https://archive.md/Bn3Dz

> 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.

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