The most powerful radio signals we’ve sent so far would be nigh indecipherable garbage to any civilization that came across it.
And if they somehow did manage to decipher it, it would comprise a cross section of hot cultural garbage that would be useless to an alien civilization for purposes of learning much about humanity.
If they exist and are anything like us, they aren’t dedicating many, if any, resources to shooting powerful radio signals into space specifically to communicate with alien intelligences, much less information to decipher those signals.
I would think that the signal would count for months or years, and then sned some mathematical equations, then begin sending communication instructions.
Yes, IIRC TV broadcasts from Earth fade to below the level of the background noise within a couple of light years thanks to the inverse square law. Not even aliens around Proxima Centauri are watching… what was on TV 4 years ago? Let’s say eagerly anticipating the premiere of Better Call Saul.
If we know that they’re intelligent, then that means that we’ve intercepted some sort of communication from them (which may or may not have been directed to us, but it’s from them). So we’d be working very hard to understand that communication. And most circumstances that would lead to us intercepting one communication would lead to us intercepting many. So we’d have have lots of communications to interpret (which would both make the interpretation easier, and mean more once we had interpreted them)./QUOTE]
I think this would become a major factor in our development, to the point we dumped more resources into coming up with a way to eavesdrop on this civilization and whatever nuggets of information it might let slip than in exploring our own part of the galaxy*. Assuming, of course, they aren’t coincidentally just a few technologies behind us in everything. But even then…
*With the caveat that if we got it into our heads that we were in a position to intercept all kinds of information (even distilled down to what they might put into their version of a sitcom) from a civilization hundreds or thousands of years more advanced than us, and someone determined that we could get a much better signal (lose less data) by setting up space receiver stations throughout the Kuiper Belt, then we’d do it. It’d be like an addiction for us, I think, if we knew that every missed signal might contain the next leap forward.
I find it interesting how many people post statements like “how could an alien technology do this”, or that an alien megastructure would absorb this EM spectrum. Or that Proxima b isn’t suitable for life to evolve. For evidence of intelligence in the universe, we have a sample point of 1. Nothing’s off the table. It’s fun to watch because our ability to perceive the universe is getting better, and it’s about time we find something really weird.
The hypothetical could work without radio. Proof of alien life could also take the form of something like the Voyager golden record. If we received such an artefact, that would be strong proof of an alien civilization. It might contain a decipherable message whereby we could determine where their system is, and then we could calculate that it was 10,000 years away.
That fits the OP: we do not need a feasible means of communication, we only need to have proof that alien intelligent life existed 10,000 years ago.
