this post was submitted on 28 May 2026
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submitted 18 hours ago* (last edited 18 hours ago) by zedgeist@lemmy.world to c/science@lemmy.world
 
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[–] kryptonianCodeMonkey@lemmy.world 6 points 4 hours ago* (last edited 3 hours ago) (1 children)

200 light years radius is for radio signals to reach someone. 100 years radius for possibly receiving a signal back.

And that is if they received our signals, are able to identify that they are artificial signals out of the background noise of the rest of the universe because the signal degrades and gets weaker as the broadcast expands, they decide to send a reply back (even though they just recieve chatter at that point, not intentional communication to them), and then actually sends us a signal back. It's no wonder that hasn't happened yet.

There's around 10-15,000 stars in a 100 light years radius. The chance that any of those stars have habitable planets with intelligent life with the technology to receive and send radio signals and is listening for extraterrestial signals and can discern those broadcasts from background noise and would reply to chatter... that's a small chance. For context, we have only been explicitly listening for and sending signals intended for extraterrestrials for 64 years ourselves, so an identical civilization 100 light years away that received and replied to us immediately would still have 36 years of transit left on their reply.

[–] KneeTitts@lemmy.world 2 points 1 hour ago* (last edited 1 hour ago) (1 children)

200 light years radius is for radio signals to reach someone. 100 years radius for possibly receiving a signal back

So I have more bad news, the strength of our radio signals is not very strong either so by about 20ly, they fade into background noise so no one would be able to pick them up at all. (could be a lot less than 20ly too, possibly 5 ly depending on the signal)

[–] kryptonianCodeMonkey@lemmy.world 1 points 25 minutes ago

Yeah I figured that that distance was wishful thinking.