We also have no reason to believe that we'd be able to detect other civilizations, even if there were millions out there. They might well be using other means of communication. Even if they were using the very thing we were looking for, it's still likely we would miss them - even if they were right next door to us. From SETI's FAQ[1]:
> If an extraterrestrial civilization has a SETI project similar to our own, could they detect signals from Earth?
> In general, no. Most earthly transmissions are too weak to be found by equipment similar to ours at the distance of even the nearest star. But there are some important exceptions. High-powered radars and the Arecibo broadcast of 1974 (which lasted for only three minutes) could be detected at distances of tens to hundreds of light-years with a setup similar to our best SETI experiments.
It always seemed odd to me that people call this a paradox.
From the perspective I gathered through understanding a very beautiful unified theory (not my model) - this is exactly my point.
EM waves as we use it are useless for long distance communications. I even doubt that those waves will still be detectable in a different solar system as the general assumptions that our vacuum is a very homogeneous is not true for me (the underlaying dimensions are for me, but not the vaccum as we know it). I have much more effects that cause disturbances of such waves.
Inside a solar system, there are also better techniques that are more stable in propagation then our Hertz EM waves. But unfortunately, we adopted a form of Maxwell Equations that are not suitable to describe the phenomena (the original equations in quaternion math can however). Nicolas Tesla did a lot of research in this area, but it is not very well known/understood. (From the model I'm using 3 forms are derived. As far as I dug into Tesla, he worked with 1 form. The 3rd form is the interesting one but very hard to produce /detect.)
> If an extraterrestrial civilization has a SETI project similar to our own, could they detect signals from Earth?
> In general, no. Most earthly transmissions are too weak to be found by equipment similar to ours at the distance of even the nearest star. But there are some important exceptions. High-powered radars and the Arecibo broadcast of 1974 (which lasted for only three minutes) could be detected at distances of tens to hundreds of light-years with a setup similar to our best SETI experiments.
It always seemed odd to me that people call this a paradox.
[1] https://www.seti.org/faq#obs1