What Causes the Casimir Effect and Its Implications for Vacuum Energy?

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Discussion Overview

The discussion centers around the Casimir effect, specifically its causes and implications for vacuum energy. Participants explore the theoretical underpinnings of the effect, its relation to quantum field theory, and potential applications or limitations of the phenomenon.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant expresses confusion about the Casimir effect, questioning the connection between vacuum fluctuations, vacuum polarization, and the absence of photons between the plates.
  • Another participant suggests that the vacuum contains electromagnetic waves and virtual particles, which are inhibited by the presence of the plates, leading to a force that pushes them together.
  • There is a question about whether the Casimir effect can be applied broadly or if it is merely a theoretical curiosity.
  • Some participants argue that while the electromagnetic Casimir effect is the strongest and most measurable, other fields like scalar, spinor, and nonabelian gauge fields could also contribute to the effect.
  • One participant discusses the potential for extracting energy from the vacuum using Casimir plates, while another counters that the energy obtained is merely potential energy that was initially input when configuring the plates.

Areas of Agreement / Disagreement

Participants exhibit a mix of agreement and disagreement. While there is some consensus on the nature of the Casimir effect and its measurement, there are differing views on its practical applications and the possibility of extracting usable energy from it.

Contextual Notes

Participants highlight limitations in understanding the effect, particularly regarding the role of different fields and the nature of energy extraction from the vacuum. There is an ongoing exploration of the implications of the Casimir effect without reaching definitive conclusions.

arroy_0205
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I still do not understand the Casimir effect, more precisely what causes this. In the usual example of a parallel square plate kept very close to each other in vacuum, the plates feel an attractive force. This is a purely quantum field theoretic effect. My doubts are:

1. It is said that in vacuum there is no photon in between the plates but all the possible vibrational modes are present. We build an expression out of the quantities h, c and a (plate separation) but the amplitude of any wave do not occur since we are dealing with vacuum. I am not able connect vacuum fluctuation and vacuum polarization with this effect. Can anyone explain.

2. Why should only the electromagnetic field cause casimir effect? why not scalar/spinor/nonabelian gauge fields?
 
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The vacuum is awash with electromagnetic waves and various particles, from all sorts of sources, stars etc. In addition it has a high level of energy from the em and particle pairs that pop in and out from the vacuum energy, only constrained by the pairing of energy and time in the uncertainty relationship.
If you put two plates close together it inhibits those waves and particles, both real and virtual, that need at least a half-wave space to exist. The closer you put them, the more waves etc are excluded.
Thus there's more energy outside than inside. The difference shows as a force pushing the plates together.
 
So can we apply casimir force to anything or is it a useless 'nice to know' thing?
 
arroy_0205 said:
2. Why should only the electromagnetic field cause casimir effect? why not scalar/spinor/nonabelian gauge fields?

by all means, they do! but the EM casimir is MUCH stronger, and therefore measurable.


Denton said:
So can we apply casimir force to anything or is it a useless 'nice to know' thing?

Well, one might say that everything is "useless" - so I'm not sure how to take that!

We won't be building bridges with Casimir cranes anytime soon! Nor will we by flying to Mars in a Casimir-powered engine! But it is a physical effect, and it can be measured, and it might have something to do with things like the cosmological constant or stabilization of extra dimensions in string theory, or it might be important for nanotech devices, or who knows what else.

So sure, it's "useful".

Unless you couldn't care less about such things...
 
We should consider how to get energy out of the vacuum in a usable form. Casimir plates are a 'one shot' source of energy - now, how to make that a continuous source.
 
map19 said:
We should consider how to get energy out of the vacuum in a usable form. Casimir plates are a 'one shot' source of energy - now, how to make that a continuous source.

You can't. The energy you "get out" of the Casimir effect was put in when you configured the plates. It's ordinary potential energy, nothing more, nothing less. You can't get any more energy out than you put in.
 

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