How could we communicate with an alien civilisation linguistically? How could we bootstrap our messages above sending them mathematical formulas and constants of nature, so that they will decode them into actual words? I think it would be trivial to communicate them our word e.g. for "water": send them the atomic numbers of oxygen and twice hydrogen. Likewise, you probably could encode organic molecules and eventually the full genetic code of the human species via such sequences of numbers. But there's now an "encoding gap". I just can't see an easy way to convert such bare formulas corresponding to physical data/chemical formulas into actually linguistic constructs, like the words for "planet" or verbs like "transmit".

Picture unrelated