| Good comment. Life needs some kind of chemistry that doesn't lock up into compounds so stable they're hard to crack apart, but allows compounds stable enough to build structures.
Carbon, hydrogen, oxygen, and nitrogen are suck a system. That's why organic chemistry is a thing. There aren't that many families of elements with that property.
Ammonia and silicon based life have been suggested. But none of the alternatives have very promising chemistry. See [1]. Life is probably stuck with CHON, in the "goldilocks zone" where water exists as a liquid. We now know that planets are not rare. Many extrasolar planets have been discovered. A few are promising. The systems with known extrasolar planets might have smaller, more interesting planets, too small to be detected at interstellar ranges. But stars are a long way away. Unless FTL is possible (which it probably isn't, because causality would break), the most we can hope for is someone to talk to by radio or something similar. See the Drake Equation.[2] There's been progress on firming up the numbers since the 1950s. [1] https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemi... [2] https://en.wikipedia.org/wiki/Drake_equation |
Radio communications between tween solar systems require more energy than we have. We couldn't detect earth level civilizations in the nearest solar system (which probably doesn't have earth like life) even if both of us by chance aimed at each other at the correct time.