Why should the future resemble the past? Well, for one thing, it always has. But that is itself an observation from the past. As the philosopher David Hume pointed out in the middle of the 18th century, we can’t use our experience in the past to argue that the future will resemble it, without descending into circular logic. What’s more, physicists remain unable to explain why certain fundamental constants of nature have the values that they do, or why those values should remain constant over time.
The question is a troubling one, especially for scientists. For one thing, the scientific method of hypothesis, test, and revision would falter if the fundamental nature of reality were constantly shifting. And scientists could no longer make predictions about the future or reconstructions of the past, or rely on past experiments with complete confidence. But science also has an ace up its sleeve: Unlike philosophy, it can try to measure whether the laws of nature and the constants that parameterize those laws are changing.
Via Complexity Digest