==graviational== 

 I do more basic proofreading than science, which led me to this apparent typo: "Obviously, the entropy increases (due to graviational in fall) and this has the effect that the universe has become cooler than this simple model predicts." I almost corrected it to "gravitational", but that makes the sentence look backwards. Gravitational in fall of a meteorite, for instance, would convert gravitational potential energy to heat energy, and get hotter, not cooler - although I agree that it would increase entropy. Did I discover a typo and/or a more serious mistake?