qqp question1: If I show a red coloured light to a self driving Uber will it stop? Can these cars understand speed limits and sign boards like go slow? question2: "Given that time slows inversely to speed, does it follow that time should progress at a fixed ""lower"" rate at the speed of light and likewise that if an object is motionless in space, then time passes at a fixed ""faster"" rate, therefore Earth time can be measured as a ratio of these rates?"