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Quantum vacuums

  1. May 1, 2012 #1

    I been reading about an experiment that took place involving two metals plates in a vacuum, of which they are drawn together by quantum energy pressure differences between the plates and behind the plates.

    But this made me wonder, if this draws them together, is this not similar to gravity with two objects in space being drawn together? How do they know for sure that its not the same thing?

    I should mention im self teaching myself so i end up some times getting confused :P
  2. jcsd
  3. May 1, 2012 #2
    What you are referring to is called the Casimir Effect. As to whether one can confuse it with gravity keep in mind that our theory(ies) of gravity don't simply tell us qualitatively that "two massive things are attracted" but tell us by how much and how this force of attraction changes with the mass of the plates and their separation. The same is true of the Casimir force (off the top of my head I believe the Casimir force falls of with the inverse 4th power of the separation). So if you were to do an experiment to verify the existence of the Casimir force you wouldn't simple put two plates close together and see "if there an attraction at all", you would instead see how this force varies with separation (and possibly material) and make sure the data matched the appropriate equation. Remember, physics is QUANTITATIVE.
  4. May 1, 2012 #3


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    Opposite ends of magnets attract too. That doesn't make that force the same as gravity either.

    To add to what Many_S_Theory said: gravity falls by the inverse 2nd power of separation. Also, gravity has other important characteristics (such as time dilation) not shared by the Casimir effect.
  5. May 1, 2012 #4
    In experiments on the Casimir force, the gravitational attractions experienced by the these very small mirrors is very small, orders of magnitude too small to account for the attraction.
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