Comment on wat

db0@lemmy.dbzer0.com ⁨2⁩ ⁨days⁩ ago

• fonix232@fedia.io ⁨1⁩ ⁨day⁩ ago

  Not necessarily.

  The expansion of the universe here doesn't necessarily mean matter moving faster than light.

  Think of the universe as a 3+1 dimensional ballon - specifically, the 3D space we occupy is the 2D surface of the balloon. As you blow air into the ballon, that 2D space expands.

  Now, it's a simplistic example mainly because we're three dimensional beings and thus can't easily wrap our heads around a 4D space where one of the surfaces is three dimensional. You run into the same issue as e.g. trying to visualise a tesseract (a four dimensional cube). So a balloon has to do.

  And since this expansion of our universe technically happens outside of it, the general laws of physics - such as the speed of light - do not apply.

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  • db0@lemmy.dbzer0.com ⁨1⁩ ⁨day⁩ ago

    That’s what I meant. Since matter isn’t moving at the speed of light, if we assume the universe expansion is due to the movement of its edge objects, then it cannot expand faster than 2c. If the expansion is happening for a different unrelated reason than the edge objects ofc that’s something else

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    • fonix232@fedia.io ⁨1⁩ ⁨day⁩ ago

      Your presumption that there’s an “edge” is at fault here. Consider the surface of the ballon (or rather- a bubble) - it’s continuous, just like our universe. And that’s why it’s hard to explain how a 3D space can expand seemingly without a center point - because said center point is not within the constraints of this 3 dimensional space, just like how the center of a balloon or bubble is not on the two dimensional surface but in the center.

      so just like the surface of an expanding bubble, the expansion of our universe doesn’t happen in a plane we can conceptualise easily - it’s a 4 (or possibly more!) dimensional expansion, of which we are just the surface, therefore the expansion appears as if everything literally drifted away from everything - which should be impossible in a 3D space but not when you add a fourth axis.

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      • db0@lemmy.dbzer0.com ⁨1⁩ ⁨day⁩ ago

        I don’t know much about astrophysics, but it seems to me the analogy breaks down. Unlike a balloon, the universe does not move on a medium, so the only way to surmise it’s size is by its edges (i.e. the objects at its farthest edges). So the important thing here is how fast those edges move (the dots, on the balloon) which can never be higher than the speed of light. What am I missing?

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