3 ms·
So a real universal UTC should have a unit of seconds that assumes a perfectly homogenous universe, with each user responsible for correcting for the depth of t
by hnuser123456 2y ago
So a real universal UTC should have a unit of seconds that assumes a perfectly homogenous universe, with each user responsible for correcting for the depth of their local gravitational well/hill.
- nyrikki 2y agoNo, there is no 'real universal' time, just agreed upon reference frames. UTC uses TAI, which is a weighted average of global atomic clocks. Any physically realized time standards will have errors. Proper time is the only invariant form under GR.
- fanf2 2y agoUTC is defined on the rotating “geoid” which is the modern version of mean sea level. If you happen to be NIST (one of the USA’s principle time labs) or Schriever space force base (which hosts the ground-based reference atomic clocks for the GPS satellite fleet) you need to adjust the speed of your clocks slightly to compensate for being in Colorado 1 mile above sea level.
- toast0 2y agoUniversal Time would really need to be based on seconds passing at the center of mass of the universe. Each observer could run their own clock, and calculate adjustments from there. Although that might not be very convenient.
- hnuser123456 2y agoWhy would it have to be at the center of mass of the universe? I am going ahead and assuming that if every observer assumed that their local observable universe was homogenous, then in most global (co-moving) locations across the entire universe, we would have similar results, but I am eager for someone smarter's reply.
- hnuser123456 2y agoAlso, is the CMB not a reference frame?