# Assuming space is infinite can our observable universe be an island amongst an archipelego?

According to recent measurements our observable universe is roughly 93 billion light years in diameter; also it appears (according to WMAP measurements) that spacetime is flat.

Supposing space is infinite.

It seems to me that it isn't outside logical possibility that there is another observable universe completely outside of our observational range and so far away it has no appreciable effect on the curvature of our universe.

Note, I'm not using the word universe here as everything in space.

• Perhaps you might be interested in Tegmark's Parallel Universes, arXiv:astro-ph/0302131, in particular Level I: Regions beyond our cosmic horizon ("the uncontroversial cosmological concordance model"). May 13, 2013 at 22:22
• I'm not clear on what's being asked. How can an "observable universe" be "completely outside of our observational range?" Doesn't that mean it's observable and unobservable, which would be a contadiction? Why do you only care about this other region's effect on the curvature of our region? All interactions propagate at a maximum speed of c, including gravity, which is what propagates curvature effects (gravity is curvature). To the extent that I understand what's being asked, I think the answer is yes, cosmological event horizons exist, and 2 observers can be in disjoint observable regions.
– user4552
May 13, 2013 at 22:29
• @BenCrowell (and Mozibur) I presume that te OP means (non-intersecting) Hubble volumes? May 13, 2013 at 22:31
• @Crowell: It's difficult to express exactly what I'm saying given I'm not aware of current terminology here. It would perhaps be easier with a diagram. I think my title says it a lot better than the body of the question. May 13, 2013 at 22:38
• @Gugg: I don't think that interpretation makes sense, since the OP uses the word "observable," and the Hubble volume is smaller than the observable volume: physics.stackexchange.com/q/12819/4552
– user4552
May 13, 2013 at 22:38