Mystery of Dark Energy: Unravelling the GR Expansion of Universe

[meteor]

It seems that there's perhaps some preference within the physics community to a dark energy with constant energy density (e.g. cosmological constant). NASA scientists declared months ago that they bet for a cosmological constant
But I prefer a model with dependence on time. Examples of such models are quintessence, phantom energy and k-essence
Phantom energy (aka superquintessence) postulates an increase of dark energy density over time. So the universe will end violently tearing all apart in the Big Rip, aka Big Smash
Quintessence is a scalar field that varies over time and also has dependence on space ( so it will be more dense in some localizations than in others). It actually exercises negative pressure, but exercised positive pressure in the past! So, it can perhaps exercise positive pressure in the future (leading to a Big Crunch?)
K-essence also varies in space and time, its equation of state varies over time but its always w>(-1)
I prefer the model of quintessence because I think that the acceleration is not going to be eternal. Since I'm also a fan of Loop Quantum Cosmology and this theory has recently forecasted the possibility of the universe undergoing a Big Crunch, it's a model perfect for me

 

[turbo]

I too expect that there will be time-dependant variation at the fundamental level (structure and coarseness of space-time, for instance) and I also expect that the Einsteinian space-time "curvature" caused by embedded mass will be better visualized as gradients in the properties of the basic units of space-time (density, orientation, energy states...). These space-time gradients will be found to cause "gravitational lensing" redshifting, and other effects, not gravity itself.

Gravity (as expressed as force acting over a distance) is very weak and should not be invoked as a force capable of bending the paths of photons passing nearby. The amount of mass needed to provided such refraction might overstate the mass of a galaxy or galactic cluster by quite a large amount (a pretty common problem these days, with about 96% of the mass of the universe tied up in invisible undetectable "dark matter").

 

[Nereid]

I too expect that there will be time-dependant variation at the fundamental level (structure and coarseness of space-time, for instance) and I also expect that the Einsteinian space-time "curvature" caused by embedded mass will be better visualized as gradients in the properties of the basic units of space-time (density, orientation, energy states...). These space-time gradients will be found to cause "gravitational lensing" redshifting, and other effects, not gravity itself.

Gravity (as expressed as force acting over a distance) is very weak and should not be invoked as a force capable of bending the paths of photons passing nearby. The amount of mass needed to provided such refraction might overstate the mass of a galaxy or galactic cluster by quite a large amount (a pretty common problem these days, with about 96% of the mass of the universe tied up in invisible undetectable "dark matter").

Something like dark matter, which can't be accounted for within the Standard Model, and which we can't get into the lab to zap and prod, surely causes many folk heartburn.

However, to call it 'undetectable' does a considerable disservice to the ingenuity of observational astronomers. In particular, there is a consistency in the observations which is a challenge for alternative views - estimates of the mass of dark matter in rich clusters are consistent across three independent types of observation - X-ray data on IGM gas temperature (assume equilibrium, derive mass), redshift data on galaxy velocity dispersion (apply virial theorem, derive mass), and gravitational lensing (both weak and strong; assume Einstein, derive mass).

For at least one cluster, the distribution of dark matter has been derived (not just the mass), and a nice piccie made - if it ain't DM, what is it a piccie of? http://www.astro.caltech.edu/~tt/0024/CL0024II.pdf

 

[Garth]

For at least one cluster, the distribution of dark matter has been derived (not just the mass), and a nice piccie made - if it ain't DM, what is it a piccie of? http://www.astro.caltech.edu/~tt/0024/CL0024II.pdf

Thank you for a nice reference; "what is it a 'piccie' of?" How about dark baryonic matter?

In my post #12 on this thread I referred to two papers from an Indian team that show in the "Freely Coasting Universe", which is expanding strictly linearly, the mass density of ordinary baryonic matter is aboput 20% and not a maximum of 4% as in the standard paradigm.

Therefore this stuff does not have to be re-invented, we know it already and are made of it!
Garth

 

[turbo]

Something like dark matter, which can't be accounted for within the Standard Model, and which we can't get into the lab to zap and prod, surely causes many folk heartburn.

However, to call it 'undetectable' does a considerable disservice to the ingenuity of observational astronomers. In particular, there is a consistency in the observations which is a challenge for alternative views - estimates of the mass of dark matter in rich clusters are consistent across three independent types of observation - X-ray data on IGM gas temperature (assume equilibrium, derive mass), redshift data on galaxy velocity dispersion (apply virial theorem, derive mass), and gravitational lensing (both weak and strong; assume Einstein, derive mass).

For at least one cluster, the distribution of dark matter has been derived (not just the mass), and a nice piccie made - if it ain't DM, what is it a piccie of? http://www.astro.caltech.edu/~tt/0024/CL0024II.pdf

Well, we have fundamentally different views of this, so I'll try to state mine succinctly. First of all the picture of dark matter is not real in any sense - it is only a guess at how this invisible stuff "might" be distributed to explain the amount of "gravitational lensing" (a misnomer) observed through that cluster. I would like to see this same group show us how the dark matter needs to be distributed around a typical spiral galaxy in "just" such a way as to cause the differential rotations they exhibit. I'm afraid that dark matter gets very messy in that area.

As an optician, I am very interested in the behavior of light and other electromagnetic waves. Since detecting and measuring these radiations are the primary means by which we explore our universe, I am sensitive to quandries and puzzles regarding our understanding of light. You already know about some of my struggles with discordant redshift.

I suggest that we be parsimonious and NOT invoke the existence of dark matter to explain lensing. Right now, we know that massive objects exist, we know that massive objects distort space-time, and we know that light propogates through space-time. We have all the ingredients we need for lensing. The simplest explanation for "gravitational lensing" is that masses distort space-time and the distorted space-time refracts light passing through it, resulting in lensing. There is no need for dark matter, nor should we call this "gravitational" lensing. The lensing is cause by refraction of light passing through a space-time domain that is distorted by the presence of mass. The refraction is not caused by gravity (in the Newtonian sense). Newtonian gravity is an extremely weak force of attraction between massive bodies, and photons are not massive in any real sense. Their paths can be deflected however by density differences in the medium through which they travel - Space-Time.

How does mass distort space-time? Does it cause gradients in the distribution, orientation and/or energy state of the basic units of space-time? These are the questions that will have to be answered (probably by the LQG or String people) before quantum physics and relativity can be united. The optical qualities of clusters might hold clues as to how we can expect the distortion of space-time to manifest itself. The LQG people are modeling space-time as if it comes in discrete units with lengths, areas, and volumes quantized at the Planck level. What do these basic units of space-time do in the presence of mass? That's the tough part.

 

[Nereid]

Well, we have fundamentally different views of this, so I'll try to state mine succinctly. First of all the picture of dark matter is not real in any sense - it is only a guess at how this invisible stuff "might" be distributed to explain the amount of "gravitational lensing" (a misnomer) observed through that cluster. I would like to see this same group show us how the dark matter needs to be distributed around a typical spiral galaxy in "just" such a way as to cause the differential rotations they exhibit. I'm afraid that dark matter gets very messy in that area.

As an optician, I am very interested in the behavior of light and other electromagnetic waves. Since detecting and measuring these radiations are the primary means by which we explore our universe, I am sensitive to quandries and puzzles regarding our understanding of light. You already know about some of my struggles with discordant redshift.

I suggest that we be parsimonious and NOT invoke the existence of dark matter to explain lensing. Right now, we know that massive objects exist, we know that massive objects distort space-time, and we know that light propogates through space-time. We have all the ingredients we need for lensing. The simplest explanation for "gravitational lensing" is that masses distort space-time and the distorted space-time refracts light passing through it, resulting in lensing. There is no need for dark matter, nor should we call this "gravitational" lensing. The lensing is cause by refraction of light passing through a space-time domain that is distorted by the presence of mass. The refraction is not caused by gravity (in the Newtonian sense). Newtonian gravity is an extremely weak force of attraction between massive bodies, and photons are not massive in any real sense. Their paths can be deflected however by differences density in the medium through which they travel - Space-Time.

How does mass distort space-time? Does it cause gradients in the distribution, orientation and/or energy state of the basic units of space-time? These are the questions that will have to be answered (probably by the LQG or String people) before quantum physics and relativity can be united.

First let's clear up our terminology ... observational astronomers use the phrase 'gravitational lensing' rather loosely, referring to both 'true gravitational lensing' (what you expect from a straight-forward application of GR to the EM images of a distant object seen 'through' a closer, massive one - arcs, multiple images, magnification, etc), and image distortion as EM is deflected by passing 'near' a massive body (sometimes called 'weak lensing', or 'gravitational shear'; it's also the (in)famous 1919 eclipse photos through to Cassini, the Sun being the massive object).

Next, let's see if we agree on 'nearby' examples of 'lensing'. AFAIK, deflection of EM has been observed in our solar system, by both the Sun and Jupiter, and the most accurate data are consistent with GR to 1 part in ~10⁴; in these cases, the mass of the Sun (and Jupiter) are obtained independently of the deflection, and those mass estimates are consistent with a great deal of physics. Does either turbo-1 or Garth have an alternative theory to account for these solar system observations?

Within the Milky Way, a number of programs have detected transient gravitational lens events - a massive object passes into the line of sight from Earth to a distant star, the star appears to brighten, then fade. This is usually interpreted as the lensing object being a closer star. Again, the observations are consistent with GR, and include caustic crossing events as well as later, direct observations of the lensing star. (If any reader is unfamiliar with this work, please say so and I'll post links). Does either turbo-1 or Garth have an alternative theory to account for these Milky Way (and LMC/SMC?) observations?

For relatively nearby galaxies, SDSS researchers have published papers showing the average radial distribution of mass around the galaxies, from the 'shear' distortions in images of more distant galaxies. This work is statistical; the 'shear signal' is quite weak, but shows up clearly when many galaxies are analysed (and there's no shear signal around bright stars - as expected). It's here that DM becomes evident - the mass required to produce the observed shear (and its distribution) are larger than that inferred from the light observed from these galaxies. Does either turbo-1 or Garth have an alternative theory to account for these relatively local galaxy observations?

 

[Nereid]

Thank you for a nice reference; "what is it a 'piccie' of?" How about dark baryonic matter?

In my post #12 on this thread I referred to two papers from an Indian team that show in the "Freely Coasting Universe", which is expanding strictly linearly, the mass density of ordinary baryonic matter is aboput 20% and not a maximum of 4% as in the standard paradigm.

Therefore this stuff does not have to be re-invented, we know it already and are made of it!
Garth

Well I finally got around to downloading and reading these papers (they are essentially the same; the more recent one is longer and has more details). There was one refence that I couldn't find on the internet: "A study of consistency of linear coasting with gravitational lensing statistics has recently been reported". I think this 'freely coasting universe' idea is quite interesting; it'd be great to hear what marcus, pmb_phy, Chronos, and others think of it!

Although it's a bit OT (DM, not DE), I was left quite puzzled by the Gehlaut et al papers and their account of DM; maybe Garth can help me out.

It seems that Gehlaut et al claim to have a cosmology that is consistent with the WMAP (and other CMBR) observations (most of their paper is devoted to this), nuclide abundance data (though they discuss only element abundance, plus deuterium), the expansion rate observations (including the recent, distant Type Ia SN data), inferred age of the universe vs oldest object observations (though this is not examined in much detail), and multiple quasar images ('true' gravitational lensing, though it is apparently discussed elsewhere).

As Garth says, the DM 'seen' in large galaxies and clusters is 'cold, baryonic matter' in Gehlaut et al. But what baryons? And what about the DM in dwarf galaxies? It seems to me Gehlaut et al still have the same challenge as that which generations of astronomers faced, right back to Zwicky: the DM isn't gas (it doesn't show up as either emission or absorption), dust (ditto), dim or failed stars (MACHO, OGLE etc would have seen that), old stars such as faint white dwarfs or neutron stars (ditto) ... so it is exotic baryons? or pebbles rocks and comets?

Lastly, for this post, Gehlaut et al say "there would just be enough neutrons produced, after nucleosynthesis commences, to give [...] and metallicity some 10⁸ times the metallicity produced in the early universe in the standard scenario. This metallicity is of the same order of magnitude as seen in lowest metallicity objects." But they don't state a) what primordial metallicity they predict, nor b) what the metallicity of the lowest metallicity objects actually is!

 

[meteor]

A pair of models that can interest to someone...
http://xxx.lanl.gov/abs/astro-ph/0409033
"On the Accelerated Expansion of the Universe"
this model postulates the acceleration of the expansion is due to fermion degeneracy pressure of neutrinos of the intergalactic medium

Also, Trans-Planckian Dark energy
http://arxiv.org/abs/hep-th/0212027

 

[Garth]

Neried asks whether I have another explanation for the DM observations and gravitational lensing at different scales. I do not, I am quite happy with the idea that a) gravitaitonal lensing occurs and is as predicted by GR (it is the same in SCC) and b) that Dark Matter exists. My argument is though it is Dark in the sense of being non-luminous, not in the sense of being some unknown new type, or state, of matter. In a freely coasting universe (as in SCC) it is just ordinary baryonic matter as the baryonic cosmological density is about 20 % and not restricted to 4% as in the standard model. If there is a problem in identifying exactly what form it takes then that problem is no greater than in the standard paradigm. It could be bricks, or Jupiters or a population of black holes or whatever, I do not claim to be able to solve all the mysteries at once, just that it should not necessary to multiply mysteries by adding these extra 'epicycles' (Inflation, DM, DE) to keep the old paradigm afloat.
Garth

 

[Chronos]

It is certainly true the Standard Model has evolved over time. I don't think it is accurate to characterize that process as being ad-hoc. I am also reluctant to discard the model in favor of a more radical approach, such as 'free coasting'. Not that other models don't have their attractive features. That is why they are still being kicked about. The more relevant issue is the Standard Model has an imposing mountain of observational and theoretical support. The others do not. Fortunately, different researchers have different opinions and all the viable options will continue to be explored. At present, the Standard Model is the reigning heavy weight champ and any challenger will have to deliver a knockout punch to claim the title.

The 'freely coasting' model proposed by Gehlaut etal is interesting. The paper did put me in full skeptic mode early on when they asserted "First of all, the use of Einsteins equations to describe cosmology has never been justified." The rational for making this rather shocking statement was not very convincing. On the whole, however, it has some nice features. None of those annoying particle or cosmological horizons to address. It also appears to be concordant, although I think some issues were rather thinly supported and others largely ignored. The following papers present some of these issues.
http://adsabs.harvard.edu/cgi-bin/n.....67L&db_key=AST&high=40d9fbf26c22275
http://adsabs.harvard.edu/cgi-bin/n....373L&db_key=AST&high=40d9fbf26c23948
http://adsabs.harvard.edu/cgi-bin/n....543K&db_key=AST&high=40d9fbf26c23948
It seemed pretty obvious the lack of an inflationary epoch in the very early universe posed a problem. Solving it by inserting repulsive gravity without offering a mechanism was a pretty big pill to swallow. You also end up with a universe where recombination did not occur until ~10^7 years as opposed to ~10^5 years after the big bang. The explanation for elemental abundance was not great, but, OK. At least it left room for falsifiable predictions. All in all, I did not feel it solved more problems than it created, but, that's not necessarily a bad thing.

 

[Garth]

It is certainly true the Standard Model has evolved over time. I don't think it is accurate to characterize that process as being ad-hoc. I am also reluctant to discard the model in favor of a more radical approach, such as 'free coasting'. Not that other models don't have their attractive features. That is why they are still being kicked about. The more relevant issue is the Standard Model has an imposing mountain of observational and theoretical support. The others do not. Fortunately, different researchers have different opinions and all the viable options will continue to be explored..

One concern of mine is the absolute confidence placed in the standard model: it is called "precision cosmology", its deductions are presented as facts, it is assumed that it has been robustly established beyond doubt as an intellectual edifice standing on several pillars. Attack one we are told (RAS lecture 2004) and the others will continue to securely support the paradigm. However this confidence ignores the fact that three of these pillars are invisible, Inflation which depend on the Higgs field (we have detected the Higgs boson have we?), Dark Matter (we know what is it do we?) and Dark Energy (we know what we are talking about do we?) In their day the addition of epicycles to the Ptolemaic system was no more "ad hoc" than our addition of these "entities".

”Entia non sunt multiplicand praetor necessitatem” (Entities should not be unnecessarily multiplied) Ockham’s (Occam’s) razor.

The reason "the Standard Model has an imposing mountain of observational and theoretical support" is because it has been so well funded and the alternatives not, yet it is the essence of the scientific method that alternative theories against which the standard model can be tested should be encouraged. As I have pointed out on several posts cosmological observations are all theory dependent, change the theory and those observations change too. The important thing is to have consistency and an economy of "entities".

At present, the Standard Model is the reigning heavy weight champ and any challenger will have to deliver a knockout punch to claim the title.

Maybe, just maybe, Gravity Probe B will deliver this.

Solving it by inserting repulsive gravity without offering a mechanism was a pretty big pill to swallow.

Agreed, but SCC provides the mechanism.

"Cosmologists are often in error but never in doubt"

 

[turbo]

Next, let's see if we agree on 'nearby' examples of 'lensing'. AFAIK, deflection of EM has been observed in our solar system, by both the Sun and Jupiter, and the most accurate data are consistent with GR to 1 part in ~10⁴; in these cases, the mass of the Sun (and Jupiter) are obtained independently of the deflection, and those mass estimates are consistent with a great deal of physics. Does either turbo-1 or Garth have an alternative theory to account for these solar system observations?

Within the Milky Way, a number of programs have detected transient gravitational lens events - a massive object passes into the line of sight from Earth to a distant star, the star appears to brighten, then fade. This is usually interpreted as the lensing object being a closer star. Again, the observations are consistent with GR, and include caustic crossing events as well as later, direct observations of the lensing star. (If any reader is unfamiliar with this work, please say so and I'll post links). Does either turbo-1 or Garth have an alternative theory to account for these Milky Way (and LMC/SMC?) observations?

For relatively nearby galaxies, SDSS researchers have published papers showing the average radial distribution of mass around the galaxies, from the 'shear' distortions in images of more distant galaxies. This work is statistical; the 'shear signal' is quite weak, but shows up clearly when many galaxies are analysed (and there's no shear signal around bright stars - as expected). It's here that DM becomes evident - the mass required to produce the observed shear (and its distribution) are larger than that inferred from the light observed from these galaxies. Does either turbo-1 or Garth have an alternative theory to account for these relatively local galaxy observations?

Relativity predicts the distortions caused by massive spherical objects very well. We should not expect the relationship to hold when the distribution of the mass is non-spherical or diffuse. This is too simplistic.

Let me explain in optical terms: The power of a lens is determined by its refractive index (relative to the surrounding media) and its curvature. You can produce essentially identical optical effects with very different lenses, for example 1) a highly refractive lens with shallow curvature and 2) a lens with lower index of refraction and steeper curvature.

In the example of a roughly spherical or cylindrical cluster of galaxies, the volume of space-time distorted by that mass will likely be similarly curved. This will create a strongly refractive "lens" in space-time.

As for relative refractive index: the cluster is very massive and the space in front of and behind the cluster is relatively free of mass. This will create a very strong relative refractive index, since space-time in the cluster will be highly distorted and space time in front of and in back of the cluster will be relaxed, creating strong gradients through which light must pass. Again, this results in a more refractive lens.

In this model, it is not possible to determine the mass of a galactic cluster by measuring the distortions caused by lensing and simply extrapolating back to the amount of lensing caused by a planet or a star. In fact with these ideal conditions of: 1) strongly-curved lensing region and 2) strong gradients in space-time distortion between the cluster and its relatively mass-free surroundings, we should expect the lensing effect to be very strong. Using relativity to try extrapolate cluster mass in such a situation will lead to a gross overstatement of the mass involved.

For background (for those I have not already bored to tears): The concept of discrete space-time units with dimensions quantized at the Planck scale leads naturally to the question "what does mass do to local space-time, and what is the nature of the distortion that it causes?" Since space-time is the medium through which light propogates, we must then ask "what will the distorted space-time do to light crossing it and what should we expect to observe as a result?" We're probably going to need a dynamical theory of LQG or something similar before we can model the effects of mass on space-time (and vice-versa) and accurately predict the effects of space-time variations on impinging EM. We should expect visible optical effects, however, and strong lensing by mass-dense galactic clusters is appropriate and expected, at least to me.

I approach all of this in purely optical terms because that is the nature of my training and because the primary means by which we observe our universe is the collection and analysis of EM radiation. If we don't understand the effects of the propagating medium on the radiation, our fundamental understanding of EM is flawed and our naive observations will lead us to make wrong conclusions. I believe that measuring the lensing of a galactic cluster and using those measurements to posit a cloud of invisible non-baryonic dark matter to make up the "missing" mass is just such a mistake.

 

[meteor]

Garth, I've reading a bit about your Self creation Cosmology and I'm not sure how you eliminate dark energy. I think that you get rid of General Relativity and create a new Cosmology where the universe is actually not accelerating. Is that correct?
------------------------------------------------------------------------

More models...
Seems that some investigators are playing with the idea of "Solid Dark Energy".For example, a representative of this idea is this model of 1998 by Bucher, where he proposes that dark energy is due to a frustrated network of domain walls. don't be mislead by the title. though the title is "Is the dark matter a solid?", the paper also exposes this idea of dark energy caused by domain walls
http://arxiv.org/abs/astro-ph/9812022

 

[Chronos]

Relativity predicts the distortions caused by massive spherical objects very well. We should not expect the relationship to hold when the distribution of the mass is non-spherical or diffuse. This is too simplistic.

Let me explain in optical terms: The power of a lens is determined by its refractive index (relative to the surrounding media) and its curvature. You can produce essentially identical optical effects with very different lenses, for example 1) a highly refractive lens with shallow curvature and 2) a lens with lower index of refraction and steeper curvature.

In the example of a roughly spherical or cylindrical cluster of galaxies, the volume of space-time distorted by that mass will likely be similarly curved. This will create a strongly refractive "lens" in space-time.

As for relative refractive index: the cluster is very massive and the space in front of and behind the cluster is relatively free of mass. This will create a very strong relative refractive index, since space-time in the cluster will be highly distorted and space time in front of and in back of the cluster will be relaxed, creating strong gradients through which light must pass. Again, this results in a more refractive lens.

In this model, it is not possible to determine the mass of a galactic cluster by measuring the distortions caused by lensing and simply extrapolating back to the amount of lensing caused by a planet or a star. In fact with these ideal conditions of: 1) strongly-curved lensing region and 2) strong gradients in space-time distortion between the cluster and its relatively mass-free surroundings, we should expect the lensing effect to be very strong. Using relativity to try extrapolate cluster mass in such a situation will lead to a gross overstatement of the mass involved.

For background (for those I have not already bored to tears): The concept of discrete space-time units with dimensions quantized at the Planck scale leads naturally to the question "what does mass do to local space-time, and what is the nature of the distortion that it causes?" Since space-time is the medium through which light propogates, we must then ask "what will the distorted space-time do to light crossing it and what should we expect to observe as a result?" We're probably going to need a dynamical theory of LQG or something similar before we can model the effects of mass on space-time (and vice-versa) and accurately predict the effects of space-time variations on impinging EM. We should expect visible optical effects, however, and strong lensing by mass-dense galactic clusters is appropriate and expected, at least to me.

I approach all of this in purely optical terms because that is the nature of my training and because the primary means by which we observe our universe is the collection and analysis of EM radiation. If we don't understand the effects of the propagating medium on the radiation, our fundamental understanding of EM is flawed and our naive observations will lead us to make wrong conclusions. I believe that measuring the lensing of a galactic cluster and using those measurements to posit a cloud of invisible non-baryonic dark matter to make up the "missing" mass is just such a mistake.

Crap=crap. Using non-relevatistic reference frames to make your point is... unconvincing. Please explain how the observational evidence takes the stink off your theoretical cow pie.

 

[turbo]

Crap=crap. Using non-relevatistic reference frames to make your point is... unconvincing. Please explain how the observational evidence takes the stink off your theoretical cow pie.

I guess you've had a bad day, Chronos, so I'll let the rudeness slide.

Observational evidence = Galactic clusters exhibit very strong lensing. They lens so strongly that if you try to extrapolate their masses using the simple relativistic model, the calculated mass will be many times larger than that of the observed matter in the cluster.

Conventional astronomers cannot reconcile this with the standard model, but instead of trying to find where the model is broken, they instead claim that the "missing" mass is really there in the form of non-baryonic "dark matter". Of course, it is distributed in just such a manner as to produce the excess lensing. These are the same people who invoke non-baryonic "dark matter" to explain the discordant rotational curves of spiral galaxies. Of course, the "dark matter" again obligingly distributes itself in a very special non-uniform way to fix the rotational problem.

Somehow conventional cosmologists cannot bring themselves to examine these fundamental problems with their models. Instead, they invent "dark matter" that behaves in very special ways in each relevant circumstance. You might as well substitute obedient "fairies" or "angels" for "dark matter". As a very wise man once sang "When you believe in things you don't understand, you will suffer."

 

[Garth]

Garth, I've reading a bit about your Self creation Cosmology and I'm not sure how you eliminate dark energy. I think that you get rid of General Relativity and create a new Cosmology where the universe is actually not accelerating. Is that correct?

O.K. I am not getting rid of GR but modifying it. Einstein had two concerns over GR, the fact that it did not fully include Mach's Principle and the fact that it did not locally conserve energy. The Brans Dicke (BD) theory modified GR to include a Machian scalar field but retained the Equivalence Principle conserving energy-momentum in doing so; SCC modifies BD to include the local conservation of energy.
There are two conformal frames of measurement (of mass, length and time) in the theory. One is the Jordan frame (JF) in which the full theory describing gravitational orbits is formulated, this conserves energy, and the other is the Einstein frame (EF) in which the conservation of energy-momentum and the EEP are recovered, this is canonical GR in vacuo; the trajectories of test particles are the geodesics of GR.
The presence of the scalar field alters the GR cosmological expansion of the universe, the Friedman equations, so that in the EF the universe expands in a strictly linear fashion. When dealing with atoms i.e. in BB nucleo-synthesis it is easier to work in this frame. The Indian team have already done the work for me!
In the JF the universe isn't expanding at all. It is eternal and static with particle masses that increase, clocks that speed up and rulers that shrink, all exponentially according to exp(Ht).
The theory also is highly determined by H - there is no room for manoeuvre. However the values it comes up with are consistent with those that seem to be observed - although the interpretation of those observations is of course open to debate. The theory determines a moderate amount of false vacuum energy - 11% and a reasonable amount of matter - 22%. Hence the density available for gravitational lensing galaxy cluster dynamics etc. is 33%. And that is all that is required.

The EF universe is a hyper-cone and the JF universe is a projection of this, a hyper-cylinder where the long axis of symmetry in both cases is cosmological time. Both the cone and the cylinder are spatially flat; you can slit both time-like up one side and unroll them into a 'sheet'.
The 'Freely Coasting' universe produces about 20% baryons so you don't have to invent any extra Dark Matter, it is all dark baryons in some form or other - I know this poses a problem in identifying exactly what, I don't claim to solve all the mysteries at once! And spatial flatness means the WMAP data can be satisfied without inventing Dark Energy, although the false vacuum might be thought to be such – its effect is observed in the form of the Casimir force.
An economy of "entities"?

 

[turbo]

Chronos, you are quick to insult, and slow to apologize.

I guess you've had a bad day, Chronos, so I'll let the rudeness slide.

Observational evidence = Galactic clusters exhibit very strong lensing. They lens so strongly that if you try to extrapolate their masses using the simple relativistic model, the calculated mass will be many times larger than that of the observed matter in the cluster.

Conventional astronomers cannot reconcile this with the standard model, but instead of trying to find where the model is broken, they instead claim that the "missing" mass is really there in the form of non-baryonic "dark matter". Of course, it is distributed in just such a manner as to produce the excess lensing. These are the same people who invoke non-baryonic "dark matter" to explain the discordant rotational curves of spiral galaxies. Of course, the "dark matter" again obligingly distributes itself in a very special non-uniform way to fix the rotational problem.

Somehow conventional cosmologists cannot bring themselves to examine these fundamental problems with their models. Instead, they invent "dark matter" that behaves in very special ways in each relevant circumstance. You might as well substitute obedient "fairies" or "angels" for "dark matter". As a very wise man once sang "When you believe in things you don't understand, you will suffer."

Chronos, I guess you are really busy. Maybe you would like to post a response next week...or later. You routinely demand all "relevant maths" when you want to embarass other posters, so I'll give you a few days to come up with the goods. You might need the time.

 

[Chronos]

Agreed. Examples include
http://www.earth.uni.edu/~morgan/ajjar/Cosmology/cosmos.html
Turbo and I argue all the time. We have fun with it, most of the time. He is a good guy and very bright.

 

[turbo]

And spatial flatness means the WMAP data can be satisfied without inventing Dark Energy, although the false vacuum might be thought to be such – its effect is observed in the form of the Casimir force.
An economy of "entities"?

For those unfamiliar with Zero Point Energy, here is a link to a primer on the Casimir effect.

http://math.ucr.edu/home/baez/physics/Quantum/casimir.html

One thing not often mentioned in discussions of this effect is that although the virtual particle-antiparticle pairs have opposite spins, charges, timelines etc, and cancel each other in those respects, each particle has mass. The ground state of pure "vacuum" is therefor massive.

 

[Garth]

The ground state of pure "vacuum" is therefor massive.

Which leads to the inconsistency of explaining dark energy by vacuum zero point energy: ZPE is over 120 orders of magnitude too large.

However as a further point of information about SCC; the theory requires and determines a moderate amount of ZPE if space-time suffers curvature. Its density near the Earth is 10^-9 gms/cc, and cosmologically 0.11 of critical density.

One further test of the theory is its prediction that there is an upper limit on the Casimir force which the theory suggests tends to zero as 'curvature' tends to 'flatness'. Therefore, according to SCC, this limit should be detectable in the solar gravitational field between the orbits of Jupiter and Saturn (depending on the sensitivity of the apparatus).

 

[turbo]

One concern of mine is the absolute confidence placed in the standard model: it is called "precision cosmology", its deductions are presented as facts, it is assumed that it has been robustly established beyond doubt as an intellectual edifice standing on several pillars. Attack one we are told (RAS lecture 2004) and the others will continue to securely support the paradigm. However this confidence ignores the fact that three of these pillars are invisible, Inflation which depend on the Higgs field (we have detected the Higgs boson have we?), Dark Matter (we know what is it do we?) and Dark Energy (we know what we are talking about do we?) In their day the addition of epicycles to the Ptolemaic system was no more "ad hoc" than our addition of these "entities".

”Entia non sunt multiplicand praetor necessitatem” (Entities should not be unnecessarily multiplied) Ockham’s (Occam’s) razor.

The reason "the Standard Model has an imposing mountain of observational and theoretical support" is because it has been so well funded and the alternatives not, yet it is the essence of the scientific method that alternative theories against which the standard model can be tested should be encouraged. As I have pointed out on several posts cosmological observations are all theory dependent, change the theory and those observations change too. The important thing is to have consistency and an economy of "entities".

I agree with every point in your post, but would like to add a thought that seems to escape many otherwise bright people. Consistency does not automatically equate to accuracy. Supporters of the Standard Model point to its consistency as "proof" of its accuracy; however, as you and I both frequently mention, the Standard Model is consistent only because of the epicycles tacked onto it to keep it usable. Dark Matter, Dark Energy, and Inflation should be viewed as measures of just where and how badly the Standard Model fails to accurately model our Universe. These failures may be related.

 

[turbo]

Here you go Chronos!

Crap=crap. Using non-relevatistic reference frames to make your point is... unconvincing. Please explain how the observational evidence takes the stink off your theoretical cow pie.

It took quite a bit of digging (and I get sidetracked very easily) but here is a very cogent paper from a researcher (Puthoff) taking exactly the same approach I am using to model lensing without resorting to the curved space-time of General Relativity. He substitutes Polarized Vacuum for curved space-time in General Relativity, with some interesting extensions that I had not anticipated.

Outside of a basic understanding of optics, I don't have the math skills to explain my ideas about lensing in ways that are understandable to physicists or mathemeticians, which is probably why Nereid seemed puzzled by my insistence that the GR concept of "gravitational lensing" is inaccurate in light of the quantized structure of space-time envisioned by LQG. You may remember that for some time, I have been exploring whether vacuum energy might be polarized (oriented by local fields):

https://www.physicsforums.com/showthread.php?t=37724
https://www.physicsforums.com/showthread.php?t=28868

After you read Puthoff's paper, you will know why I've been pursuing this. One question still bugging me is this: Can mass create such extreme distortion of the units of space-time that the virtual pairs that define ZPE do not have room to arise (like the small gap between the plates of the Casimir Effect experimental equipment). I may eventually have to reconcile the concept that "space-time" belongs in the Einsteinian GR, and that the fine structure of space-time in a quantum extension of GR will more properly be expressed as vacuum energy.

Puthoff models the space-time distortion caused by mass as polarization of the vacuum field (ZPE) and equates the variable polarization as a change in refractive index. He then explains "gravitational lensing" in terms of the optical properties of the lensing media. That seemed to offend you terribly when I did it, Chronos, judging from the tone of the quote above. I wonder if you think his paper stinks, too? At least, you get math with his "theoretical cow pie".

http://www.arxiv.org/abs/gr-qc/9909037

 

[Nereid]

Neried asks whether I have another explanation for the DM observations and gravitational lensing at different scales. I do not, I am quite happy with the idea that a) gravitaitonal lensing occurs and is as predicted by GR (it is the same in SCC) and b) that Dark Matter exists. My argument is though it is Dark in the sense of being non-luminous, not in the sense of being some unknown new type, or state, of matter. In a freely coasting universe (as in SCC) it is just ordinary baryonic matter as the baryonic cosmological density is about 20 % and not restricted to 4% as in the standard model. If there is a problem in identifying exactly what form it takes then that problem is no greater than in the standard paradigm. It could be bricks, or Jupiters or a population of black holes or whatever, I do not claim to be able to solve all the mysteries at once, just that it should not necessary to multiply mysteries by adding these extra 'epicycles' (Inflation, DM, DE) to keep the old paradigm afloat.
Garth

Thanks Garth; this has been troubling me since I first read your SCC paper!

So you pays your money and you places your bets:
1) concordance cosmology (full of non-baryonic dark matter - collisionless, interacts via gravity only)
2) MOND (does wonders with galaxy rotation curves and dwarf galaxies; fails for clusters, doesn't incorporate Relativity)
3) SCC, or 'free-coasting' universes (no such thing as non-baryonic dark matter; not even hints on what form all the dark baryonic matter might be in).

Garth, doesn't it bug you intensely that you haven't got a handle on what form the 'missing' baryonic matter is in? I mean, just about every possibility has been constrained - in many cases quite severely - and the sums keep coming up way short.

 

[Nereid]

It is certainly true the Standard Model has evolved over time. I don't think it is accurate to characterize that process as being ad-hoc. I am also reluctant to discard the model in favor of a more radical approach, such as 'free coasting'. Not that other models don't have their attractive features. That is why they are still being kicked about. The more relevant issue is the Standard Model has an imposing mountain of observational and theoretical support. The others do not. Fortunately, different researchers have different opinions and all the viable options will continue to be explored. At present, the Standard Model is the reigning heavy weight champ and any challenger will have to deliver a knockout punch to claim the title.

The 'freely coasting' model proposed by Gehlaut etal is interesting. The paper did put me in full skeptic mode early on when they asserted "First of all, the use of Einsteins equations to describe cosmology has never been justified." The rational for making this rather shocking statement was not very convincing. On the whole, however, it has some nice features. None of those annoying particle or cosmological horizons to address. It also appears to be concordant, although I think some issues were rather thinly supported and others largely ignored. The following papers present some of these issues.
http://adsabs.harvard.edu/cgi-bin/n...A&A..39...67L&db_key=AST&high=40d9fbf26c22275
http://adsabs.harvard.edu/cgi-bin/n...A...265..373L&db_key=AST&high=40d9fbf26c23948
http://adsabs.harvard.edu/cgi-bin/n...J...344..543K&db_key=AST&high=40d9fbf26c23948
It seemed pretty obvious the lack of an inflationary epoch in the very early universe posed a problem. Solving it by inserting repulsive gravity without offering a mechanism was a pretty big pill to swallow. You also end up with a universe where recombination did not occur until ~10^7 years as opposed to ~10^5 years after the big bang. The explanation for elemental abundance was not great, but, OK. At least it left room for falsifiable predictions. All in all, I did not feel it solved more problems than it created, but, that's not necessarily a bad thing.

Well said Chronos! The three papers are quite interesting; as I particularly liked the first, I'm going to paste some text from the abstract here: "Compared with Friedmann models of the universe, the distant SNe are too faint even for a freely coasting, "empty" universe, barring other influences that could dim the events. This result is independent of the absolute calibration of the peak luminosity, which is needed to derive the Hubble constant. Possible noncosmological explanations could be gray dust, with properties that do not change the color of the objects significantly, evolution of the explosions, or deamplification by gravitational lensing. Current indications are that none of these alternatives alone can explain the dimness of the distant SNe.

[...]

However, current lack of understanding of the explosion physics and the radiation transport of SNe Ia encumbers any investigation of evolutionary changes. Any change in the peak luminosity of SNe Ia must be inferred from indirect observations, such as light-curve shape, colors, and spectral evolution. At the moment, many of the distant SNe do not have the required data set for a detailed investigation of these parameters. The near-uniform light-curve and spectral evolution of SNe Ia can be used as accurate cosmic clocks to demonstrate the time dilation as predicted from expanding world models. The test has been performed through both photometry and spectroscopy, and is fully consistent with the predictions. The supernova (SN) results can be reconciled only with cosmological models that provide some form of acceleration. The simplest such models either include the cosmological constant or refer to a decaying particle field ("quintessence").[/color]"

One may dislike 'epicycles', but short of saying 'gee, I haven't a clue about what the good observational data are telling us', what alternatives to 'dark energy' and 'dark matter' are there? (at the risk of boring everyone totally senseless, I personally don't think the distant SNe data are good enough yet, nor all potential 'non-cosmological' causes fully understood; I'm glad that Leibundgut at least partially agrees).

I'm also not as relaxed as Chronos seems to be about the freely coasting models and 'primordial abundances'; there's no new physics, so Gehlaut et al, let's have precise predictions on nuclide abundances (not just 'metallicities', nor even 'elemental')!

One small thing: "Standard Model" - I know this is used by particle physics folk to describe QCD, the zoo of particles, the hypothesised Higgs, ... is it also commonly used to describe the \LambdaCDM cosmologies?

 

[Nereid]

One concern of mine is the absolute confidence placed in the standard model: it is called "precision cosmology", its deductions are presented as facts, it is assumed that it has been robustly established beyond doubt as an intellectual edifice standing on several pillars. Attack one we are told (RAS lecture 2004) and the others will continue to securely support the paradigm.

Wasn't it ever thus? Aren't these folk human too? On top of which, the big institutions now pay marketing folk to write PRs; they have to justify their jobs too!

Best address it by good work, not moaning.

However this confidence ignores the fact that three of these pillars are invisible, Inflation which depend on the Higgs field (we have detected the Higgs boson have we?), Dark Matter (we know what is it do we?) and Dark Energy (we know what we are talking about do we?) In their day the addition of epicycles to the Ptolemaic system was no more "ad hoc" than our addition of these "entities".

Do you have a link to the RAS lecture? AFAIK, the three pillars are nucleosynthesis (primordial nuclide abundance), the Hubble relationship (expanding universe), and the CMBR.

The reason "the Standard Model has an imposing mountain of observational and theoretical support" is because it has been so well funded and the alternatives not, yet it is the essence of the scientific method that alternative theories against which the standard model can be tested should be encouraged. As I have pointed out on several posts cosmological observations are all theory dependent, change the theory and those observations change too. The important thing is to have consistency and an economy of "entities".

It's worth taking the time to look at these in some detail.

First (she said, sounding once again like a broken record), most of the top quality data is in the public domain; anyone can get it and do their own analyses.

Second, I'll issue an open challenge on the 'cosmological observations are all theory dependent, change the theory and those observations change too' claim: while the *papers* reporting the observations may be written with certain theories built into the analyses, can you show that the underlying *data* have such built in? This PF thread, about the CMBR, has a link to a 1999 Tegmark paper on analysing the BOOMERANG, WMAP, and Planck data, to remove foregrounds (it was written before all three even started); unless I misunderstood the paper, the *data* from these three could comprise both the 'cosmological signal' (free of any theory) as well as the 'foregrounds'; how a researcher chooses to analyse the data - wrt a particular cosmological model - is up to her!

The challenge: what (cosmologically relevant) observational data has been collected with 'cosmological theories' built-in?

 

[Nereid]

I guess you've had a bad day, Chronos, so I'll let the rudeness slide.

Observational evidence = Galactic clusters exhibit very strong lensing. They lens so strongly that if you try to extrapolate their masses using the simple relativistic model, the calculated mass will be many times larger than that of the observed matter in the cluster.

Conventional astronomers cannot reconcile this with the standard model, but instead of trying to find where the model is broken, they instead claim that the "missing" mass is really there in the form of non-baryonic "dark matter".

With respect turbo-1, I think it's a little different:
- GR works
- GR predicts the bending of light by mass
- we observe something that looks exactly like what GR predicts (many tests done to support this)
- the mass (amount, distribution) estimated by assuming GR is large, this amount of mass is larger than what we would expect from the M/L ratios of luminous objects (e.g. galaxies).
- However, the 'non-luminous mass' estimated from straight application of GR is ~OOM the 'total mass' estimated from not one but TWO independent sets of observations (X-ray and velocity dispersion).

So the choices are: 1) throw out GR (the only mass that's 'really there' is that we can estimate from the distribution of light); 2) keep GR (the mass that we estimate from the images and GR is much higher than that we infer from the light).

These are the same people who invoke non-baryonic "dark matter" to explain the discordant rotational curves of spiral galaxies. Of course, the "dark matter" again obligingly distributes itself in a very special non-uniform way to fix the rotational problem.

Indeed; again, if the only thing were rotational curves, it'd qualify as an epicycle; however, to sound even more like a broken record, the DM estimates that you get from the galaxy rotation curves are consistent with estimates of the amount of DM from independent observations!

Somehow conventional cosmologists cannot bring themselves to examine these fundamental problems with their models. Instead, they invent "dark matter" that behaves in very special ways in each relevant circumstance. You might as well substitute obedient "fairies" or "angels" for "dark matter". As a very wise man once sang "When you believe in things you don't understand, you will suffer."

Hmm, remind me again what a wise woman said about the wisdom of throwing out GR?

 

[Garth]

Thank you Neried for some much valued constructive criticism of SCC!

Garth, doesn't it bug you intensely that you haven't got a handle on what form the 'missing' baryonic matter is in? I mean, just about every possibility has been constrained - in many cases quite severely - and the sums keep coming up way short.

Not really! Though it would be nice to resolve this problem, I don't pretend, or even expect, to be able to solve all the questions at once!

But let me ask you, doesn't it bug you that you haven't got a handle on what form the DM is in? I know there is a whole zoo of possibilities but each seems to have its own problems, just this last week New Scientist reports that neutrinos are now out of the picture. : (NS 4 Sep 04 pg 39 "Weighing the invisible")

As for Bruno's Leibundgut comments "Compared with Friedmann models of the universe, the distant SNe are too faint even for a freely coasting, "empty" universe, barring other influences that could dim the events." He was referring to an empty Friedmann universe, the Freely Coasting universe requires a new gravitational paradigm, it is not empty and so his analysis is not appropriate. "Change the theory and the observations/deductions change too".

One may dislike 'epicycles', but short of saying 'gee, I haven't a clue about what the good observational data are telling us', what alternatives to 'dark energy' and 'dark matter' are there?

May I humbly suggest SCC for your consideration?

so Gehlaut et al, let's have precise predictions on nuclide abundances

The work on nuclide abundances in the freely coasting cosmology is coming along, despite a lack of funds I believe, and one problem is that Deuterium comes out with a low primordial abundance that has to be reconciled by spallation later. But the nuclide abundances of the Standard \LambdaCDM model developed out of about two decades of intense research - give the alternatives a chance!

Best address it by good work, not moaning.

Do you have a link to the RAS lecture? AFAIK, the three pillars are nucleosynthesis (primordial nuclide abundance), the Hubble relationship (expanding universe), and the CMBR.

I am not moaning, just asking questions and seeking possible alternative against which the standard models may be tested, isn't this what good science is all about?
The RAS lecture was given by Prof. J.P. Ostriker (IoA) entited "Concordance Cosmology" on May 14th at the RAS Monthly meeting. It was very good but I couldn't help reflect on the invisibility of those three pillars I mentioned. Of course I agree that your pillars are sound, just that there are other ways of explaining them viz: SCC and the freely coasting universe.

In the Standard model the theory that all our cosmological observations are dependent on is GR! I distinguish between the raw data (red shift, angular size, apparent magnitude etc.) and observation, which is deduced from the data (recession, curvature etc.) For example, the fact that the CMB WMAP data indicate flatness is taken to mean that the cosmological density parameter is unity, but this only applies if the GR cosmological equations hold. They do not in alternative theories such as BD or SCC

I thank you again for a decent discussion and criticism of my ideas - Garth.

 

[turbo]

With respect turbo-1, I think it's a little different:
- GR works
- GR predicts the bending of light by mass
- we observe something that looks exactly like what GR predicts (many tests done to support this)
- the mass (amount, distribution) estimated by assuming GR is large, this amount of mass is larger than what we would expect from the M/L ratios of luminous objects (e.g. galaxies).
- However, the 'non-luminous mass' estimated from straight application of GR is ~OOM the 'total mass' estimated from not one but TWO independent sets of observations (X-ray and velocity dispersion).

Yes GR works for LOTS of observations, but it seems not to work very well at the galactic scale and it fails utterly at very small scales. Now why does GR fail to predict the behavior of clusters without plugging in dark matter? My hunch is that GR fails to properly model the effects of matter on ZPE (classical space-time in the GR view) and vice-versa, which is why I have been digging up papers on LQG, ZPE etc, and bugging people like you by stating cosmological problems in non-relativistic terms. When the dust clears, I believe we will find that the mysterious "missing mass" is simply ZPE interacting with matter. The ZPE that we observe in the Casimir effect is 120 OOM weaker than predicted by theory, possibly because the virtual pairs that form ZPE are oriented quite randomly. It may be that the potential of the ZPE field is not unlocked until it is polarized (oriented, densified, etc) by the presence of very large masses. The folks at CIPA model both inertial mass and gravitational mass as interactions between matter and the ZPE field. Since I found their site yesterday, I've been devouring papers and articles linked to it.

http://www.calphysics.org/index.html

So the choices are: 1) throw out GR (the only mass that's 'really there' is that we can estimate from the distribution of light); 2) keep GR (the mass that we estimate from the images and GR is much higher than that we infer from the light).Indeed; again, if the only thing were rotational curves, it'd qualify as an epicycle; however, to sound even more like a broken record, the DM estimates that you get from the galaxy rotation curves are consistent with estimates of the amount of DM from independent observations!Hmm, remind me again what a wise woman said about the wisdom of throwing out GR?

Nereid, I would not throw out GR, any more than I would throw out the Newtonian model of gravitation. They are both useful. When you have a useful tool you do not throw it away. If you encounter a job where your tool is not appropriate to the task, however, you should realize its limitations, use the tool only where appropriate, and try to develop a better tool for the tough jobs. That one is choice 3), which you did not list. Choice 4) is to establish an extension for GR that keeps it from breaking down at very small scales. I don't hold out much hope for 4), but think 3) is promising.

GR breaks down at very small scales (where ZPE lives) and I believe that this failure is the source of the misapprehension about the "missing mass" on very large scales. If the CIPA folks are right, we do not need dark matter, dark energy, Higgs Bosons, WIMPS, etc. to explain the gravitational behavior of the Universe, simply the interaction of matter with vacuum energy.

If I understand ZPE properly, its energy potential is 120 OOM larger than the observed Casimir Effect, so plenty of energy could be developed from just a small amount of polarization. The reason we don't see ZPE in the macro world is that it is all pervasive and exists at the lowest energy possible. There is no "contrast" in the ground state.

 

[Garth]

If I understand ZPE properly, its energy potential is 120 OOM larger than the observed Casimir Effect, so plenty of energy could be developed from just a small amount of polarization. The reason we don't see ZPE in the macro world is that it is all pervasive and exists at the lowest energy possible. There is no "contrast" in the ground state.

But shouldn't we see massive curvature from all this energy? Garth

 

[turbo]

But shouldn't we see massive curvature from all this energy? Garth

I stole this directly from the CIPA site:

But isn't the energy density of the ZPF so high that it would have an enormous gravitational effect, just like a huge cosmological constant?
Not necessarily. If gravitation derives from the ZPF (and possibly the other quantum vacua) and changing dielectric properties of space, then the energy of the ZPF cannot gravitate. Gravitation would consist of minute changes in the ZPF in the presence of matter in analogy to the minute changes in the ZPF that an accelerating particle experiences. Indeed, one would be able to derive the principle of equivalence if we had a complete quantum vacuum-based theory of inertia and gravitation (including possibly the weak and strong interaction zero-point fields). But certainly the ZPF would not act on itself to gravitate; that would be impossible in this picture. The argument about a huge cosmological constant arising if you take the ZPF literally misses the point that a self-consistent ZPF basis for both inertia and gravitation would necessarily preclude this.

I haven't discovered how this was derived (in a published paper) yet, but am still searching. CITEbase is addictive and each relevant citation can lead to other interesting paper. For instance, I have been chided for using optical models to explain the "gravitational" refraction of light, and having never been a researcher in physics I meekly assumed that my approach was novel and unconventional enough to earn me status as a crackpot. Thanks to CITEbase, earlier today I ran across this paper, in which the author cites the work of over a dozen physicists who have developed non-relativistic optical models for gravitational refraction over the course of the last 80+ years. This does not mean my optical approach is correct, of course, but If I'm wrong, I've at least got company.

http://citebase.eprints.org/cgi-bin/citations?id=oai%3AarXiv%2Eorg%3Aastro%2Dph%2F0302273