Comparison of the Mainstream and the Self Creation Freely Coasting models

  • Thread starter Garth
  • Start date

Chronos

Science Advisor
Gold Member
11,398
738
I'm not trying to conserve energy locally, just globally. That is where the objection arises.
 

Garth

Science Advisor
Gold Member
3,572
105
Chronos said:
I'm not trying to conserve energy locally, just globally. That is where the objection arises.
Then you remain in the Einstein frame of SCC - that is GR.
However the theory also fully incorporates Mach's Principle, by including that scalar field, and the question is whether Mach's Principle & the Local Conservation of Energy are physically important or not.

The three distinguishing tests of SCC, the GPB geodetic measurement, the test of whether photons 'fall' at the same 'rate' as particles, and the test of whether the Casimir force is dependent on s-t curvature, are ways of empirically discovering the validity of this approach and falsifying it. Fortunately we won't have too long to wait...

Garth
 
Last edited:

Garth

Science Advisor
Gold Member
3,572
105
3) Homogeneity and Isotropy

11. Where do we go from here?
SpaceTiger said:
If you wish to entirely change a paradigm, you must re-interpret all of the observational evidence in the context of the new paradigm before you can safely say that your theory is viable.
That is precisely my intention in this thread

SpaceTiger said:
3) Homogeneity and Isotropy
Most models of the universe assume that it is uniform to translations in space (homogeneous) and uniform in direction (isotropic). This does not mean that every point in space is the same on all scales (it obviously isn't), but rather that the universe is smooth on the largest scales. By analogy, the surface of a spherical balloon is homogeneous and isotropic, despite having small bumps and wiggles if you look at it closely enough. Although this point is not controversial (even believers in steady-state cosmology like homogeneity and isotropy), it is actually more difficult to prove than, for example, expansion. Difficult, but not impossible.

The first and most convincing line of evidence (if you believe the big bang) is the cosmic microwave background radiation. If it really is a fingerprint of the early universe, then its extreme uniformity implies homogeneity to one part in 104.
Smoothness was one of the set of three: the horizon, density and smoothness problems of the Friedmann model that Inflation provided an solution for. The reason these three parameters of the universe were problems, i.e. why was the sky isotropic if regions of it are not causally connected, why is its density close to unity, why was the universe so homogeneous, was caused by the deceleration of the universe. Deceleration over the entire age of the universe would have driven these parameters away from the Friedmann flat model solution. Inflation, on the other hand, a short violent exponential acceleration, had the ability of driving these parameters onto the flat model solution.

The strictly linearly expanding model, i.e. the freely coasting model, of which SCC is an example, does not have these problems in the first place, thus removing the need for inflation, the first of the mainstream model’s ‘epicycles’.

In SCC a scalar field is the source for the matter field and in the distant past it had the boundary condition of homogeneity. Matter in the earliest phases of the Jordan frame of SCC would have consisted of a homogeneous sea of virtual particles, which having very little mass would have a long life-time. Inertial mass was endowed onto these particles by the scalar field, a real input of energy that converted virtual into real particles.

The homogeneity of the earliest universe is not in doubt as the CMB is homogeneous to greater than one part on 104, however how did the anisotropies of galactic clusters, galaxies, stars, planets and eventually people form from that smooth continuum? This will be the subject of a future post.

Garth
 
Last edited:

pervect

Staff Emeritus
Science Advisor
Insights Author
9,575
841
Chronos said:
I'm not trying to conserve energy locally, just globally. That is where the objection arises.
Garth's theory actually has a number that represents "the energy of the universe" that is a constant - you would probably call this a global quantity. Don't be confused by the name he has chosen to give his energy conservation principle. His energy conservation principle is different than that of GR's, because he includes the energy that is in his "scalar field" into the total energy.

GR does not have this notion - there is no notion of the "total energy of the universe", strictly speaking. Strictly speaking, one requires either a timelike Killing vector, or an asymptotically flat space-time to define energy. FRW spacetime in general doesn't have either notion, so it doesn't have a conserved energy.

GR's notion of energy has been called "improper" and "nonlocal". This was a matter of concern for a long time. Emily Noether explained why this had to be true - Hilbert noticed the problem after formulating the Hilbert action, and he asked Emily to work on the problem, which she did.

A quote from http://gsdl.enc.org/external/search/gsdl_view_catalog_record/0,4140,curl%253D%25252Fgsdl%25252Fexternal%25252Fresearchers%25252Fresearchers%25255Fscience%2526version%253Dgraphics%2526id%253D4290,00.shtm [Broken]

Abstract: This paper presents a historical account of Emily Noether's proof of two thereoms which have had a great impact on modern physics. Emmy Noether proved two deep theorems, and their converses, on the connection between symmetries and conservation laws. Because these theorems are not in the mainstream of her scholarly work, which was the development of modern abstract algebra, it is of some historical interest to examine how she came to make these discoveries. The present paper is an historical account of the circumstances in which she discovered and proved these theorems which physicists refer to collectively as Noether's Theorem. The work was done soon after Hilbert's discovery of the variational principle which gives the field equations of general relativity. The failure of local energy conservation in the general theory was a problem that concerned people at that time, among them David Hilbert, Felix Klein, and Albert Einstein. Noether's theorems solved this problem. With her characteristically deep insight and thorough analysis, in solving that problem she discovered very general theorems that have profoundly influenced modern physics. This resource is appropriate for all users, particularly for girls and women, because it acknowledges women's contributions to STEM.
Garth's theory, because of the scalar field and the way it's constructed, DOES have a local (in the mathematical sense used in the paper above) defintion of energy. There is another confusing issue here - physicists and mathemeticians have totally different notions of what local energy conservation means.

Anyway, if you realize that Garth's theory has a different notion of energy, one that is always conserved in his theory (it's a true "proper" or local conservation, unlike GR's "improper" conservation) - a notion of energy that's different than the GR notion of energy because it includes the energy in a "scalar field" present in his theory, you'll be on the right track.

If you also go "hmmm, how does Garth's theory get around Noether's thoerem? Does it wind up not being diffeomorphism invariant, because the scalar field gives you in essence a preferred frame?", I *think* you'll be on the right track, though I'm not 100% sure of this point.
 
Last edited by a moderator:

Garth

Science Advisor
Gold Member
3,572
105
pervect said:
If you also go "hmmm, how does Garth's theory get around Noether's thoerem? Does it wind up not being diffeomorphism invariant, because the scalar field gives you in essence a preferred frame?", I *think* you'll be on the right track, though I'm not 100% sure of this point.
Thank you for that link, you may also be interested in Nina Byers [URL [Broken] Noether’s Discovery of the Deep Connection Between
Symmetries and Conservation Laws[/URL].

There were two questions left after the formulation of GR, treated separately: the local conservation of energy and the full inclusion of Mach's Principle. Emmy Noether dealt with energy-conservation early on and Brans and Dicke tried to deal with Mach's Principle in the 1960's.

SCC deals with both questions simultaneously.

The problem with the local conservation of energy is that the measurement of energy is frame dependent, in order to conserve energy you need to specify a frame of reference in which it is conserved, a preferred frame. I use Mach's Principle to select that frame.

The question of preferred frames in SCC is a deep one.
The field equations (Jordan frame) are manifested covariant, there are no preferred frames, although the matter field energy-momentum tensor is not conserved. (It is when conformally transformed into the Einstein frame). However if you select one particular fame, the 'Machian' Centre-of-Mass (Momentum) frame for the system in question then in that frame of reference energy is locally conserved.

I hope this helps.

Garth
 
Last edited by a moderator:

selfAdjoint

Staff Emeritus
Gold Member
Dearly Missed
6,764
5
Garth said:
Thank you for that link, you may also be interested in Nina Byers [URL [Broken] Noether’s Discovery of the Deep Connection Between
Symmetries and Conservation Laws[/URL].

There were two questions left after the formulation of GR, treated separately: the local conservation of energy and the full inclusion of Mach's Principle. Emmy Noether dealt with energy-conservation early on and Brans and Dicke tried to deal with Mach's Principle in the 1960's.

SCC deals with both questions simultaneously.

The problem with the local conservation of energy is that the measurement of energy is frame dependent, in order to conserve energy you need to specify a frame of reference in which it is conserved, a preferred frame. I use Mach's Principle to select that frame.

The question of preferred frames in SCC is a deep one.
The field equations (Jordan frame) are manifested covariant, there are no preferred frames, although the matter field energy-momentum tensor is not conserved. (It is when conformally transformed into the Einstein frame). However if you select one particular fame, the 'Machian' Centre-of-Mass (Momentum) frame for the system in question then in that frame of reference energy is locally conserved.

I hope this helps.

Garth

I would call the Machian principle not a question, as if physics demanded it, but a philosophical preference. Einstein was a Machian at first but found his theory did not support it and was able to abandon it. I am not criticising SCC, just pointing out that there does not appear to be a crying need to build Mach into one's theories.
 
Last edited by a moderator:

Garth

Science Advisor
Gold Member
3,572
105
selfAdjoint said:
I would call the Machian principle not a question, as if physics demanded it, but a philosophical preference. Einstein was a Machian at first but found his theory did not support it and was able to abandon it. I am not criticising SCC, just pointing out that there does not appear to be a crying need to build Mach into one's theories.
Yes, selfAdjoint, thank you for that observation. I was using the word 'question' to mean 'the question of whether it should be included or not', it may even be emphasised by calling it a 'problem' instead.
The 'question' about Mach's Principle is closely related to the 'question', or 'problem' of the local conservation of energy. Quoting from my link above to that paper of Byers:
The failure of local energy conservation in the general theory was a problem that concerned people at that time, among them David Hilbert, Felix Klein, and Albert Einstein.
Energy conservation in the general theory has been perplexing many people for decades. In the early days, Hilbert wrote about this problem as ‘the failure of the energy theorem ’. In a correspondence with Klein [3], he asserted that this ‘failure’ is a characteristic feature of the general theory, and that instead of ‘proper energy theorems’ one had ‘improper energy theorems’ in such a theory. This conjecture was clarified, quantified and proved correct by Emmy Noether.
It is important to see the significance of this "failure of the energy theorem" in GR, for example:

In a laboratory on Earth (a 'supported frame of reference') you lift a stationary kilogram weight and put it on a shelf. Where has the energy used to lift it gone to? You have expended energy in lifting it and so your total energy, has gone down. Yet (in GR) the 'rest' mass of the weight has not altered, so where has the energy gone? The standard answer is "into the field".

In GR "there is transfer of energy to and from the gravitational field and it has no meaning to speak of a definite localization of the energy of the gravitational field in space.........
At any given spacetime point one may choose a set of coordinates for which the gravitational fields vanish (guv reduces to the flat spacetime Minkowski metric and the Christoffel symbols vanish). This is guaranteed by the equivalence principle which states that one can always choose a coordinate system such that spacetime in the neighborhood of a given point is Minkowski (flat). Thus one may see why it is not meaningful to speak of a localized energy density for gravitational fields."
" (Quoted from Byers' paper)

Thus, while it may seem that "there does not appear to be a crying need to build Mach into one's theories", is there a crying need to build in a local conservation of energy? That conservation requirement needs a frame of reference and that is why Mach is also required to select out such a 'preferred' frame.

The standard answer is to say there isn't a need for either, but the maverick in me has long suggested that in fact there is! As GPB is testing both theories at present we may not have to wait much longer to find out.

Garth
 
Last edited:

Garth

Science Advisor
Gold Member
3,572
105
Age of the Universe

Next, from "Review of Mainstream Cosmology"
SpaceTiger said:
4) Age of the Universe
Firstly, there are globular clusters. From what we know about stellar evolution, we can model populations of stars and, under the assumption that they were all born at the same time, determine their age. When we do this with Milky Way globular clusters, we get an age of around 12 +- 3 billion years. Not technically a determination of the universe's age, but certainly a lower limit.

What about radioactive elements? Can we somehow use them to infer the age of the universe? It turns out that we can. Recent detections of Uranium-238 and Thorium-232 in stars have allowed us to use the traditional radioactive dating method to obtain an age of 12.5 +- 3 billion years. Again, a lower limit, but completely independent from and consistent with that from stars.

Finally, there are the measured cosmological parameters. When brought together and analyzed carefully, we can very tightly constrain the age of the universe to be 13.7 +- 0.2 billion years. It is very reassuring that this is consistent with both of the above ages. In fact, the standard model predicts that the Milky Way should have formed very early in the life of the universe, so the fact that the other two ages are of the same order (and not much less) is also consistent. One way to falsify the standard model would be to find something that is significantly older than 13.7 billion years. For a while, the globular cluster measurements were thought to represent such a falsification, but with the improvement of both our globular cluster measurements and our cosmological measurements, we are now finding nice agreement.
I thank ST for this clear exposition of the mainstream view.
It is important to note the age parameters, already posted, #2 on this thread, that have been determined by the standard interpretation of the WMAP data.
Hubble time, tH is given by tH = 10.2/h Gyrs.
where H = h.100 km/sec/Mpsc.
WMAP determines h = 0.72
so tH = 14.2 Gys .

In a spatially flat, matter dominated dust Friedmann universe
R(t) = R0(t/t0)2/3
and the present age of the universe = 2/3tH = 9.44 Gyrs.

Thus the universe looks 'a bit young' for the components within it: i.e. the globular clusters and radioactive fossils. Furthermore, the universe would be even younger if the density or pressure were greater.

However all is not lost, acceleration in the past would have meant that the universe had been expanding more slowly in the ancient past and therefore is older than it at first seems today. This acceleration can be produced by inserting negative pressure into the Friedmann equations.

Therefore the observation that SN Ia in high red shift galaxies were fainter than expected was seized upon as a solution to two specific problems, as these observations provided evidence that the universe had accelerated in the past, if interpreted in the GR paradigm.
1. The universe 'is older than it looks' thereby resolving the age problem.
2. This negative pressure could be caused by Dark Energy that provided the extra cosmological density required for closure (Omega = 1).

But note that this DE has to be carefully modelled, in ST's words, "These things were invented to explain the data, not the other way around." (post #38 in "Mainstream" thread).

The mainstream model requires massive acceleration in the earliest universe - Inflation. However the expansion has to be that of a radiation dominated universe R(t) = R0(t/t0)1/2 for BBN (primordial nucleosynthesis) to be correct. So DE is insignificant in this period, but then becomes significant in the 'dark ages' and early galactic age, but would appear to be insignificant again in the modern epoch otherwise we could detect it locally.

In comparison the Freely Coasting model, as produced by the SSC gravitational field equations, has a simple evolution R(t) = R0(t/t0) and the age of the universe is simply 14.2 Gys. The independently determined ages of its various components sits comfortably within this constraint, as do the formation of Pop III stars, quasars and the earliest galaxies.

There is no acceleration, no DE, and yet the model fits the distant SN Ia data, here, page 4 as recognised by Perlmutter 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).
Finally, as there is no requirement to make up the density closure because the total Omega = 0.33, why "multiply the entities" with the "invention" of DE?

Garth
 
Last edited:

Kea

859
0
Garth said:
In comparison the Freely Coasting model, as produced by the SSC gravitational field equations, has a simple evolution R(t) = R0(t/t0) and the age of the universe is simply 14.2 Gys.
Interestingly, this is similar to the age calculated by the recent Wiltshire Machian cosmology.
 

Garth

Science Advisor
Gold Member
3,572
105
Kea said:
Interestingly, this is similar to the age calculated by the recent Wiltshire Machian cosmology.
That is interesting. Note that model also adds Mach to GR, and also finds it does not need DE to explain cosmological constraints. Does it have any specific falsifiable tests as SCC does?

Garth
 

Kea

859
0
Garth said:
Does it have any specific falsifiable tests as SCC does?
Hi Garth

Well, yes, but it's early days yet. An improved version should appear shortly. A reanalysis of WMAP data could take a long time. It really depends on whether or not an experimental group becomes interested in it, I guess.

Cheers
Kea :smile:
 

Garth

Science Advisor
Gold Member
3,572
105
Kea said:
Interestingly, this is similar to the age calculated by the recent Wiltshire Machian cosmology.
Note also that Kolb (Edward W?) was the author of the original " A coasting cosmology " paper.
Perhaps there is an even closer relationship between the two theories.

Garth
 

turbo

Gold Member
3,028
45
Here are three lectures giving Rocky Kolb's thoughts on Dark Matter and Dark Energy. Given at SLAC August 2003. You may find his approach refreshing.

http://www-project.slac.stanford.edu/streaming-media/SSI/2003/ram/SSI_8_4am1.ram [Broken]
http://www-project.slac.stanford.edu/streaming-media/SSI/2003/ram/SSI_8_5am1.ram [Broken]
http://www-project.slac.stanford.edu/streaming-media/SSI/2003/ram/SSI_8_6am1.ram [Broken]
 
Last edited by a moderator:

hellfire

Science Advisor
1,047
1
Garth said:
In comparison the Freely Coasting model, as produced by the SSC gravitational field equations, has a simple evolution R(t) = R0(t/t0) and the age of the universe is simply 14.2 Gys.
How do you calculate this? For a linearly expanding universe the age is equal to the inverse of the Hubble parameter and this yields 13.77 Gy.
 
Last edited:

Garth

Science Advisor
Gold Member
3,572
105
hellfire said:
How do you calculate this? For a linearly expanding universe the age is equal to the inverse of the Hubble parameter and this yields 13.77 Gy.
You are correct, thank you for spotting that.
I copied the wrong value, from where I cannot remember,
tH = 10.2/h Gyrs. wrong!
in fact tH = 9.78/h Gyrs.
where H = h.100 km/sec/Mpsc.

So if h = 0.72 then tH = 13.6 Gyrs.

What value of h are you using?

All this means to my argument is that all my time values have to be adjusted by a factor 13.6/14.2 = 0.958. i.e. 5% less.

Garth
 
Last edited:

hellfire

Science Advisor
1,047
1
Garth said:
What value of h are you using?
0.71, I had in mind this was the WMAP best fit value.
 

Garth

Science Advisor
Gold Member
3,572
105
hellfire said:
0.71, I had in mind this was the WMAP best fit value.
I don't think the second significant figure is very robust, but we do have a much better handle on Hubble time than previously - unless there is some systematic error.

...Like my value tH = 10.2/h Gyrs; I've been wondering where I got this value from and remembered I did a 'back of an envelope' calculation at the beginning of this thread. I must have mistaken the reciprocal somewhere; 1.02 = 1/0.978..... :blushing:

Garth
 

Garth

Science Advisor
Gold Member
3,572
105
Therefore, not wanting to be remembered on PF for a number of mistakes, :blushing:, I here correct my post #2, however the basic arguments that depend on these numbers has not changed.

The look back time tl as a function of red shift z is given by:
In GR
tl/tH = (2/3)(1 - 1/(1 + z)3/2)
In SCC
tl/tH = (1 - 1/(1 + z))



With tH = 9.78/h Gyrs.
Lets take the WMAP determination of h = 0.71 so tH = 13.8 Gys.
and the age of the universe = 2/3tH = 9.18 Gyrs. in GR.
(Note: acceleration since z = 6 can considerably increase this age of the universe without affecting the calculated durations from BB below).
And the age of the universe = 13.8 Gyrs. in SCC.

Using tz=x to be the age of an object now observed at a red shift x, we have for time after BB:

For "re-combination" - the surface of last scattering of the CMB, z = 1000,
tz=1000 = 206,000 yrs. in GR
tz=1000 = 13.8 Myrs. in SCC

for the onset of metallicity, i.e. Pop III stars, z = 20
tz=20 = 67.8 Myrs. in GR
tz=20 = 657 Myrs. in SCC

for quasar 'ignition' z = 8
tz=8 = 241 Myrs. in GR
tz=8 = 1.53 Gyrs. in SCC

for 'modern' metallicity in Quasar SDSS J1030+0524 z = 6.28
tz=6.28 = 332 Myrs. in GR
tz=6.28 = 1.90 Gyrs. . in SCC.

The comparison shows that there is considerably more time for the development of Pop III stars, Quasars and early metallicity than in the mainstream model.

Garth
 
Last edited:

Chronos

Science Advisor
Gold Member
11,398
738
Just to be fair to the mainstreamers, the vanilla GR prediction for the age of the universe [and look back time] is not generally accepted. Most would offer values closer to those obtained using Ned Wright's calculator:

http://www.astro.ucla.edu/~wright/CosmoCalc.html

Plugging in WMAP values yields these results:

Current age of universe: t = 13.67 Gy
z = 1000 t = 436,000 years
z = 20 t = 182 My
z = 8 t = 652 My
z = 6.28 t = 896 My

Also per WMAP, recombination occured around z = 1089, which occurs at t = 378 My.
 
Last edited:

Garth

Science Advisor
Gold Member
3,572
105
Chronos said:
Just to be fair to the mainstreamers, the vanilla GR prediction for the age of the universe [and look back time] is not generally accepted. Most would offer values closer to those obtained using Ned Wright's calculator:

http://www.astro.ucla.edu/~wright/CosmoCalc.html

Plugging in WMAP values yields these results:

Current age of universe: t = 13.67 Gy
z = 1000 t = 436,000 years
z = 20 t = 182 My
z = 8 t = 652 My
z = 6.28 t = 896 My

Also per WMAP, recombination occured around z = 1089, which occurs at t = 378 My.
Thank you for that Chronos as I said my numbers were based on the plain Einstein-de Sitter universe, a spatially flat dust filled model,
R(t) ~ t2/3.
Acceleration extends my ages and that depends on the extent of the acceleration period and the equation of state used for Dark Energy. As neither of these two factors are known the result is very problematic. Is there another New Wright page where he shows the equations used in his 'calculator'?
Garth
 

hellfire

Science Advisor
1,047
1
Garth said:
Is there another New Wright page where he shows the equations used in his 'calculator'?
You can check my cosmological calculator here. It is not as elaborated as Ned Wright ones, but the code is far simpler (cc_e.js). It is of free use, and if you have any questions about equations I can answer via PM. By the way, the age 13.67 Gly for the standard model follows from the assumption of 0.27 Omega matter, 0.73 Omega Lambda (w = -1) and h = 0.71.
 
Last edited:

Garth

Science Advisor
Gold Member
3,572
105
hellfire said:
You can check my cosmological calculator here. It is not as elaborated as Ned Wright ones, but the code is far simpler (cc_e.js). It is of free use, and if you have any questions about equations I can answer via PM. By the way, the age 13.67 Gly for the standard model follows from the assumption of 0.27 Omega matter, 0.73 Omega Lambda (w = -1) and h = 0.71.
Thank you hellfire,the standard model does seem to be clustering around those values.

The model would be more robust if we knew exactly what DE was. (if anything!)

The acceleration of the universe in the past depends on the equation of state of DE w = -1 relates to the cosmological constant, (hence 'Lambda' of LCDM), and false vacuum energy (ZPE anybody?), whereas w = -1/3 would be that of a string network, and w < -1 for 'quintessence'.

The model also requires the universe to be spatially flat, and therefore infinite, but where are the low mode anisotropies in the WMAP/BALLOON/COBE data? As I have pointed out on several occasions the data is also concordant with a conformally flat model such as a cone (freely coasting - SCC Einstein frame), or a cylinder (Einstein's original static model - SCC Jordan frame) or a torus. Any of these would be finite in size and able to explain the low mode deficiency in the CMB anisotropies.

Also note that the standard model critically depends on not only the interpretation of the WMAP data but also on that of the distant SN Ia luminosity data. That data is also concordant with the freely coasting model as in my link in post #33, here, page 4 and recognised by Perlmutter 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).
.

Comparing times from BB between the LCDM model as above and SCC we have:
Using tz=x to be the age of an object now observed at a red shift x, we have for time after BB:

For "re-combination" - the surface of last scattering of the CMB, z = 1089,
tz=1089 = 378,000 yrs. in GR
tz=1089 = 12.7 Myrs. in SCC

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

for quasar 'ignition' z = 8
tz=8 = 652 Myrs. in GR
tz=8 = 1.53 Gyrs. in SCC

for 'modern' metallicity in Quasar SDSS J1030+0524 z = 6.28
tz=6.28 = 896 Myrs. in GR
tz=6.28 = 1.90 Gyrs. . in SCC.

This comparison, using "Mainstream model" parameters, still shows that there is considerably more time for the development of Pop III stars, Quasars and early metallicity than in the mainstream model.

Garth
 
Last edited:

Chronos

Science Advisor
Gold Member
11,398
738
The WMAP result suggesting reionization began around z = 20 is the tightest, and most model resistant constraint in current mainstream theory. The SCC limit is obviously more palatable. The other early events, such as rapid evolution of metallicity are not so troubling - at least to this point. Our weak understanding of stellar and galactic chemical evolution deserves much of the blame. But then again, it is not clear why reionization occured at the pace it did [some would say too fast, some too slow]. The evolution of metallicity and reionization could easily be connected. The observations we need to resolve these, and other stubborn problems unfortunately reside in the cosmic 'dark ages' [z>6]. Some exciting projects are, however, in the works:

LOFAR
http://www.lofar.org/p/ast_sc_epoch.htm [Broken]

Square Kilometer Array
http://www.skatelescope.org/pages/science_gen.htm [Broken]
 
Last edited by a moderator:

Garth

Science Advisor
Gold Member
3,572
105
Chronos said:
The WMAP result suggesting reionization began around z = 20 is the tightest, and most model resistant constraint in current mainstream theory. The SCC limit is obviously more palatable. The other early events, such as rapid evolution of metallicity are not so troubling - at least to this point. Our weak understanding of stellar and galactic chemical evolution deserves much of the blame. But then again, it is not clear why reionization occured at the pace it did [some would say too fast, some too slow]. The evolution of metallicity and reionization could easily be connected. The observations we need to resolve these, and other stubborn problems unfortunately reside in the cosmic 'dark ages' [z>6]. Some exciting projects are, however, in the works:

LOFAR
http://www.lofar.org/p/ast_sc_epoch.htm [Broken]

Square Kilometer Array
http://www.skatelescope.org/pages/science_gen.htm [Broken]
Thank you for that. Yes the reionisation (even a very Extended reionization epoch) and metallicity are most probably connected - to Pop III stars, but how big and how many of them? If you have a few very large Pop IIIs then the ionisation will be patchy and metallicity likewise.

SCC would suggest that primordial metallicity and high primordial baryonic density (~22%) would allow many smaller Pop IIIs to form (100 - 1000 solar mass) that would produce a smoother ionisation pattern and distribution of metallicity than in the standard model. They would then leave behind IMBH's of that mass range constituting the DM today.

Is this too 'hand waving' a possibility?

Garth
 
Last edited by a moderator:

Chronos

Science Advisor
Gold Member
11,398
738
Everything is up for grabs until we have more and better observations of the hidden pieces of the puzzle. The tail end of the epoch of reionization is just within our observational grasp [the Gunn Peterson trough]. It currently looks like reionization will turn out to be a messy affair - something akin to starbursts in galactic evolution:

http://arxiv.org/abs/astro-ph/0411152
How Universal is the Gunn-Peterson Trough at z~6?: A Closer Look at the Quasar SDSS J1148+5251

http://arxiv.org/abs/astro-ph/0505065
Taxing the Rich: Recombinations and Bubble Growth During Reionization
 

Related Threads for: Comparison of the Mainstream and the Self Creation Freely Coasting models

Replies
0
Views
2K
  • Last Post
Replies
15
Views
3K
Replies
1
Views
2K
  • Last Post
Replies
1
Views
4K
Replies
6
Views
3K
Replies
1
Views
2K
  • Last Post
Replies
8
Views
3K
Top