Quote Originally Posted by Tellos Athenaios View Post
Right now Humans can't travel to the moon, actually. There are numerous projects under way to restore that “capability” but right now we can't do much more than take the Sojuz shuttle between ISS and Earth.
Oh, c'mon; you know what I meant. All we need to do is to initiate a project, and we can. We have/know the technology required. The same thing could have happened to alien civilizations - they visited a few alien solar system, and thought they were awesome since they could; but eventually they got bored and didn't like the costs that came with it.

While the prospects of “some kind of alien” are looking good (assuming that we ignore French and Texan ones who merely behave in an alien fashion) those of “intergalactic travel” or “alien encounters” are much less good. So far our best bet of weird quantum physics dimensions travel is that you essentially do unto a proton what would melt you out of existence were such a thing done unto your yourself. (Nevermind the outrageous amounts of energy that are required to get you colliding with something roughly your own size at roughly the same amount of eV per relevant particle in your body.)
There are also the ideas of hibernation, multi-generation space ships etc. We don't have to rely on too exotic theories for interstellar space travel to be possible.