SNe Ia, Implications, Interpretations, Lambda-CDM...

[Mike C]

This doesn't tell me anything about the degree of error in these observations or the effect of this error.

 

I already told you that the SN 1a's that were observed in the Virgo Cluster had the largest error margins in comparison to the other 7 methods of distance measurements. This error margin was +/-5 megaparsecs that is equivalent to 16.3 million light years. So in relation to this distance, this is an error margin of +/-30%.

The dark energy observations are at a distance that is 560 times further than the Virgo Cluster (approximately). So if you multiply this VC error by the differnce in distances, that compounds the error by 560 times.

Although the percentage is still the same for both distances, this 30% margin of error is too great to give those DE evaluations too much credibility.

 

So in my opinion, they have about as much credibility as the BBT.

 

I really do not understand. Surely not all the SNe Ia observed were in the Virgo Cluster. What is the relationship between this cluster and the sample of supernovae observed?

 

I cannot answer that but I would think that the observations in the VC that is much nearer to us would have greater credibility than those distant DE observations.

 

It was not expected, but it was one of the things that the observation was able to measure. It influences the second derivative of the scale factor, which was the target of the observations.

 

Is that a long way of saying that you don't have a physical theory upon which to base your criticisms?

 

Well, I do rely more on visualizations for solutions rather than math.

 

After all, the BBT has no real evidence for its promotion.

Einsteins mass/energy formula is wrong since we should all know that basic physics says 'forces' create the energies.

The eruptions on our Sun is being promoted as 'magnetic field' eruptions when observational proof says that impacting comets cause these eruptions.

 

That is why I have reasons to question the current teachings in science.

 

Mike C

[coldcreation]

A brief example of how gravitating zero point energy causes "dark energy." Consider a universe that has real scalar particles in it, described by a field [imath]phi[/imath] with action...

 

Will, I shall get back to this post as soon as possible. Thanks for your patiences, and for your double post...

 

 

 

It is thus a true constant of nature, a fundamental one (the value of which is fixed for all times, again, in my opinion (based on empirical data), equal to zero).

 

Perhaps you can explain how something can be both a constant of nature and equal to zero everywhere. I think I'll develop an "angel constant" and claim that it is a true constant of nature that is zero everywhere.

 

Certainly in a mathematical sense, whenever zero or infinity are used as numbers, there are problems that arise - especially here, in light of the fact that both fundamental physical constants and mathematical constants are dimensionless. However, fundamental physical constants are determined strictly by physical measurement and are not defined by combinations of pure mathematical constants. So it is possible for a fundamental physical constant to have a zero value if indeed it is measured to be so.

 

The value of zero for the cosmological constant can be ascertained empirically - without having to probe deep into the universe. Indeed that value can be determined right here in the solar system...

 

 

 

The interpretation of "negative pressure" to describe lambda is untenable, for a variety of reasons. I argue that there is no such thing as negative pressure. All pressure must be positive. There is therefore the need for an absolute scale (similar to the Kelvin temperature scale, where absolute zero is the starting point, the ultimate limit of coldness, beyond which, even in principle, temperature cannot drop).

 

Indeed, it is very similar, since there are applications for temperature below absolute zero.

 

Negative absolute zero temperature

 

• Certain semi-isolated systems (for example a system of non-interacting spins in a magnetic field) can achieve negative temperatures; however' date=' [b']they are not actually colder than absolute zero[/b]. They can be however thought of as "hotter than T = ?", as energy will flow from a negative temperature system to any other system with positive temperature upon contact.[my bold]

 

Surely these are not temperatures colder than absolute zero. My comparison therefore seems to hold.

 

 

 

Lambda would thus be defined as the ultimate limit of pressure equal to zero pressure. The implications of this interpretation are profound and far-reaching, since it requires the identification of a new law of nature which would explain a fundamental constant of nature: lambda.

 

So what you are saying is that you want to introduce a totally new concept, give it the same name as an existing constant (or the purposes of confusion?) ? A concept that goes against the existing well established laws of physics that use terms like "negative pressure" and has no conceptual or empirical support behind it?

 

Not at all. This is not a new concept. It is an interpretation of Einstein's cosmological constant, a property of empty space which act to counter gravity, where before it was just a term in the field equations (without real physical meaning), now defined. It does not go against any law of physics, quite the contrary, it espouses every physical law in a very general way, both conceptually and empirically.

 

Negative pressure is not based on any established physical law, not is it used as a term in any physical law (contrarily to what you write).

 

 

 

In my opinion, this explanation of negative pressure is untenable. So is this one. And these definitions do not apply to lambda.

 

They aren't very good entries, but what can one expect from Wikipedia? The negative pressure of the cosmological constant is associated with the basic mathematics of general relativity.

 

Yes, but when it was removed from the field equations it made little difference. The term had never found a proper description that could be measured empirically. Now that is possible, but not quite in the way you imagined. It needs to be done model-independently.

 

 

 

"It's weird negative pressure" (Dr. Krauss).

 

Yes, it's very weird if one does not address it in the actual scientific terms but instead dresses it up for a pop audience.

 

Even in scientific terms dark energy is weird. I agree with modest that there is something intuitive about it, but sometimes intuition is not the best arbitrator when it come to science.

 

 

 

Yes, it can be related to pressure just as gravity can be related to pressure. But does not mean that it is pressure at all (let alone with a negative sign).

 

Sure. But what does the actual physics say?

 

I will address this in my comment to Will's post

 

 

 

Two problems with this hypothetical state (negative pressure) are that it can never be detected empirically, thus the term ‘dark’ energy, and it always requires new physics (something that is not physics).

 

The term "dark energy" arises because it's a new cosmological idea to popular science journalism. That this cosmological behaviour is related to negative pressure is something that can be measured. You even linked to a study that was all about trying to determine the equation of state of this energy density, and that determines the pressure!

 

Yes, and in that paper, if I recall, there are studies underway to determine if dark energy is a cosmological constant or something else (such as quintessence).

 

 

 

For Einstein to have excluded the cosmological term for reasons of ‘aesthetic’ simplicity, before ever having spelled out a fully persuasive and unambiguous elucidation of its meaning, is as understandable as it is forgivable.

 

It is forgivable in the sense that we can forgive him for removing a part of the mathematics of his theory without good grounds. That doesn't mean that every scientist should ignore the empirical results regarding this part of the theory.

 

Recall that Einstein formally abandoned the cosmological-term in 1932 after having reviewed the theoretical work of Friedmann and the experimental discoveries of Hubble (see Pais 1982 p. 288). This was when the idea of an initial explosion began raising its ugly head. It is a sweet paradox that today the blunder-lambda resurfaces with a new pretext: to explain why the universe appears to be accelerating.

 

 

 

However, for cosmologists to have reinvented and savored the principle (despite Einstein’s original motivations and ambitions for having introduced lambdda, i.e., to secure a stationary universe) and exploit it as the propulsion mechanism, the driving force, the ‘tantamount’ negative pressure, that produced the cosmic repulsion or the acceleration of expansion, bestows real physical meaning to the expression paradoxical.

 

If you would read through the mathematics of the theory, you would see that there is nothing to negative pressure in this case that isn't forced by Einstein's mathematical theory.

 

I will address this problem in my comments to Will's post...

 

 

 

What vacuum experiments do demonstrate is that zero pressure is the ultimate limit inherent in nature.

 

What about the applications of negative pressure listed in the wikipedia article that you linked to? Are the technologies based on these principles not actually operating?

 

If you refer to this: "Negative pressure is a term used to describe a pressure less than that of a surrounding fluid (such as the air). The term comes from gauge pressure pressure gauges, which measured a pressure against air pressure" or to Cavitation, it is hard to see how this type of technology could in any natural was apply to lambda or dark energy, since cavitation, for example, is known to cause spots of high temperature and emits shock waves (a source of noise) which would be in principle detectable. To my knowledge, there is no such effect observed with respect to dark energy.

 

 

 

The interpretation of "negative pressure" to describe lambda is untenable, for a variety of reasons. I argue that there is no such thing as negative pressure. All pressure must be positive.

 

PhysBang is right. "negative pressure" "cosmological constant" "vacuum energy" are all verbal descriptions to something that has only one mathematical meaning in GR. As Will pointed out, if you rearrange the field equations with lambda on the stress-energy tensor side it shows clearly its effect. The stress energy tensor of the vacuum equals lambda over eight pi times the metric tensor. So, when you say lambda is not a negative pressure of the vacuum - there would appear to be no discernible mathematical meaning behind that.

 

Rather than looking at the problem from an abstract mathematical point of view I have focused on a wide range of observational, conceptual and qualitative perspectives. The latter, I realize, is not the norm in physics, though in light of the problems that revolve around gravity (spacetime curvature) and its unification with other so-called 'forces' of nature, as well as QM, and, in light of what I see as a fine-tuning in nature, both locally and (I suspect) globally, I began the endeavor to try and understand what is observed, in the simplest fashion possible, i.e., to explain observations with a minimum amount of natural laws. In the process, I came to the conclusion that one natural law was missing from the text books. That law has to do with both gravity and Einstein's cosmological terms (without the introduction of new physics).

 

 

When you say new physics has to be invented to cope with new observations - I honestly don't know what new physics you are referring to. The physics has been there since GR was envisioned and would seem to work to describe the SNe 1a observations. If lambda is the 'new physics' then I am thoroughly confused.

 

The new physics I refer to includes cold-dark matter, i.e., nonbaryonic matter (whatever that means, thought to comprise 24% of the mass-energy density). I realize there are potential candidates for this 'substance' but it seems something 'new' is missing from physics before the problem is resolved. In my response to Will's excellent post above, I will attempt to explain why, as far as dark energy is concerned, new physics is required. It will be a difficult task, but one I am preparing to confront, since I will be using conventional weapons rather than weapons of mass destruction. :)

 

 

I think we should investigate deeper lambda in the field equations and in their metric solutions particularly the FLRW metric or perhaps a vacuum solution, because it feels like some key ingredient is missing in our conversation. It feels like we think we are discussing the same thing while perhaps we are not.

 

I think, since your post above, Will's post above (as well as yours) went into sufficient detail. I would prefer to go into detail of what effects (if any) can be observed locally (here in the solar system, or in the Local Group) than to elaborate further on the maths (since there seems to be either something amiss, or something extra, involved in the equations).

 

 

CC,

 

De Sitter's Model and Luminosity-Distance in Cosmology

RC Barnes; 1981; Ro. Astro. Soc. 195, 959;

 

Seems to discuss exactly what you've been discussing. I just skimmed over it, but I'm sure I can read it in detail soon. It discusses apparent vs. intrinsic brightness at redshift in de Sitter's model vs. other models. It was obviously written before SNe 1a data.

 

Thanks for this link. The abstract looks promising. I have yet to read the rest. I had not heard of this paper before...

 

 

CC

[PhysBang]

I already told you that the SN 1a's that were observed in the Virgo Cluster had the largest error margins in comparison to the other 7 methods of distance measurements. This error margin was +/-5 megaparsecs that is equivalent to 16.3 million light years. So in relation to this distance, this is an error margin of +/-30%.

The dark energy observations are at a distance that is 560 times further than the Virgo Cluster (approximately). So if you multiply this VC error by the differnce in distances, that compounds the error by 560 times.

Although the percentage is still the same for both distances, this 30% margin of error is too great to give those DE evaluations too much credibility.

But does this error corrupt the entire sample? Are the same techniques used in the Virgo Cluster the same techniques used for all SNe Ia? Does the error affect the measurement of the second derivative or just the first?

After all, the BBT has no real evidence for its promotion.

Sure, aside from observed homogeneity, measurements of the Hubble parameter, observed element abundances, measurements of parameters from large-scale structure, and measurements from the SNe Ia, it has no evidence.

Einsteins mass/energy formula is wrong since we should all know that basic physics says 'forces' create the energies.

Hunh?

That is why I have reasons to question the current teachings in science.

But not to actually do science yourself? Why don't you get involved and do the work yourself?

[modest]

I would prefer to go into detail of what effects (if any) can be observed locally (here in the solar system, or in the Local Group) than to elaborate further on the maths (since there seems to be either something amiss, or something extra, involved in the equations).

 

That would be best if we could measure it in as small a system as possible, but I wonder how likely that is? It looks like there have been claims that it can be done with range data to mars landers:

 

Solar and stellar system tests of the cosmological constant, and:

La constante cosmológica

 

Others claim it isn’t possible to put constraints on lambda with distances as small as our solar system:

Interplanetary Measures Can Not Bound the Cosmological Constant

 

So, I'm not sure how approachable it is from that angel.

 

-modest

[capricornicis]

:Wink:Equation for detecting dark matter

 

x = dark matter

B = stars

S = space

T = time

G = gases

 

X = [( BG + BG )-( G*G)]+(B/g* B/g)/T*S:ebomb:

[Mike C]

But does this error corrupt the entire sample? Are the same techniques used in the Virgo Cluster the same techniques used for all SNe Ia? Does the error affect the measurement of the second derivative or just the first?

 

From what I understand about the SN 1a's research is that they get a copy of the light curves pattern to derive their conclusions of distance as a measurement.

If elemental data is made, this would involve an xray telescope.

Those are my opinions.

 

Sure, aside from observed homogeneity, measurements of the Hubble parameter, observed element abundances, measurements of parameters from large-scale structure, and measurements from the SNe Ia, it has no evidence.

 

This homogenity is overplayed since the structures we see represent all phases of star and galactic formations.

Since all these structures went through the same evolutionary process in this BBT, then you should expect to see more similarities in the structures that we do not see.

 

But not to actually do science yourself? Why don't you get involved and do the work yourself?

 

I am involved in solving most all the questions that the BBT creates.

And that is what the BBT does, create a lot of questions. The evidence you cite above can be applicable to the SSU as well.

 

Mike C

[coldcreation]

 

A brief example of how gravitating zero point energy causes "dark energy." Consider a universe that has real scalar particles in it, described by a field...

 

• [snip. Sorry I had to remove your beautiful equations, they came out funny in the quote. Probably due to formating]
  

 

Hence, the cosmological constant is completely equivalent to vacuum energy!

 

So, to recap- I have demonstrated that

1. Vacuum energy (what you call zero point energy) gravitates as a fluid with negative pressure.

2. This vacuum energy/pressure whatever you want to call it is exactly equivalent to a cosmological constant as Einstein introduced it.

 

Care to comment?

-Will

 

 

 

Part I

 

 

 

First, very nice presentation Will.

 

However, despite what you have written, which appears convincing, one of the most important goals of cosmology (and particle physics) remains to illuminate the properties and the origin of dark energy (a component thought to contribute 73% of the energy density and responsible for accelerating expansion). Despite what you have exemplified, there remain many open questions concerning dark energy, e.g., related to scalar field models, how it would (if at all) evolve in time, interact with baryonic matter, and how it could be (if at all) related to cold dark matter (and/or neutrinos). Some additional outstanding questions remain, e.g., what kind of local effect could differential between lambda, dark, energy, quintessence models, why lambda would not participate in curvature (i.e., what role lambda plays in geometric terms) yet contribute to time dilation of the electromagnetic spectrum, the role, if any, lambda could play in mediating equilibrium in self-gravitating bounded astrophysical systems (from simple two-body systems up to super cluster scale), what are it limitations (i.e., will it lead to a "big rip"?). If indeed dark energy comprises 73% of the total density now, why at redshift z = 2 (10 Gyr ago) if Ho = 71, was the vacuum energy density only 9% of the total density? And why would vacuum density attain 96% of the total density 10 Gyr from now (without invoking the anthropic principle)? (See the The Dicke Coincidence Argument).

 

Secondly, despite what you have written (and I've seen it before expressed slightly differently), understanding the cosmological constant remains, today, the most outstanding problem in contemporary theoretical physics (with cold dark matter, CDM, running close behind).

 

My point is that, despite what you write, there seems to be very little known about dark energy, lambda, vacuum energy (what you call zero point energy) or whatever you want to call it (I've even seen it described as an anti-gravity effect). The problem is similar to the high-energy physics counterpart where a vacuum energy density is employed for spontaneous symmetry breaking in the Higgs mechanism: something that today still remains to be seen. I question the use of lambda (or vacuum energy density if you prefer) on the same scale used by the density parameter Omega. The problem for modern cosmology is that without dark energy (and CDM) the observations of SNe Ia lead to the astounding possibility (probability) that the universe never went through a hot dense phase when the scale factor was zero, i.e., meaning there was no Big Bang.

 

A nearly flat cold-dark-matter-vacuum-energy dominated model had to be adopted to save the big bang.

 

Furthermore, I have always considered lambda as a state of the vacuum (empty space) that would act counter to gravity. When I wrote lambda is not negative pressure, I was referring to pressure on an absolute scale (where negative pressure would be equivalent to negative absolute pressure (anti-pressure). This is what I disagree with in the case of lambda, not that it is a relative 'negative' pressure.

 

I have no problem with gauge pressure or relative negatives pressures, those are observed every day, even in my own apartment. I do, on the other hand, have problems with negative pressure of the kind proposed by inflation theory, which quite frankly have nothing to do with zero-point energy (ground energy). ZPE or ground energy are real positive energies - the effect of which are directly observed in earth-based experiments - and which by by consequence of being real energy (even though very small) gravitated like ordinary matter and energy, and which exert positive absolute pressure (i.e., -1 atm gauge pressure measured relative to atmospheric pressure) (or a relative negative pressure, i.e., a pressure less than that of a surrounding fluid (such as the air) - since the pressure of a partial vacuum is below atmospheric pressure, the term 'negative pressure' is often used. Absolute pressure is considered the current pressure relative to the absolute vacuum (if absolutely no atmosphere is present, pressure is zero). Therefore there is certainly no such thing as negative absolute pressure, of the kind postulated by inflation with its false vacuum (the slow roll transition seems to be something else), or even by some models of dark energy.

 

In contrast, if what you describe above, when you write negative pressure, refers to a type of gauge pressure, then it is difficult to see how normal energy associated with zero-point or ground energy would not gravitate like normal matter, i.e., it seems ZPE would contribute to the gravitational potential (however small), not something opposed to it, and thus decelerate the expansion along with the mass-energy density, rather then forcing the expansion to increase at an accelerated pace.

 

 

 

Take a look at the first illustration in this link:

 

Vacuum Energy Density, or How Can Nothing Weigh Something?

 

 

It shows a piston moving in a cylinder filled with a "vacuum" containing quantum fluctuations. In the space outside the cylinder there is "nothing" with zero density and pressure. In other words, there is a "false vacuum" in the cylinder and "true vacuum" outside. Clearly this scenario violates energy conservation.

 

This is the type of simple experiment that should be performed up at the International Space Station. I suspect, and I could be mistaken, that it will be impossible to demonstrate the tenability of this argument, i.e, it would be impossible to create a "false vacuum" or a space with negative absolute pressure. That would be experimental proof that the cosmological term is not what it has been made out to be. It would be empirical evidence that rules out the negative pressure state. It would show that you can't produce more vacuum, that space cannot be created, that the vacuum cannot be expanded, that space cannot expand...that lambda is equal to zero.

 

 

_____________________

 

 

One way to measure the value of lambda (to prove its value is precisely zero) would be by using a stabilized cesium atomic clock with high nominal fractional frequency stability place at the earth-sun Lagrangian saddle point LI, and another point for comparison far removed from L1 but at the same distance from earth. Time dilation and redshift should be measured in order to test the gravitational potentials along the lines of sight. Why? How? That will be the subject of another post....[Part II?]

 

 

 

 

CC

[coldcreation]

:Wink:Equation for detecting dark matter

 

x = dark matter

B = stars

S = space

T = time

G = gases

 

X = [( BG + BG )-( G*G)]+(B/g* B/g)/T*S:ebomb:

 

Hello capricornicis,

 

Welcome to Hypography.

 

Could you be more specific? Do you imply that this equation could be used to measure dark energy, or lambda, locally or globally?

 

It would help, instead of just providing an equation to explain it, what you would do with it, where, and why.

 

Can you elaborate?

 

Thanks

 

CC

[coldcreation]

I will not be defending these claims (for various reasons), but here is an interesting alternative to the dark energy interpretation for the SNe Ia data:

 

QSSC re-examined for the newly discovered SNe Ia, Vishwakarma, Narlikar, 2004

 

ABSTRACT: We examine the possible consistency of the quasi-steady state model with the newly discovered SNe Ia. The model assumes the existence of metallic dust ejected from the SNe explosions' date=' which extinguishes light travelling over long distances. We find that the model shows a reasonable fit to the data, which improves if one takes account of the weak gravitational lensing effect of the SNe which have been observed on the brighter side.

 

INTRODUCTION: The high redshift supernovae (SNe) Ia explosions look fainter than they are expected in the Einstein-deSitter model, which used to be the favoured model before these observations were made a few years ago. This observed faintness is generally explained by invoking some hypothetical source with negative pressure often known as ‘dark energy’, the simplest and the most favoured candidate being a positive cosmological constant ?. This happens because the metric distance of an object out to any redshift can be increased by incor- porating a ‘fluid’ with negative pressure in Einstein’s equations. However, a constant ?, is plagued with the so called cosmological constant problem:...

 

CONCLUDING REMARKS: ...Contrary to the widespread belief that these caveats do not matter or have already been allowed for, we retain a healthy skepticism of this test as contributing to a ‘precise’ determination of cosmological parameters. For this reason we are satisfied with the level of ‘goodness of fit’ obtained here for the QSSC. The fit could no doubt be improved by tinkering with the parameters; but given the observational uncertainties, we do not feel it worthwhile to undertake that exercise[/quote']

 

 

 

CC

[coldcreation]

...here is another interesting study:

 

Is the evidence for dark energy secure? (2007)

 

Abstract Several kinds of astronomical observations' date=' interpreted in the framework of the standard Friedmann–Robertson–Walker cosmology, have indicated that our universe is dominated by a Cosmological Constant. The dimming of distant Type Ia supernovae suggests that the expansion rate is accelerating, as if driven by vacuum energy, and this has been indirectly substantiated through studies of angular anisotropies in the cosmic microwave background (CMB) and of spatial correlations in the large-scale structure (LSS) of galaxies. However there is no compelling direct evidence yet for (the dynamical effects of) dark energy. The precision CMB data can be equally well fitted without dark energy if the spectrum of primordial density fluctuations is not quite scale-free and if the Hubble constant is lower globally than its locally measured value. The LSS data can also be satisfactorily fitted if there is a small component of hot dark matter, as would be provided by neutrinos of mass ?0.5 eV. Although such an Einstein–de Sitter model cannot explain the SNe Ia Hubble diagram or the position of the “baryon acoustic oscillation” peak in the autocorrelation function of galaxies, it may be possible to do so, e.g. in an inhomogeneous Lemaitre–Tolman–Bondi cosmology where we are located in a void which is expanding faster than the average. Such alternatives may seem contrived but this must be weighed against our lack of any fundamental understanding of the inferred tiny energy scale of the dark energy. It may well be an artifact of an oversimplified cosmological model, rather than having physical reality.[/quote']

 

 

 

CC

[modest]

...here is another interesting study:

 

Is the evidence for dark energy secure? (2007)

 

 

I had the same thought when you started this thread. What if it's an effect of an inhomogeneous universe. I found this paper:

 

Supernova Ia observations in the Lemaitre–Tolman model

 

which is a very convincing proof against that kind of thing.

 

-modest

[Erasmus00]

However, despite what you have written, which appears convincing, one of the most important goals of cosmology (and particle physics) remains to illuminate the properties and the origin of dark energy.

 

This is indeed true, but I think the problem is that no one knows the exact Lagrangian for the universe, and so first principles calculations of the zero point energy are difficult/impossible. My above presentation has a small slight of hand, everything is handled classically. Loop diagram corrections increase [imath]\rho_{vac}[/imath]. Without renormalization, the correction would be infinite.

 

However, its worth noting that its very difficult (without exact super symmetry, impossible) to get that [imath]\rho_{vac}[/imath] is exactly 0.

 

Despite what you have exemplified, there remain many open questions concerning dark energy, e.g., related to scalar field models, how it would (if at all) evolve in time, interact with baryonic matter, and how it could be (if at all) related to cold dark matter (and/or neutrinos)

 

This is certainly true, but a handful of unanswered questions at the edge of science are natural. What seems certain is that zero point energies exist, and are responsible for at least some of the observed "dark energy."

 

If indeed dark energy comprises 73% of the total density now, why at redshift z = 2 (10 Gyr ago) if Ho = 71, was the vacuum energy density only 9% of the total density? And why would vacuum density attain 96% of the total density 10 Gyr from now (without invoking the anthropic principle)? (See the The Dicke Coincidence Argument).

 

The evolution of the density of vacuum is actually well understood. It remains constant. Hence, as the scale factor of the universe increases, the density of matter and radiation decrease and "dark energy" plays a larger and larger role.

 

Secondly, despite what you have written (and I've seen it before expressed slightly differently), understanding the cosmological constant remains, today, the most outstanding problem in contemporary theoretical physics (with cold dark matter, CDM, running close behind).

 

I agree, but I think that its essentially a particle physics problem (how to calculate zero point energy of the vacuum), rather than a cosmology problem (in which the vacuum energy density can be inferred from measurements.

 

My point is that, despite what you write, there seems to be very little known about dark energy, lambda, vacuum energy (what you call zero point energy) or whatever you want to call it

 

If you notice from my calculation, there is a great deal of circumstantial evidence that something like dark energy should exist. If particle physics and GR are both true, the vacuum should behave like "dark energy."

 

The problem is similar to the high-energy physics counterpart where a vacuum energy density is employed for spontaneous symmetry breaking in the Higgs mechanism: something that today still remains to be seen.

 

But the symmetry is certainly broken. The weak theory predicts perfectly to the accuracy we can measure. There is certainly a whole lot of indirect evidence for some higgs sector. A simple scalar field is just the easiest.

 

The problem for modern cosmology is that without dark energy (and CDM) the observations of SNe Ia lead to the astounding possibility (probability) that the universe never went through a hot dense phase when the scale factor was zero

 

But we have empirical evidence the universe was once hot and dense (the CMB). The universe MUST have been in thermal equilibrium at some point (or it wouldn't be a perfect blackbody, which is what is observed). Hence, it must have been much, much smaller. The fact that the universe has a well defined positive is INCREDIBLY strong evidence for a big bang.

 

I have no problem with gauge pressure or relative negatives pressures...ZPE or ground energy are real positive energies .... exert positive absolute pressure

 

What I demonstrated in my calculation is that a positive energy density ZPE behaves as if it has a NEGATIVE ABSOLUTE pressure. Hence, the experiments that measure zero point energy (Casimir effect) essentially measure negative absolute pressure.

 

Now, in terms of the piston picture you supplied, I think you don't understand the idea of a false vacuum. In the picture the "nothing" outside the piston is actual nothing (no space, no nothing). Because ANY vacuum has quantum fluctuations. There is no "true" vacuum (no fluctuations) the way you describe.

 

At some point, I'll try to figure out a nice way to describe false-vacuum inflation, however, its more technical and I fear I can't do it in a non-technical way.

-Will

[coldcreation]

.

 

 

Part II

 

 

This is indeed true, but I think the problem is that no one knows the exact Lagrangian for the universe, and so first principles calculations of the zero point energy are difficult/impossible. My above presentation has a small slight of hand, everything is handled classically. Loop diagram corrections increase [imath]rho_{vac}[/imath]. Without renormalization, the correction would be infinite.

 

Thanks for pointing that out. It is an understandable slight of hand that doesn't pass by without notice.

 

The point should be made, too, there is still no observational or experimental evidence that confirms a relation (let alone unification) between GR and quantum field theory, QFT, (with its enormous vacuum component). Particularly, there is no evidence for the coupling between gravitational effects and quantum vacuum energy. It is not certain, when quantum fields are considered in a general relativistic curved spacetime, that the cosmological constant problem can be unambiguously formulated, except in very special cases. (See for example A Critical Examination of the Cosmological Constant Problem). Only with a clear, unambiguous, physical interpretation of the vacuum energy concept - and for this I believe it is essential to elucidate the physical mechanism and meaning of lambda - could there be formulated a realistic metric (of the type you expressed).

 

Without a precise meaning attached to the physical component of vacuum energy I don't see how the problem can be reconciled, or how the quantitative value of vacuum energy can be associated with a the cosmological term of Einstein's field equations. Certainly, on observational grounds, the SNe Ia data can place restriction on its value depending on the model adopted (and an approximate vacuum state can be defined), but for various reasons I remain skeptical of the model formulated from observation (Lambda-CDM) since the vacuum energy is required in huge proportion (73% of the mass-energy density).

 

 

 

This is certainly true, but a handful of unanswered questions at the edge of science are natural. What seems certain is that zero point energies exist, and are responsible for at least some of the observed "dark energy."

 

Good point, only here, it would seem that the edge of science has been treacherously surpassed.

 

I too am certain that zero point energy exists, but my skepticism resides in its assumed connection to lambda, and its position at the interface between QFT and GR.

 

 

"To believe with certainty we must begin with doubting."

(King Stanislaus of Poland)

 

 

The evolution of the density of vacuum is actually well understood. It remains constant. Hence, as the scale factor of the universe increases, the density of matter and radiation decrease and "dark energy" plays a larger and larger role.

 

It's not that simple. It appears to be a possibility (speculative perhaps) that the vacuum energy can decay into photons (unless I misunderstood).

 

See Decay of the vacuum energy into cosmic microwave background photons

 

In addition, if some for of inflation occurred very early on, then the universe went through an exponential expansion, slowed down, then accelerated again.

 

• ABSTRACT: We examine the possibility of the decay of the vacuum energy into a homogeneous distribution of a thermalized cosmic microwave background (CMB)' date=' which is characteristic of an adiabatic vacuum energy decay into photons. It is shown that observations of the primordial density fluctuation spectrum, obtained from CMB and galaxy distribution data, restrict the possible decay rate...[/quote']
  

  Or check this out: Cosmic vacuum energy decay and creation of cosmic matter

   

  • ABSTRACT:*In the more recent literature on cosmological evolutions of the universe' date=' the cosmic vacuum energy has become a nonrenouncable ingredient. The cosmological constant ?, first invented by Einstein, but later also rejected by him, presently experiences an astonishing revival. Interestingly enough, it acts like a constant vacuum energy density would also do. Namely, it has an accelerating action on cosmic dynamics, without which, as it appears, presently obtained cosmological data cannot be conciliated with theory. As we are going to show in this review, however, the concept of a constant vacuum energy density is unsatisfactory for very basic reasons because it would claim for a physical reality that acts upon spacetime and matter dynamics without itself being acted upon by spacetime or matter.[/quote']
    

     

     

     

     

    Secondly, despite what you have written (and I've seen it before expressed slightly differently), understanding the cosmological constant remains, today, the most outstanding problem in contemporary theoretical physics (with cold dark matter, CDM, running close behind).

     

    I agree, but I think that its essentially a particle physics problem (how to calculate zero point energy of the vacuum), rather than a cosmology problem (in which the vacuum energy density can be inferred from measurements.

     

    I think it essentially both a particle physics problem and a cosmological problem. The inference (from measurements) you refer to seems more like a gross pathological extrapolation (to me), a model-dependent artifact, based on observations (SNe Ia) that show a significant deviation from linearity (in both z and rise time, i.e., time dilation, or even spacetime dilation in the look-back time) in contrast to the three famous (or infamous) Friedmann models predicted before 1998.

     

     

    My point is that, despite what you write, there seems to be very little known about dark energy, lambda, vacuum energy (what you call zero point energy).

     

    If you notice from my calculation, there is a great deal of circumstantial evidence that something like dark energy should exist. If particle physics and GR are both true, the vacuum should behave like "dark energy."

     

    The problem for modern cosmology is that without dark energy (and CDM) the observations of SNe Ia lead to the astounding possibility (probability) that the universe never went through a hot dense phase when the scale factor was zero.

     

    But we have empirical evidence the universe was once hot and dense (the CMB). The universe MUST have been in thermal equilibrium at some point (or it wouldn't be a perfect blackbody, which is what is observed). Hence, it must have been much, much smaller. The fact that the universe has a well defined positive is INCREDIBLY strong evidence for a big bang.

     

    Yes, there is a great deal of circumstantial evidence. However, one must be careful when using the term "empirical evidence." Indeed there are several models (QSSC included) that predict a perfect blackbody. So what you call "strong evidence" is also strong empirical evidence for competing models. (I've already linked the Burbidge-Hoyle, 1998, ApJ which accounts for the observed spectrum and its non-hot-dense-state origin). All that is lacking is a sound physical mechanism for the thermalization of the radiation, but I believe that can be surmounted rather easily (even without the dubious "iron whiskers") when spacetime is treated as a physical "3D surface" rather than as nothing, or as a simple coordinate system - in a process similar to vacuum polarization.

     

    Here I insert my pet theory: The CMB would be produced, as stipulated by QSSC, from the energy released in the synthesis of cosmic He from hydrogen burning stars. This energy (in the form of radiation) is thermalized and quantified as vacuum polarization is quantified by the vacuum polarization tensor which describes the dielectric effect as a function of the four-momentum carried by the stellar radiation photons. Thus the CMBR and its corresponding blackbody spectrum depend on the momentum transfer from the radiation to the manifold (the vacuum), which acts as "wall," i.e., stellar radiation escaping into the environment (interstellar and intergalactic space) would have to "reflect" off the 3D vacuum manifold multiple times, in which process it is nearly entirely absorbed, thermalized (here I would have to go into the lengthy description of the mechanism which is beyond the scope of this discussion), and remains in thermal equilibrium (the energy absorbed is equal to the energy emitted). In other words, the continual emission and absorption of photons is responsible for the observed thermal equilibrium.

     

    So similarly to vacuum polarization, which describes a process where virtual electron-positron pairs in the vacuum are produced by a background electromagnetic field, this (QSSC related) pet theory describes a process in which the stellar emission (electromagnetic field background) contribution produces the observed CMB thermal blackbody spectrum. And, due to the observed inhomogeneity of both local and large-scale distribution of matter, there is an observable residual imprint (the anisotropy peaks due to adiabatic density perturbations) of the CMB blackbody radiation power spectrum temperature in terms of the multipole moment (angular scale). That is the simple version, since it excludes, for now, an in-depth look at phenomena such as interactions with hot gas, acoustic oscillations, diffusion damping and spacetime curvature of the universe (no of which would be a byproduct of an initial hot-dense state).

     

     

     

    What I demonstrated in my calculation is that a positive energy density ZPE behaves as if it has a NEGATIVE ABSOLUTE pressure. Hence, the experiments that measure zero point energy (Casimir effect) essentially measure negative absolute pressure.

     

    True, but there is a big difference (in terminology and physical interpretation) between the essential behavior of ZPE as a negative absolute pressure and a true negative absolute pressure, which is impossible. Just as (again) there is a big difference between the interpretation of thermodynamic temperatures behaving as negative absolute (negative quantities) on the Kelvin scale when they are identical to infinite temperature (i.e., a system with a negative absolute temperature is actually hotter than an identical system with an infinite temperature).

     

     

     

    Now, in terms of the piston picture you supplied, I think you don't understand the idea of a false vacuum. In the picture the "nothing" outside the piston is actual nothing (no space, no nothing). Because ANY vacuum has quantum fluctuations. There is no "true" vacuum (no fluctuations) the way you describe.

     

    Yes, indeed there is a paradox to be identified there. Note the caption for the illustration:

     

    • The animation above shows the piston moving in the cylinder filled with a "vacuum" containing quantum fluctuations' date=' while the region outside the cylinder has "nothing" with zero density and pressure. Of course the politically correct terms are "false vacuum" in the cylinder and "true vacuum" outside, but the physics is the same.[/quote']
      

      Without a "true vacuum" ground state outside the piston the illustration means nothing, since the comparison of 'inside' and 'outside' cannot take place, i.e., there is no comparison possible. The hypothetical "false vacuum" in the illustration would be relative to nothing; meaning the "physics" would not be "the same," since the pressure of a space essentially empty of matter (a "real vacuum" or a high vacuum, even if only partial) is always relative to a gaseous pressure much less than standard atmospheric pressure.

       

      The "false vacuum" by definition (or lack of definition), is a philosophical concept that can never observed in practice, or even in principle. The concept that there is a barrier preventing the field from rolling down from a higher energy of a false vacuum to the true vacuum ground state is founded on highly speculative metastable sector of quantum field theory that speculates tunneling (such as the Hawking-Moss instanton, string landscape,) can be caused by fluctuations or the creation of high energy particles.

       

      It would appear the controversy regarding the physicality of false vacua metastability are here to stay. Unfortunately, illustrations (or artist renditions) of the kind linked above, do nothing (pun not intended) to resolve the issue.

       

      The inflationary response to the standard model was indeed the response of a small group of revolutionary thinkers. Yet a prosaic bias distinguishes their thinking about nature, artistic license, understood in the way Guth (particularly) might have expressed it, the highest of the arts, a creative, exhilarating burst of zeal, a kind of erudition that falls short, as yet, in detaching what is seen in nature from pure imagination, i.e., there is no separation between fact and fantasy, between real and false.

       

      The false vacuum, then, does not begin, or even end, at the capricious limit of the otherworldly. Inflation possesses what seems a self-ruling informal flexibility. This, since the inception of inflation over a quarter century ago, has not appeased those who find its unfounded irrational core

       

       

       

      At some point, I'll try to figure out a nice way to describe false-vacuum inflation, however, its more technical and I fear I can't do it in a non-technical way.

      -Will

       

      To prove the possible existence of this decisive false vacuum state, it is not enough to describe it technically or mathematically.. It is a new breed of physics, one that has not been tested and one that is unlikely ever to be tested, and so, in my opinion, it is not physics at all. I am not arguing that there is strong evidence against the false vacuum, but rather, that there is no evidence. Again, in my personal opinion, inflation and its false vacuum state is not so much a failed model as it is a model that never came into being.

       

      Certainly when Guth created inflation he must have realized that he was in for a prolonged headache. His false vacuum would forever haunt the natural world. The problem is exponential, since the false vacuum cannot disappear. Its power, as Guth had seen, lies in its performance enhancing capability of flattening of the universe, solving all the setbacks of the standard model (horizon problem, etc.) with one supreme sweep. But the power, as I see it, and as the interpretation of the Type Ia Supernovae observations would demonstrate, lies in the power of apocalyptic ideas: nothing less.

       

       

       

      Inflation was selling a dream to people but couldn’t make it come true.

       

       

       

       

       

       

      CC

[Erasmus00]

. The point should be made, too, there is still no observational or experimental evidence that confirms a relation (let alone unification) between GR and quantum field theory, QFT, (with its enormous vacuum component). Particularly, there is no evidence for the coupling between gravitational effects and quantum vacuum energy.

 

This is partially true. However, IF quantum field theory is a more or less correct theory, and IF GR is a more or less correct theory, the result follows unambiguously (which is what I showed above). As someone who works in high energy, I have the highest regard for quantum field theory, and so I start from a framework that both GR and QFT theory are valid frameworks. (though perhaps wrong in some detail). The calculation rests on very general, robust features of each theory.

 

(See for example A Critical Examination of the Cosmological Constant Problem).

 

They argue for different formulations of quantum field theory, which I argue violated Occam's razor- why muck with an elegant theory to avoid complications because you don't like them?

 

Without a precise meaning attached to the physical component of vacuum energy I don't see how the problem can be reconciled, or how the quantitative value of vacuum energy can be associated with a the cosmological term of Einstein's field equations.

 

I believe that associating "dark energy" with "zero-point energy" is PHYSICALLY well defined. It is however, mathematically ambiguous.

 

I too am certain that zero point energy exists, but my skepticism resides in its assumed connection to lambda, and its position at the interface between QFT and GR.

 

If zero-point energy exists, IT MUST behave exactly as a cosmological constant. We cannot change this without dramatically altering the framework of GR.

 

It's not that simple. It appears to be a possibility (speculative perhaps) that the vacuum energy can decay into photons (unless I misunderstood).

 

From very general thermodynamic considerations, this might be true. However, I cannot think of (and have never seen) a field theory that would allow this to happen without dramatically altering physical laws.

 

See Decay of the vacuum energy into cosmic microwave background photons

 

In addition, if some for of inflation occurred very early on, then the universe went through an exponential expansion, slowed down, then accelerated again.

 

 

Indeed there are several models (QSSC included) that predict a perfect blackbody....All that is lacking is a sound physical mechanism for the thermalization of the radiation

 

Thats the whole point! There isn't a sound physical mechanism to thermalize the radiation, HENCE the model doesn't predict a perfect blackbody! Plus, (because it has no thermal contact), it is impossible for the QSSC universe to have a well defined temperature.

 

This energy (in the form of radiation) is thermalized and quantified as vacuum polarization is quantified by the vacuum polarization tensor which describes the dielectric effect as a function of the four-momentum carried by the stellar radiation photons.

 

This doesn't work because it won't scatter to produce a blackbody spectrum at all. You can get various shapes depending on the particle content of your vacuum (what you allow photons to scatter off of), but you won't get a thermal spectrum. You can't get to an equilibrium process because a good stable vacuum would produce no real photons.

 

And, due to the observed inhomogeneity of both local and large-scale distribution of matter,

 

The large scale (Megaparsec scales) distribution of matter IS homogenous.

 

And lastly, due to time constraints I will refrain from a lengthy discussion on the concept of the "false vacuum," but I will point out there is a large amount of direct experimental evidence of these concepts available in solid state physics/phase transitions. These are usually called "quasi-stable" states. It isn't an unknown concept at all, but actually quite familiar.

-Will

[modest]

De Sitter's Model and Luminosity-Distance in Cosmology

RC Barnes; 1981; Ro. Astro. Soc. 195, 959;

 

Seems to discuss exactly what you've been discussing. I just skimmed over it, but I'm sure I can read it in detail soon. It discusses apparent vs. intrinsic brightness at redshift in de Sitter's model vs. other models. It was obviously written before SNe 1a data.

 

Thanks for this link. The abstract looks promising. I have yet to read the rest. I had not heard of this paper before...

 

 

Looks like the standard brightness-distance formula is used on de Sitter's model as well as others. Also, a 'de Sitter model' is here defined as zero density and deceleration of -1.

 

While I would tend to agree with this, I believe it's not what you are looking for nor making an argument towards. Sure looked like it at first glance :xx:

 

-modest

[coldcreation]

Looks like the standard brightness-distance formula is used on de Sitter's model as well as others. Also, a 'de Sitter model' is here defined as zero density and deceleration of -1.

 

While I would tend to agree with this, I believe it's not what you are looking for nor making an argument towards. Sure looked like it at first glance ;)

 

-modest

 

You are correct modest. What is interesting are the observations: Notably, the time dilation factor shown in the SNe Ia data, and its possible relation to the de Sitter effect. Wether of not the data is indicative of the actual de Sitter effect is a question that should be studied. For example, if the data tends toward a quadratic relation at large distances remains to be seen.

 

My particular interest is not only with the observed time dilation as a function of a potential de Sitter-like metric - which calls for a phenomenon that affects the time dimension, but too, the gravitational phenomenon; the curvature of spacetime itself.

 

So, in addition to the slowing down of the time-like intervals (of distant clocks so to speak) with distance (as seen from our rest frame, and compared to local time), the spatial increments too are dilated with distance. Both effects are really the result of geometry, i.e., in a curved spacetime manifold both redshift and time dilation go hand in hand.

 

This is my point (again): The SNe Ia data can either be interpreted as an acceleration of expansion within the last few Gyr (which translates to a slower expansion in the distant past relative to the present time), or the data can be interpreted as a result of spacetime curvature in a static universe. The observations in the latter case show that the large-scale geometric structure is hyperbolic (in accord with de Sitter's spacetime), since the data shows time dilation and greater redshift (making high-z SNe look further away than they should be when the redshift-distance relation is linear, or nearly so).

 

In the case of the former (the standard interpretation), geometry is practically not an issue; meaning that motion dominates the field, causing both increase in redshift (because every photon is degraded in energy) and time dilation ( due to the stretching of the path length in the travel time resulting is the dilution in the rate of photon arrival) with distance (thus two factors of (1 + z).

 

Both scenarios are interesting from the point of view that they are both derived from GR, albeit, the latter more so since it describes a strictly non-Euclidean continua - within which every photon is degraded in energy along with the dilution in the rate of photon arrival due to the geodesic path in the travel time - rather than an inertial phenomenon in a Euclidean, or quasi-Euclidean frame (the standard view).

 

Simply put, the dilution in the rate of photon arrival may not be due to the stretching of the path length (at an increasing rate) as a function of time. It could be due to a cosmological non-linear geometric Gaussian curvature of the 4-D general relativistic spacetime metric through which light must propagate.

 

I have yet to find a paper on this exact solution. :xx: Perhaps I should write one myself.

 

 

 

:)

 

 

 

CC

[modest]

I have yet to find a paper on this exact solution. :xx: Perhaps I should write one myself.

 

The person's name completely escapes me at the moment and this may not be accurate as I read it many years ago and my memory of it is incomplete at best, but:

 

The very very first person to discover "the de Sitter effect" was ____. He did so by analyzing how much of one stars light would be received by another star. He found that the light dropped of non-linearly in de Sitter's metric and this is eventually called the de Sitter effect - or maybe he named it that (I don't know).

 

It seems to me that what he must have worked out was a brightness to distance function for de Sitter's original model. He was not solving for redshift, I remember that much.

 

If apparent and intrinsic brightness are to be presented very much differently with "de Sitter time" then perhaps we could get a hold of that paper. If I am right, it would have exactly what is needed.

 

-modest