The Diffusion Dilemma
On the sun-baked plains of the American Midwest in 1892, a revolution was loudly sputtering to life: the tractor, an engine which signaled the end of the era of animal power and the beginning of the age of machine power. This machine was not just a piece of equipment; the tractor was a manifestation of an exponential shift in energy density, from animal metabolism to coal burning, empowered by discoveries in thermodynamics. But diffusion of the tractor, screeching across the horizon, took much l