The main issue comes from someone trying to build a library for this. For example, try answering the question "what time was it 2y 46d 2h 15m ago on the moon in lunar time?" (assuming it was asked on Earth, in some known timezone). Needing to look up from some table on a time server to answer all these questions sounds like a nightmare.

[–] jarfil@beehaw.org 8 points 7 months ago* (last edited 7 months ago)

On Earth, there is a table with leap seconds... and sometimes they're negative. That alone, is a good reason why writing time libraries is better left to people who specialize in writing time libraries.

The relativity part, also made me think: Luna orbits Earth at about 3600Km/h... but Earth's equator itself, "orbits" Earth's poles at 1600Km/h... so if one has relativity effects on time, half that speed must be having some relativity effects too, right...? Someone on the South Pole would also see a clock on the equator go some microseconds slower per day... and all the clocks at different latitudes, and everyone relative to everyone else, so you can't tell "precisely" the time on Earth without taking into account the exact location... 😬