The classical isoperimetric inequality in R^3 states that the surface of
smallest area enclosing a given volume is a sphere. We show that the least area
surface enclosing two equal volumes is a double bubble, a surface made of two
pieces of round spheres separated by a flat disk, meeting along a single circle
at an angle of 120 degrees.Comment: 57 pages, 32 figures. Includes the complete code for a C++ program as
  described in the article. You can obtain this code by viewing the source of
  this articl

Hass, Joel

Schlafly, Roger