[weare138]

Another possible explanation is advanced civilizations quickly move on to more advanced forms of communication. We're already on the cusp of quantum communication. Would we even still be using radio in 100 years? A couple hundred years of our civilization using radio technology would only be an extremely brief period of time on the cosmological scale. Maybe technologically advanced civilizations progress in rapid jumps like ours did with the industrial revolution, the age of electronics and now the digital/information age. We're looking for other civilizations at our current level of technology which may be a brief window of time overall for technologically advanced civilizations.

And if they are at our current level of technology they would be stuck on their planet like we are and have no viable way to reach us no more than we could reach them.

Or they could still be using radio but using fully encrypted communications. Weak signals reaching Earth from over vast distances would appear like and get lost in the background noise of cosmic radiation.

[simne]

Quantum communications are not totally hidden. One in any case could detect some strangeness on emissions from target star.

Even encrypted communications MUST be different from space/star emissions.

What Quantum communications are, they will very early show you, that somebody hearing your quantum emissions.

And yes, if aliens will hear our cellular network, they first will see, that Earth radio emissions are just about Sun radio emissions, they will not understand content, but will see too much radio emissions from planet.

If we will use Quantum radars (lasers) to probe nearest stars, we will know very fast (speed of light), that somebody intercept emissions.

So, exists possibility, aliens already know that we looking on them (hear them), but they remain undetected, and same trick could use Earth.

Sure, aliens could use data from such probes, to make shadow shields, to not emit to sides, where detected hearing.

[weare138]

Quantum communications are not totally hidden.

True but at the same time we would have to be looking for it but we're currently mostly concentrating on radio signals.

[simne]

Ok, you are wrong. We now trying to find ANYTHING looking artificial (unnatural). This could be radio emission, light emission, infrared emission, or anything other we could detect.

Just radio emission is not enough to prove something artificial. For example, Jupiter have very powerful radio emissions, you could receive them by ordinary radio receiver.

But radio emissions are most comfortable to work with, that's why PRIVATE persons invest to this.

[simne]

Sure, but how to do this?

[simne]

Sure, one could use direct quantum communications, but looking, how hard it moving, could exist some fundamental limitation on number of entanglements one could produce in limited time.

So, most probably, these effects will be widely used to detect hearing, but communications themselves will be some sort of classic encrypted, for better speed.