Lambda-CDM theory - Woo or not?

[Michael Mozina]

Finally! Yes, particle kinetic energy and pressure ARE unrelated in this aspect of the vacuum.

Er, I think a better way to phrase it would be to say that they are unrelated in some aspect of your "religion".

This is not a negative particle pressure. The dark energy can not be a bath of fast-moving particles.

What can it be (physically speaking)?

It's a constant energy density. In GR, where what you care about is E and dE/dV, a constant energy density has the same GR properties as a negative pressure. A gas-like, photon-like, or plasma-like energy density has the same GR properties as a positive pressure. Dark energy is not gas-like at all.

What is it?

 

[GeeMack]

What is it?

Uh, dark energy?

 

[Michael Mozina]

a) "... because I blustered my way through the Casimir Effect threads".

Um, no you just got through telling me that EM fields don't do the -rho act, and we all agreed that EM fields were the "cause" of that particular effect! You guys can't even keep your stories straight!

b) Remember HYPOTHESIS, Michael? The dark energy hypothesis is indeed positing something that has not been confirmed to exist. If we already had detected dark energy directly---for example, in a lab experiment---then it wouldn't be a hypothesis. The fact that we have not detected it is not an argument against it---that's what makes it (still) a hypothesis. HYPOTHESIS.

"God energy did it" is also a hypothesis by these weak standards. Where the empirical teeth the sets your "hypothesis" apart from religion?

 

[ben m]

Then what does (physically speaking) define pressure in vacuum Zig?

Pressure is defined as the way that energy changes with volume. P = -dE/dV.

Similarly; temperature is defined as the way entropy changes with energy, 1/T = dS/dE.

These are the *fundamental* definitions of pressure and temperature. If you *use* them to describe a classical gas---bouncing atoms in a box---you *derive* the fact that classical gases have positive pressure and temperature. If you use them to describe a quantum two-state system, you find that these systems can have positive or negative temperature. If you use them to describe a black hole you find that black holes have nonzero temperatures.

If you use them to describe the quantum vacuum, you find that the pressure (-dE/dV) is negative. Nothing to do with bouncing atoms.

Don't like it? Fine, make up your own word for the quantity -dE/dV---let's call it "Idiotitropy", not "pressure". If you go into to the equations of GR, you will find that the behavior of the Universe depends on the *idiotitropy* of its consitutents. Dark energy has negative idiotitropy. (Dark matter, photons, plasma, stars, and gas all have positive idiotitropy, which happens to be equal to their pressure.)

 

[Ziggurat]

Then what does (physically speaking) define pressure in vacuum Zig?

The same thing that defines pressure everywhere else. Which you haven't figured out.

You've got three options:
1) Provide a definition of pressure to demonstrate that you know what it is.
2) Admit that you don't know what pressure is, and I'll provide you with a definition.
3) Continue to wallow in your self-imposed ignorance.

Edit: looks like ben already gave you the answer. Let's see if you can figure out what it means. The smart money is on "no".

 

[ben m]

Do you want to know what the hypotheses are for "real things" that have vacuum energy density? Vacuum fluctuations of orginary virtual particles (a well-known feature of particle physics, visible in the Casimir effect) are one example hypothesis. A cosmological constant (an allowable, underlying feature of the geometry of spacetime) is another example hypothesis. A field condensate, akin to the Higgs condensate---a standard feature of particle physics, expected to be visible at the LHC---is another example hypothesis. And so on.

What can it be (physically speaking)?

So much for reading comprehension. Would all-caps help? Blinking text?

 

[Reality Check]

FYI, your concept was never all that 'complex', just too "general" and self serving. It's also based on a circular feedback loop:
...snipped usual display of ignorance crackpottery...

Wrong

1. Acceleration is observed. We understand that is an effect that has a cause.
2. We describe a set of possible causes (based on GR) as dark energy.
   There are other possible causes.

The effect just happens to be not measurable in conceivable lab experiments. You blame scientists for this. Anyone with 2 brain cells blames the universe.

The definition of dark energy is not vague. I was just dumbing it down in the hope that you might be able to understand it. Obviously it is impossible to dumb dark energy down far enough fro your level of intellect without making the definition wrong.

...
There is no correlation between the observation of acceleration and "dark energy' except in your head. It's entirely impotent in the lab!

That is completely what we expect from someone who has to believe that stars do not exist (they are entirely impotent in the lab) !

 

[Michael Mozina]

So much for reading comprehension. Would all-caps help? Blinking text?

An example of what I actually asked for would do the trick.

http://www.internationalskeptics.com/forums/showpost.php?p=6287851&postcount=3545

Your analogies are completely and utterly inappropriate and unrelated to the topic of negative pressure. Sol just eliminated the EM field from consideration and yet you're claiming it's somehow helpful in your argument about negative pressure. That's complete and utter baloney! EM fields don't do that negative pressure trick. They do a positive pressure trick because they involve kinetic energy in "moving particles".

The bottom line is that you cannot even come up with any other known form of energy that does that nifty negative pressure trick and the Casimir effect is utterly unrelated to "negative pressure". Reread sol's post ben.

 

[Tim Thompson]

Random Dark Dumbness II

Unless both you and Birkeland are incorrect, the EM field *MUST* be responsible for that "unknown acceleration" and our term "dark energy" is now understood to be directly related to the EM field.

Not even close. To begin with, we already know for a fact that electromagnetic forces cannot be responsible. I have already discussed this many times, but since you seem uninterested in an honest discussion, it is no surprise that you always ignore it (see Dark Energy and Empirical Science II and the classical electromagnetism links therein). But more generally, since when is anything that Birkeland did, right or wrong, at all relevant to the dark energy problem anyway? Birkeland was interested in trying to figure out what caused aurorae, and postulated a flow of charged particles from the sun as an explanation. But cosmological dark energy is not logically connect to the aurorae in any way, nor to the solar wind, nor to any flow of charged particles. So the whole idea you present here is illogical at best.

You guys have all these various "magnetic reconnection" theories to tinker around with, but each and every one of them is simply a theory about the way the EM field manifests itself in the solar system.

Not even close, but since you seem uninterested in an honest discussion, it is no surprise that you systematically reject the controlled laboratory experiments in which magnetic reconnection is observed to happen (see Dark Energy and Empirical Science VI and the magnetic reconnection links therein).

Unless you can demonstrate that "dark energy" is somehow empirically related to acceleration of plasma/objects (like the EM field in the lab), you really just have a "religion', one that epically fails to have any effect here on Earth.

Whether or not dark energy has an observable effect here on Earth is not even relevant to the discussion. As for empirical demonstrations, that has already been done. But, since you seem uninterested in an honest discussion, it is no surprise that you have never even bothered to look at it (see Empirical Evidence for Dark Energy).

What you've done here is you've created a nice 'religion' that cannot ever actually be "falsified" because it's too generic. That applies not only to your "Dark energy" concepts, but also to inflation, dark matter, etc. All of these terms of so vague as to be 'unfalsifiable" because because they all ultimately represent generic labels that define our human ignorance.

The booming voice of ignorance. There is nothing at all in this paragraph that is even close to correct. Dark energy, inflation, dark matter, are all exceptionally falsifiable. Indeed, the falsification/verification process is underway and open to scrutiny. But, since you seem uninterested in an honest discussion, it is no surprise that you have never even bothered to look at it (see Inflationary Cosmology is Real Science and links therein).

... but now you've created a theory so specific and so impotent in the lab that it entirely unfalsifiable because it's entirely impotent outside of your mythology.

Falsifiability does not require laboratory experiments, nor does empirical science in general. But, since you seem uninterested in an honest discussion, it is no surprise that you have chosen to actually re-define words, or whole concepts, so as to avoid ever discussing any real science. You choose to ignore real empirical science, and that choice destroys everything you have to say (see Dark Energy and Empirical Science VI and the empirical science links therein).

But Ben, I'm not proposing any *NEW* forces of nature! I'm simply rearranging *KNOWN* forms of matter and energy and looking for empirical solutions to existing problems.

That argument entirely depends on whether the acceleration is *internally driven* or *externally* (to this physical universe) driven.

Could you be any more dishonest than this? After railing & insulting & belittling everyone about controlled laboratory experiments and using only known laws of physics, you are willing even to go outside the entire physical universe, to save your own failed religion. By your own standards, the very ones you demand everyone else adhere to, this is not acceptable. Had any of us seriously suggested a cause outside the physical universe you would have responded with a stream of insults. Consider yourself lucky we don't treat you the same way you think everybody else should be treated.

 

[Ziggurat]

EM fields don't do that negative pressure trick. They do a positive pressure trick because they involve kinetic energy in "moving particles".

You were just given a definition of pressure. And yet, you persist in claiming that pressure is something completely different. Just how willfully clueless are you, Michael?

The bottom line is that you cannot even come up with any other known form of energy that does that nifty negative pressure trick and the Casimir effect is utterly unrelated to "negative pressure". Reread sol's post ben.

Reread it yourself. Sol was talking about photons. The Casimir effect isn't about photons, but vacuum expectation values of the field.

 

[Michael Mozina]

This is fascinating behavior at this point. Long ago you were *ALL* trying to tell me that the Casimir effect was related to "negative pressure". Sol just explained that EM fields produce *POSITIVE* pressure and therefore are ruled out from consideration in your search for the mythical negative pressure monster. The Casimir effect is directly related to the EM field. You've literally destroyed your own argument about the Casimir effect being an example of "negative pressure in a vacuum" and yet you expect me to believe you know what you're talking about at the level of empirical physics.

 

[ben m]

I guess I should have used the all caps.

An example of what I actually asked for would do the trick.

Your analogies are completely and utterly inappropriate and unrelated to the topic of negative pressure.

I guess you're unqualified to judge. Those were not analogies, those were (just like I said) examples of actual hypotheses for what the dark energy actually is. It could be virtual particles, or a field condensate, or an aspect of classical spacetime. That's what you asked for. What did you expect, "it could be neutrinos"?

Too bad you understand none of these things. If you analyze the hypothesis (HYPOTHESIS) of a field condensate using quantum mechanics and GR correctly---not using some classical-gas analogy, not using a terrella photo, and not guessing wildly---it is clear that a field condensate is a viable candidate for the underlying "real thing" whose gravitational effects we're seeing.

Sol just eliminated the EM field from consideration and yet you're claiming it's somehow helpful in your argument about negative pressure.

Sol eliminated the classical Maxwell's Equation version of E&M. ( Do you agree with that, finally? Good, then you can discard Plasma Cosmology at last.) The Casimir effect does not arise in classical E&M. It arises from virtual quantum particles.

That's complete and utter baloney! EM fields don't do that negative pressure trick. They do a positive pressure trick because they involve kinetic energy in "moving particles".

VIRTUAL particles, Michael. I put that word in there for a reason. Why did you ignore it? (Oh, because you don't understand it anyway, and ignoring it gave you an excuse for a nice rant. Again.)

Again, so much for reading comprehension.

 

[Dancing David]

The arrows and squigley lines!

 

[Michael Mozina]

VIRTUAL particles, Michael. I put that word in there for a reason. Why did you ignore it?

Um, I did not 'ignore it', I busted your whole show with it.

Vacuum fluctuations of orginary virtual particles (a well-known feature of particle physics, visible in the Casimir effect) are one example hypothesis.

You specifically linked this right back to the Casimir effect that is *CAUSED* by the EM field. We can demonstrate it's related to the EM field simply by using plastic instead of metals. Your VP's don't do much of anything to plastic.

 

[Ziggurat]

This is fascinating behavior at this point.

Indeed. You still can't figure out what pressure means, and are making no effort to do so. Quite fascinating.

Long ago you were *ALL* trying to tell me that the Casimir effect was related to "negative pressure".

Indeed.

Sol just explained that EM fields produce *POSITIVE* pressure

Photons do. But the Casimir effect isn't the result of photons.

The Casimir effect is directly related to the EM field.

Yes: the vacuum expectation value. Not real photons.

You've literally destroyed your own argument about the Casimir effect being an example of "negative pressure in a vacuum"

No. You're literally being clueless.

and yet you expect me to believe you know what you're talking about at the level of empirical physics.

And you expect anyone to believe you about negative pressure when you don't even understand the definition of pressure?

 

[sol invictus]

This is fascinating behavior at this point. Long ago you were *ALL* trying to tell me that the Casimir effect was related to "negative pressure".

Vacuum energy can either have negative energy and positive pressure or negative pressure and positive energy, depending on the type of excitation that creates it. Pick your poison.

Sol just explained that EM fields produce *POSITIVE* pressure and therefore are ruled out from consideration in your search for the mythical negative pressure monster.

What I said applies to classical configurations of the EM field, and to photon gasses (like the cosmic microwave background or the light in the room you're in now). It does not apply to Casimir energies/pressures, regardless of what produces them (virtual photons or something else).

The Casimir effect is directly related to the EM field. You've literally destroyed your own argument about the Casimir effect being an example of "negative pressure in a vacuum" and yet you expect me to believe you know what you're talking about at the level of empirical physics.

There's a Casimir effect for all particle species, actually, it just happens to be easiest to measure for photons.

 

[sol invictus]

You specifically linked this right back to the Casimir effect that is *CAUSED* by the EM field. We can demonstrate it's related to the EM field simply by using plastic instead of metals. Your VP's don't do much of anything to plastic.

So why do experiments on the Casimir effect demonstrate that its pressure is negative?

 

[Reality Check]

This is fascinating behavior at this point. Long ago you were *ALL* trying to tell me that the Casimir effect was related to "negative pressure". Sol just explained that EM fields produce *POSITIVE* pressure and therefore are ruled out from consideration in your search for the mythical negative pressure monster. ... .

This is fascinating ignorance and abysmal reading comprehension from you at this point.
sol invictus was not taking about the Casimir effect (negative pressure caused by virtual photons). He was talking about the real photons in an EM field that happen to exert a positive pressure.

Off topic (not that this thread really has a topic anymore except as a futile attempt to educate Michael Mozina):
A little thought experiment.
Think about the the pressure exerted on a negatively charged plate by a positive charged plate. The normal component of the EM force is in the opposite direction to a corresponding force that would be exerted on the plate by a gas. The definition of pressure means that force exterted by a gas is considered to be positive leading to a positive pressure.

Michael Mozina
I wonder what you think the sign of the normal force exerted on the plate by the charge is and what this means for the sign of the pressure?
If you thnk that it is positive then why would the force (and so the pressure) go to zero if we add a gas between the plates?

 

[Ziggurat]

So why do experiments on the Casimir effect demonstrate that its pressure is negative?

Obviously the experiments are wrong. I suspect it's because they're not empirical.

 

[Michael Mozina]

So why do experiments on the Casimir effect demonstrate that its pressure is negative?

They don't.