A spherical cow is a humorous metaphor for highly simplified scientific models of complex real life phenomena. The implication is that physicists will often reduce a problem to the simplest form they can imagine in order to make calculations more feasible, even though such simplification may hinder the model's application to reality. The concept is well enough known that it can be referred to in scientific discourse without explanation.
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 only works in the case of spherical cows in a vacuum".
It is told in many variants, including a spherical horse in a vacuum, from a joke about a physicist who said he could predict the winner of any horse race to multiple decimal points, but only provided it was a perfectly elastic spherical horse moving through a vacuum.
The concept is well enough known that it can be referred to in scientific discourse without explanation.
The joke sometimes shows up outside the physics community. In an episode of the sitcom The Big Bang Theory, Leonard Hofstadter tells the joke with a slight variation, the punchline mentioning "spherical chickens in a vacuum".[not in citation given]
- Atwood machine
- Fermi problem
- Frictionless plane
- Isolated system
- Naïve physics
- You have two cows
- Shelton, Robin; Cliffe, J. Allie. "Spherical Cows" nasa.gov
- Doyle, John (10 May 2001). "Computational biology: Beyond the spherical cow". Nature 411 (6834): 151–152. doi:10.1038/35075703. PMID 11346778. Retrieved 22 February 2014.
- Washington Post: "The Coase Theorem"
- Kirkman, T. W. (1996). "Spherical Cow: A Simple Model". Statistics to Use. Retrieved 2007-02-19.
- 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.
- 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.
- Vancouver Observer: "When Nerds Go Viral" - mentions the joke on Big Bang Theory as an example of how nerd culture is going mainstream
- "Consider a Spherical Cow" University Science Books
- "Fedora 18 Is Codenamed The Spherical Cow". phoronix.com. 2012. Retrieved 2012-05-11.
- NASA:Exploration of the Universe Division - Supernova models as spherical cows
- Hubble Heritage Gallery Page: related history from Space Telescope Institute