2 Replies Latest reply on Feb 21, 2013 6:21 AM by Mitsuru Yamada

    An Electromagnetic Thought Experiment.  Which answer do you choose?

    Mitsuru Yamada

      How do you think will the result be if the following experiment were to be done?

      The experimental setting is this.

      Think a large vacuum chamber with a pane through which the interior can be seen.

      Assume there is a desk in the vacuum chamber.

      And place on the desk a soft air tight bag of about 1 litter capacity made of electrical conductor skin.

      Connect  an optical glass fiber with the inlet of the bag.

      Connect the other end of the glass fiber with a powerful laser generator.

      For the initial condition, assume that the interior of the chamber and the interior of the bag are both complete vacuum, so that the bag should be placed on the desk in a state of completely squashed, flat shape.

      Finally assume for simplicity that the electrical conductivity of the skin of the bag is infinite, so that we can neglect the possible joule heat dissipation.

       

      Now let us begin the experiment.

      It is simple.  We will only just switch on the laser generator.

      Then what do you think will happen?

       

      Answer 1:  There will be no change in the chamber, even if we increase the laser power.

      Answer 2:  The skin of the bag will begin to shine, but the shape of the bag remains to be squashed state yet.

      Answer 3:  The bag will be inflated by the inflow of momenta of photons from the laser equippment.

       

      Come on!  The problem is that simple.  How do you think?  How do you think?

       

      A troublesome kid

      February 10, 2013

        • Re: An Electromagnetic Thought Experiment.  Which answer do you choose?
          ohrvvurm

          Answer 2:  The skin of the bag will begin to shine, but the shape of the bag remains to be squashed state yet.

            • Re: An Electromagnetic Thought Experiment.  Which answer do you choose?
              Mitsuru Yamada

              Dear Sir,

              Thank you for your response.

              I am sorry to be late to answer to you.  I was waiting for other's responses too.

              I am very sorry if my wording was insufficient in the first blog.

              I wished to mean a bag having skin like an aluminum foil.

              Its metallic optical reflectance is 100%. It is not a black-body.

              So that the photons injected from the laser equippment will be reflected back completely elastically.

              As a reaction, I believe that the entire surface of the interior of the bag must feel a radiation pressure.

              So, if the weight of material constituting the bag is sufficiently light practically, then the bag must be inflated until a balance between the reaction pressure from the skin and the whole inflow of the radiation pressure from the laser equippment is reached.  My opinion is for Answer 3.

              Please refer to a physics dictionary if you would like.

              And do you know about "Solar Sail" which is being planned by Planetary Society?

              Sincerely,

              M.Y.

              February 21, 2013