According to chatgpt, our current earth-based radio telescopes would only be able to detect signals equivalent to radio leakage from earth at a distance of 1 light year.
The presence or current lack of alien signals at the very least bounds estimates of local population density and what energy scale they're operating on. Currently there's no nearby Type 1 Kardashev scale civilizations.
When it came time for questions I asked. So, if we were at Alpha Centari could we detect signals from earth with the tech we currently have? They said "No". That was 2019. Maybe tech is better today?
(Well, none pointing at stars at least. There are some spy sats pointed down.)
https://research.google/blog/exploring-a-space-based-scalabl...
One exception is the far side of the moon to get away from radio noise. But other than that, there's no reason to put a radio telescope in space.
> there's no reason to put a radio telescope in space
sadly isn't as true as it once was ..
* https://www.aanda.org/articles/aa/full_html/2024/09/aa51856-...
Once that constellation is fully expanded as intended, the planned chinese constellation joins it, and other nations (India?, the EU?) pile on, things will get even noisier.
The dark side of the moon offers hope, but it's still a lot of addiional awkwardness and expense that could be avoided with better attention to "the commons".