Spherical cow

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Spherical cow is a metaphor for highly simplified scientific models of reality. The phrase comes from a joke about theoretical physicists:

A spherical cow jumps over the moon.

Milk production at a dairy farm was low so the farmer wrote to the local university, asking help from academia. A multidisciplinary team of professors was assembled, headed by a theoretical physicist, and two weeks of intensive on-site investigation took place. The scholars then returned to the university, notebooks crammed with data, where the task of writing the report was left to the team leader. Shortly thereafter the farmer received the write-up, and opened it to read on the first line: "Consider a spherical cow in vacuum. . . ."^[1]

As with any mathematical joke, it is told in many variants.^[2]

In Russian, a spherical horse in vacuum ^[3] ^[4] from a joke about predicting race results is well known and is widely used common parlance.

The point of the joke is that physicists will often reduce a problem to its simplest form in order to make calculations more feasible, even though such simplification may hinder the model's application to reality.

Popular culture

The joke is referred to by Leonard Hofstadter in the form of a "spherical chicken" in the American sitcom The Big Bang Theory ("The Cooper-Hofstadter Polarization").

It is used in the title of at least one book: Consider a Spherical Cow: A Course in Environmental Problem Solving by John Harte.^[1]

Chris Morris makes a literal reference to Spherical Cows in his spoof documentary series Brass Eye.