• bitwaba@lemmy.world
    link
    fedilink
    arrow-up
    1
    ·
    3 months ago

    Light travels along geodesics that curve because spacetime itself is curved. Geodesics are curves that minimize distance between two points in a curved space. They are considered straight lines in a curved space, but it’s right there in the definition. Geodesics are curves. Our reality is a curved space, therefore straight lines in our curved space are curves. They are not straight.

    Our reality is not matiematically flat. It is matiematically curved.

    • Blue_Morpho@lemmy.world
      link
      fedilink
      arrow-up
      1
      ·
      3 months ago

      From the point of view of light, it is traveling in a straight line. It does not observe the curve therefore spacetime isn’t curved to it. There is no preferred reference frame.

      It is the same with special relativity. If a particle is moving at near light speed, you observe it as heavier. But from the particle’s point of view it is you who are moving and you are heavier.

      Curved spacetime is a mathematical transformation to reconcile the different reference frames in the same way time dilation is a transform between reference frames.

      There is no absolute frame of reference.

      • bitwaba@lemmy.world
        link
        fedilink
        arrow-up
        1
        ·
        3 months ago

        You’re not taking about the same thing as everyone else.

        You’re comparing reality to reality, curvature to curvature. We’re talking mathematical theory. There’s nothing about our reality of spacetime that meets the definition of mathematically flat.

        Type however many paragraphs you want about reference frames. None of them adhere to being mathematically flat. They are all curved spacetime.

        • Blue_Morpho@lemmy.world
          link
          fedilink
          arrow-up
          1
          ·
          edit-2
          3 months ago

          There is no absolute frame of reference!

          Light travels mathematically straight in one frame of reference but curved in another. Both are correct. You use mathematical transforms to map one coordinate system onto another in the same way you can map a mathematical straight line into curved geometry.

          https://www.einstein-online.info/en/spotlight/equivalence_light/

          Look at the example they gave of light in an accelerating elevator (which is actually an example written by Einstein in one of his books on relativity). One has straight light and the other is curved. Both reference frames are correct.

            • Blue_Morpho@lemmy.world
              link
              fedilink
              arrow-up
              1
              ·
              3 months ago

              The math that describes light in one reference frame is a mathematically perfect straight line. In a different reference frame the math that describes light is curved.

              Just like a straight line in one coordinate system can be transformed into a curved line in another system.

              • bitwaba@lemmy.world
                link
                fedilink
                arrow-up
                1
                ·
                3 months ago

                You’re just repeating yourself. It doesn’t make you right.

                A straight line in a curved space that adheres to the curved space is still a curved line. An actual straight line exists between the two same points that is shorter than the path light would take. That is the mathematical minimum distance.