• Question: why are bubbles round?;)

    Asked by emilyxoxo to James, Marcus, Martin, Rob, Suzanne on 19 Mar 2012.
    • Photo: Suzanne McEndoo

      Suzanne McEndoo answered on 19 Mar 2012:

      Because it’s the way of enclosing the most area with the least surface, and has the least surface tension, so it’s the most stable shape for a bubble.

      There is a branch of physics, foam physics, which studies the shapes of bubbles and foams under different conditions.

    • Photo: James Boone

      James Boone answered on 19 Mar 2012:

      In science, surfaces of materials are high in energy (everything in the universe wants to be at an energy as low as possible) and therefore having more surface costs energy. Let’s pretend that we could make a CUBE shaped bubble whose side length was 1cm. This means that the bubble has a surface area of 6 square cm. If we now took a ROUND bubble of diameter 1cm (fits inside the cube shaped bubble), the surface area would be just 3.1 square cm. (I think this argument is flawed in some way, but let’s overlook the subtlety for now). So for a given size round bubbles are lower in energy than any other shape.

    • Photo: Marcus Gallagher-Jones

      Marcus Gallagher-Jones answered on 21 Mar 2012:

      I think it comes down to energetics. The greater the surface area of an object the greater the surface tension and so the more energy required to hold the object together. Nature is pretty conservative and likes to expend as little energy as possible so bubbles take a round shape. It’s also common in other things and is why most cells are (generally) round.

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