Why does vacuum have properties?

[jijopaul]

I'm a fresher in PF. If I'm posting indecently, please forgive..
Vacuum is something empty. It contains nothing. Then why should it have properties like permeability, permittivity etc.?

 

[San K]

I'm a fresher in PF. If I'm posting indecently, please forgive..
Vacuum is something empty. It contains nothing. Then why should it have properties like permeability, permittivity etc.?

Welcome to the physics forums Jijopaul

"Vacuum contains nothing" is old physics.

New/deeper physics is being discovered.

Vacuum is space that contains no matter, however Vacuum still "contains/is" space.

Vacuum also contains "fields".

In the (QED) Vacuum the electric and magnetic fields have zero average values, but their variances are not zero.

There are fluctuations in the vacuum because of the uncertainty principle.___________________________________________________

There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy

 

[Naty1]

The vacuum is not empty..it is something...Virtual particles are undetected excitations of the vacuum..some say the source of the vacuum energy. For one thing, the 'vacuum' is also spacetime. And curved spacetime is gravity. A dynamic spacetime, that is, a dynamic geometry is cosmological expansion and with the vacuum energy creates real particles...

For more, read about 'vacuum energy' in Wikipedia


Here is a quote I liked from Wikipedia. Keep in mind the quantum fluctuations that are grown with accelerated cosmological expansion can be thought of as a mix of 'real and virtual particles' ...which are also field amplitudes...[analogous to the real and imaginary numbers for real and virtual particles]. The vacuum is full of field excitations of various types.

There is not a definite line differentiating virtual particles from real particles — the equations of physics just describe particles (which includes both equally). The amplitude that a virtual particle exists interferes with the amplitude for its non-existence; whereas for a real particle the cases of existence and non-existence cease to be coherent with each other and do not interfere any more. In the quantum field theory view, "real particles" are viewed as being detectable excitations of underlying quantum fields. ... In this sense, virtual particles are an artifact of perturbation theory, and do not appear in a non-perturbative treatment.

 

[jijopaul]

Thank you all..