Like the title says, could we ever catch up with the expanding universe?


closed as unclear what you're asking by Kyle Kanos, Brandon Enright, Kyle Oman, user10851, Jim May 23 '14 at 17:58

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 3
    $\begingroup$ What do you mean "catch up"? $\endgroup$ – Kyle Kanos May 23 '14 at 15:34
  • $\begingroup$ I guess theoretically physically $\endgroup$ – Adsy May 23 '14 at 15:36
  • 2
    $\begingroup$ That still doesn't make sense. We are in the universe, how can we "catch up" to something we live in? $\endgroup$ – Kyle Kanos May 23 '14 at 15:37
  • 2
    $\begingroup$ @Adsy There is no edge $\endgroup$ – DavePhD May 23 '14 at 16:16
  • 2
    $\begingroup$ @Adsy How could something which by definition encompasses everything have an edge? $\endgroup$ – Jim May 23 '14 at 17:57

The rate of expansion, in terms of velocity relative to us, is proportional to distance from us according to Hubble's Law.

So beyond a certain distance, the velocity is greater than the speed of light and we can not "catch up" to a region that is too distant.

(This is somewhat of an oversimplification, because the rate of expansion could accelerate or decelerate over time, but observations show accelerating expansion that will continue to accelerate).

  • 1
    $\begingroup$ It's worth noting that most of the volume of the visible universe is already beyond our "communication horizon": light that we emit today will never reach very distant galaxies as the expanding universe carries them away from us. $\endgroup$ – rob May 23 '14 at 17:10
  • $\begingroup$ also note that light we emit right now will eventually reach galaxies that currently recede with $v_{\mathrm{rec}}=c$; while there are regions of space that we no langer can "catch up" to, these aren't simply the ones with recession velocities above $c$! $\endgroup$ – Christoph May 23 '14 at 17:36

Not the answer you're looking for? Browse other questions tagged or ask your own question.