I'm a huge Alien, Predator, and Sci-Fi movie fan..
So you think if they were asleep that long they'd have long beards? But you believe we have the technology to travel to distance stars that take millions of light years and can live that long???Just sayin' there is this thing called "suspense of disbelief" when you watch certain genres of movies. Sci-fi being one of them.
Initially it was a let-down to me. I saw the first Alien movie in theaters back in '79 and was in awe. Not really the story I though Ridley Scott was going to tell. A bunch of my other "geek" friends saw it and we discussed. Afterwards I had a greater appreciation for it. Prometheus was actually pretty deep...
I would suggest either picking up or borrowing the version that has the commentary... They explain alot of things...