So, I'm not into writing or creating any new worlds, but this question (or a set of questions) was bothering me for a while and I thought it's a good place to ask.

  1. If there exists an alien civilization in a nearby star system (i. e. Alpha Centauri) and it has a similar technology level to ours (producing the same amount of radio noise), would we be able to detect it?
  2. Are we at this point 100% sure there are no such civilizations in nearby star systems?
  3. If there's a civilization nearby with similar technology to ours (or more advanced but still scientifically plausible) do they already know that we're here?
  • $\begingroup$ Also worth reading: space.stackexchange.com/questions/17765/… $\endgroup$ – Morris The Cat Aug 5 '19 at 14:22
  • $\begingroup$ Welcome to worldbuilding. We have a 1 question per post policy, while you have 3 questions here, and I am not fully sure they are about worldbuilding. Moreover, you are using the hard science tag, are you sure about it? Please take the tour and visit the help center, then narrow down your question and make it fit our scope. $\endgroup$ – L.Dutch - Reinstate Monica Aug 5 '19 at 14:22
  • $\begingroup$ Hi, thanks for the linked questions. That's basically what I've been looking for, so this one can be closed. $\endgroup$ – Przemysław Czechowski Aug 5 '19 at 14:46
  • $\begingroup$ You should have got a notification about the duplicate. If you accept the suggestion, the question will be closed as duplicate automatically. $\endgroup$ – L.Dutch - Reinstate Monica Aug 5 '19 at 15:04