Atomic clocks are so sensitive now that it's possible to desync them while they're in the same room [0] [0]: https://www.nist.gov/news-events/news/2010/09/nist

Atomic clocks are so sensitive now that it's possible to desync them while they're in the same room [0] [0]: https://www.nist.gov/news-events/news/2010/09/nist-pair-aluminum-atomic-clocks-reveal-einsteins-relativity-personal-scale https://www.nist.gov/news-events/news/2010/09/nist-pair-alum...