D_Ethan_Bones t1_jdlbd8w wrote on March 25, 2023 at 6:02 AM

My own personal guess for (lack of finding alien civilization) is that we've only barely gotten started searching.

Extent of human radio broadcasts. If we were overlapping with another such circle, how well would we know - how well would we have known 25 years ago, 50 years ago, 75 years ago? People finding the cosmic background might have found something else with it but we're still finding exoplanets because our vision is steadily improving. They were in an impenetrable fog at the turn of the century.

"We'll know when we're older" is what I would call an optimistic answer. Maybe there is something interesting out there, but we will need further tech advances or at least more time to use what we have. AI and future humans hopefully improve upon what we've got already.

sumane12 t1_jdlj54u wrote on March 25, 2023 at 7:52 AM

This is the answer.

Considering life on this planet went through atleast 5 major extinction events and took 4 billion years to create creatures intelligent enough to leave the planet, it's likely that space faring civilizations are extremely rare. Now let's give a low range estimate that the first intelligent creatures arrived approximately 4 billion years after the big bang, that gives them at the very maximum, a 9 billion light year sphere of radio broadcast. Given that the observable universe is 93b light years accross, that first civilization would have only sent out radio waves in 10% of the universe, which means we could very easily be in a part of space that it hasn't reached yet.

This all falls apart if FTL is achieved, but I suspect if that's the case, then it won't really matter.