thanks - i guess I'm still missing something then? i thought that if bob travels at really close to the speed of light, say .9999995c then his time could slow-down by close to 1000x (according to the calculator at http://www.1728.org/reltivty.htm) . so maybe we're not talking years, but...
I think i understand that if my friend, let's call him bob - were to travel to the moon and back at near the speed of light, when he got back, it would seem like only seconds to him but centuries could easily have passed on Earth once he comes back to a stop.
my question is - if bob launched...