[l3robot]

I think the reasoning of the Fermi paradox is that "at some point in time" a distant civilization must have been using EM wave to communicate. Now, considering the number of planets, it must exists a civilization in the universe that sits at a distance that let us sense this EM dominated past. And this even if in their own local time, they use fancy new tech. Even if they were not trying to communicate with us per se. Their own radiation should be measured.

[alextingle]

We would only be able to detect our own everyday transmissions at a distance of a few dozen light years. So the galaxy might be full of EM emitting civilizations, and we wouldn't have detected them.