Critique of Mainstream Cosmology

[Garth]

From the Review of Mainstream Cosmology thread.

"Even mainstream ideas can be wrong" is not really a position that should be described and championed so much in this thread. Maybe you should start a new thread, perhaps entitled "Critique of Mainstream Cosmology"?

Here I have started just such a thread.

This thread is not the place to discuss a multitude of speculative ideas, rather it is intended as a discussion of observations that may raise questions about the consensus $\Lambda$CDM model.

I start with a discussion of Lieu's eprint on today's physics ArXive. LCDM cosmology: how much suppression of credible evidence, and does the model really lead its competitors, using all evidence?

I demonstrate in this article that while some of ($\Lambda$CDM) is based upon truth, at least just as much of $\Lambda$CDM cosmology has been propped by a paralyzing amount of propaganda which suppress counter evidence and subdue competing models.

Can this claim be substantiated?

Garth

 

[Wallace]

Looks like we overlapped posts Garth, your thread is a better approach, I'll edit the other one to send people here.

This should be a good discussion, looking forward to it!

 

[Wallace]

To get the discussion going a bit, I'd have to say the Lieu paper is over the top and goes to far. However, in amongst the rant there are some important and in my opinion very valid and interesting points. There are observations that are troublesome to LCDM (and to wCDM more generally) and these clearly don't get the attention they deserve.

Lieu suggests two alternative models are almost as supported by the data as LCDM, on this point he is talking rubbish. The table in his own paper makes in pretty clear to start with that LCDM is far better supported. However science can be much more precise than his crude binary table. It is not enough to say that a model is or is not supported by the data, we need to know how certain we are about it. It's a small field that we call statistics, and when we confront the models to the data and run the number LCDM wins by a huge margin.

The reason the LCDM is the dominant theory is that if you run it by all the evidence it gives a good (but not perfect) fit to (almost) all the available data. Compared to any other suggested model LCDM wins hands down.

The most important point Lieu makes though is that just because it is the best model, does not mean it is right. I would have to agree that cosmologists do frequently go too far in their hubris over the wonderful achievement of the concordant model.

There is clearly far more evidence in favour of LCDM than against it, but if the evidence against is conveniently ignored then the danger is that it will drive an over-reaction against the standard model, which is fundamentally what I think this paper is. LCDM, warts and all is still impressively robust to the data, and trying to dress it up to be even better is probably a mistake.

One final comment is that the purpose of Lieu's paper fundamentally seems to be about money. He wants some of the big cash that is heading towards 'dark energy' projects to come his way instead (okay and to some others as well). However what I think he doesn't realize, or at least doesn't acknowledge, is that almost all so called 'dark energy' missions will generate a wealth of data that is highly relevant whatever the theoretical basis of cosmology is. So if someone came up with a great theory tomorrow that seemed to explain the data better than LCDM and maybe did away with the nasty unknowns of dark matter and or dark energy, then the big budget dark energy missions like Plank and SNAP would still be just as relevant to probing the details of this new theory.

If LCDM is wrong then we are even more in the dark about our Universe than if it is right. To me, uncertainty over the validity of LCDM is more of a reason to go out and test it rather than a reason not to bother! We have a theory of our universe that contains at least 3 very uncertain elements (inflation,DM & DE/CC). However, despite the fact that the theory is so bizarre, it is what the majority of the evidence points to! Therefore we need to do two things, one is as Lieu suggests and look more carefully at the minority of contrary evidence to see how significant we can push the disagreement between theory and observation, but the second thing is that contrary to Lieu's suggestion we really do need to push on with the 'mainstream' big surveys to see how far we can push the agreement, and in the case of DE, nail down it's properties to find what true micro-physical theories for it might be reasonable.

 

[Garth]

Wallace I cannot agree more!

Lieu's paper makes three claims, each of which will bear some discussion.

1. Observations have been 'cherry-picked' to support the mainstream model. (Section 4 - page 7)

2. Other observations exist that question that model yet are ignored and even suppressed by the community. (Abstract- page 1)

3. Funding is channelled into mainstream projects, thus alternative models remain untested and 'on the shelf'. (Conclusion - page 13)

We may wish to deal with these one by one. Certainly the nub of the matter is 2, that is whether there are, actually, observations that contradict the mainstream model.

Garth

 

[marcus]

To get the discussion going a bit, I'd have to say the Lieu paper is over the top and goes to far. However, in amongst the rant there are some important and in my opinion very valid and interesting points. There are observations that are troublesome to LCDM (and to wCDM more generally) and these clearly don't get the attention they deserve.

Lieu suggests two alternative models are almost as supported by the data as LCDM, on this point he is talking rubbish. The table in his own paper makes in pretty clear to start with that LCDM is far better supported. However science can be much more precise than his crude binary table. It is not enough to say that a model is or is not supported by the data, we need to know how certain we are about it. It's a small field that we call statistics, and when we confront the models to the data and run the number LCDM wins by a huge margin.

The reason the LCDM is the dominant theory is that if you run it by all the evidence it gives a good (but not perfect) fit to (almost) all the available data. Compared to any other suggested model LCDM wins hands down.

The most important point Lieu makes though is that just because it is the best model, does not mean it is right. I would have to agree that cosmologists do frequently go too far in their hubris over the wonderful achievement of the concordant model.

There is clearly far more evidence in favour of LCDM than against it, but if the evidence against is conveniently ignored then the danger is that it will drive an over-reaction against the standard model, which is fundamentally what I think this paper is. LCDM, warts and all is still impressively robust to the data, and trying to dress it up to be even better is probably a mistake.

...

I like this statement a lot. It has the right balance.
GR must be wrong (since it has singularities and is at best only an effective classical theory) but historically the alternatives have tended to be worse.

LCDM based on GR must be wrong as well (behold its great warts! as Wallace points out) but it is a beautiful fit in many many ways and all the alternatives so far seem to be worse.

It is an exciting moment in history to be watching because an improved model cosmology MUST emerge (with LCDM being both so wrong and at the same time so right) and the most strenuous efforts to check LCDM can only help this process happen.

 

[Wallace]

I like this statement a lot. It has the right balance.
GR must be wrong (since it has singularities and is at best only an effective classical theory) but historically the alternatives have tended to be worse.

LCDM based on GR must be wrong as well (behold its great warts! as Wallace points out) but it is a beautiful fit in many many ways and all the alternatives so far seem to be worse.

It is an exciting moment in history to be watching because an improved model cosmology MUST emerge (with LCDM being both so wrong and at the same time so right) and the most strenuous efforts to check LCDM can only help this process happen.

Is Newtonian gravity wrong? No, just valid in certain regimes. The same is almost certainly true of GR. The LCDM is based on GR, but only in the regime in which we think GR is valid. We don't encounter singularities in the use of GR to define the LCDM model with a FRW metric (Since we only describe t>0 not attempt to talk about t=0 in the LCDM model).

Before you dismiss LCDM as being 'so wrong' consider the evidence against. Lieu mentions two things only, soft X-ray emission from clusters and the lack of SZ effect in WMAP. The first of these is highly dependent on how clusters are modeled (in terms of density profile etc) , and the second is very hard to do observationally and again requires a lot of modeling of clusters that is uncertain.

You can, as Lieu points out, find papers in the literature that do not find any conflict with LCDM for every piece of evidence he claims refutes LCDM. All he s saying is that there are also papers (mainly his) that arrive at different conclusions about these effects.

So before you gleefully dismiss the mountain of surprisingly concordant data, realize that their is no uncontroversial evidence against LCDM. The only thing I get from Lieu, as expressed in my previous post, is that given these uncertainties in areas that look like they may be troublesome to LCDM, we should look at them more closely and give greater acknowledgment to the disagreement between different research groups.

There is only one reason the reasonably abandon the LCDM model to the scrap heap at this time. Theoretical prejudice. The data, such that it is, does not support this move. Remember that Lieu has been writing anti-LCDM papers for years and as is guilty of cherry picking results to support his preconceived position as anyone. Is it just as likely the Lieu would suddenly find some new data or method of his supports LCDM as it is that Dave Spergel would do the reverse (in both cases somewhat slim one would think).

 

[marcus]

my post was intended as approval and corroboration of the one of yours that preceded it.

I am consistently a proponent and expounder of LCDM, which I contemplate with delight and with amazement that it fits so much data so well.

Indeed I suspect there is little differerence between our positions on that score.

I think your analogy with Newtonian gravity is very apt. Newton gravity is elegant and amazingly accurate in a certain regime. What is exciting is when one comes to a point in history where it is realized that such a successful theory is not fundamental and is only an effective theory that works in a certain domain of applicability. Then one can hope to see a more fundamental theory emerge.

the warts or flaws in LCDM that I referred to are the ones YOU mentioned.
the flaws in GR which I mentioned are wellknown, and do it no dishonor.
thank goodness GR is wrong, so we shall have the privilege to see a more fundamental theory of gravity appear (probably duplicating GR to a large extent except at extreme scale or near classical singularities)

Let neither of us accuse the other of "gleefully dismissing" either GR or LCDM

Pax

==============
BTW I found Lieu's paper yesterday and had a look at it, but didn't think it so good. I liked Simon White's paper of a few weeks ago but Lieu paper
seemed more like sorehead to me----potentially serious issues but aggravated by an exaggerated presentation. So I decided NOT to post a link here about the paper, or start a thread about it. The next morning I saw that both you and Garth chose to start threads. You may be right---the paper may merit discussion. I'm not yet convinced.

 

[marcus]

I start with a discussion of Lieu's eprint on today's physics ArXive. LCDM cosmology: how much suppression of credible evidence, and does the model really lead its competitors, using all evidence?

I demonstrate in this article that while some of LCDM is based upon truth, at least just as much of LCDM cosmology has been propped by a paralyzing amount of propaganda which suppress counter evidence and subdue competing models.

Can this claim be substantiated?

I doubt it can be substantiated. LCDM is the best model going and testing its limits with more and more observation is the traditional way to do science.

Besides, a lot of research has been and is being devoted to checking how close w is to -1. That is, to ruling out some kind of dark energy that is not equivalent to a cosmo. constant.
and a lot has been devoted to checking that Lambda is CONSTANT. so people are always probing around the margins, and checking for variants of standard LCDM

My feeling is Lieu paper is not very appetizing and I have no urge to discuss it.

In your thread you broach a more general topic. Basically what are the observations that show us where LCDM might be weak, and possibly subject to improvement?

That's very interesting and well worth discussing. I hope you get knowledgeable people to contribute.

About the MONEY question---I think the direction of funding has been great and that the LCDM has been an organizing principle in identifying good research and observational strategies.
Lieu, when he complains about bad direction of the funding, sounds like a sorehead IMHO. I think they've done a great job and have launched and set up great space and groundbased instruments.
And the signs are that observational astro is on a roll and this will continue.

So Lieu is so off-base I don't even see a need to talk about his paper.
Unless it starts being influential, which I don't expect.

Garth, this is what I LIKE about your original post, and it doesn't need to have much to do with Lieu's paper. Good question to discuss on its own:

This thread is not the place to discuss a multitude of speculative ideas, rather it is intended as a discussion of observations that may raise questions about the consensus $\Lambda$CDM model.

 

[Nereid]

It seems to me that Lieu makes a mistake that can be seen rather often in 'agin the mainstream' public pronouncements - that effort devoted to testing a reasonably well-established theory could be better spent testing an alternative theory ... despite the fact that the alternative is demonstrably inferior, in terms of its match with relevant observational results*.

As Wallace has already noted, a great many of the proposed tests of LCDM models should serve as equally good tests of many, if not most, alternatives.

Further, many proposed tests, if properly conducted, should show flaws in LCDM models in ever harsher light.

And the astonishingly rich trove of high quality astronomical observations, available to anyone with a broadband internet connection, surely presents any developer of alternative theories with fantastic opportunities.

It gets worse, for Lieu and any others trying to make a similar case ... the very lack of control over what we observe is also a reason why effort will continue to be devoted to astronomy's many facets - soft x-ray emission from clusters and groups is of considerable (astrophysical) interest, irrespective of any cosmological implications it might (or might not) have; getting a good handle on the nature of irregular dwarf satellite galaxies is something many astronomers will want to do, no matter what role DM (or GR, or ...) may play on the cosmological stage.

It's not a zero sum game.

*I'm turning up the contrast of course.

 

[Chronos]

Observables still trump alternative theories. It is the one thing LCDM has going for it that the others do not. Naysaying does not replace observational evidence.

 

[Garth]

As far as claim 1. is concerned (Observations have been 'cherry-picked' to support the mainstream model), we will have to see what other observations there are that might have been ignored.

As far as claim 3 is concerned (Funding is channelled into mainstream projects, thus alternative models remain untested and 'on the shelf') - a claim made by Arp even though in the 1970's he had been given an inordinate amount of telescope time to investigate his conjecture that quasar red shifts were not cosmological, as Nereid has pointed out many of the tests of GR and the standard model will also test the alternatives to them, as Gravity Probe B is doing at this moment.

However my own work has thrown up a question about the equivalence principle that could be tested: the question, "Do photons 'fall at the same rate' as free-falling particles?" A question I think that is as equally important as the Eötvös-type experiments yet that has not been tested in the laboratory. (The deflection of light by the Sun is not a clean test as the free-falling component is convoluted with the space-curvature component.) Now where may I get funds to put this to the test...

Which leaves us with claim 2 - are there observations that contradict the mainstream model?

Lieu includes a selection of seven out of what he calls a "long list of counter evidence", however, as Wallace pointed out, only two have any substance; soft X-ray emission from clusters and the lack of SZ effect in WMAP, and it is highly problematic whether they actually provide "counter evidence".

I have my own list of questions for the $\Lambda$CDM model, both cosmological and questions about the GR theory on which it is based.

The overall question of course is the the fact that the inflaton particle required by Inflation, the DM particle and DE itself have not yet been discovered in the 'laboratory' even after three decades of research. This together with the apparent difficulty in producing a quantum gravity theory leads one to understand we are missing something.

Cosmologically I ask the following questions:
1. Are SNe Ia Standard Candles?
2. Is there an Age Problem in the Mainstream Model?
3. Are the Cosmological Coincidences just coincidences?
4. The Axis of Evil, is there a low-l mode deficiency in the WMAP power spectrum?

Of local questions I list a few, which question whether we fully understand GR, even in the solar system:
1.The Pioneer Anomaly.
2. The Fly-by anomaly.
3. The fact that the residual anomaly in Uranus' orbit, after Neptune is accounted for, is not explained by Pluto (mass 2 OOM too small).
4. Why does the residual increase in the Earth's rotation rate, after other factors are removed, equal Hubble's constant? (h=0.67) See Leslie Morrison and Richard Stephenson, 1998, Astronomy & Geophysics Vol. 39 October, The Sands of Time and the Earth’s Rotation and again by Stephenson, 2003, Astronomy & Geophysics Vol. 44 April, Historical eclipses and Earth’s rotation.
They obtain △T/day/cy = −6 x 10⁻⁴ sec/day/cy, which is equal to H if H = 67km.sec⁻¹Mpc⁻¹.We wait to the end of the year to see if the hint of a non-GR residual in the GP-B results is substantiated.

Just food for thought...

Garth

 

[marcus]

Well Garth, you started the thread for this purpose

This thread is not the place to discuss a multitude of speculative ideas, rather it is intended as a discussion of observations that may raise questions about the consensus $\Lambda$CDM model.

and now you have offered for discussion some sample observations that raise questions about the standard cosmo model.

I have my own list of questions for the $\Lambda$CDM model, both cosmological and questions about the GR theory on which it is based.

The overall question of course is the the fact that the inflaton particle required by Inflation, the DM particle and DE itself have not yet been discovered in the 'laboratory' even after three decades of research. This together with the apparent difficulty in producing a quantum gravity theory leads one to understand we are missing something.

Cosmologically I ask the following questions:
1. Are SNe Ia Standard Candles?
2. Is there an Age Problem in the Mainstream Model?
3. Are the Cosmological Coincidences just coincidences?
4. The Axis of Evil, is there a low-l mode deficiency in the WMAP power spectrum?

Of local questions I list a few:
1.The Pioneer Anomaly.
2. The Fly-by anomaly.
3. The fact that the residual anomaly in Uranus' orbit, after Neptune is accounted for, is not explained by Pluto (mass 2 OOM too small).
4. Why does the residual increase in the Earth's rotation rate, after other factors are removed, equal Hubble's constant (h=0.67), see Leslie Morrison and Richard Stephenson, 1998, Astronomy & Geophysics Vol. 39 October, The Sands of Time and the Earth’s Rotation and again by Stephenson, [2003, Astronomy & Geophysics Vol. 44 April], Historical eclipses and Earth’s rotation. They obtain △ T/day/cy = −6 x 10⁻⁴ sec/day/cy, which is equal to H if H = 67km.sec⁻¹/Mpc.

I will try to follow suit---maybe in a different style but with parallel intention

I think LCDM looks like a KLUDGE, tinkered manyways to fit, and that any cosmology has to be a kludge as long as it is based on GR. Until we have a theory of space time and matter that is more fundamental than GR, all the cosmology models are going to be somewhat funnylooking.

No disrespect to either LCDM or GR, both are great!

But the more tinkered and contrived our best fit looks the more it is begging for a more fundamental theory. The situation is very hopeful because QG replacements for GR are in the works and because the consensus Kludge cosmology shows what the more fundamental theory must aim to accommodate and make natural (instead of contrived)

 

[turbo]

I will try to follow suit---maybe in a different style but with parallel intention

I think LCDM looks like a KLUDGE, tinkered manyways to fit, and that any cosmology has to be a kludge as long as it is based on GR. Until we have a theory of space time and matter that is more fundamental than GR, all the cosmology models are going to be somewhat funnylooking.

No disrespect to either LCDM or GR, both are great!

But the more tinkered and contrived our best fit looks the more it is begging for a more fundamental theory. The situation is very hopeful because QG replacements for GR are in the works and because the consensus Kludge cosmology shows what the more fundamental theory must aim to accommodate and make natural (instead of contrived)

Marcus, I agree entirely. Penrose keeps saying that both GR and quantum theory will have to change before they can be unified, but I suspect that GR will take the bigger hit by far. Consider: If Einstein had known that the rotation curves of spiral galaxies are too flat to be explained by GR, and that clusters exhibit far more binding force and stronger lensing than expected, would he have blamed that on the existence of a mysterious entity that cannot be detected by any means, or would he have considered that gravitational attraction and inertial effects might vary with location, based on the local matter-density? After reading his 1920 Leyden address and his 1924 essay "On the Ether" I know where I'd put my money. GR's failure on galactic and cluster scales should not be surprising, since so little was known about our universe in 1917. It is a wonderful model within the domain of its applicability, but now we need something more fundamental and more general than GR.

 

[Nereid]

Nice list Garth (I'll comment on it later).

Taking advantage of the informality of this forum, here is a very much off-the-top-of-my-head list of possible topics and questions, relating to GR and cosmology:

* tests of strong field GR, using SgrA* and binary pulsars: what regions of parameter space can we realistically hope to explore?

* gravitational wave detectors - LIGO etc: non-detection sometime in the next decade would trigger a crisis, I think; detection would open a new window, with all that that implies

* UHECR research - anisotropy, local sources, GZK limit, etc: another new window, maybe a crisis triggered too?

* DM searches, both terrestrial and astronomical (e.g. XENON, gamma-ray astronomy as a means of detecting SUSY DM particle decays)

* AMANDA and other neutrino 'telescopes': mostly (cosmological) serendipity

* hi-res, deep x-ray studies of cluster environments: homogeneity of the ICM, cluster to cluster variation, structure within the ICM, ... I feel at least part of the CMB/WMAP/SZ 'problems' may be due to over-simplifications about the ICM

* ⁶Li and ⁷Li abundance: IIRC, this is the only significant mismatch between theory and observation, for primordial light nuclide abundances

* hi-res DM profiles of Local Group objects - MW, M31, M33, ... right down to the smallest dwarfs, GCs, ... and stellar streams: the more precisely the distribution of DM can be characterised, the sharper the tests that can be done of competing theories about its nature.

(to be continued)

 

[Chronos]

DM clustering is very poorly understood. DM constitutes the vast majority of mass in the universe, but is almost unnoticeable, save on large scales. And even then, mapping it is exquisitely difficult. It is also capriciously distributed, not smooth. It could account for the 'axis of evil' as well as other apparent artifacts in the CMB data. I find it more interesting than distressing for the LCDM model. A DM detector would be fascinating.

 

[Garth]

This paper by Alexander Unzicker, a teacher at the Pestalozzi-Gymnasium Munchen, presents an interesting review of the problems I am interested in: Why do we Still Believe in Newton's Law ? Facts, Myths and Methods in Gravitational Physics

Garth

 

[turbo]

Thank you for that link, Garth. Interesting reading - a nice summary by an author willing and able to present observational evidence without couching it in terms of the assumptions that so frequently accompany their description.

 

[Garth]

Of local questions I list a few, which question whether we fully understand GR, even in the solar system:
1.The Pioneer Anomaly.
2. The Fly-by anomaly.
3. The fact that the residual anomaly in Uranus' orbit, after Neptune is accounted for, is not explained by Pluto (mass 2 OOM too small).
4. Why does the residual increase in the Earth's rotation rate, after other factors are removed, equal Hubble's constant? (h=0.67) See Leslie Morrison and Richard Stephenson, 1998, Astronomy & Geophysics Vol. 39 October, The Sands of Time and the Earth’s Rotation and again by Stephenson, 2003, Astronomy & Geophysics Vol. 44 April, Historical eclipses and Earth’s rotation.
They obtain △T/day/cy = −6 x 10⁻⁴ sec/day/cy, which is equal to H if H = 67km.sec⁻¹Mpc⁻¹.

The residual Pioneer Anomaly, after allowing for 'normal physics' from on-board systematics, and the residual spinning up of the Earth, after allowing for tidal braking, both can be explained by a clock drift between ephemeris and atomic clocks equal to the Hubble parameter.

But we may ask, "Is the PA to be seen in the orbits of the outer planets?"

Generally the answer given is no, but as I have pointed out we cannot explain Uranus' orbit, after allowing for Neptune, by the perturbations of Pluto and other 'http://www.iau.org/iau0601.424.0.html ', the masses of the trans-Neptunian planets are 2 OOM too small. So, what about Neptune itself?

It appears there is an unexplained residual in its orbit as well, consider Rawlins' 1970 paper: http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1970AJ...75..856R&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf .

Abstract
The recently discarded Lalande prediscovery Neptune sightings are reduced anew in a way that depends little on instrumental uncertainties. The resulting discord between observation and the 1968 integration amounts to about -7" in longitude.

Now that Lalande prediscovery observation of Neptune (he recorded it but did not recognise he had discovered a new planet! ) was made in 1795 and the -7" arc corresponds to a 7/15 seconds of time discrepancy which equals 0.467 secs. over 1968 - 1795 = 173 years.

This corresponds to a time discrepancy, or annual clock drift in which the atomic clock is speeding up relative to the ephemeris clock, of 0.467/(365.25x24x3600) per 173 years, which equals 8.55 x 10^-11 yr^-1 and this is equal to Hubble's parameter if H = 84 km.sec⁻¹Mpc⁻¹!

So within the bounds of error of the observation it seems that the Hubble parameter turns up again!

These 'Hubble Parameter' clock drifts are getting to be a bit of a habit, perhaps the universe is trying to tell us something!

Just more food for thought.

Garth

 

[Garth]

As that observation of Neptune seems to be significant, especially as a confirmation that the PA may apply to the Outer Planets after all, it would be important to study it further.

There is a Letter to the Editor of Nature from Charles T. Kowal & Stillman Drake: Galileo's observations of Neptune.

The planet Neptune was discovered in 1846. As its period of revolution is almost 165 years, Neptune has not yet completed one revolution since its discovery. Largely as a result of this, its orbit is not known with a precision comparable to that of the inner planets. A pre-discovery measurement of Neptune's position by Lalande in 1795 differs from the predicted position by 7 arc s. There is some debate about whether this discrepancy is real or an error of measurement1. Clearly, it would be worthwhile to find other pre-discovery observations of this planet. One possible way of finding such observations is to search for close approaches of Neptune to other objects which were frequently observed. Neptune was actually occulted by Jupiter in January 1613 and September 1702 (ref. 2). By 1702 the telescope was in widespread use, and examination of manuscripts of that period should reveal cases where Neptune was seen near Jupiter and mistaken for a star. The abundance of possible material, however, makes a search for such observations lengthy. We have found that Galileo observed the planet Neptune on 28 December 1612 and 28 January 1613. The latter observation may be of astrometric value, and differs by 1 arc min from the predicted position of Neptune. Galileo also detected the motion of Neptune.

This was answered by Rawlins Galileo's Observation of Neptune; and Reply but I don't have access to the Abstract.

So it appears the pre-discovery observations of Neptune are unclear as to whether there is an anomaly or not.

Garth

 

[Garth]

As far as claim 1. is concerned (Observations have been 'cherry-picked' to support the mainstream model), we will have to see what other observations there are that might have been ignored.

As far as claim 3 is concerned (Funding is channelled into mainstream projects, thus alternative models remain untested and 'on the shelf') - a claim made by Arp even though in the 1970's he had been given an inordinate amount of telescope time to investigate his conjecture that quasar red shifts were not cosmological.

Arp is still at it; from today's physics arXiv: A concentration of quasars around the jet galaxy NGC1097.

His thesis is that quasars are ejected from active galaxy nuclei. And although I am not convinced at all, it makes an interesting case to examine Lieu's claims.

6.1. Epilogue

It was commented on the title page of this web posting that the paper had been rejected by the Astrophysical Journal Letters. Thus the editor spake: “Your paper has not been able to convince either of two independent referees. . . . “No suppression of your work has been done through my action since you are welcome to submit your paper to a different journal.”

The information supplied here should enable the readers to decide for themselves the value of the data and its discussion. But perhaps more important it enables a judgment on the core structure of current science.

The question is simply one of a statistical analysis of the data, is Arp making a false correlation or not? And if not are his observations being deliberately ignored because it does not fit the mainstream model?

Garth

 

[Chronos]

Scientists, I think, are too self righteous and opportunistic to miss the chance to jump on the right bandwagon. As they say in Arkansas . . . "If the wagon is empty, it might be on fire." I think Arp is still impaling his white whale with weird statistics. And I mean no disrespect to the man or his ideas. He is an unconventional thinker and bolder than most, which is certainly no crime. I disagree with his conclusions, which is also no crime.

 

[turbo]

The question is simply one of a statistical analysis of the data, is Arp making a false correlation or not? And if not are his observations being deliberately ignored because it does not fit the mainstream model?

Garth

Arp makes the case for the locality of quasars based on apparent overdensities and association with local galaxies. If quasars are at the distances implied by a mainstream interpretation of their redshifts, they should not exhibit any association with local galaxies - in fact they should be isotropically distributed across the sky. He has shown any number of times that quasars are not isotropically distributed - this time using data from a deep survey, which should help to quell the choruses of "cherry picking" and "selection effect" that are used to shout down his work. The most likely response from the mainstream in this case will be that NGC1097 is lensing background quasars and making them more visible than they would otherwise be. One problem with this flip dismissal (used against Arp previously, I might add) is that we might expect to see some lensing effects from a very massive object over separations of a few arc-minutes, but over separations of a whole degree? NED gives the major and minor axis of NGC 1097 as 9.3 arc-min and 6.3 arc-min, yielding an area of roughly 48 arc-min². The apparent quasar overdensity (at a radius of one degree) covers an area of 11,304 arc-min² - quite a feat of "lensing".

 

[Chronos]

It remains a wild proposition, IMO. How many observational constraints need to be adjusted if that proposition is correct? Too many for my comfort level.

 

[Garth]

The residual Pioneer Anomaly, after allowing for 'normal physics' from on-board systematics, and the residual spinning up of the Earth, after allowing for tidal braking, both can be explained by a clock drift between ephemeris and atomic clocks equal to the Hubble parameter.

But we may ask, "Is the PA to be seen in the orbits of the outer planets?"

Generally the answer given is no, but as I have pointed out we cannot explain Uranus' orbit, after allowing for Neptune, by the perturbations of Pluto and other 'http://www.iau.org/iau0601.424.0.html ', the masses of the trans-Neptunian planets are 2 OOM too small. So, what about Neptune itself?

It appears there is an unexplained residual in its orbit as well, consider Rawlins' 1970 paper: http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1970AJ...75..856R&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf .

Now that Lalande prediscovery observation of Neptune (he recorded it but did not recognise he had discovered a new planet! ) was made in 1795 and the -7" arc corresponds to a 7/15 seconds of time discrepancy which equals 0.467 secs. over 1968 - 1795 = 173 years.

This corresponds to a time discrepancy, or annual clock drift in which the atomic clock is speeding up relative to the ephemeris clock, of 0.467/(365.25x24x3600) per 173 years, which equals 8.55 x 10^-11 yr^-1 and this is equal to Hubble's parameter if H = 84 km.sec⁻¹Mpc⁻¹!

More thoughts on the subject -Search for a Solution of the Pioneer Anomaly

It will be difficult for a simple modification of the Newtonian inverse-square law or a new metric theory of gravity, both of which demand a universality of free fall, to explain the Pioneer anomaly. If one invokes a new metric theory (as an extension of the Einstein idea) and thereby fits the Pioneer anomaly, that attempt will very likely play havoc with solar-system dynamics somewhere else; for example an obvious failure to t observations of natural bodies in the outer solar system. If the Pioneer anomaly is new physics, something more subtle is most likely involved.
We therefore have to conclude that it is unlikely that the Pioneer anomaly is caused
by new physics. Such discoveries are rare. However, it is not ruled out. It is possible
that the Pioneer anomaly could be something importantly new. For that reason, and
also because we want to be able to account for every source of systematic error in deep
space navigation, we continue to pursue the study of spacecraft trajectories, whether in
deep space or during planetary encounters. We recommend that you stay tuned. This
anomaly will be resolved eventually, one way or the other

Somebody else who thinks it may be a clock drift: Pioneer anomaly: a drift in the proper time of the spacecraft .

Isn't it nice that not all the problems are solved?

Garth

 

[turbo]

Hi, Garth. For me, the most compelling explanation for the PA does not rely on unmodeled mechanics nor modified gravity, but on a variable speed of light in a vacuum.

Here is a paper by Ranada that explains the effect well.
http://arxiv.org/PS_cache/gr-qc/pdf/0211/0211052v3.pdf

 

[jonmtkisco]

For what it's worth (not much), I don't think there is any chance that gravity or the speed of light varies with scale or distance from Earth. I also see no reason to spend much time (other than entertainment time) on theories that require additional dimensions, strings, or other exotica.

My primary concern is that the leading cosmologists have dived so deep into theories based on hyper-advanced, abstract math that they may have lost the forest for the trees. I am not convinced that anyone is taking enough time to cross-map recent observations against the basic metrics of the LCDM model. For example, why is apparently exactly NOBODY studying this concept of "momentum of expansion", which is fundamental to every expansionary model, but to my knowledge has never been explicated mathematically or physically in any detail? Is it that self-obvious?

If you look back in history, Einstein was the one of the few physicists/cosmologists who presented theories that looked preposterous on their face but were soon universally accepted. A number of his theories have been proved, but much work remains to be done. I wish we would focus more on proving General Relativity before we continue building ever more abstract and expensive structures on top of it. For example, it's straightforward to apply the "curvature of space" by gravity as a mathematical model for fields such as gravity and electromagnetics. But what does it actually mean PHYSICALLY that space is curved? What are the implications of that for other physical aspects of our world? And just because an object traveling through a gravitational field moves equivalent to how it would move if space were curved, does that really prove that space curves? Is there no other physical explanation for the same mathematical result? To just say, "yeah the math works" and move on seems indefensible. I don't want to fight against the theories, I just want to be convinced that potential proofs are being explored which tie back logically to the visible world, and that other such alternatives are being ruled out on a scientifically disciplined basis.

 

[SpaceTiger]

My primary concern is that the leading cosmologists have dived so deep into theories based on hyper-advanced, abstract math that they may have lost the forest for the trees. I am not convinced that anyone is taking enough time to cross-map recent observations against the basic metrics of the LCDM model.

You must be kidding. That's about all that cosmologists do nowadays. In fact, it's difficult for an observer's idea to get much attention in cosmology if it can't be used to measure one of the fundamental parameters of the cosmological model (e.g. H_0, sigma_8, dark energy) or test the LCDM model's validity.

In the pure physics community, cosmology is often viewed as a workshop for their "fundamental" theories of nature, so you'll see a lot of discussion about strings, LQG, etc, but it's certainly not the case that the fundamental assumptions and parameters of LCDM are going untested.

 

[oldman]

Special Relativity and the Pioneer Anomaly

Here is another of my silly suggestions.

Special Relativity tells us that the mass of a moving object increases with its velocity. This fact is taken into account when designing particle accelerators, where the mass of interest is the inertial mass of the particles.

By the equivalence principle the gravitational mass of a moving object also increases with velocity (this has been kindly confirmed for me by Pervect in a recent thread "Raindrops and gravity" in the relativity forum). This fact is of no concern in designing accelerators and is of little general interest. Situations are not common where a change in gravitational interaction due to motion is perceptible.

From the perspective of an observer on the Pioneer probe the sun's mass will be observed to be increased by the sun's motion relative to the probe. The sun's gravitational attraction will be enhanced by a factor of gamma over the Newtonian value.

Has this tiny effect been taken into account in calculating the probe's trajectory?

 

[Garth]

Here is another of my silly suggestions.

Special Relativity tells us that the mass of a moving object increases with its velocity. This fact is taken into account when designing particle accelerators, where the mass of interest is the inertial mass of the particles.

By the equivalence principle the gravitational mass of a moving object also increases with velocity (this has been kindly confirmed for me by Pervect in a recent thread "Raindrops and gravity" in the relativity forum). This fact is of no concern in designing accelerators and is of little general interest. Situations are not common where a change in gravitational interaction due to motion is perceptible.

From the perspective of an observer on the Pioneer probe the sun's mass will be observed to be increased by the sun's motion relative to the probe. The sun's gravitational attraction will be enhanced by a factor of gamma over the Newtonian value.

Has this tiny effect been taken into account in calculating the probe's trajectory?

You are trying to solve a GR problem (gravitational acceleration) by cobbling together Newtonian gravity with SR. The method does not work, such as in the Newtonian-SR calculation of the gravitational bending of a light beam, in which it gives half the correct answer.

SR effects are already accounted for in GR and apart from such effects as the extra GR precession of Mercury's orbit (noticeable because Mercury is so close to the Sun) the GR trajectories are almost identical to Newtonian ones, and especially so in the outer solar system.

The fact that the Pioneer spacecraft do not appear to be following the exact Newtonian free fall path is therefore interesting.

At ~70 AU the Newtonian acceleration towards the Sun is ~ 10^-2 m.sec^-2 and the Pioneer anomalous acceleration is (8.74 ± 1.33) × 10^-10 m.sec^-2 on top of this.

Garth

 

[oldman]

You are trying to solve a GR problem (gravitational acceleration) by cobbling together Newtonian gravity with SR. The method does not work ...

Garth

Thanks for the quick reply, Garth. I don't want to interfere with the gist of your thread, especially since I think the effect I mentioned is sadly too small by a factor of about 100 to account for the PA. But I do believe it exists: I think you are mixing GR with SR unnecessarily. Tomorrow I'll post my reasons for saying this in the relativity thread I mentioned.

 

[Garth]

I don't want to interfere with the gist of your thread, especially since I think the effect I mentioned is sadly too small by a factor of about 100 to account for the PA. But I do believe it exists: I think you are mixing GR with SR unnecessarily.

I'm not mixing them, you don't have to, the SR effects of a Lorentz transform are already included in GR as it stands.

The point is that it appears the spacecraft are not following the free falling geodesics of GR...

Garth

 

[oldman]

I'm not mixing them, you don't have to, the SR effects of a Lorentz transform are already included in GR as it stands.

I agree now. Thanks. See my post today --- #5 in "Raindops and Gravity", Relativity Forum.

 

[oldman]

The point is that it appears the spacecraft are not following the free falling geodesics of GR...

Garth

I've now got straightened out by Ich and Pervect in the relativity forum, and have a last question: you mentioned that "the Pioneer anomalous acceleration is (8.74 ± 1.33) × 10-10 m.sec-2 " Is this the difference between the GR acceleration and the Pioneer acceleration, or between the Newtonian acceleration and the Pioneer acceleration?

 

[Garth]

I've now got straightened out by Ich and Pervect in the relativity forum, and have a last question: you mentioned that "the Pioneer anomalous acceleration is (8.74 ± 1.33) × 10-10 m.sec-2 " Is this the difference between the GR acceleration and the Pioneer acceleration, or between the Newtonian acceleration and the Pioneer acceleration?

It's between the Newtonian acceleration and the Pioneer acceleration; at that range from the Sun the GR and Newtonian accelerations are identical to within observational limits.

Garth

 

[Garth]

Hopeful signs of the Pioneer Anomaly: Evaluating Newly Recovered Data.

The Pioneer 10/11 spacecraft yielded the most precise navigation in deep space to date. However, their radio-metric tracking data received from the distances between 20--70 astronomical units from the Sun consistently indicated the presence of a small, anomalous, Doppler frequency drift. The drift is a blue frequency shift that can be interpreted as a sunward acceleration of $a_P = (8.74 \pm 1.33) \times 10^{-10} m/s^2$ for each particular spacecraft . This signal has become known as the Pioneer anomaly; the nature of this anomaly remains unexplained.
New Pioneer 10 and 11 radio-metric Doppler data recently became available. The much extended set of Pioneer Doppler data is the primary source for new upcoming investigation of the anomaly. We also have almost entire records of flight telemetry files received from the the Pioneers. Together with original project documentation and newly developed software tools, this additional information is now used to reconstruct the engineering history of both spacecraft . To that extent, a thermal model of the Pioneer vehicles is being developed to study possible contribution of thermal recoil force acting on the two spacecraft . In addition, to improve the accuracy of orbital reconstruction, we developed a new approach that uses actual flight telemetry data during trajectory analysis of radio-metric Doppler files. The ultimate goal of these efforts is to investigate possible contributions of the thermal recoil force to the detected anomalous acceleration.

It sounds as if they have some way to go before any results from this study ...

Garth