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.
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Jrs580
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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?
 
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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?
 
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  • #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
 
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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
 
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What are field fluctuations in the vacuum?

Field fluctuations in the vacuum refer to the spontaneous and temporary changes in the strength and direction of electromagnetic fields that occur in empty space. These fluctuations are a result of the uncertainty principle in quantum mechanics.

How do field fluctuations affect particles?

Field fluctuations can affect particles by causing them to spontaneously appear and disappear, a process known as particle-antiparticle pair production. This can also lead to changes in the energy and momentum of particles.

Can field fluctuations be observed?

Field fluctuations cannot be directly observed, as they occur at a very small scale and are constantly changing. However, their effects can be observed through experiments and calculations, such as the Casimir effect.

Do field fluctuations have any practical applications?

Yes, field fluctuations have practical applications in areas such as quantum computing and cosmology. They also play a crucial role in our understanding of the fundamental laws of physics.

Can field fluctuations be controlled or manipulated?

Currently, field fluctuations cannot be controlled or manipulated, as they are a natural phenomenon. However, scientists are researching ways to harness and utilize these fluctuations for various purposes, such as energy generation and communication.

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