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Spherical cow

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

The spherical cow is a humorous metaphor for highly simplified scientific models of complex phenomena.[1][2][3][4] Originating in theoretical physics, the metaphor refers to physicists' tendency to develop toy models that reduce a problem to the simplest form imaginable, making calculations more feasible, even if the simplification hinders the model's application to reality.

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.[5]

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,[6] 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.[7][8] 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".[9]

Cultural references[edit]

A GIF of a spherical cow.
A GIF of a homotopy from a spherical cow to a more typical one
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.[10] A 2015 paper on the systemic errors introduced by simplifying assumptions about spherical symmetries in galactic dark-matter haloes was titled "Milking the spherical cow – on aspherical dynamics in spherical coordinates".[11]

References to the joke appear even outside the field of scientific modeling. "Spherical Cow" was chosen as the code name for the Fedora 18 Linux distribution.[12] 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.[13] In the space gravity simulator educational video game Universe Sandbox, a spherical cow was added as a user-placeable object in March 2023.[14]

See also[edit]


  1. ^ Shelton, Robin; Cliffe, J. Allie. "Spherical Cows". Supernova Remnant Group. NASA Goddard Space Flight Center. Archived from the original on 9 October 1999.
  2. ^ Kaiser, David (2014-04-25). "The Sacred, Spherical Cows of Physics". Nautilus Quarterly.
  3. ^ Carroll, Sean. "How spherical-cow philosophy makes hard physics problems easy". New Scientist. Retrieved 2023-04-27.
  4. ^ Allain, Rhett. "What is up with the spherical cow?". Wired. ISSN 1059-1028. Retrieved 2023-04-27.
  5. ^ Lee, Timothy B. (September 4, 2013). "The Coase Theorem is widely cited in economics. Ronald Coase hated it". The Washington Post.
  6. ^ Kirkman, T. W. (1996). "Spherical Cow: A Simple Model". Statistics to Use. Retrieved 2007-02-19.
  7. ^ Mager, Birgit; Evenson, Shelley (1 February 2008). "Art of Service: Drawing the Arts to inform Service Design and Specification". In Hefley, Bill; Murphy, Wendy (eds.). Service science, management and engineering: education for the 21st century. Springer. p. 80. doi:10.1007/978-0-387-76578-5_12. ISBN 978-0-387-76577-8. Retrieved 28 September 2011.
  8. ^ Birattari, Mauro (15 April 2009). "Some Considerations on the Experimental Methodology". Tuning Metaheuristics: A Machine Learning Perspective. Studies in Computational Intelligence. Vol. 197. Springer. pp. 183–184. doi:10.1007/978-3-642-00483-4. ISBN 978-3-642-00482-7. Retrieved 1 September 2012.
  9. ^ Stellman, Steven D. (1973-12-28). "A Spherical Chicken". Science. 182 (4119): 1296. doi:10.1126/science.182.4119.1296.c. PMID 17733092. S2CID 29103654. Retrieved 18 Feb 2017.
  10. ^ Harte, John (1988). Consider a Spherical Cow: A Course in Environmental Problem Solving. AIP Publishing. ISBN 978-0-935702-58-3.
  11. ^ Pontzen, Andrew; Read, Justin I.; Teyssier, Romain; Governato, Fabio; Gualandris, Alessia; Roth, Nina; Devriendt, Julien (1 August 2015). "Milking the spherical cow – on aspherical dynamics in spherical coordinates". Monthly Notices of the Royal Astronomical Society. 451 (2): 1366–1379. arXiv:1502.07356. doi:10.1093/mnras/stv1032. Retrieved 6 December 2022.
  12. ^ Larabel, Michael (2012-05-01). "Fedora 18 Is Codenamed The Spherical Cow". Phoronix. Retrieved 2023-06-06.
  13. ^ Huva, Amy. "When nerds go viral". Earth Matters. The Vancouver Observer. Archived from the original on 2019-12-05.
  14. ^ "A Comet, an Asteroid, and a Planet Walk into the Solar System | Update 32.2". Universe Sandbox. 2023-03-23. Retrieved 2023-03-27.

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