Einstein was right! Atomic clocks and space-time symmetry

Einstein was right, that is what two research groups concluded based on their collaborative work with atomic clocks. Well, to be precise, he is at least right to the degree of 10^-21 (which is 0.000000000000000000001, so super accurate). What was he right about? He was right about that the speed of light is exactly the same regardless of the direction it would travel.

Who cares that the speed of light is the same in any direction? Well, Einstein’s theory of general relativity actually hinges ...