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Quantum optical application of Pascal Principle

  1. Jul 26, 2007 #1

    Supose you have an U tube, in which the inner walls are made absolutelly reflective. Now, put a termical state (temperature T) for the radiation field inside the tube and close it with reflective discs which can slide without friction. Supose further that de diameter of the tube in its terminations are not equal. For the sake of definiteness, lets assume 2 sq meters cross section in one side and 10 sq meters in the other. My question is: Taking into account light pressure effects, is the Pascal principle valid in this quantum optical context ?

    Best Regards

  2. jcsd
  3. Jul 26, 2007 #2
    Why do you think that light exhibits "different" behaviour in this case ?

  4. Jul 26, 2007 #3

    Suppose you have an U tube with different areas (A1 and A2) in its terminals.
    Thinking mechanically (not with photons) , now imagine you start to put thin wires through this tube, the length of which are exactly equal to the tube. Suppose this wires do not have friction with one another, so that they can slide freely along.

    In the limit where these wires become geometrical lines, you will have the U tube filled with infinitely many wires, each one going from A1 to A2. Applying a force F in one end of a given wire will require an equal force F at the other end of the same wire in order to maintain the equilibrium. As it happens to all wires we may say that if forces comunicate with continuum density from one plate (A1) to the other (A2), the equilibrium condition will not be p1 = p2 but F_r1 = F_r2, where F_r is resultant.
    This gedanken experiment seems to me to act like a proof of the finiteness of the space nature, specifically in what concerns force propagation.

    As light is thought to be a field, with infinitelly mane degrees of freedom, it occurs to me to ask if experimentaly this principle of equal pressure will show up.

    Best wishes

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