User:ArmadilloFromHell/Spherical cow

A spherical cow is a highly simplified model of reality. Just as a real cow has a complex, time-dependent shape that is not very much like a sphere, so a "spherical cow" model may deviate from reality in many regards (but one hopes captures some basic characteristics). I first heard of "spherical cows" ca 1975 as part of a joke:

Ever lower milk prices were driving a dairy farmer to desperate measures. Two years ago, he had his barn wired for sound and tried "Beethoven for Bovines" but milk production dropped 2%. Last year he signed up for "hex the herd" where Genuine Santa Barbara WitchesTM remotely hexed your herd for health and higher production. (The ad had said its hexes were the cause of California's improved milk production, but it didn't seem to work in Wisconsin.) So this year he drove to town to consult the ultimate power source: a theoretical physicist. The physicist listened to his problem, asked a few questions, and then said he'd take the assignment, and that it would take only a few hours to solve the problem. A few weeks later, the physicist phoned the farmer, "I've got the answer. The solution turned out to be a bit more complicated than I thought and I'm presenting it at this afternoon's Theory Seminar". At the seminar the farmer finds a handful of people drinking tea and munching on cookies---none of whom looks like a farmer. As the talk begins the physicist approaches the blackboard and draws a big circle. "First, we assume a spherical cow..."