Lambda-CDM theory - Woo or not?

[Ziggurat]

Zig, it stills comes back to exactly the same issue.

I notice that you aren't actually addressing the issue I raised: do you or do you not understand how P=F/A is equivalent to [latex]$P=-\frac{\partial E}{\partial V}$[/latex]? Once you answer that, we can move on to what negative pressure means, and then we'll be in a position to talk about when it does and doesn't exist.

You're confused by your own math evidently.

Quite the charge coming from a man who can't even do any math.

 

[Ziggurat]

I liked the force definition better.

Do you or do you not understand why the two forms are equivalent? If you understand why they are equivalent, then your personal preference will obviously be irrelevant. If you do not understand why they are equivalent, then you don't understand enough physics, math, or both.

Do you have a great need to stuff E in there or what?

It is a convenient form of the definition for many purposes.

 

[The Man]

Yes, I'm aware of the fact it is used interchangeably with "vacuum energy". I just personally think it's a misleading term. There is "energy flowing" through the system at all times. It never achieves a "zero point", so why call it a "zero point"? Ground state energy might make sense, but "zero point energy" does not.

Sure it does, it is the point at which the system has a zero energy potential, or more specifically the amount of energy you can extract from that system is zero, hence zero point energy. Of course I explained all of that to you before.

 

[edd]

I liked the force definition better. Do you have a great need to stuff E in there or what?

The physics doesn't care, but from an explanatory point of view, using the E is very useful as it demonstrates which volume - and therefore which side of the plates - the work being done affects. This will help guide you to the difference between that and a more commonplace positive pressure system and why the sign for the pressure in the Casimir case is opposite, and why the system differs from a system with multiple competing positive pressures.

 

[Reality Check]

Yes, I'm aware of the fact it is used interchangeably with "vacuum energy". I just personally think it's a misleading term. There is "energy flowing" through the system at all times. It never achieves a "zero point", so why call it a "zero point"? Ground state energy might make sense, but "zero point energy" does not.

There is no "energy flowing". Energy does not flow through the system. Quantum fluctualtions create energy fluctuations inside the system.

One more time:
Zero point in zero point energy is not a description of the energy. Just like vacuum in vacuum is not a description of the energy.
Zero point/vacuum/ground state are descriptions of the system containing the energy and happen to be synonyms for the same thing.

To use your "logic": The energy in the system never achieves a vacuum so why call it a vacuum energy?

 

[GeeMack]

It's amazing......

I had no idea at the start of this conversation how truly "lost" you folks are when it come to actual physical processes and pure physics. You can't tell the difference between "negative" and "less than", and when it comes to the actual physical processes that produce "pressure" you're absolutely clueless.

You seem to think that pretty much everyone in the world who is involved as a professional instructor, researcher, or scientist in the fields of physics, cosmology, astrophysics, and related sciences is an idiot and Michael Mozina is the one individual who actually knows what he's talking about. Don't you ever find it interesting that in over 5 years of you running your mouth on various forums, the general opinion is virtually unanimous that it's the other way around? How do you explain that, Michael? You always seem to avoid answering that question. Why is it that you are so incapable of explaining your crackpot views in a way that anyone else agrees with you? Are you just the crappiest communicator in the entire field of physics? Or might it be that you're just plain wrong?

 

[Reality Check]

The Casimir effect is *not* an example of "negative pressure" in a vacuum. It's an example of a "pressure difference" between the outside and inside of the plates. Period.

And that "pressure difference" just happens to be negative - a small "pressure" on one side of the plate minus a larger "pressure" on the outside of the plate = a negative pressure. Period.

However you are missing one big point with your obsession on the Wikipedia diagram: The arrows are not pressures. They are forces as in the caption "Casimir forces on parallel plates". This is obvious since pressures are scalar quantities. They do not have directions.

The arrows in the diagram thus show that the net forces on each plate produce an attractive force bewteen the plates. The equivalent diagram is to just subtract the force vector on the outside of each plate from the force vector on the inside of the plate. The result is big blue arrows pointing away from the inside of the plates and no outside forces (arrows). Thus there is an attractive force normal to the surface of the plates. The convention is that attractive forces are negative and so p = F/A gives a negative pressure.

FYI: Why are attractive forces considered as negative?
Consider 2 equal and opposite forces acting on an object. The net force must be zero, i.e. adding the force vectors gives a vector with a magnitude of zero. That means that the magnitudes of the 2 forces must be opposite in sign. Applying a convention that repulsive forces are positive has the convenient result that everyday pressures are then calculated to be positive. This means that attractive forces always produce negative pressures.

 

[edd]

And that "pressure difference" just happens to be negative - a small "pressure" on one side of the plate minus a larger "pressure" on the outside of the plate = a negative pressure. Period.

I disagree with you on this point. As I've posted before, if you have some situation like gases in three volumes as:

2 atm | 1 atm | 2 atm

then the dividing walls between each chamber might be pushed together, but the pressures are all positive on both sides of the walls. If the walls move together due to the greater external pressure, then work is done by the outer volumes upon the inner one, and the energy in the centre volume rises.
Michael would be right in his arguments if the above system did represent something like the Casimir case, but it doesn't, and he's wrong.

 

[temporalillusion]

The basic problem with your premise MM is that your mental model you've constructed requires there be a maximum possible theoretical pressure. You should be able to calculate that, predict what it will be. You said 1 atmosphere before, but then you backtracked from that but you haven't brought forward any other number, either experimentally measured or theoretically derived.

 

[Michael Mozina]

You seem to think that pretty much everyone in the world who is involved as a professional instructor, researcher, or scientist in the fields of physics, cosmology, astrophysics, and related sciences is an idiot and Michael Mozina is the one individual who actually knows what he's talking about.

Pure baloney. The guys the wrote the WIKI article and created the diagrams obviously knew what they were talking about, as did the author of the article I cited. It's this little group that seem to be clueless.

http://physicsworld.com/cws/article/news/32380

The result is that the total field inside a gap between conductors cannot produce enough pressure to match that from outside, so the surfaces are pushed together.

That individual clearly understands QM. It's your industry that is clueless when it comes to actual physics, not the entire scientific world.

 

[Reality Check]

Pure baloney. The guys the wrote the WIKI article and created the diagrams obviously knew what they were talking about, as did the author of the article I cited. It's this little group that seem to be clueless.

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

And then "guys the wrote the WIKI article and created the diagrams" state that the pressure is negative. They show Casimir's derivation that the pressure is negative. They cite experiments that measure a negative pressure.

http://physicsworld.com/cws/article/news/32380

That individual clearly understands QM. It's your industry that is clueless when it comes to actual physics, not the entire scientific world.

You do understand that a repulsive force that pushes surfaces apart is exerts a pressure that is positive?
You do understand that this means that an attractive force that pushes surfaces together exerts a pressure that must be negative?

Or maybe you think that if we combine the 2 opposite forces and make them equal then there is still pressure exerted despite the fact that the net force is zero?

ETA: The "That individual clearly understands QM" in the quote is the science reporter - not the scientists who did the experiment.
Guess what - reporters alter their language to suit the audience.

ETA2: The experiment has been published by the scientists involved at The critical casimir effect universal fluctuation-induced forces at work and does have a paragraph similar to the Physics World report. They quote Casimir that the force per unit area of the Casimir effect is negative.

MM: You have posted that you are happy with definition of pressure as p = F/A. If F/A is negative then is p negative?

 

[GeeMack]

Pure baloney. The guys the wrote the WIKI article and created the diagrams obviously knew what they were talking about, as did the author of the article I cited. It's this little group that seem to be clueless.

No, Michael. The diagram does not mean what you think it means.

And again I'll ask my question, because for some reason you've avoided answering. I'm sure you'll agree with me on this point: If you are correct, you're obviously incapable of communicating effectively like a normal English speaking human being. After all, everyone in this conversation, and with almost no exceptions everyone you've babbled to on forums for the past several years thinks you're wrong. So, your communication skills must be darn near useless or you simply don't know what you're talking about and you are just plain wrong. Which do you think it is?

 

[The Man]

Pure baloney. The guys the wrote the WIKI article and created the diagrams obviously knew what they were talking about, as did the author of the article I cited. It's this little group that seem to be clueless.

[qimg]http://upload.wikimedia.org/wikipedia/commons/thumb/4/44/Casimir_plates.svg/300px-Casimir_plates.svg.png[/qimg]

http://physicsworld.com/cws/article/news/32380



That individual clearly understands QM. It's your industry that is clueless when it comes to actual physics, not the entire scientific world.

Oh, right our “industry that is clueless when it comes to actual physics”. The same industry that designed and built the computer you are now using to read this. As well as flash memory and produced utilizing scanning tunneling and atomic force microscopes. That are dependent on our understanding of quantum tunneling. Not to mention the plasma etching equipment responsible for the production of integrated circuits for the past, oh, 30 years.


ETA:
If you had actually bothered to read that article you would have seen that they were talking about the vacuum field, zero point energy and negative pressure. Indicating that, unlike you, they knew what they were talking about.

 

[Tubbythin]

Pure baloney. The guys the wrote the WIKI article and created the diagrams obviously knew what they were talking about, as did the author of the article I cited. It's this little group that seem to be clueless.

Are you completely incapable of comprehending what you're reading? Have you read the article at all.

A few quotes from the wiki article which explicitly disagree with the nonsense you've been spouting:

This force has been measured, and is a striking example of an effect purely due to second quantization.

Although the Casimir effect can be expressed in terms of virtual particles interacting with the objects, it is best described and more easily calculated in terms of the zero-point energy of a quantized field in the intervening space between the objects.

The vacuum has, implicitly, all of the properties that a particle may have: spin, or polarization in the case of light, energy, and so on. On average, all of these properties cancel out: the vacuum is, after all, "empty" in this sense. One important exception is the vacuum energy or the vacuum expectation value of the energy.

Casimir's observation was that the second-quantized quantum electromagnetic field, in the presence of bulk bodies such as metals or dielectrics, must obey the same boundary conditions that the classical electromagnetic field must obey. In particular, this affects the calculation of the vacuum energy in the presence of a conductor or dielectric.

The Casimir force per unit area Fc / A for idealized, perfectly conducting plates with vacuum between them is
F_c/A=-(hbar.c.pi²)/(240.a⁴).

And from the linked page on Casimir Pressure (my bolding):

Because Casimir force between conductors is attractive then the Casimir pressure in space between the conductors is negative.

 

[Klimax]

I notice that you aren't actually addressing the issue I raised: do you or do you not understand how P=F/A is equivalent to [latex]$P=-\frac{\partial E}{\partial V}$[/latex]? Once you answer that, we can move on to what negative pressure means, and then we'll be in a position to talk about when it does and doesn't exist.

If I may:
1)I would integrate [latex]$P=-\frac{\partial E}{\partial V}$[/latex] over V to get P=-E/V
2)then E=F.s where F-force and s-one component of V replaces E in P=-E/V
3)Results in P=-Fs/V =>P=-Fs/As => P=-F/A

Am I correct,Ziggurat?

P.S.:I did it since MM refuses to do it...

 

[Michael Mozina]

Oh, right our “industry that is clueless when it comes to actual physics”. The same industry that designed and built the computer you are now using to read this.

Really? You designed and built the computer I put together myself from parts? Are you're trying to claim astronomers built the microprocessor because it was developed during the Apollo missions?

 

[Michael Mozina]

No, Michael. The diagram does not mean what you think it means.

Yes, it does.

And again I'll ask my question, because for some reason you've avoided answering. I'm sure you'll agree with me on this point: If you are correct, you're obviously incapable of communicating effectively like a normal English speaking human being. After all, everyone in this conversation, and with almost no exceptions everyone you've babbled to on forums for the past several years thinks you're wrong.

Without exception, *every* creationist I have ever talked with thinks I'm wrong. So what? I learned a long time ago I can't change other people's opinions. They must do that themselves.

So, your communication skills must be darn near useless or you simply don't know what you're talking about and you are just plain wrong. Which do you think it is?

I think my communication skills are fine, but like all creationists you have an emotional attachment to being "right" even though you have no empirical support of your position. There is no such thing as "inflation". Guth quite literally made it up in his imagination and it has become a "MEME" within your industry. Dark energy is as "real" as "magic". SUSY particles have never been seen in an actual experiment.

I used to believe that a logical conversation with a creationist would eventually lead to them changing their mind, but I learned a long time ago that human beings are a stubborn lot, and not necessarily driven by "logic" and common sense and rational thought. This scenario is a perfect example. There cannot ever be a "zero pressure" vacuum because our technology (and nature) are incapable of producing a pure vacuum without atoms and without energy flowing through it. There will always be some amount of "pressure" in every vacuum chamber we ever create. The best "vacuum" you might ever hope to achieve would be a "zero pressure" chamber. There is nothing in physical reality that you could add or subtract from a zero pressure vacuum to create a "negative pressure". It's physically impossible.

This debate about pressure is really just a distraction because you can't produce empirical evidence of inflation, DE or SUSY dark matter, and your whole belief system depends on them. Without them you can't justify your chosen creation date any better than any other creationist.

Since you can't empirically justify your creation story and you can't damn me to hell for my insolence, you are forced to attack individual. Yawn.

 

[Ziggurat]

If I may:
1)I would integrate [latex]$P=-\frac{\partial E}{\partial V}$[/latex] over V to get P=-E/V
2)then E=F.s where F-force and s-one component of V replaces E in P=-E/V
3)Results in P=-Fs/V =>P=-Fs/As => P=-F/A

Am I correct,Ziggurat?

Sorry, but that's not correct. You will notice that you ended up with the wrong sign, and the sign is rather critical, especially in the current debate. I'll wait a bit more to see if Michael wants to respond, but if you're itching for the correct solution, I can PM you.

 

[Michael Mozina]

Are you completely incapable of comprehending what you're reading? Have you read the article at all.

Yes, do you?

Physicists in Germany have made the first direct measurements of the “critical Casimir effect”, a classical analogue of the strange quantum effect that draws two conducting surfaces together in a vacuum. They also say that the classical effect can be easily tuned to repel rather than attract for reducing undesirable friction in nanomachines.

The quantum Casimir effect comes about because a vacuum always contains fluctuating electromagnetic fields. Normally these fluctuations are roughly the same everywhere, but two close conducting surfaces set “boundary conditions” that limit the number of allowed field frequencies between them. Only waves that can fit multiples of half a wavelength between the surfaces resonate, leaving non-resonating frequencies suppressed. The result is that the total field inside a gap between conductors cannot produce enough pressure to match that from outside, so the surfaces are pushed together.

They are "pushed together" because the pressure on the outside of the plates is "greater than" the pressure between them. That is why the blue arrows are bigger on the outside than on the inside, but all the arrows point *towards the plate*.

 

[Michael Mozina]

I disagree with you on this point.

You guys better keep up a consistent front or the whole show is going to fall apart.