{ Installment 8 of Ivan Illich’s Energy and Equity series }
Degrees of self-powered mobility
A century ago, the ball-bearing was invented. It reduced the coefficient of friction by a factor of a thousand. By applying a well-calibrated ball-bearing between two Neolithic millstones, a man could now grind in a day what took his ancestors a week. The ball-bearing also made possible the bicycle, allowing the wheel-probably the last of the great Neolithic inventions-finally to become useful for self-powered mobility.
Man, unaided by any tool, gets around quite efficiently. He carries one gram of his weight over a kilometer in ten minutes by expending 0.75 calories. Man on his feet is thermodynamically more efficient than any motorized vehicle and most animals. For his weight, he performs more work in locomotion than rats or oxen, less than horses or sturgeon. At this rate of efficiency man settled the world and made its history. At this rate peasant societies spend less than 5 per cent and nomads less than 8 per cent of their respective social time budgets outside the home or the encampment.
Continue reading Energy and Equity: Degrees of self-powered mobility