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Permeability of free space question

  1. Jun 9, 2007 #1
    Hi everyone,

    Been doing some reading on permeability lately... My question is would
    the permeability of free space (u0) be related in any way to the
    vacuum
    energy density or would it remain the same regardless (4PIx10-7)?

    For eg would u0 be lower inside the space between the Casimir plates
    where the energy density is lower then outside the plates or the
    same?
    Thanks for your time.

    Cheers, Paul Titze.
    http://wizlab.com/marine
     
  2. jcsd
  3. Jun 9, 2007 #2
    captpaul101@hotmail.com wrote:
    >
    > Hi everyone,
    >
    > Been doing some reading on permeability lately... My question is would
    > the permeability of free space (u0) be related in any way to the
    > vacuum
    > energy density or would it remain the same regardless (4PIx10-7)?
    >
    > For eg would u0 be lower inside the space between the Casimir plates
    > where the energy density is lower then outside the plates or the
    > same?
    > Thanks for your time.
    >
    > Cheers, Paul Titze.
    > http://wizlab.com/marine


    http://arXiv.org/abs/gr-qc/0107091
    http://arXiv.org/abs/quant-ph/0010055
    Phys. Lett. B236 354 (1990)
    Phys. Lett. B250 133 (1990)
    J Phys A26 2037 (1993)
    Scharnhorst effect

    It has never been demonstrated - propagation normal to the surfaces
    makes for a short experiment!

    --
    Uncle Al
    http://www.mazepath.com/uncleal/
    (Toxic URL! Unsafe for children and most mammals)
    http://www.mazepath.com/uncleal/lajos.htm#a2
     
  4. Jun 12, 2007 #3
    Looking up the definition, permeability is the degree of magnetization
    of a material that
    responds linearly to an applied magnetic field.

    So the permeability of free space (uo = 4PIx10^-7) is the degree of
    magnetizaton of free space
    that responds linearly? to an applied magnetic field. Magnetization
    being a measure of the
    magnetic dipole density.

    This is why one observes vacuum birefringence for eg as this polarizes
    the dipoles in the quantum
    vacuum when one applies a strong enough magnetic field. If the vacuum
    fluctuations are created as
    particle/antiparticle pairs (which act as magnetic dipoles?) and since
    the vacuum energy density
    is lower between the Casimir plates this would mean that these vacuum
    fluctuations are partly
    suppressed (less particle/antiparticle pairs) between the plates. If
    the magnetic dipole density
    is less between the plates then the permeability of the Casimir vacuum
    should be less then that
    compared to free space? u(Casimir) < u0 ?

    These are only simple arguments, better go through the maths first...
    are there any papers out
    there that specifically touch on this subject? Can't seem to find much
    on arXiv... What I'm really
    interested to know is if there is a relation between vacuum
    permeability and vacuum energy density...

    Cheers, Paul Titze.
    http://wizlab.com/marine
     
  5. Jun 12, 2007 #4
    Paul, perhaps you should look at permittivity rather than permeability.
     
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