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Analogy of casimir effect with moving boats

  1. Mar 13, 2010 #1
    During lunch today a friend told me that two boats running parallel to one another can be attracted to each other by an effect similar to the Casimir effect. The water waves between the boats are quantized, and there winds up being slightly less pressure from between the boats than from outside. She indicated this was an observable thing - something you actually have to take into consideration if you ever have two boats sailing side by side.

    Has anybody heard of this, know a name for it, can give a good reference of where to learn more about the effect, or have any comments on the physics?
  2. jcsd
  3. Mar 13, 2010 #2


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    *If* there exists such a "force", which I have not heard of previously, I would expect that it is more due to the Bernoulli effect from the wind/current being forced between the boats than to any Casimir effect analog having to do with the waves.

    In any case, a quick google search reveals that this is probably all nonsense anyway:

  4. Mar 13, 2010 #3


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    Whether or not such effects are actually observed at sea, the description is close to what happens. The Casimir effect occurs because the vacuum state has fluctuating electric and magnetic fields. This gives rise to a vacuum energy (which is infinite but actually it could be zero in our case because forces deal with the change in energy, so we can renormalize it at will and not change the results). Placing scatterers into the vacuum changes the allowable modes for the fluctuating fields. This in turn changes the energy of the vacuum. If we were to infinitesimally shift one of the scatterers, it would in turn infinitesimally shift the vacuum energy. This change in energy due to a displacement is the Casimir force.
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