# Comparison of the Mainstream and the Self Creation Freely Coasting models

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From the paper A very extended reionization epoch ? the suggestion is that there was a late period of Pop III star re-ionisation that finished at z>=10.5. This would then date the end of such stars, the ‘transition red shift’.
However, in order that the photon flux does not violate the Lyman-α Gunn-Peterson optical depth constraints at z & 6, the PopIII star formation rate should start decreasing around ztrans ~ 11. This value of ztrans is marginally consistent with the observations of NIRB.
As a comparison therefore, the active lifetime of Pop III stars in the two models is calculated to be: (Using LCDM values for the GR model)

For the onset of metallicity, i.e. 'ignition' of Pop III stars, z = 20
tz=20 = 182 Myrs. in GR
tz=20 = 657 Myrs. in SCC

for the transition period, i.e. the end of Pop III stars, z = 10.5
tz=10.5 = 450 Myrs. in GR
tz=10.5 = 1.31 Gyrs. in SCC

Thus the active lifetime of Pop III stars is
268 Myrs in GR and 653 Myrs in SCC,
(alright, perhaps not to that accuracy!) i.e. over twice as long. Note that if this late re-ionisation period does not in fact exist then the transition period is much earlier and the Pop III lifetimes drastically reduced.

Two questions again; should this transition period be observable as a background of very early hyper-novas, and, in the SCC model, could these Pop III stars then leave behind the present DM in the form of IMBHs?

Garth

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Chronos
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Suspending disbelief, for the moment, the question becomes - can reionization be complete at z = 6 by the usual accounting system for the age of the universe [around 1 billion years after BB]? That seems to be a good question and frankly I don't have a good answer to that one. I will try to find one. You make my brain hurt sometimes.

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Pop III stars are expected to be short lived; if they all formed from the 'same' post re-combination cosmological gas then they might be expected to burn themselves out within a short time more or less simultaneously and thus complete re-ionisation.

I see the difference between the two theories as being the primordial metallicity and baryonic density. The presence of significant primordial metallicity in SCC would allow smaller Pop III to form IMHO and the greater baryonic density would spawn far more of them. Thus re-ionisation and IGM metallicity could be more homogenous than in GR, and the present DM could consist of Pop III end products in the form of IMBHs ([102 - 104]Msolar).

Garth

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5) Flatness

Next from the "Review of Mainstream Cosmology" thread:
SpaceTiger said:
What do we mean when we say the universe is flat? Well, in short, we mean that the space can be described by normal Euclidean geometry; for example, the angles of a triangle add up to 180 degrees. In fact, the latter is exactly what we usually use in our attempts to determine flatness. One could actually go out and perform such an experiment by constructing a giant triangle (with, say, laser beams shooting from one mountain to another) and measure the angles of this giant triangle. If, within the uncertainties, the angles added up to 180 degrees, one would conclude that the space in that region was approximately flat. Of course, we know now that the space near the earth's surface is very well approximated as flat, but there was no way for the ancients to be sure of this.

Likewise, without a direct measurement, there's no way that we can be sure whether or not the space in the observable universe is flat. This kind of thing is very difficult to do locally because we only expect the universe's curvature to be noticable on large scales (that is, at high redshift). It turns out the most effective method is to analyze the anisotropies in the cosmic microwave background (CMB), a last-scattering "surface" that was formed at around z ~ 1100 [For more information on the microwave background, see marlon's What is Cmb thread]. By looking at the length scale on which the CMB is most anisotropic, we can determine very precisely the flatness of the universe. Using WMAP, we were able to determine that the universe was flat to very high precision:

$$\Omega=1.02 \pm 0.02$$

For those not familiar with that notation, $$\Omega=1$$ is a flat universe. Buried in this notation, however, is an important assumption. What it really means is

$$\Omega=\frac{\bar{\rho}}{\rho_c}=\frac{8\pi G\bar{\rho}}{3H^2}$$

where $$\bar{\rho}$$ is the average density of the universe and H is Hubble's constant. This is an elegant description of how mass curves space. That is, general relativity tells us that not only can we measure the geometry of space itself, but we can also infer its geometry by measuring how much mass and energy occupy it. This should be kept in mind when one considers that the total energy density of the universe has been measured to correspond approximately to that needed to flatten the universe. In other words, the pictures are consistent -- the geometry is flat and the contents are sufficient to flatten it.

In the following sections, I'll describe exactly what those contents are and how we measure their total contribution to the curvature of the universe.
Thank you again to ST for this clear exposition of the mainstream model.

The only evidence that the universe has closure, or near, closure density
$$\Omega_t=\frac{\bar{\rho}}{\rho_c}=\frac{8\pi G\bar{\rho}}{3H^2} = 1$$
is the analysis of the CMB data.

Every other measurement of density, galactic cluster velocity profiles, lensing etc, yield an average density of $$\Omega_m= 0.2 - 0.33$$.
The difference is attributed to Dark Energy in the mainstream model.

The observation of cosmological flatness is consequently very dependent on the CMB data, together, of course, with the natural predilection of the theory of inflation to that closure density. It is therefore important to see whether that is the only, or indeed the best interpretation of the CMB data.

The data consists of measurements of the angular size of CMB anisotropies which themselves arose from density fluctuations in the surface of last scattering. The angular sizes can be plotted against the depth of intensity fluctuations.
diagram here
Notice the good fit of the data at the first and subsequent peaks of the data points to the standard flat model line.

However, notice also the dropping away of the data points from that line at the largest angular scales.

This discrepancy is found also in the COBE and BALLOON data set and therefore seems to be a robust feature of the universe.

How can this be explained?

The standard flat model is infinite and these largest fluctuations should be present as predicted, on the other hand, if the universe were actually finite then such a deficiency at large angular scales would be expected as there would not be enough space in the early universe for these largest density fluctuations to exist.

Taking the low mode data points as well as the peaks it would be more accurate to describe the CMB anisotropy power spectrum as being consistent with a conformally flat and finite model.

Other plausible explanations of the discrepancy are being sought, however AFAIK none has been found.

The topology of a conformally flat and finite universe is modelled by either a cylinder or a cone. Draw a set of angles on a flat sheet of paper. That model represents the infinite flat mainstream model universe. Now roll the sheet into a cylinder, or cut out a sector and roll the sheet into a cone. In either case the angles do not change; conformal transformations preserve angles.

Therefore we can say that a conformally flat and finite model fits the WMAP data better than the mainstream infinite flat LCDM model.

SCC predicts a precise cosmological model, it is highly determined and therefore highly falsifiable. That prediction is of a static cylindrical model in its Jordan conformal frame and a freely coasting conical BB model in its Einstein conformal frame.

In either frame the model is conformally flat and finite. The SCC models are therefore more concordant with the WMAP data set than the mainstream LCDM model.

Garth

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More about the low mode, large angle anisotropy deficiency: again diagram here ; taken from http://arxiv.org/PS_cache/astro-ph/pdf/0302/0302207.pdf [Broken] page 29.
Garth said:
This discrepancy is found also in the COBE and BALLOON data set and therefore seems to be a robust feature of the universe.
How can this be explained?
Garth said:
Other plausible explanations of the discrepancy are being sought, however AFAIK none has been found.
What other explanations might there be?

The first is the shortfall does not actually exist but is simply a statistical quirk: The Statistical Significance of the Low CMB Mulitipoles
Some authors have argued that this discrepancy may require new physics. Yet the statistical significance of this result is not clear. Some authors have applied frequentist arguments and claim that the discrepancy would occur by chance about 1 time in 700 if the concordance model is correct. Other authors have used Bayesian arguments to claim that the data show marginal evidence for new physics. I investigate these confusing and apparently conflicting claims in this paper. I conclude that the WMAP results are consistent with the concordance LCDM model.
Whereas others have found a correlation with local geometry: Low-order multipole maps of CMB anisotropy derived from WMAP
We confirm the Tegmark et al. (2003) result that the octopole does indeed show structure in which its hot and cold spots are centred on a single plane in the sky, and show further that this is very stable with respect to the applied mask and foreground correction. The estimated quadrupole is much less stable showing non-negligible dependence on the Galactic foreground correction
which has been jumped on by the 'ban the BB' school.

What is to be made of this?

The standard interpretation is that of Efstathiou above, i.e. the discrepancy does not exist. However others disagree and in particular a possible correlation of the lowest modes with local geometry suggests it is real, but may have nothing to do with cosmology!

My suggestion?

In SCC the geometry is simple in the static Einstein conformal frame.

The universe has a scale size of $$\sqrt{12} H^{-1}$$ and the surface of last scattering is at a distance of $$-H^{-1}ln(1+z)$$, where z = 1028, so the universe at last scattering subtends $$2 \pi \sqrt{12} /ln(1+z)$$ rad across the sky. This is 3.14 rad or 179.60, that is, the first mode.

Therefore SCC predicts that there should not be any anisotropy at mode one.

The inference is that the low mode WMAP data consists of two sources superimposed on each other, a local large angular scale effect with a signal of modes 1 -> ~10(?), and a CMB signal of a (conformally) flat universe that zeros at mode 1.

Is this plausible?

Note: One problem with this model is that such a angle subtended by the whole universe at recombination is that one would expect 'circles in the sky' in the WMAP data. These do not seem to exist.

Garth

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Garth said:
In SCC the geometry is simple in the static Einstein conformal frame.

The universe has a scale size of $$\sqrt{12} H^{-1}$$ and the surface of last scattering is at a distance of $$-H^{-1}ln(1+z)$$, where z = 1028, so the universe at last scattering subtends $$2 \pi \sqrt{12} /ln(1+z)$$ rad across the sky. This is 3.14 rad or 179.60, that is, the first mode.
......................
Note: One problem with this model is that such a angle subtended by the whole universe at recombination is that one would expect 'circles in the sky' in the WMAP data. These do not seem to exist.
On the other hand ..... Constraining the Topology of the Universe
The first year data from the Wilkinson Microwave Anisotropy Probe are used to place stringent constraints on the topology of the Universe. We search for pairs of circles on the sky with similar temperature patterns along each circle. We restrict the search to back-to-back circle pairs, and to nearly back-to-back circle pairs, as this covers the majority of the topologies that one might hope to detect in a nearly flat universe. We do not find any matched circles with radius greater than 25 degrees. For a wide class of models, the non-detection rules out the possibility that we live in a universe with topology scale smaller than 24 Gpc.
Note: The SCC 'circles in the sky' are ~1800 across (dipole). Are these worth looking for amongst the much deeper dipole mode caused by the Earth's motion relative to that surface of last scattering?

Garth

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Chronos
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Weird science

Thanks for relieving my headache, Garth. Your explanation remains tempting. But it is my duty to stick with the conservative view - dang it. Your questions are still too hard. Trust me, if I had a really good alternative, I would have already unloaded it on you. I like to think I have come up with a few, but nothing that blows it out of the water. Your arguments are sound, the math appears flawless... how annoying. I'm to the point I'm secretly rooting for GPB to affirm your 'wild' speculations.

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I've been thinking hard about the 'circles in the sky', worried that their non-detection might be a 'stake in the heart' of SCC.

First my calculation above does not use the standard recombination z, correcting that, (yet again ), to z =1089 we obtain:

The universe has a scale size of $$\sqrt{12} H^{-1}$$ and the surface of last scattering is at a distance of $$-H^{-1}ln(1+z)$$, where z = 1089, so the universe at last scattering subtends
$$2 \pi \sqrt{12} /ln(1+z)$$ rad = $$2 \pi \sqrt{12} /ln(1090)$$ rad across the sky. This is 3.11 rad or 178.30, that is, still the first mode.

Therefore SCC predicts that there should not be any anisotropy at mode one.

However, I am pretty convinced that in a conformally flat universe with the topology the Jordan frame cylindrical model, there should be no circles in the sky at all. Instead the visible universe at that z, bounded by our light cone, is enlarged by a cosmological lensing effect across the whole sky. Or am I missing something?

Garth

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Chronos
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Garth said:
The only evidence that the universe has closure, or near, closure density is the analysis of the CMB data.
A point to consider. Supernova data can also be used to measure the curvature of the universe:
New Constraints on $\Omega_M$, $\Omega_\Lambda$, and w from an Independent Set of Eleven High-Redshift Supernovae Observed with HST
http://arxiv.org/abs/astro-ph/0309368

You may not want to give up on 'circles in the sky' just yet. This heavily cited paper is a good jumping off point for discussing the high angular CMB anisotropy: 
The significance of the largest scale CMB fluctuations in WMAP
http://arxiv.org/abs/astro-ph/0307282

The jury is still out as to whether the universe is truly flat by these papers:

A Hint of Poincar\'e Dodecahedral Topology in the WMAP First Year Sky Map
http://arxiv.org/abs/astro-ph/0402608

Missing Lorenz-boosted Circles-in-the-sky
http://arxiv.org/abs/astro-ph/0403036

CMB Anisotropy of the Poincare Dodecahedron
http://arxiv.org/abs/astro-ph/0412569

The Shape of Space after WMAP data
http://arxiv.org/abs/astro-ph/0501189

Enjoy.

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Chronos said:
A point to consider. Supernova data can also be used to measure the curvature of the universe:
New Constraints on $\Omega_M$, $\Omega_\Lambda$, and w from an Independent Set of Eleven High-Redshift Supernovae Observed with HST
http://arxiv.org/abs/astro-ph/0309368
The most important diagram in this analysis is Figure 6 on page 23 of that paper. Notice that they do not plot, for comparison, the empty universe $$\Omega_M=\Omega_\Lambda=0$$. This was plotted in the original paper by Permutter et al. as I posted above: here, page 24.
The middle solid curve is for (Omega M,Omega L) = (0,0). Note that this plot is practically identical to the magnitude residual plot for the best-fit unconstrained cosmology of Fit C, with(Omega M, Omega L) = (0.73,1.32).
So the evidence for a $$\Omega_M=0.28, \Omega_\Lambda=0.72$$, or thereabouts, universe is degenerate and also concordant with the freely coasting model.

Note that the SCC model is closed whereas the freely coasting is open, it is the Milne empty hyperbolic model.
There will be a difference between the two at large R(t).

Thank you for those other links I shall study them.

Garth

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Chronos
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Garth said:
...Notice that they do not plot, for comparison, the empty universe . This was plotted in the original paper by Permutter et al. as I posted above: here, page 24.
Agreed, which is why I did not intend to suggest it was contraindicating. Merely a technical point I thought worth mentioning. I also botched the link to the seminal paper on large angular anisotropy - which I corrected [doh!]. I hope you find the other papers interesting. I spent a fair amount of time on that project. The nominal WMAP result [omega = 1.02] predicts a closed universe. I went surfing for some supporting ideas, and that is what I came up with.

Chronos
Gold Member
Garth said:
...Notice that they do not plot, for comparison, the empty universe . This was plotted in the original paper by Permutter et al. as I posted above: here, page 24...
Agreed, which is why I did not intend to suggest it was contraindicating. Merely a technical point I thought worth mentioning. I also botched the link to the seminal paper on large angular anisotropy - which I corrected [doh!]. I hope you find the other papers interesting. I spent a fair amount of time on that project. The nominal WMAP result [omega = 1.02] predicts a closed universe. I went surfing for some ideas, and that is what I came up with. The last paper in my listing was pretty interesting.

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Chronos said:
I hope you find the other papers interesting. I spent a fair amount of time on that project. The nominal WMAP result [omega = 1.02] predicts a closed universe. I went surfing for some ideas, and that is what I came up with. The last paper in my listing was pretty interesting.
Yes thank you, I did find those papers interesting. However, the need to invoke a multiple connected topology might be stretching the mainstream model a little far to make it fit the WMAP data. Other papers do not find such firm evidence of such topology: A Hint of Poincar\'e Dodecahedral Topology in the WMAP First Year Sky Map.
Continuing:
SpaceTiger said:
6) The Matter Density

The matter density is, quite simply, the average space density of matter in the universe. It is usually parameterized relative to the critical density:

$$\Omega_m=\frac{\rho_m}{\rho_c}$$

This is the density of all non-relativistic matter, including the stuff we're made of (baryonic matter) and the dark matter that has so far eluded our detectors. It does not include photons, relativistic particles, or dark energy.

Since it includes the stuff we can't see, the estimates of $$\Omega_m$$ must be dynamical; that is, they must be inferred from gravitational influence of the matter. Doing this in a variety of systems (on both small and large scales), we can directly measure the total amount of matter in the universe. These methods tend to give values in the range:

$$\Omega_m \sim 0.2 - 0.3$$

Remember that $$\Omega_m=1$$ would mean that the matter density was exactly sufficient to flatten the universe. Recently, several other independent measurements, including the peculiar velocity field of galaxies, the power spectrum, and the CMB, have given values that are in the same ballpark. In fact, measurements of the matter density have been confirmed in so many different ways that it was previously believed that we lived in an open universe with $$\Omega\simeq \Omega_m \simeq 0.3$$. With the recent CMB and supernovae measurements, however, we now believe that the remainder of the energy density required to flatten the universe is in some other form, this mysterious dark energy.
Again thank you to SpaceTiger for that informative post on the mainstream model.

We note again that, apart from the WMAP data, other measurements of the average density of the universe put
$$\Omega_m \sim 0.2 - 0.3$$.
The value $$\Omega_{total} > 1$$ is based on the interpretation of the WMAP anisotropy power spectrum as ‘flat’. That is the distribution of angular diameters of anisotropies of a certain ‘depth’ is as predicted by a spatially flat model. Fitting in other data from the distant SN Ia etc. agrees with a (theory dependent) value slightly larger than 1,~1.02. However, as I have posted above, conformal transformations of the metric leave angles invariant, therefore the data is also consistent with conformally flat models, such as a hyper-cylinder, hyper-cone or torus (locally flat).

The SCC model is highly determined to be either a hyper-cylinder in its Jordan frame or a hyper-cone in its Einstein frame. It is therefore consistent with the WMAP data without the need to invoke "the remainder of the energy density required to flatten the universe is in some other form, this mysterious dark energy", i.e. it does not need this extra 'epicycle'.

Furthermore, as above it fits the SN Ia data as well.

This highly determined model requires a specific density from first principles, no ‘curve fitting’ or parameter ‘tweaking’ are involved. Just as inflation in its natural form requires a $$\Omega_{total} = 1$$, so SCC requires:
$$\Omega_{total} = \frac 13 = 0.33$$
and a
$$\Omega_m = \frac 29 = 0.22$$.
The difference:
$$\Omega_{fv} = \frac 19 = 0.11$$ is required to be that of the false vacuum, i.e. ZPE.

In other words the densities required by the theory are exactly those as observed and measured by lensing, cluster dynamics and other techniques, moreover, as the false vacuum density is determined to be a finite and reasonable value, it resolves the ‘Lambda’ problem as well.

Garth

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Chronos
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I disagree with your reasoning Garth.

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Chronos said:
I disagree with your reasoning Garth.
Thank you, but which part do you disagree with Chronos?
Garth

Chronos
Gold Member
Yikes, only left out about all but the first sentence. Copy and paste is not without peril. Will get back to you on that.

Phobos
Staff Emeritus