Why are bubbles round?
We pop open the unbelievabubble physics of soapy water
Bubbles occur when a thin film (for example, of soapy water) traps some gas (for example, air). The molecules in the film are attracted to each other, which not only holds the film together, but also makes it shrink to the smallest possible area.
The smallest area enclosing any given volume? A sphere. Therefore, the film will shrink to cover a sphere, and then can’t shrink any further because of the trapped air. Thus, bubbles end up as round.
Asked by: Emily Wilson, Birmingham
Read more:
- How does bubble bath work?
- Why are soap bubbles rainbow coloured?
- Why do champagne bubbles rise from the bottom of a glass?
- Why do waves bubble and turn white when they break?
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Authors
Jon is a Professor of Physics at University College London. He works on the ATLAS experiment at the CERN Large Hadron Collider.
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