C.S. Lewis once propounded the theory that Scientifiction (what science fiction was called in the days when he was writing it) was really the modern form of the Greek epic like the Odyssey. In the days of Homer you could set a tale in a land where all the normal rules didn’t apply by merely putting it on an island no one has been to in the Mediterranean sea. Since modern man has been to all of the islands in the Mediterranean, we have to put the far-off lands farther off. In the 1800s it was still possible to put it deep underground, as in H.G. Wells’ Journey to the Center of the Earth, but in the 1900s the only real candidate was on another planet.
I think that this theory is essentially correct, especially as regards science fiction which is about adventurous exploration of places as yet unknown. I don’t think it applies nearly as much to space empires made up entirely of humans which are set in the far future as much to have a free hand with the political setup as for any other reason. But space exploration is the sort of story I’m writing for NaNoWriMo this year, and I’m having a lot of fun with it. But unfortunately, (so far) writing relatively hard sci-fi, where faster-than-light travel and free energy for propulsion are my only two main cheats, this brings me into language difficulties with encountering new species. There’s no plausible way in a relatively hard sci-fi way to have two creatures who developed along entirely different evolutionary pathways would have worked out the same language when they may not even both have heads.
I believe I’ve basically just committed myself to ignoring the problem of microbe contamination; when two unrelated species meet there’s an overly good chance that one or the other will contaminate the other with microbes to which the other has no resistance and thus inadvertently wipe most or all of the other species out. Basically, an even worse case of what happened when Europeans came into contact with Native Americans. This is basically an insoluble problem since we need our symbiotic bacteria to live. One could, possibly, confine everyone to leak-proof space suits on away missions, but that has its own problems, especially where the fun is concerned.
But language is just really a problem. If one can’t speak to another or even figure out that the other is speaking, it really cuts down on the dramatic possibilities. On the plus side, my story is set within a Christian universe so I could always introduce something like a “soul stone” which allows rational souls to communicate without words. For added fun, it could even be something like a statue to the archangel Gabriel.
Anyway, the point is that hard sci-fi is very difficult to write without plot holes for the sort of stories one often wants to write because the sort of stories we often want to write are not really about outer space in the future. That setting is just our excuse.