Buchdahl's theorem
= Buchdahl's theorem
{wiki=Buchdahl's_theorem}
Buchdahl's theorem is a result in general relativity concerning the maximum mass of a spherical, isotropic, perfect fluid star in equilibrium. Specifically, the theorem states that the maximum ratio of a star's mass \\( M \\) to its radius \\( R \\) is constrained by: \\\[ \\frac\{M\}\{R\} \\leq \\frac\{4\}\{9\} \\\] when measured in geometrized units (where \\( G = c = 1 \\)).