The p-widths of a surface

The \(p\)-widths of a closed Riemannian manifold are a nonlinear analogue of the spectrum of its Laplace--Beltrami operator, which corresponds to areas of a certain min-max sequence of possibly singular minimal submanifolds. We show that the \(p\)-widths of any closed Riemannian two-manifold correspond to a union of closed immersed geodesics, rather than simply geodesic nets. We then prove optimality of the sweepouts of the round two-sphere constructed from the zero set of homogeneous polynomials, showing that the \(p\)-widths of the round sphere are attained by \(\lfloor \sqrt{p}\rfloor\) great circles. As a result, we find the universal constant in the Liokumovich--Marques--Neves--Weyl law for surfaces to be \(\sqrt{\pi}\). En route to calculating the \(p\)-widths of the round two-sphere, we prove two additional new results: a bumpy metrics theorem for stationary geodesic nets with fixed edge lengths, and that, generically, stationary geodesic nets with bounded mass and bounded singular set have Lusternik--Schnirelmann category zero.