i’d love to have expiration dates for facts. would make it much easier to assess whether a piece of data is still good. some fields change every few years, others take centuries. i find it hard to take any non-fiction book older than ~5 years seriously.

Facts change all the time. Smoking has gone from doctor-recommended to deadly. We used to think the Earth was the center of the universe and that Pluto was a planet. For decades, we were convinced that the Brontosaurus was a real dinosaur. In short, what we know about the world is constantly changing.

But it turns out there’s an order to the state of knowledge, an explanation for how we know what we know. Samuel Arbesman is an expert in the field of scientometrics—literally the science of science. Knowledge in most fields evolves systematically and predictably, and this evolution unfolds in a fascinating way that can have a powerful impact on our lives.

Doctors with a rough idea of when their knowledge is likely to expire can be better equipped to keep up with the latest research. Companies and governments that understand how long new discoveries take to develop can improve decisions about allocating resources. And by tracing how and when language changes, each of us can better bridge generational gaps in slang and dialect.