Ever notice how many SF stories, TV shows, and movies conveniently assume Our Intrepid Explorer can easily communicate with Never Before Seen Alien? Sometimes there's no attempt to explain it -- of course everyone in the Pegasus Galaxy speaks English (Stargate Atlantis). Never mind that their ancestors came from Earth before English came about, and often from halfway around the globe from the land became known as England.
Both parties speaking English in a First Contact situation certainly moves along the plot, but it demands much willing suspension of disbelief. The SFnal workaround is the universal translator (UT). This is a computer program that translates between any two languages. Some UTs require varying amounts of exposure to the new language, others can translate immediately.
(Before I continue ... there are many excellent stories that forthrightly tackle the challenges of establishing communications. A particularly mind-stretching favorite of mine is "Story of Your Life," by Ted Chiang.)
Is a UT plausible, or is it only a trope to move along plots?
For this post, let's take the easy case. That's the know-it-all UT. It knows each new language's vocabulary, pronunciation, grammar, and idioms (among other things) before ever encountering them. The implication is that there is a small number of meta-languages, encompassing all possible languages. With the shortest of snippets as a sample, the UT can derive the special case used by the newly encountered species.
Let's consider two species.
Case A, human. Language is constructed of a few tens of sounds (phonemes) used in combinations. Basic concepts reflect sight as the primary way of experiencing the world.
Case B, the aquatic hive-mind slime molds of Rigel III. They emit and absorb complex biochemicals to sense their environment and communicate. Information is encoded in (among other things) the types of molecules, concentration levels, and concentration gradients. Reactions with ambient chemicals can degrade communications. Amorphous blobs that the Rigelians are, they have neither fronts nor backs nor sides. Their sense of direction shifts with the currents, tides, and rogue waves.
How will the human-built "universal" translator fare when Our Intrepid Explorer first meets the Rigelians?
The instant-on, no-training-required UT? Surely a trope.