Permeability of free space question

Permittivity is the measure of a material's ability to store an electric field, while permeability is the measure of a material's ability to store a magnetic field. In free space, both permittivity and permeability are constant and do not change with the vacuum energy density. However, in the presence of a strong magnetic field, the vacuum energy density can affect the permittivity and permeability, leading to effects such as vacuum birefringence. There are indeed papers that discuss this relationship, such as those referenced in the conversation above. I suggest you take a closer look at those papers and the associated mathematics to gain a better understanding of this topic.
  • #1
captpaul101@hotmail.com
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
 
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  • #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
 
  • #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
 
  • #4
Paul, perhaps you should look at permittivity rather than permeability.
 

1. What is the permeability of free space?

The permeability of free space, also known as the magnetic constant, is a physical constant denoted by μ0. It is the measure of a material's ability to support the formation of a magnetic field within itself.

2. How is the permeability of free space measured?

The permeability of free space is typically measured using a device called a permeameter. This device applies a known magnetic field to a sample material and measures its resulting magnetization. The permeability can then be calculated using this data.

3. What is the value of the permeability of free space?

The value of the permeability of free space is approximately 4π x 10^-7 H/m (henrys per meter) in the International System of Units (SI). However, this value may vary slightly depending on the measurement method and the material being tested.

4. How does the permeability of free space affect electromagnetic radiation?

The permeability of free space plays a crucial role in determining the speed of electromagnetic radiation, such as light, in a vacuum. It is also used in the calculation of the impedance of a vacuum, which is essential in understanding the behavior of electromagnetic waves.

5. Can the permeability of free space change?

The permeability of free space is considered a fundamental constant and is not known to change under normal conditions. However, it is possible for it to be altered in extreme situations, such as in the presence of high magnetic fields or in certain quantum mechanical systems.

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