My question is, how long can an alien live? Who' s to say they can' t live 600-800 years? With our medical advancements in the last 100 years, human lifespan has increased by almost 40 years in developed countries. If an alien civilization is 1 million years ahead of us, well, you do the math. The aliens might not be able to break the speed of light. The might simply be able to travel at nearly the speed of light, and with their long lifespan, a 100-200 light-year trip isn' t implausible at all. Plus, as you approach the speed of light, doesn' t time slow down? I believe it slows to as little as 1/7th the normal time. That could make trips taking thousands of normal years possible. It would seem to the travelers to take much less time. They could even build a colony or two somewhere between, so that the crews could be rotated. For what its worth, that' s how I think it could be possible without breaking the speed of light.