• zea@lemmy.blahaj.zone
    link
    fedilink
    English
    arrow-up
    11
    arrow-down
    3
    ·
    3 months ago

    If the sun disappears when? According to GR’s conception of simultaneous events, it disappears immediately.

    • tate@lemmy.sdf.org
      link
      fedilink
      English
      arrow-up
      22
      ·
      edit-2
      3 months ago

      Which two event are you talking about being simultaneous? The Sun going out and Earthers observing it? Those things will not be simultaneous in any reference frame, because they are “light-like” separated. (ie they lie on a 45 degree line in a Minkowski plot.)

      • WolfLink@sh.itjust.works
        link
        fedilink
        English
        arrow-up
        4
        ·
        3 months ago

        I think what he means is when the light from the sun disappearing arrives at earth, that’s effectively when the event of the sun disappearing happened from the earth’s perspective.

      • Zink@programming.dev
        link
        fedilink
        English
        arrow-up
        3
        ·
        3 months ago

        Yep. Imagine you’re off in space such that you, the sun, and the earth make an equilateral triangle. The sun disappears, then after 8 minutes you see it disappear. Then after ANOTHER 8 minutes you see the earth go dark, because that light had to cover two of the 8-light-minute long legs of the triangle.