Spherical cow

The spherical cow is a humorous metaphor for highly simplified scientific models of complex phenomena.[1][2] Originating in theoretical physics, the metaphor refers to physicists' tendency to reduce a problem to the simplest form imaginable in order to make calculations more feasible, even if the simplification hinders the model's application to reality.

Comic of a spherical cow as illustrated by a 1996 meeting of the American Astronomical Association, in reference to astronomy modeling

The metaphor and variants have subsequently been used in other disciplines.


The phrase comes from a joke that spoofs the simplifying assumptions sometimes used in theoretical physics.[3]

Milk production at a dairy farm was low, so the farmer wrote to the local university, asking for 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 physicist returned to the farm, saying to the farmer, "I have the solution, but it works only in the case of spherical cows in a vacuum."

It is told in many variants,[4] including a joke about a physicist who said he could predict the winner of any race provided it involved spherical horses moving through a vacuum.[5][6] A 1973 letter to the editor in the journal Science describes the "famous story" about a physicist whose solution to a poultry farm's egg-production problems began with "Postulate a spherical chicken".[7]

References in scienceEdit

Alan Turing, in his 1952 paper "The Chemical Basis of Morphogenesis", asserted: "a system which has spherical symmetry, and whose state is changing because of chemical reactions and diffusion ... cannot result in an organism such as a horse, which is not spherically symmetrical."[8]

In popular cultureEdit

A GIF of a spherical cow
A drawing of a spherical cow on skis, with the text Approksimoidaan pyöreä lehmä (Finnish for "We approximate a spherical cow").

The concept is familiar enough that the phrase is sometimes used as shorthand for the entire issue of proper modeling. For example, Consider a Spherical Cow is a 1988 book about problem solving using simplified models.[9]

Even without the concept of scientific modeling the joke is sufficiently well known to be indirectly referenced. "Spherical Cow" was chosen as the codename for the Fedora 18 Linux distribution.[10] In the sitcom The Big Bang Theory, a joke is told by Dr. Leonard Hofstadter with the punchline mentioning "spherical chickens in a vacuum", in The Cooper-Hofstadter Polarization episode.[11]

See alsoEdit


  1. ^ Shelton, Robin; Cliffe, J. Allie. "Spherical Cows". Archived from the original on 9 October 1999.
  2. ^ "Nautilus | Science Connected". Nautilus. February 7, 2021.
  3. ^ Lee, Timothy B. (September 4, 2013). "The Coase Theorem is widely cited in economics. Ronald Coase hated it" – via www.washingtonpost.com.
  4. ^ Kirkman, T. W. (1996). "Spherical Cow: A Simple Model". Statistics to Use. Retrieved 2007-02-19.
  5. ^ Hefley, Bill; Hefley, William E.; Murphy, Wendy (1 February 2008). Service science, management and engineering: education for the 21st century. Springer. p. 80. ISBN 978-0-387-76577-8. Retrieved 28 September 2011.
  6. ^ Birattari, Mauro (15 April 2009). Tuning Metaheuristics: A Machine Learning Perspective. Springer. pp. 183–184. ISBN 978-3-642-00482-7. Retrieved 1 September 2012.
  7. ^ Stellman, Steven (1973). "A Spherical Chicken". Science. 182 (4119): 1296. doi:10.1126/science.182.4119.1296-b. PMID 17733092. Retrieved 18 Feb 2017.
  8. ^ Turing, A. M. (1952). "The Chemical Basis of Morphogenesis" (PDF). Philosophical Transactions of the Royal Society of London B. 237 (641): 37–72. Bibcode:1952RSPTB.237...37T. doi:10.1098/rstb.1952.0012. JSTOR 92463. S2CID 120437796.
  9. ^ "Consider a Spherical Cow, John Harte". www.uscibooks.com.
  10. ^ "Fedora 18 Is Codenamed The Spherical Cow". phoronix.com. 2012. Retrieved 2012-05-11.
  11. ^ Huva, Amy. "When Nerds go Viral". Vancouver Observer. Archived from the original on 15 August 2016. Retrieved 6 May 2014.

External linksEdit