Crisis in Cosmology?

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Cosmology is a difficult subject, so much opinions and room for errors. The distances and timescales are quite dizzying, to say the least. But that don't mean we should stop trying to gain more answers, eh? :-)

What is the latest, most accurate value of the 'Hubble cosntant'? Is there a consensus on that?

ta,
E
 
The problem with the value of this constant only shows
how vulnerable the BB theory is.
 

jcsd

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tubo-1 dipole anisotropy is a prediction of the BB model (well not a necessary prediction, but it would be pretty bloody amazing if there was not some dipole isotropy in the CMB). In the BB model the universe is assumed to be isotrpoic in one frame only, the dipole anistropy in temp. signifies nothing more amazing than the Earth is moving relative to the surface of last scattering. The dipole isotropy is a generic featur eof even the most simplistic BB models.

The tiny quadrupole anistropy (mostly manifested in the polarization) is something that is predicted in the standard cosmology and is actually a property of the surface of last scattering rather than a property of the Earth's movement.
 

turbo

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jcsd said:
tubo-1 dipole anisotropy is a prediction of the BB model (well not a necessary prediction, but it would be pretty bloody amazing if there was not some dipole isotropy in the CMB). In the BB model the universe is assumed to be isotrpoic in one frame only, the dipole anistropy in temp. signifies nothing more amazing than the Earth is moving relative to the surface of last scattering. The dipole isotropy is a generic featur eof even the most simplistic BB models.

The tiny quadrupole anistropy (mostly manifested in the polarization) is something that is predicted in the standard cosmology and is actually a property of the surface of last scattering rather than a property of the Earth's movement.
OK, here is a paper that illustrates what I was talking about. The concept is not simple dipole anisotropy, which might be naively expect from gross movements with respect to the CMB reference frame. It is the question of why the "texture" of the CMB map is different North of the galactic plane than it is South of the galactic plane. This difference in smaller-scale anisotropy cannot be explained by the naive expectation (or at least tolerance) of a dipole anisotropy. Our movement relative to the CMB might be expected to slightly shift all the observed values of the CMB frequencies in some models, but there is no reasonable way to explain how this movement could make the texture or relative frequency depth of the small scale anisotropies in the Southern plane different from those in the Northern plane.

http://citebase.eprints.org/cgi-bin/fulltext?format=application/pdf&identifier=oai%3AarXiv.org%3Aastro-ph%2F0403353 [Broken]

From the paper:
We have shown that the planes defined by the octopole are nearly aligned with the plane of the Doppler-subtracted quadrupole, that these planes are strongly correlated with the ecliptic plane, with the dipole, and with the equinoxes. Each of these correlations is inconsistent with gaussian random skies at ≥ 99.9% C.L., and at least two of them are statistically independent. We have also seen that the ecliptic threads between a hot and a cold spot of the combined Doppler-subtracted-quadrupole and octopole map – following a node line across about 1/3 of the sky, and separating the three strong extrema from the three weak extrema of the map. We find it hard to believe that these correlations are just statistical fluctuations around standard inflationary cosmology’s prediction of statistically isotropic Gaussian
random aℓm’s.
WMAP is often touted as a highly-precise verification of the standard model. Why?
 
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SpaceTiger

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Eridanus1 said:
What is the latest, most accurate value of the 'Hubble cosntant'? Is there a consensus on that?
The Hubble constant problem is largely solved. We've converged on a value of:

71 km/s/Mpc +- 3

It looks like both the 50-group and the 100-group were wrong. :cool:
 

ohwilleke

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I'm personally going to be skeptical of the Hubble constant value above until it survives uncontested for several more years. There have been numerous occassions since they Hubble constant was formulated when new values have been outside the error bars of the previous estimate.
 

SpaceTiger

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ohwilleke said:
I'm personally going to be skeptical of the Hubble constant value above until it survives uncontested for several more years.
Fair enough, though I think if you double the error bar (71+-6), it's a pretty safe bet it's in that range, even considering the discrepant measurements
 

jcsd

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turbo-1 said:
OK, here is a paper that illustrates what I was talking about. The concept is not simple dipole anisotropy, which might be naively expect from gross movements with respect to the CMB reference frame. It is the question of why the "texture" of the CMB map is different North of the galactic plane than it is South of the galactic plane. This difference in smaller-scale anisotropy cannot be explained by the naive expectation (or at least tolerance) of a dipole anisotropy. Our movement relative to the CMB might be expected to slightly shift all the observed values of the CMB frequencies in some models, but there is no reasonable way to explain how this movement could make the texture or relative frequency depth of the small scale anisotropies in the Southern plane different from those in the Northern plane.

http://citebase.eprints.org/cgi-bin/fulltext?format=application/pdf&identifier=oai%3AarXiv.org%3Aastro-ph%2F0403353 [Broken]
What's naive about expecting dipole anisotropy? Even the paper you cite has no probelm with it. As I siad earlier it's soemthing that is acceptable in ALL big bang models not just some as you say; simple reason is that all big bang models locally incoprate special relativty, so Lorentz transforming a local refernce frame will shift the frequencies (which indeed is not bounded as relative motion can cause any frequency shift, though we would expect it to be relatively small as it is sensible to expect our solar syetm not to be moving at a termenodus speed relative to the CMB) of the photons arriving at that point in the expected manner.
WMAP is often touted as a highly-precise verification of the standard model. Why?
Unbfortunaely my knowledge of the exact reuslts of WMAP is not gerat enough to give an opinion on the conclsuion of the paper, though there are certainly it seems to me that the usal view is that such alignments are due to stasitcal anomalies depsite what the paper claims.
 
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turbo

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jcsd said:
What's naive about expecting dipole anisotropy?
I use the word "naive" as shorthand for "one might reasonably expect". I reasonably expect that if the background microwave echo of the BB is the "ground state" of our universe, the movements of the Earth, Sun, Milky Way, Local Cluster, etc in respect to that background will lead to slight shifting of the apparent wavelengths of the EM emitted by the BB. The strongest shift (caused by the largest motion relative to that frame) would result in a dipole anisotropy. In other words, the stuff in front of us would be blueshifted and the stuff in back of us would be redshifted.
 

jcsd

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Turbo-1, the 'naive' in this context usually means 'over-simplistic'

The CMB was not emitted by the big bang, it was emitted approx. 300,000 yrs after the big bang.

'Slight' is really incorrect as I siad such relative movement can cause ANY amount of doppler shift and though our velcoity relatiev to the CMB frame is not too huge the anisotropy cause dby this movemtn is by far the largest anisotropy in the CMB and is not particualrly difficult to detect.
 

turbo

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jcsd said:
Turbo-1, the 'naive' in this context usually means 'over-simplistic'
That's me! :rofl:
 
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turbo-1 said:
If current trends continue (discovery of even more highly redshifted quasars with solar and super-solar metallicities), what does that tell us about the Universe?

Possibilities include:...

4) There never was a Big Bang. We live in a steady-state universe in which even the most distant things we can ever see are roughly equivalent in metallicity to stars in own neighborhood. "Cosmological" redshift is not due to expansion of the universe, but to energy loss as EM interacts with the fields through which it propagates. The more distance EM has to travel, the more it is redshifted. Another "third rail" idea that can kill the career of an astronomer, but what if it's true?

There are lots more possibilites, including VSL, and perhaps some mix-and-match combinations of the above, but you can see where this is going. Standard-model cosmology has a lot of problems, requiring the invention of non-baryonic dark matter, dark energy, inflation, etc, to keep it afloat. It is impossible to refute all these epicycles, just as it is impossible to refute any ideas that are taken on faith. The observed high metallicities of high-redshift quasars WILL cause all these ideas to be challenged, though. It is just a matter of time. When Webb comes on-line, or when the LBT is fully operational and some spunky graduate student measures super-solar metallicity in a quasar at z~7-8 or so, the 13.7Gy Big Bang universe will be absolutely untenable. Hopefully, the standard model will be seriously re-evaluated and not just patched with another epicycle or two. The next several years will be an interesting time.
There is a wealth of data suggesting a cosmic explosion occured billions of years ago in our neighborhood of the cosmos, but to attribute that 'Big Bang' with the creation of the entire Universe is the height of myopathy.

Why would reasonable scholars believe that the cosmos is limited to that infinitesimal portion we can detect?

Theory of Reciprocity
 

Chronos

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They don't. Reasonable scholars assume it is the only portion that is observable.
 
Obviously from what turbo-1 said the BB is in deep crisis.
 

Chronos

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brightstar2005 said:
Obviously from what turbo-1 said the BB is in deep crisis.
The vast majority of scientists believe the BB is in excellent health.
 

SpaceTiger

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You guys should do like badastronomy and make a separate board for this "fringe" stuff. Casual readers might get the impression that the scientific community actually takes it seriously. Besides, it's annoying having to wade through it looking for something of scientific merit.
 

selfAdjoint

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SpaceTiger said:
You guys should do like badastronomy and make a separate board for this "fringe" stuff. Casual readers might get the impression that the scientific community actually takes it seriously. Besides, it's annoying having to wade through it looking for something of scientific merit.
We do have the Theory Development ("TD" in discussions) board, where extreme fringe stuff is put. But there's this big gray area where either there are published papers in peer-reviewed journals to be quoted, or there is genuine data which can be seen as conflicting with whatever standard models are accepted. We have to be strong monitors because of the concern you cite, but we are not high priests of some fixed and invariable Truth.
 

SpaceTiger

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selfAdjoint said:
We have to be strong monitors because of the concern you cite, but we are not high priests of some fixed and invariable Truth.
Anything seriously challenging traditional theories without being widely accepted by the scientific community seems obviously fringe to me. That doesn't mean it's wrong, just that it's as I say, "fringe." This includes MOND, anti-big bang, anti-relativity, anti-dark matter, etc. Scanning the forum, I can see posts on MOND, "leaking gravity", crisis in cosmology...almost half of them.

This has nothing to do with absolute "truth", just the current state of science. If these boards weren't magnets for crackpots, these discussions could be conducted on more even ground, but unfortunately it's the extremists that tend to be on the internet hawking their ideas, not the serious scientists. There was even a talk about this at the last American Astronomical Society (AAS) meeting. People who don't gain acceptance by the scientific community have a tendency to fight a propaganda war instead. Part of the reason so many people believe the BS is that the BSers are so much more aggressive about selling to the public.

Anyway, that's just my two cents. It's not my forum.
 

Garth

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SpaceTiger said:
Anything seriously challenging traditional theories without being widely accepted by the scientific community seems obviously fringe to me.
Would you not allow an intelligent and informed questionning of the 'traditional theories'? To my way of thinking such questions are the 'stuff' of good science.

Garth
 

SpaceTiger

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Garth said:
Would you not allow an intelligent and informed questionning of the 'traditional theories'? To my way of thinking such questions are the 'stuff' of good science.
I'm not saying it should be deleted, I'm suggesting it be moved. Most of the people questioning tradition are either ill-informed or agenda-driven, neither of which is good science. You can increase the signal-to-noise of the regular forum by putting those posts elsewhere.
 
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ohwilleke

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SpaceTiger said:
Anything seriously challenging traditional theories without being widely accepted by the scientific community seems obviously fringe to me.
Almost by definition the interesting parts of science, the ones people want to discuss, are those where traditional theories are being seriously challenged. There aren't a lot of new and interesting things be said about Newtonian mechanics in situations where neither quantum mechanics or general relativity apply. It isn't very interesting to have a discussion about the fact that the Earth and other objects in the solar system swirl about the Sun according to Kepler's laws, that our solar system is on the fringe of a large spiral galaxy, and that there are gillions of galaxies in the universe.

I'd also add that a large portion of the scientific community explores at some point in time theories that are not widely accepted by the scientific community at the time they are offered and that seriously challenge traditional theories. Indeed, a substantial proportion of the theoretical physics community is dealing with areas where this is no real scientific consensus. For example, while almost everybody agrees that the standard model of quantum mechanics has widespread phenomenological success, it is also true that probably a solid majority of quantum physics scholars believe (for reasons like apparent CP violations) that it has flaws that will be resolved with future research, and that there is no consensus on how that will be resolved. Similarly, while there is widespread agreement within the scientific community on the existence of the phenomena we call "dark matter", there is not a consensus, even among those who believe that there is some kind of dark matter out there, as to what that "dark matter" is, and a similar situation exists with "dark energy".

That doesn't mean it's wrong, just that it's as I say, "fringe." This includes MOND, anti-big bang, anti-relativity, anti-dark matter, etc. Scanning the forum, I can see posts on MOND, "leaking gravity", crisis in cosmology...almost half of them.
I would define "fringe" to mean challenges to traditional theories which are not serious. The people who simply say "God did it", or rather than looking for possible flaws in redshift methodology simply deny that red shift is being observed, or people who deny that time dialation (or some phenomena which produces experimentally equivalent results) exist, or who assert that galactic dynamics are Keplerian without considering a dark matter or MOND type modification.

There is a big difference between a minority view, which is based on evidence and an effort to apply a novel hypothesis using the scientific method, and a fringe view, which rejects the scientific method.

This has nothing to do with absolute "truth", just the current state of science. If these boards weren't magnets for crackpots, these discussions could be conducted on more even ground, but unfortunately it's the extremists that tend to be on the internet hawking their ideas, not the serious scientists. There was even a talk about this at the last American Astronomical Society (AAS) meeting. People who don't gain acceptance by the scientific community have a tendency to fight a propaganda war instead. Part of the reason so many people believe the BS is that the BSers are so much more aggressive about selling to the public.
The American Astronomical Society would be better served by being aggressive in selling widely accepted theories, and by better discussing in communication directed to the public the basis for the widely accepted theories. Scientific societies systemically underestimate the importance of popularizing science and of validating their conclusions among communities beyond those with PhDs in their own subfields.
 
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SpaceTiger

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ohwilleke said:
Almost by definition the interesting parts of science, the ones people want to discuss, are those where traditional theories are being seriously challenged. There aren't a lot of new and interesting things be said about Newtonian mechanics in situations where neither quantum mechanics or general relativity apply.
First of all, I disagree. I think most of the work that's going on now is extremely interesting and only a very small fraction of it challenges tradition/majority in any serious way. Second of all, this isn't a university, it's a message board. Let's be honest with ourselves, serious scientific progress is probably not going to be made here. Educating the forum-goers about Kepler's Laws and relativity is, in my opinion, a much more valuable pursuit than speculating about MOND.


I would define "fringe" to mean challenges to traditional theories which are not serious. The people who simply say "God did it",
Those are posts that should simply be deleted, IMO, as they would be widely acknowledged to lack scientific value.


or rather than looking for possible flaws in redshift methodology simply deny that red shift is being observed
Anybody who even questions the cosmological interpretation of redshift is fringe. Even most of these questioners would probably admit that.


There is a big difference between a minority view, which is based on evidence and an effort to apply a novel hypothesis using the scientific method, and a fringe view, which rejects the scientific method.
And there's a big difference between speculation about MOND and leaking gravity (scientific or not) and discussion about planet-finding methods. The first is definitely "fringe", as I understand the word.


The American Astronomical Society would be better served by being aggressive in selling widely accepted theories, and by better discussing in communication directed to the public the basis for the widely accepted theories.
I agree, but try finding a serious scientist who wants to spend their time doing that. It's harder than you might think.
 

ohwilleke

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SpaceTiger said:
First of all, I disagree. I think most of the work that's going on now is extremely interesting and only a very small fraction of it challenges tradition/majority in any serious way. Second of all, this isn't a university, it's a message board. Let's be honest with ourselves, serious scientific progress is probably not going to be made here. Educating the forum-goers about Kepler's Laws and relativity is, in my opinion, a much more valuable pursuit than speculating about MOND.
We certainly disagree there. Education is primarily a function of a university. A message board is more of an independent press organ. Message boards deal with news, the emphasis being on "new" (and analyze it), as they can get the word out faster than traditional journals. If I want to learn about old, settled theory, I'll buy a textbook. I go to message boards (or blogs) to learn about things that aren't yet in print.

Anybody who even questions the cosmological interpretation of redshift is fringe. Even most of these questioners would probably admit that.
Anyone who doesn't ask questions is not a scientist at all. He is a theologian. What distinguishes fringe and not fringe is how you answer questions.

And there's a big difference between speculation about MOND and leaking gravity (scientific or not) and discussion about planet-finding methods. The first is definitely "fringe", as I understand the word.
A new planet is news. A general discussion about planet-finding methods is pretty darn dull, until someone challenges those methods and proposes an alternate hypothesis (e.g. what if what you're seeing is stellar dynamics or observational error, rather than a planet?).

Also, considering that almost every university with a graduate physics program in the world has a string theorist on staff, and a large proportion of those have people doing brane theory, which is where leaking gravity comes from, it is hardly fringe. Much of what you are calling fringe really is a matter of disciplinary rivalry. Within dark matter theory, suggesting that WIMPZILLAs are dark matter is pretty mainstream. Within quantum physics, WIMPZILLAs are one of many pretty far out there possibilities that are being discussed in the context of a lack of consensus of what physics, if any, undergird the standard model. Within the GR community, suggesting that there is a non-geometrical explaination for GR is a minority view. Within the QM community, it is the mainstream view.

Likewise, I would suggest this paper: http://arxiv.org/abs/astro-ph/0412059 by Merrifield who is primarily a dark matter (not a MOND) camp phenomenologist to suggest that MOND is less fringe than you suggest.

This paper presents a brief review of the evidence for dark matter in the Universe on the scales of galaxies. In the interests of critically and objectively testing the dark matter paradigm on these scales, this evidence is weighed against that from the only other game in town, modified Newtonian dynamics. The verdict is not as clear cut as one might have hoped.
The matter receives a lot of attention in these forums precisely because there is not a clear cut answer. Gray is more interesting than black and white.

I agree, but try finding a serious scientist who wants to spend their time doing that. It's harder than you might think.
Which is why the task falls to amateurs to some extent. If you feel strongly that there is a scientific consensus and that you have a firm command of it, then perhaps you should defend it, instead of taking a de ex machina approach. And, for issues that come up repeatedly, this forum has a sticky for FAQs.

Also, a large proportion of serious scientists are also professional educators, so the resistance is more a product of a scientific culture with a bad attitude, than lack of inclination to explain science.

Also, it is worth noting the scientists are less objective in evaluating challenges to traditional theories v. defending them, then you would expect. The best predictor of a scientist's stance on those issues is birth order, i.e. is the scientist an oldest child or a younger one. See here: http://www.sciencebookguide.com/book.html?book=31
 
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Garth

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ohwilleke said:
Anyone who doesn't ask questions is not a scientist at all. He is a theologian.
A person who doesn't ask questions is a fundamentalist, in religious belief or science; theologians ask questions.

Garth
 

SpaceTiger

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ohwilleke said:
We certainly disagree there. Education is primarily a function of a university.
Universities don't generally have the reach to educate the general public. They're meant to train professionals.


Message boards deal with news, the emphasis being on "new" (and analyze it), as they can get the word out faster than traditional journals. If I want to learn about old, settled theory, I'll buy a textbook. I go to message boards (or blogs) to learn about things that aren't yet in print.
The vast majority of work is based on old theory (or only a slight variation to it). Genuine new theory (like relativity) is very rare and most of the stuff that gets posted on here is fringe and not taken very seriously by the mainstream. By acting as a conduit for this fringe work, the message board basically distills science that isn't ready for public consumption. Thus, the "news" you're getting may have a net effect of disinformation.


Anyone who doesn't ask questions is not a scientist at all. He is a theologian. What distinguishes fringe and not fringe is how you answer questions.
No, what distinguishes fringe and not fringe is hard data supporting or refuting a theory. You're describing the distinction between science and philosophy/religion. Things like non-cosmological redshift have long since been disproven to the satisfaction of at least 95% (probably more) of the scientific community. Based on the articles that are posted here, readers won't have a broad enough picture to judge that for themselves.

I admit, however, that it's not an easy job to distinguish these things if you're not in the field. That's why I'm suggesting that longshot theories in general be moved to the other forum, regardless of the trustworthiness of the source.



A new planet is news. A general discussion about planet-finding methods is pretty darn dull, until someone challenges those methods and proposes an alternate hypothesis (e.g. what if what you're seeing is stellar dynamics or observational error, rather than a planet?).
That's not the kind of challenge I'm talking about. I have no problems with that. I'm referring more to these all-encompassing pseudo-theories that claim to solve dark matter, quantum gravity, etc.


Also, considering that almost every university with a graduate physics program in the world has a string theorist on staff, and a large proportion of those have people doing brane theory, which is where leaking gravity comes from, it is hardly fringe.
It's still fringe. I know and work with professors who do that stuff, but most of them would tell you that it's not mainstream. Well, string theory is sort of mainstream in physics, but from an observational standpoint there's not hard evidence...but there's already a forum in the physics section for that.

Anyway, it doesn't matter, this is why I'm not suggesting you delete this material, just move it.


Much of what you are calling fringe really is a matter of disciplinary rivalry.
Not really. Much of what I would call fringe is done by some of my most respected peers.


Within dark matter theory, suggesting that WIMPZILLAs are dark matter is pretty mainstream. Within quantum physics, WIMPZILLAs are one of many pretty far out there possibilities that are being discussed in the context of a lack of consensus of what physics, if any, undergird the standard model.
That's not an issue of rivalry so much as it is different problems that need to be solved. Either way, though, I would also call WIMPZILLAS fringe theory, as they're just one possibility among very many.


Within the GR community, suggesting that there is a non-geometrical explaination for GR is a minority view. Within the QM community, it is the mainstream view.
This is simply untrue. All the GR people I've worked with acknowledge that geometrization fails at small scales and all the quantum people acknowledge that it works on large scales.


The matter receives a lot of attention in these forums precisely because there is not a clear cut answer. Gray is more interesting than black and white.
Funny that it doesn't get much attention where I work. Do you suppose that the faculty only talk about issues that are simply black and white?


Which is why the task falls to amateurs to some extent. If you feel strongly that there is a scientific consensus and that you have a firm command of it, then perhaps you should defend it, instead of taking a de ex machina approach.
I have better things to do than to spend hours defending positions that are firmly held in the scientific community.


Also, it is worth noting the scientists are less objective in evaluating challenges to traditional theories v. defending them, then you would expect. The best predictor of a scientist's stance on those issues is birth order, i.e. is the scientist an oldest child or a younger one.
I acknowledge that there are prejudices in the scientific community, but I hardly think that means we should be looking to amateurs for guidance. Ignorance is much worse than bias, particularly when those biases compete with one another.


Likewise, I would suggest this paper: http://arxiv.org/abs/astro-ph/0412059 by Merrifield who is primarily a dark matter (not a MOND) camp phenomenologist to suggest that MOND is less fringe than you suggest.
He's only looking at galactic scales, the problem MOND was designed to solve. MOND is much less believable when you try to apply it to cosmology. Nonetheless, it is still possible that it's correct, I don't deny that, I'm simply saying that it's an argument that continues only in the background of mainstream scientific progress. These things should always be discussed, but not at the expense of genuinely exciting scientific results...you know, ones that have a high probability of being right.
 

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