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