Space travel, as we now conceive it, is impossible.
In order to travel to the stars, we must think of space as space-time.
Crossing huge distances of space requires enormous amounts of energy, supplies and most critical of all - time.
To cross space in a timely fashion, pun intended, you must exit your starting point’s space-time and enter at your destination’s space-time.
Einstien says it is possible, all we have to do is figure out how.
Manipulation of the basic forces should give us the power to jump across space as easily as a frog jumps across a puddle of water.
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It would seem that such a traveler would have to effect the expansion rates of the entire universe both going and comming, which seems to net out alright, but how to initiate that in either direction, or frame....
I dont think we'll ever be able to do it. And if there are any ETs out there, which seems very possible, I doubt they can do it either. I suspect we'll just have to keep listening.