Everything you know will, in due course, be wrong. A review of Samuel Arbesman's The Half-Life of Facts: Why Everything We Know Has an Expiration Date in Slate:
Arbesman's book expands on a piece he wrote in 2010 for the Ideas section of the Boston Globe. That short essay, called "Warning: Your reality is out of date," laid out a theory of what Arbesman named the mesofact. "When people think of knowledge," he wrote, "they generally think of two sorts of facts." One includes the data that should never change, like the atomic weight of hydrogen, while the other comprises all the tidbits that shift from day to day, like the closing price of the Dow Jones Industrial Average. Even in the stable camp, facts can mutate: An atom's weight, for example, varies depending on the isotope. But Arbesman is more interested in a third category of knowledge, one that's nestled between the other two in terms of how amenable it is to change. These are the facts that shift too slowly for us to notice, but not so slowly that they'll only matter to our children. "Mesofacts," he says, evolve within our lifetimes but often out of view.