Physicists working at Trinity College in Dublin, Ireland, have finally made the perfect foam. Whereas most Dubliners might consider that to be the head on a pint of Guinness, Denis Weaire and his co-workers have a more sophisticated answer.
'Perfect' here means the lowest-energy configuration of packed bubbles of equal size. This is a compromise between the surface area of the bubbles and the stability of the many interlocking faces of the polyhedral bubbles in the foam. The Belgian scientist J. A. P. Plateau calculated in the nineteenth century that three soap films are mechanically stable when they meet at angles of 120°, whereas four films meet at the tetrahedral angle of about 109.5°.
So what bubble shape minimizes the total surface area while (more or less) satisfying Plateau’s rules? [Click here to read the rest of the post on Nature.com]