Lambda-CDM theory - Woo or not?

[Tubbythin]

The difference between us edd in all probability is age. You haven't yet had the time to really study this from all the various angles, and to fully get into QM and all the things that I've had a chance to do over my nearly 50 years on earth.

You tried to apply the ideal gas law to the Casimir effect! Excellently illustrating to everybody that you have next to no understanding of QM whatsoever.

 

[DeiRenDopa]

What makes it a physical impossibility? Nothing, really. You yourself don't know of a mechanism which can produce negative pressure in a vacuum, but that says nothing, really. No conservation laws would be violated by negative pressure in a vacuum, there's no violation of any thermodynamics laws by negative pressure in a vacuum, so what's the objection? Simply that you don't believe in the proposed mechanism.

But why should your objection carry any weight? After all, you've had an enormously difficult time even coming to a definition of pressure, and repeatedly confused an equation of state for a definition. Furthermore, at one point you objected to the idea of negative pressure in general, a position I already demonstrated was quite wrong. So your intuition in the matter of pressure is simply not to be trusted.

No, if we are to determine whether or not negative vacuum pressure is possible, we need to be far more rigorous about all of this than you have been. We cannot rely on Wikipedia drawings. We need to construct a quantitative model of what's under discussion. Which is exactly what I've been trying to do by starting with a definition of pressure. To my amazement, though, you have continually balked at the very first step in any logical discussion of the possibility of negative vacuum pressure: namely, arriving at a working definition of pressure.

So once again, I ask: do you understand and accept the definition [latex]$P=-\frac{\partial E}{\partial V}$[/latex]?

I'm going to toot my own horn a bit here ...

... and repeat the last part of my post #1871 in this thread, on physics and what I called the quantitative revolution (bold added, except for "only", which is bold in the original):

First, 'known forces of nature' are so known via equations and numbers only; if you work at the 'qualitative' level, you cannot have 'known forces of nature'.

Second, a century (or more) may well pass between the first publication of the equations and numbers describing a 'known force of nature' and its testing in the lab.

Third, the application of math to points on the sky can lead to acceptance of a new 'force of nature'.

And so on.

Now we know, from a great many of MM's posts, that he rejects all three of the above points, especially the third one. This alone makes his approach to science very different than that of scientists - or at least physicists - over the past four+ centuries ... and it means that the discussion we should be having is not about Birkeland, the solar wind, inflation, Einstein's EFE, negative pressure, etc; rather it should be about what constitutes science (or at least physics).

If we were to have such a discussion, I think we'd find that a key aspect of MM's approach is an unstated, and possibly unrecognised, misunderstanding of equations and numbers; in short, a world where the quantitative revolution didn't happen.

 

[Ziggurat]

What *exactly* (be very specific) did you intend to add or subtract from a "pure" vacuum (one devoid of all atoms and QM processes) to create a "negative pressure" in that vacuum?

You're jumping the gun. We first need to nail down a working definition of pressure (which I keep asking you if you accept, and you keep ignoring). Then we can examine what general conditions produce negative pressure under our adopted definition. Only after we've done that does it make sense to ask if we can add anything to a vacuum which will produce negative pressure. Iif you haven't even established what negative pressure means and what the requirements for it are (and you show no signs of having the slightest clue), then how can you even evaluate any answer I might give you?

So back to basics, Michael. I've repeatedly given you a standard text-book definition of pressure. Do you accept that definition? Do you understand that definition? If you need it explained to you, I can do that. But there's little point in proceeding any further until we establish that baseline. Why are you so resistant to doing so?

 

[temporalillusion]

What *exactly* (be very specific) did you intend to add or subtract from a "pure" vacuum (one devoid of all atoms and QM processes) to create a "negative pressure" in that vacuum?

Exhibit C that you seem to be thinking the Casimir effect is pressure from the same source that atmospheric pressure is.

If you could create perfect vacuum with not a single atom or molecule, not a single photon or neutrino, what would be the result of the experiment?

I'm asking very simple and straight forward questions, why do you ignore them?

You're the only one that doesn't accept that the article is correct, MM. I quote from it:

Case closed. If you agree with the article, you agree the pressure is negative. Can we end this idiotic discussion now?

I tried that dozens of pages ago, MM won't answer that. Or he'll claim the math is incomplete, but won't provide anything better, and will then post later again that he agrees with the article.

 

[Michael Mozina]

While there's physical reality and there's our models of it, our models are invariably mathematical as that is the best way to construct testable theories.

That is fine until you start attaching math to invisible unicorns and then trying to "test" this idea with point at the sky exercises. It's also fine as long as you don't confuse an "oversimplified math formula" for the actual physical process that it attempts to "describe". As long as you realize the the minus sign in that math formula refers to *relative* pressure, it's really not a problem. If however you confuse "lower pressure" with "negative pressure", then it's a problem. None of the blue arrows point away from any surface of any of the plates.

So if we push for a mathematically based understanding of the ideas in competition here, it is because that is the best approach to testing which of those ideas actually represents physical reality.

Well, in our world of actual physical reality, no "vacuum" is devoid of "pressure". Every vacuum has some few atoms bouncing around in it, and at some temperature. It's physically impossible to even achieve a "zero" pressure due to atoms in the chamber. More importantly to the discussion in question, the vacuum is also "full of" quantum energy that conveys kinetic energy to all objects in the chamber. It *pushes into* every single object in the vacuum against all surfaces, usually at the same rate on all sides. In *some interesting* scenarios, that QM process can convey "force" (or pressure if you prefer) onto every point of every surface of every object. There is always *positive quantum and/or kinetic energy in the system* at all times.

If you cannot understand the mathematics to the point that you misunderstand the theory and mistakenly ascribe the wrong predictions to it, you are not in a good position to test it against reality.

Likewise if you cannot understand the physical process that the mathematical formula attempts to describe, you cannot understand it's logical limits nor can you appreciate the relevancy of various signs in your mathematical equations.

We're firmly rooted in mathematical theories that offer the opportunity to be scientifically examined, rather than cartoons, which don't offer anything like the accuracy of prediction that match the accuracy of observation and experimentation that we are capable of.

You ultimately aren't capable of "controlled experimentation" with inflation, DE, SUSY particles or "negative pressure in a vacuum" because none of these things exist in nature or have any effect on nature. You may "believe" that they do, but you cannot empirically demonstrate your claim in controlled experiments. You simply "hold belief" in a "belief system" that lacks empirical support. I can show you lots of Birkeland's experiments to show you that EM fields can move plasma, and emit plasma from spheres in a vacuum. Let's see you even create a "zero pressure" vacuum chamber for us here on Earth.

 

[Michael Mozina]

You're the only one that doesn't accept that the article is correct, MM. I quote from it:



Case closed. If you agree with the article, you agree the pressure is negative. Can we end this idiotic discussion now?

You still cannot tell the difference between "low pressure" and "negative pressure". Case closed. Dude, not one single arrow points away from any surface of any plate. Get a grip. Your minus sign is simply a "relative number" that the author explained in great detail and that the WIKI article illustrates in color for you, squiggly green lines, blue arrows and the whole nine yards. Wake up and smell the coffee. Your minus sign is a "relative pressure" and still a "positive" number. Look at the the little blue arrows between the plates. They point *INTO* not *AWAY FROM* the plate.

 

[Michael Mozina]

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.

How about this part sol, or did you intend to just wallow in denial forever?

 

[Michael Mozina]

You're jumping the gun.

You're dodging the question. What did you intend to add or subtract from a "pure and empty vacuum" (devoid of everything) to achieve a "negative pressure" in that chamber?

 

[Ziggurat]

You're dodging the question.

Oh, the irony. Not to mention the hypocrisy.

What did you intend to add or subtract from a "pure and empty vacuum" (devoid of everything) to achieve a "negative pressure" in that chamber?

A field with a nonzero vacuum expectation value and positive energy density. Duh. Now let's figure out if that answer works. In order to do that, YOU need to answer MY question. But you've been resistant from the start to put any of this on a quantitative basis. Why is that?

 

[edd]

That is fine until you start attaching math to invisible unicorns and then trying to "test" this idea with point at the sky exercises. It's also fine as long as you don't confuse an "oversimplified math formula" for the actual physical process that it attempts to "describe". As long as you realize the the minus sign in that math formula refers to *relative* pressure, it's really not a problem. If however you confuse "lower pressure" with "negative pressure", then it's a problem. None of the blue arrows point away from any surface of any of the plates.

Dark energy and dark matter are invisible, just like invisible unicorns.

But if you start seeing hoofprints appear out of nowhere, and horn-marks appearing near the hoofprints, you'd better start believing in invisible unicorns.

edit: And actually, yeah, while I'm at it - the minus sign doesn't refer to relative pressure. And please stop talking about blue arrows. Pretend that cartoon doesn't exist, and start at this from the physics, not a wikipedia article.

 

[Michael Mozina]

Dark energy and dark matter are invisible, just like invisible unicorns.

But if you start seeing hoofprints appear out of nowhere, and horn-marks appearing near the hoofprints, you'd better start believing in invisible unicorns.

I don't believe you've seen enough "magicians" in action yet in your life. That is evidently the difference between us. I'd immediately start looking for the "trick".

The problem here is that I have no way to empirically validate your belief system, regardless of which of these ideas you attach your math to. In the case of inflation, it presumably doesn't even exist anymore, so there can *never* be a demonstration of "hoofprints" done right in front of my eyes for me to inspect. It would be like coming across hoofprints and *assuming* that they came from an invisible unicorn.

 

[Michael Mozina]

A field with a nonzero vacuum expectation value and positive energy density.

Word salad. Name the field. EM fields evidently aren't going to cut it because they cause the little blue arrows to always point *into* every single surface.

Duh. Now let's figure out if that answer works.

It does not work. It's word salad devoid of any physical meaning until you name the field you intend to evidently "add"? to the vacuum.

In order to do that, YOU need to answer MY question. But you've been resistant from the start to put any of this on a quantitative basis. Why is that?

I've answered your question and given you a definition of "pressure" at least 3 different times in three different ways, evidently none of which are acceptable to you, including the one's provided on WIKI. What exactly is your problem?

 

[edd]

I don't believe you've seen enough "magicians" in action yet in your life. That is evidently the difference between us. I'd immediately start looking for the "trick".

Actually, I do a bit of magic as well as cosmology. Admittedly the latter is professional.

The problem here is that I have no way to empirically validate your belief system, regardless of which of these ideas you attach your math to. In the case of inflation, it presumably doesn't even exist anymore, so there can *never* be a demonstration of "hoofprints" done right in front of my eyes for me to inspect. It would be like coming across hoofprints and *assuming* that they came from an invisible unicorn.

The 'hoofprints' for inflation are in the CMB and the universe's flatness. For dark energy it's in several cosmological observations, primarily SN type Ia's. Dark matter has perhaps more footprints than the others.

Now I wouldn't actually necessarily argue that they're metaphorically invisible unicorns, but they're invisible unguligrades of some variety.

 

[Ziggurat]

EM fields evidently aren't going to cut it because they cause the little blue arrows to always point *into* every single surface.

Argument from pictures. Sorry, not going to work.

I've answered your question and given you a definition of "pressure" at least 3 different times in three different ways, evidently none of which are acceptable to you,

No. You have only once given me an actual definition of pressure, P=F/A. Your previous attempts were complete and utter failures, marked by a display of ignorance about what it even means to define a quantity. Now I'm asking you if you understand that this definition is equivalent to the definition I gave. And you are refusing to answer. You have never answered whether or not you accepted that definition. It's really quite simple: either you understand that the two definitions are equivalent, or you don't. Yes or no. I'm really not asking for much, and yet you can't provide it. What are you scared of, Michael? Looking ignorant? It's too late for that.

 

[Tubbythin]

You're dodging the question. What did you intend to add or subtract from a "pure and empty vacuum" (devoid of everything) to achieve a "negative pressure" in that chamber?

Do you really want somebody to go back and look at the number of times you've refused to answer the simple yes or no question about the text book definition of pressure?

 

[Tubbythin]

What *exactly* (be very specific) did you intend to add or subtract from a "pure" vacuum (one devoid of all atoms and QM processes) to create a "negative pressure" in that vacuum?

Wow. You really didn't understand a single word of the wiki article did you?

 

[edd]

Wow. You really didn't understand a single word of the wiki article did you?

Quite. The addition might be... well... "QM processes", eh?

 

[Tubbythin]

Quite. The addition might be... well... "QM processes", eh?

But... but... he's older than you! So he must be correct and you must be wrong.

 

[Dancing David]

You're dodging the question. What did you intend to add or subtract from a "pure and empty vacuum" (devoid of everything) to achieve a "negative pressure" in that chamber?

Would you agree to attractive force?

 

[Perpetual Student]

Quote:
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.

Is it not true that the pressure outside is zero (or nearly so) so that the negative pressure inside results in the surfaces being pushed together?