[scientaster2]

Remember though that as you approach the speed of light, relativity starts to kick in with your time "slowing down". In other words, the inverse relationship between speed and time could allow civilizations to expand faster than it would seem possible at "normal time" speeds. Complete conjecture on my part, just a fun thing to think about!

[umvi]

This is true but the amount of energy needed to reach speeds where time dilation makes your journey seem short are just unfathomable.