Split Thread Michael Mozina's thread on Dark Matter, Inflation and Cosmology

[DazzaD]

May I also bring this up

http://arxiv.org/abs/0801.4380

for the laymen among us:


VII. CONCLUSIONS
In this paper, we have measured the cross-correlation
between the CMB and a large range of probes of the
density in a consistent way, and have calculated their
covariance taking into account their overlapping sky cov-
erage and redshift distributions. While individual mea-
surements vary somewhat depending on how the data are
cleaned and how the covariance is calculated, the overall
significance of the detection of cross-correlations is at the
∼4 5 level.

This means we looked at a hell of a lot of stuff that other people have done, loads of different ways of "looking" at the universe, and found that they pretty much all tell the same story to a very high degree of confidence.


These observations provide important independent ev-
idence for the existence and nature of the dark energy.
The observed cross-correlations are consistent with the
expected signal arising from the integrated Sachs-Wolfe
effect in the concordance model with a cosmological con-

stant. The observed signal is slightly higher than ex-pected,
higher than the expectation from WMAP best fit
model by about 1 , thus favouring models with a lower


Chances are dark energy is not just pie in the sky but a real "thing".

. However, we do not see any significant trend for the
excess as a function of redshift, and so there is no indi-cation
of an evolving dark energy density. By combining
these results with other cosmological data, we find a gen-erally
consistent picture of the behaviour of the Universe,
which is converging towards the CDM model although
the uncertainties remain considerable. The only partial
exception to this picture is the BAO result which, even
when combined with our ISW measurement, is in slight
tension with the CDM model (at ∼1 ).

No one here is claiming its all done and dusted, but we gave our best theory a serious beating (again) and its still standing up very well.

 

[DSo]

I’m trying to understand MM’s thought here and the counter arguments being presented.

Pressure = Force/Area (P=F/A)

MM thinks that Pressure cannot be absolutely negative, you can only have negative differences in relative pressure.

Now has anyone ever tested the Casimir effect inside of a man-made vacuum? (a quick read of the Wiki article says yes …)

Now I’m going to define some terms, relative to the Wikipeida cartoon that has been common in this tread

Pvac = Pressure inside the vacuum (now I know that the best man-made vacuum is nowhere near the pressure of interstellar space, etc, etc).

Fcas = Casimir Force (which I understand to be attractive in this case).

Pcas = Casimir pressure = Fcas/(Area of plates)

Now in this experiment if Pvac minus Pcas is less than zero, then does that not prove that negative absolute pressures are in fact a reality?

Does experimental data like this exist? If it does, then that should put to rest MM’s argument.

 

[DazzaD]

Does experimental data like this exist? If it does, then that should put to rest MM’s argument.

Is this any good to you?

http://prl.aps.org/abstract/PRL/v88/i4/e041804

 

[Michael Mozina]

Chances are dark energy is not just pie in the sky but a real "thing".

Here is the basic flaw in his argument. The evidence suggests that changes are that "acceleration" is not just pie in the sky but a real thing. There's no one to one correlation between "acceleration" and "dark energy". That's the flaw in that particular argument.

 

[Michael Mozina]

Is this any good to you?

http://prl.aps.org/abstract/PRL/v88/i4/e041804

It's good to me if I had any doubt the effect was 'real'. Does it help your case in any way? If so, how?

Keep in mind that even in a "vacuum" the effect is "real". The kinetic energy transfer is not between atoms in the vacuum and the plate, but between carrier particles of the EM field and the plate. All sides of all plates experience "pressure" from the particles, but pressure on the outside surfaces are "greater than" the inside. The WIKI diagrams show this two ways, in terms of an EM oriented view of QM and a "quantum foam" orientation of QM, but both show more "pressure" on the outside and "less pressure" on the inside. It's perfectly logical when you think about it.

It's not at though I am suggesting it would not occur in a vacuum or claiming that the kinetic energy transfer is between atoms and the plate. The kinetic energy transfer is between the carrier particle of the EM field and the plate, and the "pressure" is simply "greater" on the some sides and "less" on others. That's why the whole thing is related to the geometry of the experiment.

A wing on an airplane experiences similar forces. As the plane moves, it experiences "more pressure" on the bottom of the wing and "less pressure" on the top of the wing. You could write an equation to express the concept in terms of "negative pressure" on the top of the wing and it might be entirely accurate in terms of 'predicting' the flight characteristics too. It's still a "relative" pressure, not an absolute concept of pressure. Sometimes the math can be misleading if all you pay attention to is the minus sign.

 

[Dancing David]

Yes! Let's move on. What is exactly wrong with the inflation theory? I get that testing in a lab has proven elusive so far, but, as has been brought up so many times already, so have most things in theoretical physics at one time or another. So, I don't think that's grounds to dismiss it entirely. What is the *theoretical* argument against inflation theory? Where does it breakdown or seem questionable? Isn't it something already measured in the universe? (As a layman, I also get that distant measurements seem fantastic. For example, I've often wondered if the red shift indicating acceleration wasn't also caused by gravitational effects from space debris or just the effect of such a long distance; something else other than acceleration. But since I'm not formally trained in this subject, I'm pretty sure that has either been considered before or is just not relevant. That is, I think it is highly unlikely I'm going to out-think the great thinkers based on so little knowledge.)

There are about fifty pages on this somewhere, the green arrows, the green arrows, AAAAAAAAAAAAAAGGGGGGGGGGGGHHHHHHHHHH!

Help help help.



The basis of other causes of the redshift have pretty much been ruled out.

 

[Dancing David]

Are you familiar with the use of GR to invoke "negative pressure" in the cosmological models?

Say, in particular, a stress-energy tensor?

Nope but there are those darn green arrows.

 

[Michael Mozina]

I’m trying to understand MM’s thought here and the counter arguments being presented.

Pressure = Force/Area (P=F/A)

MM thinks that Pressure cannot be absolutely negative, you can only have negative differences in relative pressure.

Now has anyone ever tested the Casimir effect inside of a man-made vacuum? (a quick read of the Wiki article says yes …)

Of course it works in a vacuum because the carrier particle of kinetic energy in this case is the carrier particle of the EM field, not the atoms in the chamber! The "pressure" still effects all sides of the plates, just some sides more than others.

Just like in the wing analogy, that minus sign in your math formula is a "relative" pressure, not an absolute measurement of the overall pressure. The pressure is simply greater on one side of the plate and less on the other side.

 

[ben m]

There's no one to one correlation between "acceleration" and "dark energy".

Can I take that statement to mean, "I agree that the data shows that the expansion of the universe is accelerating"? That would be a good first step.

But I see you are still learning how "hypotheses" work.

Dark energy is a hypothesis which provides the best explanation for the acceleration (+CMB+LSS+etc as usual) data. If there were a competing hypothesis, we would entertain it. Dark energy is, however, the only known hypothesis which predicts an accelerating Universe with the CMB/LSS/BBN that we see.

(And before you suggest "electromagnetism" as the answer: nobody ever rejected plasma cosmology "because it can't account for the cosmic acceleration that was discovered in 1999-2000". We've rejected plasma cosmology consistently since the 1970s, because it disagrees with practically everything we can see in the sky.) If you can come up with a plasma cosmology that agrees with the Hubble law, CMB temperature, CMB angular power spectrum, CMB polarization spectra, LSS, BBN, rotation curves, cluster temperatures, strong lensing, weak lensing, Sachs-Wolfe, Sunyaev-Zeldovich, and the Lyman-Alpha forest, then maybe we can ask if it has a competing dark-energy-free explanation for acceleration.)

 

[Pythonic]

Of course it works in a vacuum because the carrier particle of kinetic energy in this case is the carrier particle of the EM field, not the atoms in the chamber! The "pressure" still effects all sides of the plates, just some sides more than others.

Just like in the wing analogy, that minus sign in your math formula is a "relative" pressure, not an absolute measurement of the overall pressure. The pressure is simply greater on one side of the plate and less on the other side.

Then by your logic, MM, zero cannot be real either because energy cannot be destroyed; something is always there. But I think that line of reasoning fails to realize that all measurements are comparative and not "absolute" in the sense you're using it.

 

[Michael Mozina]

Are you familiar with the use of GR to invoke "negative pressure" in the cosmological models?

Say, in particular, a stress-energy tensor?

Yes, but you'll need to throw me a bone here and use it in some meaningful physical context, explain it's use, what it relates to, etc.

I've learned over the years that various individuals have slightly different viewpoints of how things started and prefer to frame things in their own way.

How about you explain your "creation" story for me and explain when and how inflation did it's thing, what the "vacuum" might apply to, what that stress energy tensor applies to, etc.

You might try something like:

In the beginning was the (hot/cold) lumpy thing that (did/did not) have mass in the form of (fill in the blank). The "vacuum" was (fill in blank) in relationship to said lumpy thing. Inflation came from (fill in blank) and did (fill in blank) to the (hot/cold) lumpy thing.....etc.

Maybe you would personally prefer to begin your tale with the "vacuum" itself. I really don't care. I just need you put something into context for me to give you a meaningful answer and understand what you are physically trying to suggest is going on with inflation, and how that applies to a negative pressure in a vacuum.

 

[Michael Mozina]

Then by your logic, MM, zero cannot be real either because energy cannot be destroyed; something is always there. But I think that line of reasoning fails to realize that all measurements are comparative and not "absolute" in the since you're using it.

I had not really thought about it in quite that context before, but I suppose that's a fair way of looking at it. Energy cannot be created or destroyed so it must always have existed in some 'form' or another, and it will always continue to exist in some form or another.

 

[Tubbythin]

You can appeal to authority all you like

Appeals to authority are only really a fallacy when the authority appealed to is not an authority in the topic of conversation. But anyway, you said "While it is very clear that these individual understand their math *very* well, when it comes to subatomic physics, they are evidently clueless about what goes on in a vacuum at the level of kinetic energy and actual physics." However, you failed to back this up with any actual evidence. Only your blind assertion that you are correct. Baring in mind that you keep referring to what is essentially classical gas pressure to describe vacuum pressure it should be fairly obvious to anyone with even the slightest understanding of physics (ie anybody that knows the difference between a gas and a vacuum) that you have absolutely no idea what you are talking about.

but there is no physical way in the universe to get "negative pressure' out of a "vacuum".

Yes there is. As I have shown. You can say no there isn't as much as you like you're still wrong. Just like you were wrong about dark matter detectors not having control mechanisms. Just like you were wrong about the iron surface of the Sun. Just like you were wrong about the possibility of dark matter being composed of Earth sized objects. Just like you were wrong about Eddington finding the CMBR from starlight...

The lowest possible energy state of the vacuum is *ZERO*, not negative infinity.

What are you talking about?

 

[Michael Mozina]

Can I take that statement to mean, "I agree that the data shows that the expansion of the universe is accelerating"? That would be a good first step.

Yes, I'd agree with that statement.

But I see you are still learning how "hypotheses" work.

Dark energy is a hypothesis which provides the best explanation for the acceleration (+CMB+LSS+etc as usual) data. If there were a competing hypothesis, we would entertain it. Dark energy is, however, the only known hypothesis which predicts an accelerating Universe with the CMB/LSS/BBN that we see.

Fine, consider your math blatantly pilfered, and "God energy" is now your scientific/religious arch nemesis. How might we physically (empirically) tell the two "hypothesis" apart?

 

[Tubbythin]

Fine, consider your math blatantly pilfered, and "God energy" is now your scientific/religious arch nemesis.

"God energy" is not a hypothesis. Its two words you just stuck together. I guess we'll have to add "hypothesis" to the list of scientific words and phrases you completely fail to grasp.

 

[Michael Mozina]

Appeals to authority are only really a fallacy when the authority appealed to is not an authority in the topic of conversation. But anyway, you said "While it is very clear that these individual understand their math *very* well, when it comes to subatomic physics, they are evidently clueless about what goes on in a vacuum at the level of kinetic energy and actual physics." However, you failed to back this up with any actual evidence. Only your blind assertion that you are correct.

No, I also clearly explained why it's incorrect at the level of kinetic energy and "physics". The limit of 'pressure" in a vacuum is not "negative infinity", it's "zero". No vacuum anywhere on Earth or in space is "perfect", therefore it's always "positive". A "negative pressure' from a "vacuum" is physically impossible. You can ignore that fact all you like but it is the kinetic energy of the atom/subatomic particle that provides the "pressure" and some form of positive pressure exists in every vacuum.

Baring in mind that you keep referring to what is essentially classical gas pressure to describe vacuum pressure it should be fairly obvious to anyone with even the slightest understanding of physics

Um, anyone that understands even *some* physics can understand why Guth's claim is wrong and I'll keep working on you till you get it if necessary. Others will probably accept it before you finally do, but you'll eventually see that I am right. Guth chose a limit that is physically impossible. That is in fact a "mathematical" error too. Part of any good mathematical presentation of the physics must accurately describe the physical processes and "vacuums" cannot ever achieve "negative pressure". It's simply not possible. The limit of pressure in the vacuum should have been zero, not a negative number because there is no such thing as "negative kinetic energy".

Yes there is. As I have shown. You can say no there isn't as much as you like you're still wrong. Just like you were wrong about dark matter detectors not having control mechanisms.

Wait a minute. Please do not villianize me unfairly. I did not say that *ALL* dark matter detectors/experiments have no control mechanisms. I said not all of the one's I've read about have control mechanisms. Even I mentally accept the fact that LHC could make me eat empirical crow on the topic of dark matter.

Just like you were wrong about the possibility of dark matter being composed of Earth sized objects.

You can't "see" a single Earth sized object outside of our solar system yet, but you want me to believe that you've accounted for every single one of them in a galaxy already? Give me a break.

I need a beer....Is it beer:30...Oh yes it is! I'll be back....

 

[Michael Mozina]

"God energy" is not a hypothesis. Its two words you just stuck together.

Ditto on "dark energy". You observed "acceleration", not "dark energy".

 

[Michael Mozina]

Appeals to authority are only really a fallacy when the authority appealed to is not an authority in the topic of conversation.

Er, no. It's a fallacy to *assume* that the authority figure is right only because he is a recognized authority on the topic.

 

[Tubbythin]

No, I also clearly explained why it's incorrect at the level of kinetic energy and "physics".

You "explained it" using gas pressure. Gas pressure is not vacuum pressure.

The limit of 'pressure" in a vacuum is not "negative infinity", it's "zero".

No it isn't. You can say that as many times as you like. It doesn't make it true.

No vacuum anywhere on Earth or in space is "perfect", therefore it's always "positive".

The second clause does not follow from the first.

A "negative pressure' from a "vacuum" is physically impossible.

You can say that as many times as you want, it doesn't make it true.

You can ignore that fact all you like

Its not a fact. its your assertion. The only way you've tried to back it up is by talking about what is essentially gas pressure in a container. The vacuum is not a gas and it is not in a container. Therefore your defence is utterly invalid.

but it is the kinetic energy of the atom/subatomic particle that provides the "pressure"

It is not. Not in a vacuum.

and some form of positive pressure exists in every vacuum.

Again, blind assertion, no evidence to back it up.

Um, anyone that understands even *some* physics can understand why Guth's claim is wrong and I'll keep working on you till you get it if necessary. Others will probably accept it before you finally do, but you'll eventually see that I am right.

Even if Guth IS wrong you are still completely wrong.

Guth chose a limit that is physically impossible. That is in fact a "mathematical" error too. Part of any good mathematical presentation of the physics must accurately describe the physical processes and "vacuums" cannot every achieve "negative pressure". It's simply not possible.

Once again. This is a blind assertion. Please stop making blind assertion. If you want to discuss vacuum pressure, please discuss the properties of a vacuum. Please stop talking irrelevant stuff about gas pressure. Its analogous to saying "Newton's law of gravity of a force law, threfore all forces are governed by Newton's law of gravity".

The limit of pressure in the vacuum should have been zero, not a negative number because there is no such thing as "negative kinetic energy".

Vacuum pressure has nothing to do with kinetic energy. Therefore your argument is completely invalid.

Wait a minute. Please do not villianize me unfairly. I did not say that *ALL* dark matter detectors/experiments have no control mechanisms. I said not all of the one's I've read about have control mechanisms. Even I mentally accept the fact that LHC could make me eat empirical crow on the topic of dark matter.

Which dark matter detectors have you read about that don't have control mechanisms. Please produce a list.

You can't find "see" a single Earth sized object outside of our solar system, but you want me to believe you've accounted for every single one of them already. Give me a break.

Got any more straw going spare there? I never said we could account for everyone. But we can certainly say they don't contribute significantly to the "missing mass budget". Myself and others have already clearly explained why this is the case.

 

[Tubbythin]

Ditto on "dark energy". You observed "acceleration", not "dark energy".

In a sense I suppose you are right. But we have hypothesese for what dark energy might actually be. We do not have hypothese for what "God energy" is.