The mind-bending new science of measuring time (ft.com)

That one wonderful! One of the most captivating articles I’ve read in a long time.

> These clocks would lose less than a second over the age of the universe. An optical clock is so precise that if you lifted one a centimetre off the ground, it would detect the gravitational dilation foretold by Einsteinian relativity.

That's one helluva rabbit hole to go down.