphere, part of the perfect orbs of the universe that were thought to have been created by God as such. The irregular and imperfect Earth was sinful humans' abode, but the celestial orbs were God's perfection.

Galileo's drawings illustrated clear shadows in the sunlight striking the Moon, proving that the surface was irregular, cratered. He also saw many more stars than had been thought to exist. He realized that the Milky Way was not like a nebulous cloud, but was made of countless distinct stars. And he found the moons of Jupiter, that would prove to be invaluable to navigation during the great age of sail.

Above all, the intuitively God-given universe was not as had been thought since intellectual time immemorial! The Moon looked like the Earth in the sense of having been produced by similar processes.

This and later work of course got Galileo in deep trouble with the Church, and almost got him burned at the stake. But despite insincerely recanting, and eventually dying in a kind of house arrest, Galileo and even the Popes knew that times had changed. Galileo's poking around with a telescope ushered in the Enlightenment, the era--that we're still in--of empirical, measurement and observation based, methodologically anchored ways to understand the world. Skeptics could no longer get away with appealing to the ancient Greek thinkers, nor to Scripture. The world needed to be understood properly in its own terms.

Galileo did much later work, where he essentially first showed the need for repeat observation to 'smooth out' statistical and measurement uncertainty. He dealt with gravity, the principles of motion, momentum, and much else--even the nature of relative motion. His books are enjoyable reading, too (they're in dialog form).

Galileo also began the dependence of science on theory, especially theory that could be tested quantitatively. Darwin was a self-confessed innumerate, but his theory works only because its basis, called population genetics, allows us to relate historical (but unobserved) events to present-day data. No theory (and no scripture) can match its convincing power.

So, this is an anniversary to honor!

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