Why Nobody Really Knows What Time It Is

Chad Orzel in Forbes:

A couple of months ago, when I gave a talk about my forthcoming book A Brief History of Timekeeping, for the Physics and Astronomy colloquium at Union, I titled it “Does Anybody Really Know What Time It Is?” This was done largely as a nod to the title of a Chicago song that I’m just old enough to remember (a reference that went over the heads of some younger faculty…), but also in full awareness of Betteridge’s Law of Headlines.

If you’re not familiar with it, and are too lazy to click on the link, this is the joke “Law” that any time an article has a headline in the form of a question, the expected answer to the question is “No.” So I used that title specifically to set up an answer in the negative— that, in fact, nobody really knows what time it is.

That might seem like a strange thing to do, especially as I’ve written an entire book exploring several thousand years of the human obsession with timekeeping, and have been banging on about it on this blog for the last couple of months as well. As a matter of fundamental physics, though, it’s absolutely true— not because we’re not good at building clocks (this is, in fact, something we’re exceptionally good at), but because “What time is it?” is not, in fact, a well-formed question with a single definitive answer.

More here.