Beyond the Spherical Cow: A Full Multipole Expansion
Higher Multipoles of the Cow
The spherical cow approximation, a staple of theoretical physics, is rarely justified. This paper extends it into a full multipole expansion, treating the spherical cow as the first term. This enables computation of bovine potentials and interactions beyond spherical symmetry and defines the cow's geometry at higher multipole moments. The author demonstrates the calculation of multipole coefficients for a benchmark cow and applies the multipolar cow to problems like gravitational-wave spindown of a rotating cow.
No cows were harmed.
- lhd1
One of the cool facts about gravity is that the gravitational field of a body 'feels' spherical at a distance, even if those bodies are not spherical themselves. There are higher multipoles but they are increasingly suppressed the further you are from the body. So at least for gravity the spherical approximation turns out to be good and justified.
- fghorow
Perhaps this approach should be known as "The Method of MOOments"?
- lawlorino
Near miss of nominative determinism; the authors name (Lehmann) is almost the same as the Finnish word for cow (Lehmän)
- addag
My physics teacher takes the spherical roast beef as an example for heat convection.
- ninju
The Acknowledgements section, at the end of the paper, is very entertaining (as is the rest of the paper)