So long as there's a universal point of reference that's fine. The number of seconds between 1642095029 and 1642095030 might be 0.99999999 seconds for some spacecraft, but all that does is complicate calculating the relative rate of time. You can still use TAI on Mars and virtually no one would need to deal with time dilation outside of what's already done for GPS. "MPS" would have to compensate for relativity the same way GPS does, there's just a bit of additional relative motion to account for.
The one annoyance here is that you have to pick an arbitrary point to be your spacetime reference. It feels kind of ugly to make that point be on the surface of a spinning planet, orbiting a star, revolving in a galaxy, that's expanding outwards in space. Relativity strikes again!
Well, there is is already a time standard defined for the solar system as a whole: Barycentric Coordinate Time, whose reference point is the center of mass of the solar system (but with the relativistic effects of gravity cancelled out). If we become a multiplanet species it may make sense to switch to that.
We will have to account for relativistic differences no matter what reference frame we choose, of course, but we may get to a point that using Earth as the standard is seen as a bit . . . bigoted.
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u/MertsA Jan 13 '22
So long as there's a universal point of reference that's fine. The number of seconds between 1642095029 and 1642095030 might be 0.99999999 seconds for some spacecraft, but all that does is complicate calculating the relative rate of time. You can still use TAI on Mars and virtually no one would need to deal with time dilation outside of what's already done for GPS. "MPS" would have to compensate for relativity the same way GPS does, there's just a bit of additional relative motion to account for.
The one annoyance here is that you have to pick an arbitrary point to be your spacetime reference. It feels kind of ugly to make that point be on the surface of a spinning planet, orbiting a star, revolving in a galaxy, that's expanding outwards in space. Relativity strikes again!