I have always wondered about a shape of a soap bubble. Why is it always spherical and not some other shape (like, cylindrical)? And why are the layers of the soap bubbles so thin? Also when someone tries to create a giant bubble, why does it burst so easily?
The pressure acting on a bubble pushes on it. The bubble must move into the shape with the least pressure acting on it. The bubble, however, must maintain a constant volume. The shape with the smaller surface area for a constant volume is a sphere (the mathematical proof is complex), so the bubble takes on that shape.