Lambda-CDM theory - Woo or not?

[Tubbythin]

I'm not doing anything of the sort. I simply used the ideal gas law description of pressure to demonstrate the asymptote for pressure in a vacuum is 0, not negative infinity.

The ideal gas law that completely, totally and utterly ignores both quantum mechanics and relativity. How on Earth does this help in a situation which is a result of second quantization and ultra relativistic particles (and you can't get more ultra-relativistic than a photon). Like I said before, its no less stupid than using Coulomb's law to describe the force of gravity.

The QM side is still "positive pressure" as you will eventually figure out as I stuff Boyer's experiments down your throat for a week if necessary.

You're such a pleasant chap, aren't you?

 

[Tubbythin]

Why did Boyer experience *repulsion* in his experiments with a sphere in 1968?

Well, if its anything like his more recent paper, then its because he used one "perfect conductor" and one "infinitely permeable" plate. Ie, good old boundary conditions.

 

[temporalillusion]

Yep. Take a gander once at Boyer's experiments with a spherical shell. What happened and why?

The Casimir force can either be attractive or repulsive depending on the geometry and the materials in use.

I don't understand what you are trying to say. Are you saying that because it was an enclosed sphere that the pressure inside was positive?

If so, then why would it be positive or negative in a parallelepiped depending on the ratios of the sides?

No, it goes to approximately 1 atmosphere.

This is a bizarre claim, you are saying the maximum pressure the Casimir effect can have in any case is 1 atmosphere?? If I get that 1 atmosphere and bring the plates closer together I'll get no more pressure? How in the world does that happen?

And you still haven't answered the question, in the Casimir Effect article on wiki, which you agree with, where they are calculating the pressure, is the sign positive or negative?

 

[Ziggurat]

You folks are utterly and completely lost when it comes to actual physics

And yet, everyone but you understands that pressure isn't defined in terms of the ideal gas law. That qualifies as "actual physics" in my book.

 

[sol invictus]

And yet, everyone but you understands that pressure isn't defined in terms of the ideal gas law. That qualifies as "actual physics" in my book.

Oh, the latest idiocy is that Casimir pressure is defined by P = nRT/V? That's interesting, since

a) Casimir pressure doesn't scale with V

b) and it's non-zero at T=0

c) what's n?

So it makes perfect sense... except that not one of the terms on the right hand side is correct.

 

[Michael Mozina]

The ideal gas law that completely, totally and utterly ignores both quantum mechanics and relativity.

It does not. I offered to let you folks use mass rather than energy and your side balked at that idea too. There's *nothing* being ignored except what must be ignored in a vacuum. The asymptote of "pressure" is zero, even *if* we even could get to zero atoms in the box. At the level of QM, you simply have the carrier particle of the EM field doing the "pushing". There's no "negative pressure" anywhere in the box.

How on Earth does this help in a situation which is a result of second quantization and ultra relativistic particles (and you can't get more ultra-relativistic than a photon).

A photon carries kinetic energy just like any ordinary particle of energy. It's wavelength determines it's energy state. What's the big deal with conceptually understanding a photon in terms of kinetic energy? Just how do you figure a solar panel works anyway?

Like I said before, its no less stupid than using Coulomb's law to describe the force of gravity.

I think you guys must be required to minor in strawman creation.

Guth needs the vacuum (not his hot near singularity thingy) to have a negative pressure. Gravity isn't going to do anything but hold the singularity thing in place, but unless your claiming the whole thing already has mass (like a Higg's condensate?), gravity isn't much of a factor as far as I know. Guth didn't suggest his heat thing already had mass at that point. His "heat" would by necessity need to overcome any form of curvature of gravity created by the formation of particles of mass. One can only wonder where the "heat" might come from or how it might physically manifest itself during supercooling other than to emit in the form of photons into an empty "vacuum". In no case does the heat thingy have anything to do with gravity as far as I know.

The carrier particle of the EM field is a force, and has nothing to do with pressure in the vacuum chamber and it's obviously related to the Casimir effect due to the influence of the materials. The EM carrier particles carry kinetic energy from one place to another, but then what is the carrier particle of the EM field? Come on. There's no mystery here. You have photons in motion inside the vacuum, or VP's if you like. They *push* things together via their kinetic energy.

You're such a pleasant chap, aren't you?

Well what choice do I have in this arena? It's like an angry mob of wolves around here and I have to cut through the BS as quick as possible, often times with formidable effort on my part, with posts from multiple people coming at me faster than I can respond.

The bottom line here is is you have everything bass-ackwards. The kinetic energy is already and forever inside the vacuum, both in terms of atomic kinetic energy, and subatomic kinetic energy. We can never get the energy state to even an absolute zero point, let alone any form of "negative pressure" out of a vacuum. There is no such thing as negative pressure in a vacuum, not even at the subatomic level. There are particles of mass flowing through all experiments on Earth, and photons of every wavelength carry momentum and kinetic energy.

No area inside a Casimir experiment experiences "negative pressure" either. That's another of those things you really don't understand at all. Those blue arrows and green lines should have tipped you off, but alas, evidently if one *only* understands math, and does not comprehend anything about the physics, I guess the notion of "negative pressure" in positive pressure environment might sound reasonable. If however you understand anything at all about what is physically happening inside the vacuum, it becomes obvious that there is no possibility of achieving 'negative pressure" in a vacuum, not at the atomic level, and not at the subatomic level. It's physically impossible.

 

[Michael Mozina]

Oh, the latest idiocy is that Casimir pressure is defined by P = nRT/V? That's interesting, since

a) Casimir pressure doesn't scale with V

b) and it's non-zero at T=0

c) what's n?

So it makes perfect sense... except that not one of the terms on the right hand side is correct.

When did I claim that PV=nRT thing was related to the Casimir effect? You aren't even making sense. What I said is that it demonstrates that the asymptote of pressure is 0, not negative infinity.

 

[Michael Mozina]

And yet, everyone but you understands that pressure isn't defined in terms of the ideal gas law. That qualifies as "actual physics" in my book.

When discussing the "pressure" of a "vacuum" it is *the single most appropriate* definition of pressure.

 

[Ziggurat]

Oh, the latest idiocy is that Casimir pressure is defined by P = nRT/V?

Well, I think it's not quite as stupid as all that. At least I hope. What I think he thinks is that if you put a little ideal gas cylinder in mechanical contact with your other system and let it come to equilibrium, you can then figure out the pressure by looking at the volume, temperature, and quantity of your ideal gas. Of course, this doesn't work because gasses aren't ideal, and the fact that ideal gasses can't support negative pressures doesn't mean other things can't. So he's still deeply confused, but I hope not quite as badly as you suggest.

 

[Michael Mozina]

Well, I think it's not quite as stupid as all that. At least I hope. What I think he thinks is that if you put a little ideal gas cylinder in mechanical contact with your other system and let it come to equilibrium, you can then figure out the pressure by looking at the volume, temperature, and quantity of your ideal gas. Of course, this doesn't work because gasses aren't ideal, and the fact that ideal gasses can't support negative pressures doesn't mean other things can't. So he's still deeply confused, but I hope not quite as badly as you suggest.

No, he just enjoys building *outrageous* strawmen out of thin air. All I was trying to convey is that a "vacuum" is either empty or it's not. If it is not empty, it has things in it that carry and convey "kinetic energy".

Guth's theory is dead on arrival because it is physically impossible to achieve anything but something close to a "zero" pressure state in the vacuum.

Now of course there could be some giant EM *force* from the outside, but then you guys hate EU theory and that would just not be acceptable.

 

[Ziggurat]

When discussing the "pressure" of a "vacuum" it is *the single most appropriate* definition of pressure.

It's not a definition of pressure at all. Under any conditions. Even for an ideal gas. How can you still not get such a basic fact straight?

Hell, it can even give the radically WRONG pressure, as in the case of radiation pressure (which is not the Casimir effect - I'm talking real photons). Radiation pressure inside a sealed enclosure will scale as T⁴ (Reif, Thermal Physics), not as T, so the ideal gas law is rather obviously wrong, and at sufficiently high temperature, radiation pressure will always dominate gas pressure.

 

[sol invictus]

So he's still deeply confused, but I hope not quite as badly as you suggest.

It's not a definition of pressure at all. Under any conditions. Even for an ideal gas. How can you still not get such a basic fact straight?

 

[Ziggurat]

Maybe he doesn't know the definition of "definition".

 

[ben m]

No, it goes to approximately 1 atmosphere.

This is the sort of thing you could check before you post, MM. In your mental model of the Casimir force---the one in which it behaves like a gas pressure---maybe the force goes to 1atm. You can make it do whatever you want as long as you're inventing the model.

In real life---the Casimir force we're talking about, the one that specifically illustrates that your mental model is wrong---the force varies as 1/d^4, which means it gets stronger and stronger without limit as the separation d decreases. Look it up.

 

[temporalillusion]

In real life---the Casimir force we're talking about, the one that specifically illustrates that your mental model is wrong---the force varies as 1/d^4, which means it gets stronger and stronger without limit as the separation d decreases. Look it up.

Ah ha! So you ADMIT the pressure isn't negative!

 

[Reality Check]

That is the whole point! The "pressure" is not ZERO, it is *POSITIVE*. It cannot be negative, and even at the level of QM it is still a questions of *more VP's on the outside*, and less of them on the inside.

http://physicsworld.com/cws/article/news/3119



The difference between these two "forces" is visually depicted by the *LARGE ARROW* on the outside of the plates, and the "small" arrows between the plates. The difference between them is the Casimir effect.

http://upload.wikimedia.org/wikiped...simir_plates.svg/300px-Casimir_plates.svg.png

See how the little blue arrows inside the plates is pointing *OUTWARD*? That "pressure" between the plates simply *decreases* (but does not go negative) as the plates get closer together. The quantum pressure on the outside *pushes* the plate together.

What happens when the plates are such that the Casimir effect pushes the plates apart? Is this replusive force also created by a positive pressure?

Actually I asked this before and you ignored it. Here it is again.
So is this what you are saying:

• If the plates are such that the net force is replusive then the net pressure (force divided by area) is positive.
• If the plates are such that the net force is attractive then the net pressure is still positive despite the fact that the net force has changed sign.

If so your conclusion must be that the area of the plates must have also changed sign to keep the pressure positive. Can you tell us how to measure a negative area? Do we construct square plates with imaginary sides and square their imaginary lengths?

 

[The Man]

What happens when the plates are such that the Casimir effect pushes the plates apart? Is this replusive force also created by a positive pressure?

Actually I asked this before and you ignored it. Here it is again.
So is this what you are saying:

• If the plates are such that the net force is replusive then the net pressure (force divided by area) is positive.
• If the plates are such that the net force is attractive then the net pressure is still positive despite the fact that the net force has changed sign.

If so your conclusion must be that the area of the plates must have also changed sign to keep the pressure positive. Can you tell us how to measure a negative area? Do we construct square plates with imaginary sides and square their imaginary lengths?

A fallacy often employed by proponents of free energy machines. As long as you consider all forces, energy and even pressure to be positive you will always calculate an over unity efficiency. Regardless of the fact that some of that energy actually hinders the operation of the machine. Again it comes down to Newton’s third law, conservation of energy and grade school physics. Without the negatives there can be no equal and opposite reaction for any given action that one might consider to be positive.

 

[Tubbythin]

It does not. I offered to let you folks use mass rather than energy and your side balked at that idea too. There's *nothing* being ignored except what must be ignored in a vacuum. The asymptote of "pressure" is zero, even *if* we even could get to zero atoms in the box. At the level of QM, you simply have the carrier particle of the EM field doing the "pushing". There's no "negative pressure" anywhere in the box.

Oh dear. In classical mechanics momentum,p, is:
p = mv.
Therefore for a photon of 0 mass, p also equals zero. Now if we have pressure P,
P = force/Area
but
force= dp/dt.
Now since in classical mechanics p always equals 0 for photons, dp must always equal zero. Then dp/dt also equals zero, then so does force and so does pressure. Ie, in classical mechanics there is no such thing as radiation pressure. This is true for real photons too! Not just virtual ones.

A photon carries kinetic energy just like any ordinary particle of energy. It's wavelength determines it's energy state. What's the big deal with conceptually understanding a photon in terms of kinetic energy? Just how do you figure a solar panel works anyway?

Erm. They have an energy that is not related to their mass or their speed (since they have 0 mass and all have speed c).

I think you guys must be required to minor in strawman creation.

Brilliant. Absolutely brilliant. This from the mas who brought us:

Lambda-CDM theory is just the opposite. It begins with a prophetic premise. "The universe was created on such and such a date......

Guth needs the vacuum (not his hot near singularity thingy) to have a negative pressure. Gravity isn't going to do anything but hold the singularity thing in place, but unless your claiming the whole thing already has mass (like a Higg's condensate?), gravity isn't much of a factor as far as I know. Guth didn't suggest his heat thing already had mass at that point. His "heat" would by necessity need to overcome any form of curvature of gravity created by the formation of particles of mass. One can only wonder where the "heat" might come from or how it might physically manifest itself during supercooling other than to emit in the form of photons into an empty "vacuum". In no case does the heat thingy have anything to do with gravity as far as I know.

Well that one flew straight over your head didn't it. I was referring to the fact that using completely wrong formula for a pressure (ie that of a classical gas) was as stupid as using completely the wrong formula for the force of gravity.

The carrier particle of the EM field is a force, and has nothing to do with pressure in the vacuum chamber and it's obviously related to the Casimir effect due to the influence of the materials. The EM carrier particles carry kinetic energy from one place to another, but then what is the carrier particle of the EM field? Come on. There's no mystery here. You have photons in motion inside the vacuum, or VP's if you like. They *push* things together via their kinetic energy.

You're vaguely getting the idea. But you don't seem to understand that is both a quantum mechanical and a relativistic effect. And therefore using the ideal gas equation is completely, totally and utterly inappropriate.

Well what choice do I have in this arena? It's like an angry mob of wolves around here and I have to cut through the BS as quick as possible, often times with formidable effort on my part, with posts from multiple people coming at me faster than I can respond.

I'm sorry. You what. You have to cut through the BS. Who was the one trying to claim the CMB was due to starlight (despite being out by a factor of millions)? Who was the one trying to say the Cassimir effect is due to an imperfect vacuum? Who was the one trying to claim the Casimir effect was due to neurtinos. Who was the one trying to use the classical ideal gas equation to describe an effect of second quantization (and relativity). Who was the one making up strawmen like:

Lambda-CDM theory is just the opposite. It begins with a prophetic premise. "The universe was created on such and such a date......

The bottom line here is is you have everything bass-ackwards. The kinetic energy is already and forever inside the vacuum, both in terms of atomic kinetic energy, and subatomic kinetic energy. We can never get the energy state to even an absolute zero point, let alone any form of "negative pressure" out of a vacuum.

But you're the one who's just showed us that the gas pressure tends to zero as the number of gas molecules tend to zero. So if you have zero gas pressure and add quantum effects what do you get? Well in the case of the two conducting plates you get a negative pressure.

There is no such thing as negative pressure in a vacuum, not even at the subatomic level. There are particles of mass flowing through all experiments on Earth, and photons of every wavelength carry momentum and kinetic energy.

Right, but there's very few particles in a vacuum. And it is the (virtual) photons that cause the negative pressure. So why would we want to get rid of them?

No area inside a Casimir experiment experiences "negative pressure" either. That's another of those things you really don't understand at all. Those blue arrows and green lines should have tipped you off, but alas, evidently if one *only* understands math, and does not comprehend anything about the physics, I guess the notion of "negative pressure" in positive pressure environment might sound reasonable. If however you understand anything at all about what is physically happening inside the vacuum, it becomes obvious that there is no possibility of achieving 'negative pressure" in a vacuum, not at the atomic level, and not at the subatomic level. It's physically impossible.

No, the Cassimir effect tells us all we need to know. In a vacuum you can have negative pressures (since, as you so kindly pointed out to us, the gas pressure is zero).

 

[ArmillarySphere]

Even with MM's "definition" of pressure, negative values are perfectly possible. Simply bring the temperature below absolute zero, and there you go.


As an aside, it struck me that the Casimir effect might be partially responsible for vacuum welding (going to negative infinity and all that).

 

[sol invictus]

Even with MM's "definition" of pressure, negative values are perfectly possible. Simply bring the temperature below absolute zero, and there you go.

Haha - good point!

If fact, take the spin system I mentioned earlier at an energy such that T<0 (yes MM, measured in Kelvin). Now it will be easy to arrange it in such a way that the pressure is positive without affecting the temperature (for example one could add some repulsive interaction between the spins).

Then according to MM, 0>P/T=nR/V, which means either n or V is negative...