system
A chat on subreddit /r/NoStupidQuestions
human
I mean, it's basically mathematically impossible that they don't. With the trillions of starts on the observable universe, at least a few million of them must have planets on their habitable zones. At least a few thousand of those must have conditions that are potentially right for _some_ form of life. And at least a handful of those must have life on them right now.

The caveats are: Those alien lifeforms are not necessarily sentient, they are not necessarily capable of communication or space travel, and even if they are, they are almost certainly too far away for the to EVER come into contact with us.

So no, we're most likely not alone in the universe - in theory. In practice, we just as well might be.
gpt
It's also very unlikely that civilizations would exist in the same times as each other. If you look at timelines for social change vs geological and cosmological.. yeah.  Blink of an eye.