Why are free floating bubbles round?
ZomeTool Bubble Wands (or similar oddly shaped bubble wand)
Bubble Solution (in large mouthed container)
Place wand in solution
Swirl solution slightly with wand
Lift wand out of solution
Why do bubbles blown with square wands still end up round?
What happens to the cubic bubble as it sits on the wand?
What happens if you pop one side of the cubic bubble?
The water molecules in the bubble solution are drawn together. The soap allows the water to form thin films but these films are always in tension. When you blow a bubble with any shaped wand, you get air inside the bubble and a thin film making up the wall of the bubble. As this thin film is drawn together, the surface area shrinks. However, the air molecule inside the thin film are moving away from each other to take up as much volume as possible. A sphere is able to hold the greatest volume for a given surface area. The two forces (air pushing out and the thin film pulling in) balance to create spherical bubbles unless there is another surface they are touching.
When you hold the cubic bubble wand, thin films form on each face of the cube. Over time, these faces are drawn together and join leaving a smaller bubble cube inside the wand. Before this happens, if you pop one face of the cube, how does that change the way the walls are drawn together?