3 ms·

They really should have been on TAI. I guess it doesn't matter now if we won't get any more leap seconds.

cornholio 4y ago
It's worth noting that even atomic clocks run on Mars faster than on Earth, due to the different gravity. So you might expect say half of the 50 microsecond daily gain quoted in this article for the Moon, 10 miliseconds per year or a full second per century, more than enough to make you your spaceship completely miss its intended orbit. And martians will definitely want to run their own atomic clocks, making sync very problematic. So TAI is not the end all for what I expect to be a very complicated technical problem.
- eru 4y ago
  Not sure whether sync will be 'very problematic'. We already have that sort of sync happening today: when your computer is off, it runs a quartz watch. When you turn it on, it syncs via ntp. Some special boffins on Mars would run atomic clocks, and worry about synchronisation with earth. For the rest of the people running quartz clocks, they wouldn't even notice.
  - toast0 4y ago
    > Some special boffins on Mars would run atomic clocks, and worry about synchronisation with earth. I think at some point, you have to redefine utc to be based on an estimated atomic clock at the center of the sun, because it's easier for mars and earth to estimate that, than for earth to go on its merry way and mars to estimate the time on earth. Relativism is fun?
- wahern 4y ago
  > It's worth noting that even atomic clocks run on Mars faster than on Earth, due to the different gravity. The biggest effect is the Sun's gravity, followed by orbital velocity. The relative masses of the planets is negligible by comparison, though in online discussions that's almost all anybody ever seems to talk about. I can't find confirmation through other sources, and can't credibly validate it myself, but the best estimate I found for time dilation between two clocks on Earth and Mars is roughly 5.6 parts per billion, or ~177 milliseconds per year. See https://space.stackexchange.com/questions/33590/what-is-the-time-dilation-between-mars-and-earth-resulting-from-the-mass-differe/33592 https://space.stackexchange.com/questions/33590/what-is-the-...
  - cornholio 4y ago
    Wow, that's huge, and the Earth - Mars offset is likely perturbed by things like the motion of Jupiter etc. Keeping the time representations compatible and in sync will be a full time job for many people.

It's worth noting that even atomic clocks run on Mars faster than on Earth, due to the different gravity. So you might expect say half of the 50 microsecond daily gain quoted in this article for the Moon, 10 miliseconds per year or a full second per century, more than enough to make you your spaceship completely miss its intended orbit. And martians will definitely want to run their own atomic clocks, making sync very problematic. So TAI is not the end all for what I expect to be a very complicated technical problem.

eru 4y ago
Not sure whether sync will be 'very problematic'. We already have that sort of sync happening today: when your computer is off, it runs a quartz watch. When you turn it on, it syncs via ntp. Some special boffins on Mars would run atomic clocks, and worry about synchronisation with earth. For the rest of the people running quartz clocks, they wouldn't even notice.
- toast0 4y ago
  > Some special boffins on Mars would run atomic clocks, and worry about synchronisation with earth. I think at some point, you have to redefine utc to be based on an estimated atomic clock at the center of the sun, because it's easier for mars and earth to estimate that, than for earth to go on its merry way and mars to estimate the time on earth. Relativism is fun?
wahern 4y ago
> It's worth noting that even atomic clocks run on Mars faster than on Earth, due to the different gravity. The biggest effect is the Sun's gravity, followed by orbital velocity. The relative masses of the planets is negligible by comparison, though in online discussions that's almost all anybody ever seems to talk about. I can't find confirmation through other sources, and can't credibly validate it myself, but the best estimate I found for time dilation between two clocks on Earth and Mars is roughly 5.6 parts per billion, or ~177 milliseconds per year. See https://space.stackexchange.com/questions/33590/what-is-the-time-dilation-between-mars-and-earth-resulting-from-the-mass-differe/33592 https://space.stackexchange.com/questions/33590/what-is-the-...
- cornholio 4y ago
  Wow, that's huge, and the Earth - Mars offset is likely perturbed by things like the motion of Jupiter etc. Keeping the time representations compatible and in sync will be a full time job for many people.