I loved playing with soap bubbles as a kid, seeing what different kinds of shapes I could come up with, and even got a square a couple of times using the bubbles surrounding other bubbles trick. But THIS is way cool: two scientists have figured out how to get the straight edges without the assistance of other bubbles!
Hans Mayer and Rouslan Krechetnikov at the University of California, Santa Barbara, put the community straight on this matter by performing exactly this experiment on film.
Their technique is straightforward. They make a metal frame in the shape of, say, a square and dip it in water mixed with glycerol and water, 4% glycerol and sodium dodecyl sulfate–a standard soap bubble mix.
They then pass a current through one side of the metal frame which rapidly heats up and boils the liquid in contact with it. This releases one edge of the film, allowing it to retract.
But the really cool work comes from passing a current around the entire metal frame, thereby releasing all the edges and creating a “free” soap film for the first time.