In mathematics, Plateau's problem is to show the existence of a minimal surface with a given boundary, a problem raised by Joseph-Louis Lagrange in 1760. However, it is named after Joseph Plateau who experimented with soap films. The problem is considered part of the calculus of variations. The existence and regularity problems are part of geometric measure theory.
Various specialized forms of the problem were solved, but it was only in 1930 that general solutions were found in the context of mappings (immersions) independently by Jesse Douglas and Tibor Radó. Their methods were quite different; Radó's work built on the previous work of Garnier and held only for rectifiable simple closed curves, whereas Douglas used completely new ideas with his result holding for an arbitrary simple closed curve. Both relied on setting up minimization problems; Douglas minimized the now-named Douglas integral while Radó minimized the "energy". Douglas went on to be awarded the Fields Medal in 1936 for his efforts.
The extension of the problem to higher dimensions (that is, for k-dimensional surfaces in n-dimensional space) turns out to be much more difficult to study. Moreover, while the solutions to the original problem are always regular, it turns out that the solutions to the extended problem may have singularities if k ≤ n − 2. In the hypersurface case where k = n − 1, singularities occur only for n ≥ 8.
Physical soap films are more accurately modeled by the (M,0,delta)-minimal sets of Fred Almgren, but the lack of a compactness theorem makes it difficult to prove the existence of an area minimizer. In this context, a persistent open question has been the existence of a least-area soap film. The existence of such a solution was established in 2012 by Jenny Harrison of University of California, Berkeley using her theory of differential chains. Soap film regularity of her solution remains an open problem.
- Douglas, Jesse (1931). "Solution of the problem of Plateau". Trans. Amer. Math. Soc. (Transactions of the American Mathematical Society, Vol. 33, No. 1) 33 (1): 263–321. doi:10.2307/1989472. JSTOR 1989472.
- Fomenko, A.T. (1989). The Plateau Problem: Historical Survey. Williston, VT: Gordon & Breach. ISBN 978-2-88124-700-2.
- Morgan, Frank (2009). Geometric Measure Theory: a Beginner's Guide. Academic Press. ISBN 978-0-12-374444-9.
- O'Neil, T.C. (2001), "Geometric Measure Theory", in Hazewinkel, Michiel, Encyclopedia of Mathematics, Springer, ISBN 978-1-55608-010-4
- Radó, Tibor (1930). "On Plateau's problem". Ann. Of Math. (2) (The Annals of Mathematics, Vol. 31, No. 3) 31 (3): 457–469. doi:10.2307/1968237. JSTOR 1968237.
- Struwe, Michael (1989). Plateau's Problem and the Calculus of Variations. Princeton, NJ: Princeton University Press. ISBN 978-0-691-08510-4.
- Harrison, Jenny (2012). "Soap Film Solutions to Plateau's Problem". Journal of Geometric Analysis (Springer Online First).