• dohpaz42@lemmy.world
    link
    fedilink
    English
    arrow-up
    4
    ·
    3 months ago

    Honest question: if “nothing is faster than the speed of light,” then how could the universe be expanding faster than the fastest thing?

    • Nougat@fedia.io
      link
      fedilink
      arrow-up
      14
      ·
      3 months ago

      So all space is expanding. Locally, that’s “just a teeny tiny bit,” and the force of gravity is plenty strong enough to keep things up to about the size of galaxies (maybe galaxy clusters) gravitationally bound. Andromeda, for example, is the only galaxy that is heading towards us.

      But all of space is quite big. Over the vast distances of space, all of the “teeny tiny” local expansions add up. This means that the galaxies which are furthest away from us are also receding from us most quickly. This is not because those galaxies are moving through space; it’s because of all the expanding space in between them and us.

      The speed of light (in a vacuum) is the fastest anything can move through space.

      • dohpaz42@lemmy.world
        link
        fedilink
        English
        arrow-up
        3
        ·
        3 months ago

        Would a fair, albeit crude, analogy be like when I fart and the gas forces my butt cheeks apart (the expansion between two objects)? (_|_)💨

        • Nougat@fedia.io
          link
          fedilink
          arrow-up
          9
          ·
          3 months ago

          Crude, yes. Fair, no.

          Consider a balloon. Uninflated, make a mark on opposite sides, and then make a third mark right next to one of those. When you inflate that balloon, the two points on opposite sides of it become farther apart because of the stretching of the whole balloon, but the two marks right next to each other don’t become nearly as far apart, because they are only experiencing “local” expansion.

    • nothing@lemm.ee
      link
      fedilink
      arrow-up
      8
      ·
      3 months ago

      Wait until you hear about relativity.

      And also we don’t know that C is the limit entirely, but it is so far. Also, we don’t know if there are more dimensions in our reality or not because we cannot observe them. And no, I don’t have much of a better answer.

      Basically, we still know we don’t know a lot, and we probably don’t know a ton of what we don’t know that we don’t know. Also magic.

    • Vespair@lemm.ee
      link
      fedilink
      arrow-up
      5
      ·
      3 months ago

      It took my awhile to get it until somebody put it this way. The objects aren’t exactly “moving” apart from each other, rather space in between them is expanding. So instead of thinking of it like a bunch of objects in a line being pulled away from each other, instead imagine it like a bunch of vector based objects random placed on an infinite canvas - now rather than moving the objects at all, try to imagine instead reducing the scale of all of the objects equally. Now of course this isn’t perfect, as really what is happening is kind of the opposite, as the objects remain the same but the space between increases, but the relationship is the same here. So nothing is exactly “moving” in relative space, but everything is still expanding. Thus this expansion can happen infinitely without anything breaking the speed of light.