Field fluctuations in the vacuum

In summary, relativistic quantum field theory predicts quantum fluctuations in the vacuum, which can be observed in experiments such as the Casimir Effect. However, it is more accurate to refer to these fluctuations as vacuum energy rather than vacuum fluctuation. The physics involved is in the energy differences rather than the absolute value of the energy, and this can be explained through the concept of normal ordering in the Hamiltonian/Lagrangian. The Casimir effect is a result of fluctuations in charges and the electromagnetic field, and the usual calculation for this effect is a limiting case for infinite charges.
  • #1
Jrs580
19
4
How does relativistic qft predict quantum fluctuations in the vacuum? We see this in the experiment proving the Casimir Effect so we know it's physical, but why?
 
Physics news on Phys.org
  • #2
Vacuum fluctuation is not a good term, vacuum energy is better (zero point energy). Vaccum here means absence of particles.

Hard to understand your "why" question, do you want to see the casimir effect calculation or what else are you referring to?
 
  • Like
Likes topsquark
  • #3
Jrs580 said:
We see this in the experiment proving the Casimir Effect so we know it's physical
We do not. The Casimir effect can be explained purely as electromagnetic force between the electric charges in the plates: The Casimir Effect and the Quantum Vacuum
 
  • Like
Likes Demystifier and topsquark
  • #4
malawi_glenn said:
Vacuum fluctuation is not a good term, vacuum energy is better (zero point energy). Vaccum here means absence of particles.
In SR there is no physics in the absolute value of the total energy, and thus it's convenient to associate the values 0 of the Poincare-invariant vacuum state for all additive conservation laws. Formally you can achieve this with introducing "normal ordering" in the Hamiltonian/Lagrangian.

The physics is in the energy differences rather than the absolute value of the energy. There are no fluctuations in the vacuum itself but rather it's a stationary state (eigenstate of the Hamiltonian).
malawi_glenn said:
Hard to understand your "why" question, do you want to see the casimir effect calculation or what else are you referring to?
The Casimir effect is due to fluctuations of charges and the em. field. The usual calculation you find in introductory chapters of some QFT books (e.g., in Itzykson, Zuber) is a limiting case for infinite (!) charges. For details see

https://arxiv.org/abs/hep-th/0503158
https://doi.org/10.1103/PhysRevD.72.021301
 
  • Like
Likes mfb and topsquark

Similar threads

  • Quantum Interpretations and Foundations
Replies
17
Views
2K
Replies
9
Views
1K
Replies
1
Views
153
Replies
10
Views
1K
  • Quantum Physics
Replies
10
Views
1K
  • High Energy, Nuclear, Particle Physics
Replies
2
Views
10K
  • High Energy, Nuclear, Particle Physics
Replies
3
Views
2K
  • Quantum Physics
Replies
31
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
18
Views
2K
  • Quantum Physics
Replies
1
Views
567
Back
Top