Friday, January 18, 2013

Beautiful evidence


You will perhaps be familiar with the big, beautiful, self-published books of Edward Tufte, Professor Emeritus at Yale, on the visual presentation of data. The books are perfect examples of their subject -- the beautiful and effective transmission of information. Tufte has been justly called "the Leonardo of data."

The fifth of his series, Beautiful Evidence recently appeared at the college library, although it was published in 2006, so I'm late getting around to it. I'm pleased to note that he gives considerable space to Galileo's Sidereus Nuncius, or The Starry Messenger, published in 1610, an account of the great Italian scientist's first telescopic discoveries -- the mountains of the Moon, the starry nature of the Mlky Way, and the moons of Jupiter. It is a short little book, more an announcement than a treatise, establishing Galileo's precedence as a telescopic observer of the heavens. As for its place in the history of science, it reminds me a bit of Watson and Crick's paper announcing the structure of DNA.

What attracts Tufte's attention is the beautiful mix of text and illustrations -- 78 of Galileo's own drawings taking up 30 percent of the 60 printed pages. Tufte writes: "And that is the grand forever consequence of Sidereus Nuncius: from then on, all science, to be credible, had to be based on publicly displayed evidence of seeing and reasoning, and not merely on wordy arguments."

And it's true enough that Galileo stands as the pivotal figure in establishing the precedence of reproducible empirical evidence over metaphysical reflection. But that role embraces the whole of his life, his other two great books, and his ultimately tragic encounter with the keepers of dogmatic knowledge.

Galileo had predecessors as graphical recorders of close observation; think of Leonardo, or Andreas Vesalius. What makes The Starry Messenger special, I think, is the refreshingly honest glimpse it gives us into a mind slowly coming to recognize a truth for which there is no precedent. Galileo's day-by-day record of the tiny "stars" near Jupiter that he reluctantly but excitedly decides orbit the planet is as thrilling as any story I know about in science.

In Beautiful Evidence Tufte has a chapter called "Corruption in Evidence Presentation." He mentions effects without causes, cherry-picking, overreaching, "chartjunk," and the rage to conclude. Give Galileo this: He neither cherry-picks his data or overreaches, and his conclusions are open-ended enough to incite a Scientific Revolution.

Here is a page from The Starry Messenger showing on the nine stars of Orion's belt and sword visible to the unaided eye and those many more visible to the telescope. Galileo uses the phrase oculata certitudine, "visual certainty," with which he strikes a blow against the idle disputations of the philosophers and theologians.