&gt; Is this really not obvious to people? It&#x27;s about subtended angles - simple geometry.<p>If the universe is infinite and filled uniformly with stars, the 1&#x2F;r^2 falloff in the radiation captured from each star is cancelled by r^2 dependence on the number of stars at radius r. So as you integrate r from 0 to ∞, you accumulate an infinite amount of radiation.<p>Is this really not obvious to you? It&#x27;s all about infinitesimals - simple calculus.