  In the original quote I gave, I might give it your interpretation if the bolded would was changed to could. Is this what you mean?  ... um... actually it's both... that quote from the article is the in the other hand part, They first explain that the one on the shuttle is the one moving (if you stand on the earthbound POV), in the other hand you can also see the earthbound one as the one moving (if you stand on the shuttle POV)...    there lies the paradox if the one who moves is indeed the one who ages more slowly... but who's the one who moves? which one? the one on earth or the one on the shuttle? it's RELATIVE! :D ...depends on which POV you stand... if your POV is earth then TOWM is in the shuttle and vice-versa...    What they are doing here is breaking the paradox by using a third place as POV (the far away star) so it's not relative to any of the subjects involved, an outside observer we may say... but in doing so the professor assumes a lot of stuff we can't certainly know for sure... :rolleyes:     Did that make sense? :p     Exactly. Time travelling into the future is theoretically possible. Simply build a spaceship fast enough.  using that theory you wouldn't be able to travel BACK, right? a one-way ticket to the future! :D