The Willmore Energy Landscape of Spheres and Avoidable Singularities of the Willmore Flow
- 1Freie Universität Berlin
- 2Technical University Darmstadt
Abstract
We study the sublevel sets of the Willmore energy on the space of smoothly immersed 2 $ 2 $ 2 -spheres in Euclidean 3 $ 3 $ 3 -space. We show that the subset of immersions with energy at most 12 π $ 12\pi $ 12 pi consists of four regular homotopy classes. Moreover, we show that, in certain regular homotopy classes, all singularities of the Willmore flow are avoidable – that is, the initial surface admits a regular homotopy to a round sphere whose Willmore energy does not exceed that of the initial surface. This yields a classification of initial surfaces with energy at most 12 π $ 12\pi $ 12 pi that lead to unavoidable singularities. As a further consequence, we obtain an extension of the Li–Yau inequality at 12 π $ 12\pi $ 12 pi for a large class of immersed spheres without triple points. To prove these results, we glue together different instances of the Willmore flow and employ an invariant for triple-point-free immersed spheres.
Related
BibTeX
@article{maderbaumdicker2026willmore,
title = {{The Willmore Energy Landscape of Spheres and Avoidable Singularities of the Willmore Flow}},
author = {Elena Mäder-Baumdicker and Jona Seidel},
journal = {Forum of Mathematics, Sigma},
year = {2026},
month = oct,
doi = {10.1017/fms.2026.10282},
url = {https://www.cambridge.org/core/product/identifier/S2050509426102825/type/journal_article},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - The Willmore Energy Landscape of Spheres and Avoidable Singularities of the Willmore Flow
AU - Elena Mäder-Baumdicker
AU - Jona Seidel
PY - 2026
DA - 2026/10/08
JO - Forum of Mathematics, Sigma
DO - 10.1017/fms.2026.10282
UR - https://www.cambridge.org/core/product/identifier/S2050509426102825/type/journal_article
AB - We study the sublevel sets of the Willmore energy on the space of smoothly immersed 2 $ 2 $ 2 -spheres in Euclidean 3 $ 3 $ 3 -space. We show that the subset of immersions with energy at most 12 π $ 12\pi $ 12 pi consists of four regular homotopy classes. Moreover, we show that, in certain regular homotopy classes, all singularities of the Willmore flow are avoidable – that is, the initial surface admits a regular homotopy to a round sphere whose Willmore energy does not exceed that of the initial surface. This yields a classification of initial surfaces with energy at most 12 π $ 12\pi $ 12 pi that lead to unavoidable singularities. As a further consequence, we obtain an extension of the Li–Yau inequality at 12 π $ 12\pi $ 12 pi for a large class of immersed spheres without triple points. To prove these results, we glue together different instances of the Willmore flow and employ an invariant for triple-point-free immersed spheres.
SN - 2050-5094
ER -