To use a phrase from a favored professor at Weber State. I am taking a thermal physics/statistical mechanics class for fun, along with an electronics class too. One of the problems I just finished was to use the Stefan-Boltzmann law (Power is proportional to area times temperature raised to the fourth power) to find the power output of a person. But to do this I need an area formula for said person. Never fear according to Mosteller (1987) he provides the following commonly accepted formula for the surface area of an average human. (height[cm]*weight[kg]/3600)^1/2. (Or you can use the physicist's assumption of a spherical human which in the limit of Wisconsin is approximately true.) Anyway, plugging in the canonical astronomer multiplying by the number of seconds in a sidereal day and timesing by the population of the planet leaves us with about fifty five gadjillion Joules/day (5.54*10^17 J/day) in unspent energy! Its no freaking wonder the zombies want our brains and the machines want our ATP pumps!