Here’s a book I’ll be wanting to buy when it comes out as a paperback: The Half-Life of Facts.
In 1870, German chemist Erich von Wolf analyzed the iron content of green vegetables and accidentally misplaced a decimal point when transcribing data from his notebook. As a result, spinach was reported to contain a tremendous amount of iron—35 milligrams per serving, not 3.5 milligrams (the true measured value). While the error was eventually corrected in 1937, the legend of spinach’s nutritional power had already taken hold, one reason that studio executives chose it as the source of Popeye’s vaunted strength.
I always wondered what it was in spinach that gave Popeye his strength. Now I know. I also remember that he always had a pipe stuck in his mouth.
The point, according to Samuel Arbesman, an applied mathematician and the author of the delightfully nerdy “The Half-Life of Facts,” is that knowledge—the collection of “accepted facts”—is far less fixed than we assume. In every discipline, facts change in predictable, quantifiable ways, Mr. Arbesman contends, and understanding these changes isn’t just interesting but also useful. For Mr. Arbesman, Wolf’s copying mistake says less about spinach than about the way scientific knowledge propagates.
Copying errors, it turns out, aren’t uncommon and fall into characteristic patterns, such as deletions and duplications—exactly the sorts of mistakes that geneticists have identified in DNA. Using approaches adapted from genetics, paleographers—scientists who study ancient writing—use these accumulated errors to trace the age and origins of a document, much in the same way biologists use the accumulation of genetic mutations to assess how similar two species are to each other.
It’s an interesting idea that the change is predictable. But the main thing that I find attractive about this book is its clear recognition that everything we think we know, even the stuff we’re totally convinced about, has a provisional character: nothing is set in stone.
If shaky claims enter the realm of science too quickly, firmer ones often meet resistance. As Mr. Arbesman notes, scientists struggle to let go of long-held beliefs, something that Daniel Kahneman has described as “theory-induced blindness.” Had the Austrian medical community in the 1840s accepted the controversial conclusions of Dr. Ignaz Semmelweis that physicians were responsible for the spread of childbed fever—and heeded his hand-washing recommendations—a devastating outbreak of the disease might have been averted.
Science, Mr. Arbesman observes, is a “terribly human endeavor.” Knowledge grows but carries with it uncertainty and error; today’s scientific doctrine may become tomorrow’s cautionary tale. What is to be done? The right response, according to Mr. Arbesman, is to embrace change rather than fight it. “Far better than learning facts is learning how to adapt to changing facts,” he says. “Stop memorizing things . . . memories can be outsourced to the cloud.” In other words: In a world of information flux, it isn’t what you know that counts—it is how efficiently you can refresh.
I can think of a number of scientific doctrines that are all set to become tomorrow’s cautionary tales. I just wonder how people make the change. What happens when you’ve spent half your life campaigning to stop global warming, and finally learn that there never really was any anyway? What do such people say? I bet it’s something like this:
“Me? No, I never really believed all that global warming stuff. I was just a bit worried about polar bears, that’s all. And glaciers. And sea levels. And I still am, actually.”
“Well, everybody always knew that that environmental tobacco smoke was harmless. Or at least I did. But when everyone starts telling you the opposite, it’s impossible to keep disagreeing with them all the time, isn’t it? It creates discord. So I just kept my mouth shut. But I knew all along that the truth would eventually prevail.”
“Actually, I always knew that the earth went round the sun, and not vice versa. But I liked to play devil’s advocate. Anyway, it was all a long time ago.”