Lambda-CDM theory - Woo or not?

[GeeMack]

This whole conversation isn't even related to understanding the math in the final analysis.

Michael, every single issue of physics is a math problem. Stomp your feet and stuff your fingers in your ears all you want, but if you can't do math you simply cannot understand physics. If you can't do the math, put things in quantitative terms, make the numbers work and explain everything mathematically, you will never be able to understand physics. And you will never be able to explain physics to other people in a way that they will understand it. Really. You're the only one who disagrees with me on this point.

 

[edd]

Physics is on my side here folks.

How do you reach that conclusion when multiple physicists disagree and not one physicist does agree?

 

[Aitch]

Michael, every single issue of physics is a math problem. Stomp your feet and stuff your fingers in your ears all you want, but if you can't do math you simply cannot understand physics. If you can't do the math, put things in quantitative terms, make the numbers work and explain everything mathematically, you will never be able to understand physics. And you will never be able to explain physics to other people in a way that they will understand it. Really. You're the only one who disagrees with me on this point.

At the risk of giving comfort to the enemy, I'm not sure I agree with this. It's years since I studied physics seriously, but I can still read books that describe how things work/happen/whatever. Not, probably, to great depth, but a qualative description IS possible. Proving the qualitive model, making predictions based on it will take maths, but I don't think it's vital to get an overview at least.

Oh, and MM, you don't need to be a mathematician to write code. I spent years coding complex OR based programs; all you need is a decent algorithm/formulae to work from.

 

[Ziggurat]

I know that there is no possibility of removing every atom from the chamber so I *know for a fact* that the "pressure" in the chamber is greater than zero.

No. You know that the pressure due to any gas inside the chamber is greater than zero. You know nothing else. More specifically, you do not know about the contribution to the pressure from any other sources. Nor is the pressure from atoms relevant, since the pressure due to any residual gas will be the same on both sides of the plate.

I also know for a fact that the force on the outside of the plates is "greater than" the force that pushes against the inside of the plates.

Which would be true if the force outside was zero and the force inside was negative. Zero is greater than negative one. Not really a hard concept, Michael. So how can you distinguish between that and the force outside being large and positive and the force inside being small and positive? You cannot, except by creating a model and comparing that model to experiment. Which physicists have already done: they've got a model which makes predictions about the absolute pressure, and which agrees with experimental measurements of the relative pressure. But you are unwilling (and possibly unable) to actually examine the model.

Zig, there is no possibility for the pressure to be anything other than a positive number on every surface of every plate.

You say that like it's an axiom, but that's simply not the case. You need to examine the model and determine what the model says, otherwise you can say nothing about the absolute pressures.

It's just not even possible to achieve a "zero pressure' in that chamber, let alone a "negative one".

You didn't believe in negative pressures under any circumstance either, but that position was clearly wrong, so why do you have faith in your current position? And that's all it is, too: faith. Negative pressure violates no laws, so the only way to determine whether or not it exists is to examine the model and see if the model ever predicts negative pressures. But you refuse to do that.

All the blue arrows necessarily point *into* not *away from* the plates.

Again: the picture is not the model. Pictures are not physics. So stop referring to the picture, because nobody cares what the picture looks like. It's a drawing, it's not real.

The "pressure" due to atoms is "greater than zero"

How many times do you have to be told this: we're not talking about pressure due to atoms.

Physics is on my side here folks.

No, Michael, it isn't.

I didn't create those drawings or write that explanation. They were done by someone *other than* Michael Mozina.

Argument from authority doesn't cut it, Michael.

 

[Michael Mozina]

How do you reach that conclusion when multiple physicists disagree and not one physicist does agree?

While the first statement is true, the second one is not. Someone besides me created that drawing and wrote that explanation and I have no reason to believe they were even the same individual.

 

[The Man]

You've yet to provide one empirical experiment to demonstrate that nature complies with your formula all the way up to an infinite number. Let's see your lab work sol. What's the most "pressure" ever registered in one of these experiments? Was it closer to +-1ATM or infinity?

Again if you would look at your own reference you would find..

In fact, at separations of 10 nm — about a hundred times the typical size of an atom — the Casimir effect produces the equivalent of 1 atmosphere of pressure (101.3 kPa).

So based on the calculations the “Casimir effect produces the equivalent of 1 atmosphere of pressure (101.3 kPa)” “at separations of 10 nm”

As far as I know we have not yet been able to measure the Casimir effect at such separations, primarily because it is exceedingly difficult to maintain such separations in experimental measurement apparatus.

If you would look at Fig 1 on the following paper…

http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=2588&context=physics_articles

you would see that experimental results agree with theoretical predictions from 750nm down to just under 165nm. You will also note the absolute pressures that result are negative. With the maximum experimental pressure graphed at about -1060 mPa or 1.060 Pa for a separation of about 164nm. As such your expectations that experimental results should deviate from projected results at separations of 10nm or lower are without merit.

 

[Michael Mozina]

No. You know that the pressure due to any gas inside the chamber is greater than zero.

Ok, we seem to agree on at least that much.

You know nothing else.

I also know that *billions* of neutrinos blow right through every vacuum in existence. I also know that EM fields provided "pressure" or more accurately "force" of their own, that also "pushes into" every side of every object in the vacuum.

More specifically, you do not know about the contribution to the pressure from any other sources.

I have some idea of other influences based upon other fields of science, specifically QM. I know that that there is some force being applied to all surfaces in the chamber for instance.

Nor is the pressure from atoms relevant, since the pressure due to any residual gas will be the same on both sides of the plate.

That too is a simply an "assumption" on your part. I would personally *not* make that assumption. If there can be a pressure difference at the level of QM there could also be a pressure difference due to atoms too, if only due to pure random chance and physical influences. I would agree it is not necessary to *assume* there is a difference at the atomic level.

Which would be true if the force outside was zero and the force inside was negative. Zero is greater than negative one. Not really a hard concept, Michael.

There is no "negative pressure" on any side of any plate. All you are doing is subtracting one positive pressure from another positive number and coming up with a negative number based on the order you chose to do your calculation. This is exactly like the wing analogy I used early on and exactly like RC's pressurized tank analogy. So what if you can come up with a minus sign by subtracting the big number from the little one. Neither side of the wing experiences "negative pressure". Neither side of the tank experiences negative pressure, and no area in the chamber experiences "negative pressure". These are all "relative numbers" that are all related to "positive pressure". It's not that hard of a concept Zig.

 

[The Man]

At the risk of giving comfort to the enemy, I'm not sure I agree with this. It's years since I studied physics seriously, but I can still read books that describe how things work/happen/whatever. Not, probably, to great depth, but a qualative description IS possible. Proving the qualitive model, making predictions based on it will take maths, but I don't think it's vital to get an overview at least.

Oh, and MM, you don't need to be a mathematician to write code. I spent years coding complex OR based programs; all you need is a decent algorithm/formulae to work from.

The problem is, Aitch, that without understanding the math and models that ‘overview’ can be qualitatively wrong as MM clearly demonstrates with his ‘overview’ of the Casimir effect. A model must be quantitative as well as qualitative to make testable predictions that separate it from other such competing models.

 

[The Man]

I have some idea of other influences based upon other fields of science, specifically QM. I know that that there is some force being applied to all surfaces in the chamber for instance.

Please enlighten us, MM, as to what you do in fact ‘know’ about your QM “force being applied to all surfaces in the chamber for instance”.

 

[Michael Mozina]

Again if you would look at your own reference you would find..

So based on the calculations the “Casimir effect produces the equivalent of 1 atmosphere of pressure (101.3 kPa)” “at separations of 10 nm”

As far as I know we have not yet been able to measure the Casimir effect at such separations, primarily because it is exceedingly difficult to maintain such separations in experimental measurement apparatus..........

.......As such your expectations that experimental results should deviate from projected results at separations of 10nm or lower are without merit.

These two statements are in opposition. Either we *have* or we *have not* experimented at separations of 10nm or lower. Which are you claiming is true? Ultimately all I'm actually suggesting is that there is an absolute limit to this force that is likely to be a number that is larger than zero and a number that is less than infinity. 1ATM seems likely to me, whereas the physical limits of nature preclude this number from reaching infinity. If you can demonstrate otherwise, be my guest.

 

[Ziggurat]

I also know that *billions* of neutrinos blow right through every vacuum in existence.

Wow. You know something completely irrelevant to both calculations and measurements of the Casimir force. Congratulations.

I also know that EM fields provided "pressure" or more accurately "force" of their own, that also "pushes into" every side of every object in the vacuum.

Do you, now? And how do you know that? Because you saw a picture? Come now, Michael, you'll have to do better than that. How do you calculate that pressure, and what pressure do you get when you do the calculation?

That too is a simply an "assumption" on your part.

No, actually, it is not. It's a conclusion based upon understanding how atoms behave.

If there can be a pressure difference at the level of QM there could also be a pressure difference due to atoms too, if only due to pure random chance and physical influences.

Pressure differences due to random chance are called noise, Michael. And they vary with time, and they get filtered out.

There is no "negative pressure" on any side of any plate.

Again with the unsupported declarations. Let's see you do the calculations, Michael.

All you are doing is subtracting one positive pressure from another positive number and coming up with a negative number based on the order you chose to do your calculation.

No, Michael. You keep claiming that all the pressures are positive, but you have done absolutely nothing to demonstrate that this is the case. You just refer to calculations of different pressures (like the ideal gas law) which simply aren't applicable, and don't give the observed results. And you ignore the actual calculations of the model which does give the observed results.

These are all "relative numbers" that are all related to "positive pressure". It's not that hard of a concept Zig.

It isn't, and yet you fail to fully understand it. Oh, the irony. Yes, the measurements only indicate relative pressure. But based upon the measurements alone, then, it's impossible to rule out negative pressures. So the only way to do that is to consult a model which gives the correct results. What does the model say about absolute pressures, Michael? That's a question you've repeatedly ignored. I understand that you're probably not capable of doing the calculations yourself, what with your complete lack of any math skills. But you've essentially refused offers to walk you through those calculations.

 

[The Man]

These two statements are in opposition. Either we *have* or we *have not* experimented at separations of 10nm or lower. Which are you claiming is true? Ultimately all I'm actually suggesting is that there is an absolute limit to this force that is likely to be a number that is larger than zero and a number that is less than infinity. 1ATM seems likely to me, whereas the physical limits of nature preclude this number from reaching infinity. If you can demonstrate otherwise, be my guest.

I stated quite clearly “As far as I know we have not yet been able to measure the Casimir effect at such separations, primarily because it is exceedingly difficult to maintain such separations in experimental measurement apparatus.”

I also stated quite clearly that “experimental results agree with theoretical predictions from 750nm down to just under 165nm”.

My statements are not in opposition and your expectation “that there is an absolute limit to this force that is likely to be a number that is larger than zero and a number that is less than infinity. 1ATM seems likely to me, “ remains without any merit by experimentation or calculation.

 

[Michael Mozina]

Please enlighten us, MM, as to what you do in fact ‘know’ about your QM “force being applied to all surfaces in the chamber for instance”.

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

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.

Don't like an EM oriented explanation? Here, let's try one based on "VP's". The diagram arrows point exactly the same way, namely *into* the plates. Why?

http://www.casimir.rl.ac.uk/

The fluctuating virtual particles exert a "radiation pressure" on the plates which on average is greater outside the plates than between them - as shown in the diagram.

Notice how all the arrows point towards and not away from the plates just like the WIKI diagram?

Why do all these arrows in both of these diagrams point into the surfaces of every plate? Did both of these guys "screw up" when they created their diagrams of the direction of force?

 

[Tubbythin]

My bolding:

You are a lying sack of ◊◊◊◊. I wrote and sell an accounting program you idiot.

Hmm. This is coming from the person who was caught telling a blatant lie earlier in the thread and who as an alternative to the CMBR proposed something that got the CMBR peak wavelength wrong by a factor of over 700 million, tried to use the ideal gas equation as a definition of pressure and actually used the fact that he was older than somebody else as a reason why his understanding of QM was better than said poster's.
The irony of this guy knows no bounds.

 

[Tubbythin]

Only waves that can fit multiples of half a wavelength between the surfaces resonate, leaving non-resonating frequencies suppressed.

Ie. the more we move the plates apart, the more waves we can fit in. The more waves we can fit in the greater the energy density. Hence dE/dV is positive. Hence -dE/dV is negative. Hence the pressure is negative.
Congratulations Michael!

 

[ben m]

No you don't. You understand how to mechanically run through the math, but you don't understand the physical process at all. You seem to believe that a minus sign in your math formula demonstrates "negative pressure in a vacuum", but all it demonstrates is a "pressure difference" between the inside and outside of the plates, much like RC's pressurized tank analogy.

Michael, if you apply P = -dE/dV to an ideal gas, you get PV = nRT. If you don't like the minus sign, do you think that PV = -nRT in an ideal gas?

If you apply P = -dE/dV to a collection of blackbody photons, you get P = T^4. If you don't like the minus sign, do you believe that P = -T^4?

If you apply P = -dE/dV to a box spring mattress, you get that P = Akx, where k is the the spring constant per unit area and x is the compression of the mattress. If you don't like the negative sign, do you think that mattresses suck you inward (P < 0) when you compress them (x > 0)?

Seriously, MM, there is nothing wrong with P = -dE/dV (and you have not even begun trying to show something wrong.) There is nothing wrong with the standard QED calculation of E (and you have not even begun trying to show something wrong.)

The only thing wrong is your supposed "intuition" about why negative pressures can't possibly make sense to you, and your argument seems to boil down to "force vectors are always drawn with positive magnitudes".

 

[The Man]

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



Don't like an EM oriented explanation? Here, let's try one based on "VP's". The diagram arrows point exactly the same way, namely *into* the plates. Why?

http://www.casimir.rl.ac.uk/



[qimg]http://www.casimir.rl.ac.uk/casimir-plates.gif[/qimg]

Notice how all the arrows point towards and not away from the plates just like the WIKI diagram?

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

Why do all these arrows in both of these diagrams point into the surfaces of every plate? Did both of these guys "screw up" when they created their diagrams of the direction of force?

Did you miss this part..

since it is a direct consequence of the existence of Zero-Point Fluctuations: a turmoil of virtual particles that come in and out of existence and that can violate the energy-momentum conservation of the system for very short periods of time, as described by Heisenberg's uncertainty principle. The fluctuating virtual particles exert a "radiation pressure" on the plates which on average is greater outside the plates than between them - as shown in the diagram.

Again there is that reference to the Casimir force resulting from fluctuations in the zero-point energy that you claim to be ‘physically impossible’. So please tell us what is the radiation pressure that results from Zero-Point Fluctuations and thus your “force being applied to all surfaces in the chamber for instance”. You might want to try to actually understand zero-point energy if you are going to use it in your explanation as opposed to simply claiming that it is ‘physically impossible’. The fluctuations go both ways so they average to zero over time and a zero radiation pressure is greater then a negative pressure.

You should also note this tidbit from your reference, as quoted above, to “virtual particles that come in and out of existence and that can violate the energy-momentum conservation of the system for very short periods of time”. So your “force being applied to all surfaces in the chamber for instance” would require a consistent (in time) violation of energy-momentum conservation, as I have repeatedly mentioned before.

 

[Michael Mozina]

The problem is, Aitch, that without understanding the math and models that ‘overview’ can be qualitatively wrong as MM clearly demonstrates with his ‘overview’ of the Casimir effect. A model must be quantitative as well as qualitative to make testable predictions that separate it from other such competing models.

The obvious key prediction of positive pressure would be that all the arrows of force point *into* every surface of every plate. What exactly would you "predict" these arrows of force to look like if the vacuum contains "negative pressure" vs. a "positive pressure" and please explain your answer.

 

[Michael Mozina]

Did you miss this part..



Again there is that reference to the Casimir force resulting from fluctuations in the zero-point energy that you claim to be ‘physically impossible’.

Notice how you ignored the direction of force to focus on a "detail"?

IMO, the "VP" orientation of QM seems rather "dated" to me at this point. When early experiments were first performed we did not understand the notion of EM fluctuations very well, or the implications of having billions of neutrinos flowing through the "vacuum", etc. Since that time, more "contemporary" explanations like the first one I provided note that this is simply fluctuation in the carrier particles of the EM field. Even in the VP world, there is an *UNDERSTANDING* that there is *energy in the system* and it too calls this "radiant pressure" that pushes *INTO ALL SURFACES IN THE CHAMBER*.

As I have stated before, I think the term "vacuum energy" is a more accurate description only because a "zero" implies none, and there is no point in any vacuum that contains "zero" energy. There is no "zero point", only "positive pressure and kinetic energy in the vacuum".

Why are you ignoring the fact that his arrows point into the plates just like the WIKI diagram? Why did he draw it that way, with the arrows pointed into the plates? Did they both screw up, or did you just screw up?

 

[GeeMack]

The obvious key prediction of positive pressure would be that all the arrows of force point *into* every surface of every plate. What exactly would you "predict" these arrows of force to look like if the vacuum contains "negative pressure" vs. a "positive pressure" and please explain your answer.

There are no "arrows of force". When you say crazy things like that you can't possibly wonder why people think you're a crackpot without a clue.