[Kip Russell]

Who says they're using radio to communicate? I've long thought that a space faring civilization would develop communication technologies superior to radio. Perhaps using light, or even some phenomena that we're not familiar with yet.

Perhaps so, but surely some of 10,000+ civilizations would use radio.

As far as their terrestrial broadcasts, I suspect that the signals are too dispersed to be more than background hiss when they reach us.

Narrowband radio broadcasts are detectable with current technology at a distance of hundreds of light years or more.

[Windflier]

Narrowband radio broadcasts are detectable with current technology at a distance of hundreds of light years or more.

I'm curious to know how we know that, considering the fact that we don't have a receiver hundreds of light years away from here to check it.

Serious question.