If the universe is expanding faster than the speed of light, and force carrier particles move at the speed of light, wouldn't this cause infinite universal expansion? Since no forces would be acting upon the outer edge of the universe? (This doesn't account for the apparent acceleration of the universe but it does account for the lack of slowing down for the universe).

  • $\begingroup$ Could you clarify whether you're implying that the universe has edges and is held together by forces from the "inside" acting on these edges? $\endgroup$ Jan 29, 2013 at 3:22
  • $\begingroup$ Even though the universe is expanding, the universe doesn't have edges. The expansion of the universe means that at any point in the universe, it appears that distant objects are moving away. Think of a 2D universe on a balloon that is being blown up. The 2D universe is expanding, but there is no "edge" of the balloon. $\endgroup$
    – Kenshin
    Jan 29, 2013 at 3:40
  • $\begingroup$ @Chris I don't think it's justified to state that the universe has no edges like a fact, since we really can't be sure about that. It is true that the expansion of the universe is not the result of any pulling or pushing on edges, but who knows whether or not it has edges? It could perhaps be embedded in a higher dimension, like the balloon actually does have edges in 3D, they are just not observable for the creatures that live in the 2D universe of its surface. $\endgroup$
    – Wouter
    Jan 29, 2013 at 11:04
  • $\begingroup$ The Universe does seem to have a flat or slightly open geometry, which implies that it is either infinite or has edges. $\endgroup$
    – Thriveth
    Jun 26, 2013 at 21:47

1 Answer 1


Not quite. When people make statements like 'universe expanding faster than the speed of light', it refers to two different regions of the universe separated by some large distance. For a given location in space, there will always be a nearby region that is moving away slower than the speed of light---which it interacts with.

  • $\begingroup$ Well answered zhermes. $\endgroup$
    – Kenshin
    Jan 29, 2013 at 3:45
  • $\begingroup$ The cosmological redshift might serve as a good example to show that the force carriers themselves are indeed being affected by the expansion of the universe, which shows that the expansion is 'internal' to the universe, so to speak, it is not merely edges running away. $\endgroup$
    – Wouter
    Jan 29, 2013 at 11:12

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