/sci/ - Science & Math

>speculative fiction
>plausible

Complex life like we see on earth (big animals and shit, humans) are very rare. These planets which harbor complex organisms/civilizations are so rare and far spaced out that they usually die out long before they contact another civilization.

Simple life is common in the galaxy (bacteria, microbial life) They stay simple and thrive in their little hotspots on whatever world they inhabit. And every now and again due to collisions from impacts of comets and material being ejected into space, some of those lifeforms continue to live in space on whatever rock they inhabit. Sometimes those comets crash into other worlds and the lifeforms once again thrive on a new planet, and begin to evolve into other more complex things.

So in conclusion, many civilizations of beings have probably risen, evolved to a sophisticated degree, explored space and then eventually died out and went extinct millions and millions of years ago. It wouldn't surprise me that if humans ever get out there we will discover ruins of other civilizations long dead.