Higher Multipoles of the Cow
arxiv.org27 points by MrOrelliOReilly 2 days ago
27 points by MrOrelliOReilly 2 days ago
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.
for simulating gravity in particular you can do one better, since a sphere is in turn gravitationally indistinguishable from a point mass due to the https://en.wikipedia.org/wiki/Shell_theorem#Force_on_a_point...
and you can do one better than that - Birkhoff's theorem, the relativistic analogue of the shell theorem.
https://en.wikipedia.org/wiki/Birkhoff%27s_theorem_(relativi...
Anna Cramling, women’s international chess master, should review this paper, having popularized the Cow Opening.
Hmmm… Today is Sep 1st, not Apr 1st. That cow is a bit out of season :)
Submission history
From: Benjamin Lehmann [view email]
[v1] Tue, 1 Apr 2025 07:55:39 UTC (2,401 KB)
[v2] Wed, 1 Apr 2026 12:28:24 UTC (3,845 KB)
What udder nonsense.