The Casimir effect and Quantum vacuum fluctuations

[DesertFox]

The Casimir effect is a small attractive force that acts between two close parallel uncharged conducting plates. That force is caused by quantum vacuum fluctuations of the electromagnetic field.

What is the cause of the fluctuations? Or, they are uncaused (random)? At least, what are the special conditions under which the Casimir effect becomes observable?

 

[mattt]

This will help you (I hope) :

https://www.physicsforums.com/insights/vacuum-fluctuation-myth/

https://www.physicsforums.com/insights/misconceptions-virtual-particles/

https://www.physicsforums.com/insights/physics-virtual-particles/

 

[timmdeeg]

You might find Jaffe's article interesting:

https://arxiv.org/pdf/hep-th/0503158.pdf
I have presented an argument that the experimental confirmation of the Casimir effect does not establish the reality of zero point fluctuations. Casimir forces can be calculated without reference to the vacuum and, like any other dynamical effect in QED, vanish as α → 0.

 

[Demystifier]

Or, they are uncaused (random)?

Yes.

 

[DesertFox]

Yes.

Is that your guess? How do you know it?

 

[modellatore]

What is the cause of the fluctuations?

It can depend of your starting point. Is it the uncertainty principle? Is it the zero point energy of oscillators? Is it the impossibility of having zero temperature? Or perhaps quantum corrections to vacuum diagrams? Depends on what you define to be the most fundamental of these things. The latter is the easiest way of thinking about it imo.

That force is caused by quantum vacuum fluctuations

Even so because if vacuum fluctuations are caused themselves, why not assert that cause as the origin of the force?
In an exceptionally naive way you can think of field modes (not physical particles/waves yet, but how you expand a field as a complete basis of creation and annihilation operators). When a boundary condition needs to be satisfied, let it be the field has a fixed value at a fixed point, these modes are "disturbed/distorted/rearranged" in a way that satiesfies your condition. This rearrangement can cause them not to annihilate the initial vacuum (within the bounded region), so you either choose a new vacuum (annihilated by the distorted modes) or a new set of modes (that annihilate the initial vacuum in their new form). This results in the presence of particles because of the re-writing of the operators in your initial mode expansion (bogoliubov transformations). This can result in a net force.
This is far from being a rigorous physical explanation, as the mathematics makes it clearer than words, but it's a nice intuitive picture if you like to think about nature as a "compensation/equilibrium" machine.
See Birrell, Davies- Quantum fields in curved spacetime, Section 3.3 and the chapters on particle creation (moving mirrors, unruh effect, hawking radiation).

 

[modellatore]

Is that your guess? How do you know it?

They are uncaused because of how the theory is formulated, and it's formulated this way to accommodate cornerstone physical principles. They are random because they do not have a deterministic cause, and would be paradoxical otherwise. Giving them ONE cause is like choosing a starting point on a circle

 

[Demystifier]

How do you know it?

Because it's a general property of quantum fluctuations that they are related to randomness. Besides, I published a paper on this stuff: https://arxiv.org/abs/1702.03291

 

[DesertFox]

They are uncaused because of how the theory is formulated, and it's formulated this way to accommodate cornerstone physical principles. They are random because they do not have a deterministic cause, and would be paradoxical otherwise. Giving them ONE cause is like choosing a starting point on a circle

That's circular thinking par excellence. But it seems that it's decisively confirmed by the experiments.

 

[PeroK]

That's circular thinking par excellence. But it seems that it's decisively confirmed by the experiments.

Physics is circular:

Observe a phenomenon; postulate a theory to explain the phenomenon; show that the theory predicts the said phenomenon.

That said, the Casimir effect was predicted about 50 years before it was measured; which is as good as gets as far as physics is concerned.

 

[DesertFox]

Physics is circular

True, but that's a different kind of circularity.

What i pointed out is that we got a circularity WITHIN the theory itself. At least, from strictly Modern logic point of view.

 

[PeterDonis]

What i pointed out is that we got a circularity WITHIN the theory itself. At least, from strictly Modern logic point of view.

You pointed this out in response to the wrong post. Go read the paper @Demystifier linked to, and the Insights articles linked to in post #2.

 

[PeterDonis]

They are uncaused because of how the theory is formulated, and it's formulated this way to accommodate cornerstone physical principles. They are random because they do not have a deterministic cause, and would be paradoxical otherwise. Giving them ONE cause is like choosing a starting point on a circle

This is not really a good description of how QM handles this issue. I suggest reading the Insights articles linked to in post #2, and the paper @Demystifier linked to.

 

[DesertFox]

You pointed this out in response to the wrong post.

It's not clear what do you mean by "the wrong post".

Sure, that's not a forum about Logics. However, logically consistent responds may be appropriate according the PF rules.

Anyway, saying over isn't much of a help actually, but thank you for the straightforward alluding to the mentioned articles/papers.

 

[PeterDonis]

It's not clear what do you mean by "the wrong post".

I meant that you responded to post #7 by @modellatore, which, as I pointed out in post #13, is not a good description of how QM actually handles this issue--meaning that your response is basically irrelevant to the actual issue.

What you should be doing, as I said, is reading the Insights articles and the paper by @Demystifier, and then responding after you have digested what is in them.

 

[DesertFox]

I meant that you responded to post #7 by @modellatore, which, as I pointed out in post #13, is not a good description of how QM actually handles this issue--meaning that your response is basically irrelevant to the actual issue.

What you should be doing, as I said, is reading the Insights articles and the paper by @Demystifier, and then responding after you have digested what is in them.

Your clarification is incorrect.

My respond to post #7 was: "That's circular thinking par excellence."

Post #10 was like: "Physics is circular: ...". Regarding THAT post #10, I pointed out that these are two different kinds of circularity.

That's your announcements (to whom I responded, etc.) that are obviously irrelevant to the topic. Perhaps you should try to digest the dialectical line of thought in the thread while I am reading the Insights articles and the paper by @Demystifier.

 

[Vanadium 50]

You can complain about circularity all you want, but if you won't read the Jaffe paper - and it's obvious you haven't - there is little chance this will change.

 

[PeterDonis]

Your clarification is incorrect.

Your understanding of this topic is incorrect. To correct it, you need to read the references you have been given, digest them, and then ask further questions in a new thread. Unless and until you do that, further discussion is pointless.

This thread is closed.