What If Earth Were Twice as Big?

Double Earth's radius in a carefully defined thought experiment. At equal average density, volume and mass rise eightfold, surface gravity doubles, and getting to orbit becomes much harder. We follow the effects through people, mountains, buildings, atmosphere, oceans, rockets and satellites, while separating the results we can calculate from geology, climate and biology we cannot infer from size alone. 0:00 Define the impossible Earth 0:43 Eight times the material 1:18 Gravity at the new ground 2:03 A body under two g 2:51 What happens to mountains? 3:33 Buildings carry weight 4:15 An atmosphere with a shorter scale 4:57 Keeping the gases 5:40 Oceans and pressure 6:26 A difficult first kilometre 7:06 Orbit is not escape 7:54 The propellant spiral 8:37 Satellites and time 9:17 Could a rocky world exist? 10:09 What size cannot tell us 10:58 A changed civilization