We prove existence and
regularity for “soap bubbles” in ℝ2 and in surfaces, i.e., the least-perimeter way to
enclose and separate regions of prescribed area. They consist of constant-curvature
arcs meeting in threes at 120 degrees. If one prescribes the combinatorial type too,
then the arcs may bump up against each other.
Figure 1.1. Single, double, and triple bubbles in ℝ3 presumably provide the
least-area way to enclose and separate the given volumes of air. Drawings by J. Bredt
[M5]