Lambda-CDM theory - Woo or not?

[Michael Mozina]

Why don't you look at the equation at the end of the section entitled "Casimir's Calculation"?

In physics, the Casimir effect and the Casimir-Polder force are physical forces arising from a quantized field. The typical example is of two uncharged metallic plates in a vacuum, placed a few micrometers apart, without any external electromagnetic field. In a classical description, the lack of an external field also means that there is no field between the plates, and no force would be measured between them. When this field is instead studied using quantum electrodynamics, it is seen that the plates do affect the virtual photons which constitute the field, and generate a net force[1]—either an attraction or a repulsion depending on the specific arrangement of the two plates.

You folks cannot tell a *force* from "negative pressure". *Read the WHOLE article* (not just one sentence) and look at the directional components of the blue arrows! This is not "negative pressure". Hoy. It says *FORCE*, not "negative pressure", in fact the term "negative pressure" does *NOT* even appear in the article. You people are in pure denial at this point. Pressure and force are not the same thing.

 

[Michael Mozina]

That is correct: "The whole environment is *positively pressurized*" and the experimental physicists know this!
That is why they calibrate their apparatus to remove the effect of the "positively pressurized environment" and just measure the Casimir effect.

But the *NET PRESSURE IN THE CHAMBER* is consistently positive!

This sounds like we are back to you assuming that the scientists are so dumb that they do not know that their vacuum chamber is not a perfect vacuum.

It sounds to me like you're building another strawman instead of listening to my responses.

Just what magic process enables you to know what the unlabeled BLUE lines in the diagram actually are?

There is nothing "magic" about studying QM.

P.S. The Wiki article is quite clear that it is a second quantization effect of vacuum fluctuations and nothing to do with the kinetic energy of the carrier particles of the EM field (of which there is none between the plates).

Precisely (in terms of actual physics) what is the difference?

 

[Michael Mozina]

Uh, no. What you provided me with was simply a version of my own definition, with a substitution that made calculations more cumbersome unless you undid that substitution. Since it was, in fact, the same thing, how on earth can you conclude that it "busted my show"?

And that is not the definition you are using, anyways. Are you honestly pretending that you calculate relativistic mass whenever you want to calculate a pressure? No, I don't think so. So once again: how do you define pressure?

I have already done that for you. As it relates to a vacuum, how about you try:

P=nRT/V

FYI, T is measured in Kelvin.

 

[Ziggurat]

You folks cannot tell a *force* from "negative pressure".

Pressure is just force per unit area. Negative for inwards, positive for outwards. Your argument that it's just lower relative pressure was at least logical (though it failed badly when you tried to apply it to liquids under negative pressure), but the idea that we don't understand the difference between force and pressure? That's just wrong.

You people are in pure denial at this point. Pressure and force are not the same thing.

Yeah, um... they're rather related, though. If you know one, then calculating the other is fairly easy. Guess how. Oh, but it involves math. Now I understand why you can't figure it out.

 

[Ziggurat]

I have already done that for you. As it relates to a vacuum, how about you try:

P=nRT/V

FYI, T is measured in Kelvin.

Bwahahahahaha! You want to use the ideal gas law to define pressure? The ideal gas law is an approximation. It fails at high densities and/or low temperatures, where molecule size and inter-molecular interactions start to matter (but I love how you think you need to specify T is in Kelvin - actually any absolute temp scale will do). If you use it to define pressure, then your pressure will not equal force/area once you reach high densities and/or low temperature. Yes, I suppose with this definition, pressure could never go negative. But nobody with a clue defines pressure this way, and with good reason. First off, because your answers won't make sense for what pressure is supposed to mean. Secondly, because you can get situations where gasses in mechanical contact won't equilibrate their pressures as you've defined them. And thirdly, you can't even use your definition for many important cases (liquids at negative pressure being an example).

In the real world, pressure is defined independently from ideal gasses. The ideal gas law can be derived, using a few simple approximations (really two: non-interaction and point-like masses) along with a pre-existing definition of what pressure means. That's standard thermodynamics. So I was right: you are indeed deeply confused about what pressure means. You picked up that equation in a highschool chem or physics course, misunderstood what it meant, and confused the fact that it can be exploited to measure pressure over certain ranges with the (wrong) idea that it's how one defines pressure. Well, it isn't. Not if you've got a clue.

 

[Michael Mozina]

Bwahahahahaha!

And there you go again....

Your whole show is blown entirely *out of the water* and all you can do is play games.

http://en.wikipedia.org/wiki/Absolute_temperature

That my friend is what kinetic energy is all about. There is *pressure* in that chamber from the particles in that chamber. Once we remove every particle from that vacuum, you end up at *zero* pressure, and it is entirely impossible to reach a "negative pressure" in a vacuum. We can't even create a "zero pressure" vacuum on Earth.

 

[Michael Mozina]

Pressure is just force per unit area. Negative for inwards, positive for outwards. Your argument that it's just lower relative pressure was at least logical (though it failed badly when you tried to apply it to liquids under negative pressure), but the idea that we don't understand the difference between force and pressure? That's just wrong.

What is *wrong* here is your understanding of the nature of kinetic energy, and the difference between "pressure" and "force". Those bouncing particles represent "pressure" in the chamber. In theory, at the atomic scale, we might actually be able to remove them all and achieve *no* pressure. It would be impossible to achieve "negative pressure" however because even adding "antimatter" is simply going to create kinetic energy in the system and energy that can be released by it coming in contact with ordinary matter. You can't get "negative pressure" out of a vacuum, and Guth's whole paper is predicated upon this premise.

Yeah, um... they're rather related, though. If you know one, then calculating the other is fairly easy. Guess how. Oh, but it involves math. Now I understand why you can't figure it out.

Your math skills are evidently fairly limited. I've offered you two different scientific definitions of pressure, and you can't demonstrate squat with your presumed superior math skills.

 

[temporalillusion]

You folks cannot tell a *force* from "negative pressure". *Read the WHOLE article* (not just one sentence) and look at the directional components of the blue arrows! This is not "negative pressure". Hoy. It says *FORCE*, not "negative pressure", in fact the term "negative pressure" does *NOT* even appear in the article. You people are in pure denial at this point. Pressure and force are not the same thing.

Did you look at the math on the Casimir effect article? You said you agreed with it. Do you see the place where they are calculating pressure? Is the sign positive or negative?

[qimg]http://upload.wikimedia.org/wikipedia/commons/6/6d/Translational_motion.gif[/qimg]

That my friend is what kinetic energy is all about. There is *pressure* in that chamber from the particles in that chamber. Once we remove every particle from that vacuum, you end up at *zero* pressure, and it is entirely impossible to reach a "negative pressure" in a vacuum. We can't even create a "zero pressure" vacuum on Earth.

The negative pressure due from the Casimir effect has nothing to do with the molecules in the chamber, I thought you had abandoned that line of reasoning.

If you remove all the particles from the chamber you are at zero pressure. You have set the zero point by your own words. Now put the plates or whatever in that chamber. They will be drawn together. The pressure outside the plates is zero. What's the pressure between the plates so that they are drawn together? It can't be positive, because then the plates would be pushed apart. It can't be zero, because then the plates wouldn't have anything pushing on them. There's only one choice left.

 

[Michael Mozina]

Did you look at the math on the Casimir effect article? You said you agreed with it. Do you see the place where they are calculating pressure? Is the sign positive or negative?

Did you see that term *FORCE* mentioned in the article?

If you remove all the particles from the chamber you are at zero pressure. You have set the zero point by your own words. Now put the plates or whatever in that chamber. They will be drawn together.

Yes, by a *FORCE* at the level of QM. At the level of QM, much the same thing is going on, only the "standing waves" are occurring at much smaller sizes, but the *force* from outside the plates pushes the plates together and is *greater than* the force of the VP waves inside the plates. The math can be looked in several different ways, and that is why it is important to understand the *PHYSICS* of what is going on. The *pressure* can only reach zero in a vacuum. Some other *FORCE* might be useful in explaining expansion, but it has *nothing* to do with "negative pressure in a vacuum". Guth specifically requires there to be negative pressure in a vacuum and the ideal gas laws demonstrate that this is a physical impossibility.

Now if you'd like to "zap" your near singularity thingy with a giant bolt of lightning and add EM *FORCES* the mix, be my guest. On the other hand, Guth's theory is DOA because what his theory requires is physically impossible.

 

[edd]

What is *wrong* here is your understanding of the nature of kinetic energy, and the difference between "pressure" and "force". Those bouncing particles represent "pressure" in the chamber. In theory, at the atomic scale, we might actually be able to remove them all and achieve *no* pressure. It would be impossible to achieve "negative pressure" however because even adding "antimatter" is simply going to create kinetic energy in the system and energy that can be released by it coming in contact with ordinary matter.

I worry that you are thinking too much in terms of matter. If dark energy exists what makes you think it is going to be in the form of a particle that bounces round inside a box in the manner of your animation?

 

[Michael Mozina]

The negative pressure due from the Casimir effect has nothing to do with the molecules in the chamber, I thought you had abandoned that line of reasoning.

The *pressure* in the chamber is directly related to the formula:

P=nRT/V

The "force" from the Casimir effect has *nothing* to do with the "pressure" in the chamber that comes from the atomic level.

The *force* from the Casimir effect is directly related to the standing waves created in the chamber due to the *positive energy density* of our universe at the level of QM. It too is a form of "kinetic energy" that is typically expressed in terms of "virtual particles" at the level of QM. There are *more* VP's outside of the plates than there are VP's between the plates, and the *force* from outside the plates due to VP waves is "greater than' the force between the plates. The *blue arrows* demonstrate that even this process is "greater than" on the outside, and "less than" on the inside sort of process.

 

[Michael Mozina]

I worry that you are thinking too much in terms of matter.

I think you are focusing too little on the matter.

If dark energy exists what makes you think it is going to be in the form of a particle that bounces round inside a box in the manner of your animation?

IMO any form of "acceleration" of a mostly plasma universe is most likely going to be related to EM fields and has nothing whatsoever to do with "dark energy" because "dark energy" does not exist in nature.

 

[temporalillusion]

Did you see that term *FORCE* mentioned in the article?

Of course, you can't have pressure without force.

I'll ask again, where they are calculating the pressure (using the force), is the sign positive or negative?

Yes, by a *FORCE* at the level of QM. At the level of QM, much the same thing is going on, only the "standing waves" are occurring at much smaller sizes, but the *force* from outside the plates pushes the plates together and is *greater than* the force of the VP waves inside the plates.

What force? You say to understand the physics of what's going on, but you haven't described it other than saying it's a quantum level force. Are you talking about the strong force? Gravity? And you haven't said why the force applied to the plate is less on the inside compared to the outside. ETA: Sorry, didn't see your subsequent reply above.

The math can be looked in several different ways, and that is why it is important to understand the *PHYSICS* of what is going on. The *pressure* can only reach zero in a vacuum.

I don't care about Guth or inflation, I want to know the physics of what's going on.

You just said again the pressure can only reach zero in a vacuum. Ok I make a zero pressure vacuum. Then I bring the plates together and the pressure is lower between them than the zero pressure everywhere else.

With respect to the pressure everywhere else, what is the pressure between the plates? Positive or negative?

 

[edd]

The *pressure* in the chamber is directly related to the formula:

P=nRT/V

It's already been explained that this formula is inappropriate.

 

[Michael Mozina]

It's already been explained that this formula is inappropriate.

It is *not* inappropriate. A *liquid in a piston cylinder* comparison, now *that* is inappropriate. The reason he doesn't like that formula, or the MC^2 option is because it becomes apparent in both formulas that pressure can never become "negative".

 

[Michael Mozina]

Of course, you can't have pressure without force.

But you can have *force* without it being related to "pressure". Gah!

 

[edd]

It is inappropriate. It's the equation of state of an ideal gas.

The whole idea behind dark energy is that it has a different equation of state. It's not an ideal gas.

 

[temporalillusion]

The *pressure* in the chamber is directly related to the formula:

P=nRT/V

But you just said that the pressure was from virtual particles. Virtual particles are everywhere.

What's the temperature of the virtual particles? What's the number of moles of virtual particles (kind of hard to measure since they keep disappearing!)? Why would the universal gas constant apply to virtual particles? And since particles are virtual and are everywhere, but don't keep about, you can't use the volume of the test chamber to calculate the pressure.. (otherwise you could calculate the vacuum pressure with just an empty sphere, but you can't), so the volume I guess would be what, the volume of the universe?? And the volume between the plates is the volume of the universe too, since it's not enclosed.

But please, I'd like to see you use this formula to calculate the pressure on the outside and inside of the plates.. aaaand go.

The *force* from the Casimir effect is directly related to the standing waves created in the chamber due to the *positive energy density* of our universe at the level of QM. It too is a form of "kinetic energy" that is typically expressed in terms of "virtual particles" at the level of QM. There are *more* VP's outside of the plates than there are VP's between the plates, and the *force* from outside the plates due to VP waves is "greater than' the force between the plates. The *blue arrows* demonstrate that even this process is "greater than" on the outside, and "less than" on the inside sort of process.

Why are there less virtual particles between the plates?

And you said it yourself, the pressure on the outside is greater than the pressure on the inside.. So the pressure on the inside with respect to the pressure on the outside is... negative?

(And as far as I know the virtual particles way of looking at it is one way, but not really the best way if I recall properly, maybe someone who knows can comment on that).

 

[temporalillusion]

But you can have *force* without it being related to "pressure". Gah!

I never claimed otherwise, but we were talking about pressure so what relevance does a force unrelated to pressure have?

I'll ask again, where they are calculating the pressure (using the force), is the sign positive or negative?

 

[Skwinty]

Isn't it true to say that the negative refers purely to the direction of the resulting force and not that the pressure is negative in absolute terms.
It's not like a positive or negative potential as opposed to zero potential.