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WHEN bubbles burst on the surface of thick liquids they don鈥檛 collapse into a
puddle, they wrinkle up in a predictable, creased pattern. The insight could
help fashion designers deal with a geometric quandary鈥攈ow to make flat
cloth fit the rounded human body.

Rava da Silveira and a team at the Massachusetts Institute of Technology
studied the effect of a bubble of air sitting atop silicone oil, like a soap
bubble sits on bathwater. They punctured the top of a centimetre-sized bubble
with a needle and watched its collapse with a high-speed camera, recording a
radial ripple pattern forming along the bubble鈥檚 edge.

Although others have seen rippled bubbles, da Silveira鈥檚 group is the first
to describe the effect, which may also be noticeable in thick lava. The oily
film of the bubble retracts from the puncture hole as air escapes. And unlike
soap bubbles, which pop, the viscous fluid film that makes up the bubble wall
collapses so slowly that gravity pulls down the top before the walls slump. This
causes the stiff surface of the bubble to collapse into a corrugated,
predictable pattern of between 30 and 100 radial ripples.

The process 鈥渋s so highly constrained by the geometry that little else can
happen鈥�, says da Silveira. Understanding this process could help designers to
overcome similar constraints when cutting two-dimensional cloth to fit the
curves of the body. 鈥淭he geometry will have a dramatic role in making it more or
less wavy, and the clothes more or less comfortable and elegant,鈥� he says.