Quote (impulse155 @ Mar 15 2014 12:10am)
So our universe is "limited" by the distance light traveled.
Here you seem to be confusing the observable universe with the "universe as a whole".
http://en.wikipedia.org/wiki/Observable_universeQuote (impulse155 @ Mar 15 2014 12:10am)
So basically if were in a "bubble" where the distance can be defined by the distance light has traveled and there are other universes that are also limited by the same factor.
Why don't the universes collide?
Same problem.
I drew this because it might help:

your statement "So our universe is "limited" by the distance light traveled" is a reference to the yellow sphere, not the red one.
While the scale is not very accurate, it is no accident the distance between the 2 civilization's observable universes has grown. Because the red sphere is growing much faster than the yellow and blue sphere, the distance between them will only grow. Also even if they did overlap there really wouldn't be a collision since they are just calculated regions of mostly empty space.
No one knows the volume of the red sphere but it can be showed that it must be
more than 10 times the volume of the yellow (through some observations compared with some rather nasty curvature arguments).
Of course the next question might be what is outside the red sphere, maybe a big green sphere? Well this is what Subwoofer is talking about, and as he pointed out is speculation for the most part. Observation evidence essentially ends at the surface of the yellow sphere (there are a few exceptions, like the curvature argument mentioned above, but you'll note it don't say much about the area outside the yellow sphere).