3 ms·

> yielding 58.721 μs/day Can someone kind explain this unit for me? microseconds per day. Does that mean that the relativistic difference is cummulative? In o

• nh23423fefe 2y ago
  its actually not a unit either. its a dimensionless ratio
  • akira2501 2y ago
    6.79641e-10
• unholiness 2y ago
  That's right. While a day passes on earth, a day minus 58.721 μs passes on the moon (which is moving faster than the Earth). This multiplies, so after a million days a clock on the moon will read 58 seconds behind a clock on the earth.
  • pdonis 2y ago
    It's the other way around: while a day passes on Earth, a day plus 58.721 microseconds passes on the Moon. The Moon clock gradually gets ahead of the Earth clock. In an Earth-centered inertial frame, the Moon is moving faster than the Earth, but it is also at a very high altitude, and the altitude effect, which speeds up the Moon clock relative to Earth, is much larger than the speed effect, which slows it down. (Note that the above only takes into account the effects of the Earth's gravity. The paper also takes into account the effects of the Moon's gravity, which don't change the above answer qualitatively but do add small corrections numerically, so the 58.721 microseconds per day is not the actual value the paper ends up with.)
    • alganet 2y ago
      Cool, thanks! I'm assuming this affects clocks (and things) but not time, right? Time itself is no different on the moon (it's not the future there). I know this must be true otherwise we would be surrounded by time travellers by now. So, where does this cancels out? My intuition says that if we have two clocks, each clock with a display and a laser pointing to each other, and we put one of them on the moon and the other on earth, someone observing it from a third equidistant point would see both lasers blinking at the same rate. If that's true (I don't know if it is) both of your answers are kinda right, aren't they? From earth, the moon clock ticks slower compared to earth clocks, therefore it lags behind. From the moon, the moon clock ticks faster compared to earth clocks, therefore it skips ahead, and vice-versa. I am not sure though, I feel like I'm missing something.
      • pdonis 2y ago
        > I'm assuming this affects clocks (and things) but not time, right? What's the difference? > otherwise we would be surrounded by time travellers by now I'm not sure what your reasoning is here. > where does this cancels out? I don't understand the question. What is supposed to cancel out? > someone observing it from a third equidistant point would see both lasers blinking at the same rate. No, they wouldn't. > From earth, the moon clock ticks slower compared to earth clocks No, it ticks faster. That was my point.
        • alganet 2y ago
          Consider this scenario: - I get into a spacecraft, go into orbit around earth. - Once in orbit, I start accelerating until my clock ticked faster for long enough to be 1s ahead of earth. - Once I'm 1s ahead of earth, I capture transmissions my buddy sent to me of the stock exchange rates. - My buddy, on the ground, has a telescope and is ready to invest or sell stocks depending on whether I stop or keep accelerating. - My buddy now has knowledge about the future, I land and share the money we stole from the future with him. My intuition says this should be impossible, but it seems that I got the "why" wrong. Or maybe everything wrong.
          • 2y ago
  • mr_mitm 2y ago
    Moves faster than than the Earth relative to what? Isn't it the gravitational time dilation that is the relevant effect here?
  • alganet 2y ago
    Thanks!