Meet me at the Coffee Connection on Dempster, author and Northwestern University history professor Ken Alder had said. So ten minutes before the appointed hour, after speed-reading his 400-page book The Measure of All Things: The Seven-Year Odyssey and Hidden Error That Transformed the World in an airline seat with a burned-out light, I am cruising Evanston. The Coffee Connection turns out to be as elusive as the subject of Alder’s book. After a call to his home and some quick empirical research (he’s not at Blind Faith, not at Starbucks), I blunder into Cafe Express and find him ensconced at a corner table. Error, as modern science knows, is our constant companion.
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In the 18th century, error was an abomination. The heroes of Alder’s book, two French astronomers charged with measuring a 600-mile slice of the meridian–an errand they believed to be the most important scientific mission ever attempted–were seeking perfection. While the French Revolution raged around them, Jean-Baptiste-Joseph Delambre and Pierre-Francois-Andre Mechain set out from Paris, one to the north, the other to the south, to measure the distance from Dunkerque to Barcelona. The data they brought back would be used to establish a new unit of measure worthy of global use. In 1792, when their odyssey began, units of measurement and the values given to them varied, not only from one country to another but between villages and industries. A pound of bread in one town might differ in weight both from a pound of bread in another town and from a pound of iron. With such disparity, trade on anything larger than a local scale was nearly impossible. What was needed was a system of measurement based not on neighborhood tradition (or the size of a king’s foot) but on ubiquitous and eternal nature. The meter would be exactly one ten-millionth of the distance from the north pole to the equator.
But there was another, more fundamental error in the project. “Their basic assumption [that one meridian would be exactly the same length as another] was flawed,” Alder says. “They didn’t realize that the earth is not uniform. It’s lumpy, it’s warped, you can’t extrapolate from one portion of it to the whole.” The most important result of the search for the perfect meter was the recognition that science needed a way to deal with uncertainty or error in measurement. Alder says this led to the development of statistics and made modern science possible. In the end, it was the quixotic nature of the story that held him, he says: “the way it shows how messy and human the process that makes science is.”
