Thread: Ask a Scientist
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Old 04.03.2008, 21:57
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Re: Ask a Scientist

As a fizzicist with a copy of "Bubbles, drops and pearls" by the Nobel Prize winner Pierre Gilles de Gennes on my bookshelf, I thought I'd better have a shot at this.

When you shake the can or bottle, it generates lots of little bubbles that collect on the surface. When you open the bottle, the pressure drop causes them to expand really fast. No shaking = no bubbles until you open, so the foam rises slower.

The effect will disappear as soon as the little bubbles are gone. How long that takes depends... bubbles in pure water only last a second (watch as your bath is running). Bubbles in protein-rich Guinness last longer than it takes you to drink it.

Cheers!
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