This question already has an answer here:
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.
- 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?
- Are we at this point 100% sure there are no such civilizations in nearby star systems?
- 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?