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This may not count as practical, but with high-enough resolution on time we can start to make direct observations of relativistic effects. There are physicists like Ivette Fuentes starting to do direct experiments with time dilation [1].

When Einstein made his thought experiments with light clocks and described what should be observed, he didn't think we'd actually make light clocks... but we have the technology to do that literally (really, truly, actually... so sad we no longer have a word in English that means that).

[1] https://www.youtube.com/watch?v=y5V9qAETcw8

With radio astronomy, where you're measuring phase of incoming radiation, I think "more is more" applies. Would be interesting to hear from someone who actually has experience in that domain though (not me!)

The current goal is to redefine the second in terms of an optical frequency once clocks are available that offer a higher precision than 1 second over the lifetime of the universe.

https://www.nist.gov/si-redefinition/second-future