Astrophysical ambulance-chasers everywhere got a bit excited this week, and why wouldn’t they? Here are some of the headlines we read:
- Findings Raise New Questions About Dark Matter (redOrbit)
- Dark matter theory challenged by gassy galaxies result (BBC)
- More Evidence Against Dark Matter? (Science NOW)
Wow. More evidence against dark matter? I didn’t know about the original evidence.
Sadly (and I mean that — see below) there is no evidence against dark matter here. These items were sparked by a paper and a press release from Maryland astronomer Stacy McGaugh, with the rather more modest titles “A Novel Test of the Modified Newtonian Dynamics with Gas Rich Galaxies” and “Gas rich galaxies confirm prediction of modified gravity theory,” respectively.
I’m the first person to defend journalists against unfair attacks, and we all know that headlines are usually not written by the people who write the actual articles. But we can legitimately point fingers at a flawed system at work here: these articles are a tiny but very clear example of what is wrong wrong wrong about our current model for informing the public about science.
McGaugh’s new paper doesn’t give any evidence at all against dark matter. What it does is to claim that an alternative theory — MOND, which replaces dark matter with a modification of Newtonian dynamics — provides a good fit to a certain class of gas-rich galaxies. That’s an interesting result! Just not the result the headlines would have you believe.
It’s obvious what happens here. Nobody would read an article entitled “Gas rich galaxies confirm prediction of modified gravity theory” — or at least, most editors doubtless feel, fewer people would be interested in that than in evidence that went directly against dark matter. So let’s just spice up the story a bit by highlighting the most dramatic possible conclusion we can imagine drawing, and burying the caveats until the end. Net result: a few more people read the articles than otherwise would have, while many more people just read the headlines and are left with less understanding of modern cosmology than they started with. Scientists and journalists together have a responsibility to do a better job than this at making things clear, not just making things sound exciting.
But let me take this opportunity to lay out the problems with MOND. It’s a very clever idea, to start. In galaxies, dark matter seems to become important only when the force of gravity is not very strong. So maybe Newton’s famous inverse-square law, which tells us how the force of gravity falls off as a function of distance, needs to be modified when gravity is very weak. Miraculously, this simple idea does a really good job at accounting for the dynamics of galaxies, including — as this new result confirms — types of galaxies that weren’t yet observed back in 1983 when Mordehai Milgrom proposed the idea. Whether or not MOND is “true” as a replacement for dark matter, its phenomenological success at accounting for features of galaxies needs to be explained by whatever theory is true.
Which is an important point, because MOND is not true. That’s not an absolute statement; among its other shortcomings, MOND is not completely well-defined, so there’s a surprising amount of wriggle room available in fitting a variety of different observations. But to the vast majority of cosmologists, we have long since passed the point where MOND should be given up as a fundamental replacement for dark matter — it was a good idea that didn’t work. It happens sometimes. That’s not to say that gravity isn’t somehow modified in cosmology — you can always have very subtle effects that have yet to be discovered, and that’s a possibility well worth considering. But dark matter is real; any modification is on top of it, not instead of it.
Let’s look at the record:
- MOND is ugly. Actually, that’s very generous. More accurately, MOND is not a theory; it’s only a phenomenological rule that’s supposed to apply in a limited regime. The question is, what is the more general theory? Jacob Bekenstein, in an heroic bit of theorizing, came up with his Tensor-Vector-Scalar (TeVeS) theory, which hopefully reduces to MOND in the appropriate limits. Here is the action for general relativity:
And here is the action for TeVeS:
Don’t worry about what it all means; the point is that the theory underlying MOND isn’t really simple at all, it’s an ungodly concatenation of random fields interacting in highly-specific but seemingly arbitrary ways. That doesn’t mean it’s not true, but the theory certainly doesn’t win any points for elegance. - MOND doesn’t fit clusters. Long ago, rotation curves of galaxies were the strongest evidence in favor of dark matter. Very long ago. We know better now, and a mature theory has a lot more hoops it needs to jump through. The nice thing about MOND is that, despite the ugliness above, when you get down to making predictions for large astrophysical objects, there really isn’t any wriggle room: you fit the data or you don’t. It works for galaxies, but when it comes to clusters — you don’t. Not close. Proponents of MOND understand this, of course, and they’ve come up with a clever workaround. It’s called “dark matter.” That’s right — even MOND’s biggest supporters admit that you need dark matter to explain galaxies. Let’s just emphasize that for those who find all this text kind of tedious:
Even with MOND, you still need dark matter.
Some people try to claim that the necessary dark matter could be neutrinos rather than some brand-new particle, and that’s supposed to be morally superior somehow. But there’s no two ways around the conclusion that dark matter is real.
- MOND doesn’t even fit all galaxies. For almost twenty years now we’ve known that MOND fails for a certain type of galaxies known as “dwarf spheroidals.” These are small (thus the name) and hard to observe, so MONDians have come up with various schemes to explain away particular galaxies. That might even be okay — nobody said fitting the data would always be easy, even in the correct theory — except that it’s precisely this kind of extra work that is being scoffed at in the case of dark matter in these recent news items.
- Gravity doesn’t always point in the direction of where the ordinary matter is. This is the lesson of the famous Bullet Cluster (and related observations). The evidence from gravitational lensing is absolutely unambiguous: to fit the data, you need to do better than just modifying the strength of Newtonian gravity. Once again, people try to wriggle out of this in TeVeS and other MONDian approaches. However, the way they do it is by imagining that other fields have energy, which warps spacetime, and therefore a gravitational field. We have a useful phrase to describe new fields whose energy warps spacetime: “dark matter.” MOND-like theories don’t replace dark matter so much as they make it much more complicated.
- MOND doesn’t fit the cosmic microwave background. Saving my favorite for last. One of the coolest things about the temperature anisotropies in the cosmic microwave background is that they are sensitive to the existence of dark matter. In the early universe, dark matter just collapses under the pull of gravity, while ordinary matter also feels pressure, and therefore oscillates. As a result, the two components are out of phase in the even-numbered peaks in the CMB spectrum. In English: dark matter pushes up the first and third peak in the graph below, while suppressing the second and fourth peak. That would be extremely hard to mimic in a theory without dark matter; indeed, this was predicted before the third peak was precisely measured. But now it has been. And…
See that dotted line? That’s the theory with dark matter, fitting all the data. See the solid line? That’s the MOND (really TeVeS) prediction, definitively inconsistent with the data. Can some clever theorist tweak things so that there’s a MOND version that actually fits? Probably. Or we could just accept what the data are telling us.
Having said all that, I’m glad that some people are still thinking about MOND-like approaches. You can still learn interesting things about galaxies, even if you’re not discovering a new law of nature. And dark matter, to be honest, isn’t established with 100% certainty; it’s really more like 99.9% certainty, and you never know.
What’s less admirable is people (mostly outside the professional community, but not all) hanging onto a theory because they want to believe it, no matter what new information comes along. Personally, I think it would be much cooler if gravity were modified, compared to the idea that it’s just some dumb new particle out there. I’ve put some thought into the prospect myself, which helped lead to some productive research ideas. But ultimately the universe doesn’t care what I prefer. Dark matter is real — gravity could also be modified, but there’s no reasonable doubt about the dark matter. So let’s try to figure it out.
#72. Gary Godfrey:
To case 1: In this eventuality (neutrino mass < 0.2eV) LCDM will, unfortunately, not look good, because its failure on Local volume and Local Group scales will persist without any physically viable solution at hand.
Instead, this result would mean that either MOND breaks down such that some other alternative would be needed which contains MOND on galaxy scales (e.g. Moffat’s MOG needs no dark matter in clusters according to its arranged scaling) or MOND is fine but the dark matter is in baryons, as suggested by Milgrom himself.
This latter possibility is not unreasonable because about 60% of all baryons (i.e. 60% of all normal matter) has gone missing since the Big Bang and astronomers do not know where they are. Part of it could be hiding in galaxy clusters in an undetectable form.
I agree with the statement by Ben: if we see something in the data that doesn’t fit with what we know from theory, we should be open-minded and look for all possibilities, in a scientific way. Just saying this theory works in a lot of cases, it doesn’t matter that it doesn’t work here is not satisfying for me. And we do not have any direct observational evidence for dark matter. What we know is that there is something we do not understand, call it dark matter, dark energy or something else. So the question is: what is it? Can we explain it?
@ Stacy McGaugh, in re post #17,
Great post. Thank you.
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The difference here between critical and uncritical thinking hinges on the recognition of the importance of the scaling relation emerging from spiral galaxies and the emphasis on understanding it in a DM framework. For those of you who ignore the above and insist on addressing the ubiquitous problem of flat velocity curves via a global face-to-face confrontation between LCDM and MOND, you are missing the boat and draining my scientific soul. Please make the effort to read the comments by Stacy and Ben with the idea of understanding them.
@Ben# 81:
We are not discussing scientific souls. We are discussing scientific progress and testing of theories/models/hypothesis to achieve this progress,
LCDM (Einstein’s GR + cold dark matter and inflation and dark energy with unsolved issues concerning energy conservation) is being tested on real data, e.g.via rotation curves of galaxies (McGaugh’s paper under discussion here) or the distribution of matter in the Local Volume of galaxies (Peebels& Nusser’s 2010 paper) or the distribution of matter in the Local Group of galaxies (Kroupa et al. 2010 paper). And LCDM unfortunately fails to account for the data, however hard many excellently funded research groups have been trying over more than a decade now to solve the problems.
MOND is also being tested, just as rigorously. It seems to be doing much much better, but it also has fundamental issues (e.g.what does the parameter a_0 mean)?
What is a problem, not of a scientific soul but of scientific careers especially in the USA(!) is that there are too many who continue claiming that dark matter is a fact and that the standard cosmological picture is correct and excellently accounting for data. These are untruths, usually told to undergraduates, and they propagate through to how tax-payers’ money is distributed to research grants.
Thus, in the USA MOND research is essentially not possible, at least not via the funding agencies (compare with Lee Smolin’s book on “The trouble with physics”). I admire Prof. Stacy McGaugh for nevertheless having the guts to write such papers – I happen to know how difficult it actually is to get such science published nowadays. Prof. McGaugh stands out as one of the truly leading astronomers of the USA, and will be remembered for it.
In my classes, when I explain to students the problems with LCDM (showing the facts and the literature) and that there are alternatives like MOND, they get totally thrilled. You can see the spark of true scientific interest in their eyes – the students of physics, who study physics because they want to learn where the current physics fronteer is ,who try to recapture those times of Einstein and Bohr, of Planck and Heisenberg.
Suddenly they discover that today is like being back in the early 1900’s when quantum mechanics was being discovered, bit by bit, progress by progress, research paper after research paper, over many decades, to what we have today. Back then classical mechanics was the cry (as was the aether), but spectra had lines and this did not fit. Also, the measured black body spectrum just didn’t make sense. Planck started it all by introducing a trick – his h is a fitting parameter (“hilfsgroesse” in German) which made the spectrum fit. Nobody understood what it was, that it was related to energy quantisation came out much later.
So, after mentioning MOND in class, discussions arise. Can one improve on MOND? What’s the underlying physics? What does a_o mean? Is it again a “hilfsgroesse” hinting at some deeper meaning? How does structure formation work in this alternative gravitational approach, or perhaps even in other alternatives?
But then I also have to explain to the students that in order to have a scientific career, i.e. to get support through funding agencies and universities, the students have basically no option but to do LCDM. And once on that train, jumping off becomes nearly impossble, unless you live in France or Italy, perhaps in the UK, definitely _not_ in present-day Germany (which just copies the USA but in a strongly archaic-hierarchical system).
This is draining scientific progress, or, if you like, the scientific soul of today.
Wow, lots of comments for this one! I thought I should mention that any alternative theory of gravity really needs to explain the solar system tests, not just rotation curves of galaxies etc. (which are much less stringent). These are the really tricky ones to explain! 🙂
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#83 and 84:
MOND is perfect for the solar system (this is trivial).
Quantum mechanics: try computing the dynamics of a simple molecule from Schroedinger’s equation …
The field equation of MOND is quite simple, in fact a small generalisation of the Newtonian case as shown by Milgrom and Bekenstein in 1984: its field equations can be derived from a simple Lagrangian such that the conservation laws hold.
I am impressed how much misconception exists concerning MOND (it has even been called evil by a blogger elsewhere who obviously knows little about science). This does not mean to say I am MOND fan.
I’m not as well versed in this field as most of you so maybe someone can assist me in understanding something first so I can follow the discussion better. You all are talking about large scale mass movements with extremely weak accelerations derived from gravity. The universe is such that space is expanding (growing). This is not evident within gravitationally bound objects as they do not grow in size with time. But to what extent is this true, what constitutes the boundary in these extremely weak gravitational systems at which the expansion of space takes hold? And further, shouldn’t the expansion of space modify the gravitationally derived force at this boundary? Of course I’m wondering if this effect could somehow be related to MOND.
@HXPPE(#86):
This is an excellent and highly relevant question! This is the type of question we need to be asking, rather than blogging about MOND as being bad astronomy. This sort of question is at the very heart of modern theoretical physics research which needs the most brilliant minds to work on.
First of all we need to note from observations that _in_all_stellar_systems_ (!!) whenever the force from gravity becomes extremely small we “suddenly” see that the stars or gas move differently than they should. This is the centerpiece content of Stacy McGaugh’s research paper under discussion here, as well as many other research papers already published.
It is as if a resistance disappears, and this is perfectly calculated by the MOND formula which Milgrom discovered in about 1983. This change in motion happens at such a weak gravity that we cannot reach it in our solar system,not even in the vicinity of the Sun, where our Galaxy is exerting too strong a pull.
Dark-matter enthusiasts interpret this deviation from Newtonian motions to come about because of the “sudden” appearance of cold dark matter.
Now, what does this critical very weak force (or technically critical acceleration, a_0) mean? For those of us who have tested the cold-dark matter model to its demise it is quite clear that this new constant a_0 (call it Milgrom’s constant) is truly new physics at a fundamental level which is not understood yeat but which is at the very heart of the issue of the origin of mass (Higgs boson), space and time. Theoretical physicists have, so far, not arrived at a good description or theory of these problems.
Here is a citation from http://en.wikipedia.org/wiki/Modified_Newtonian_dynamics where we read:
“To explain the meaning of this constant, Milgrom said : “… It is roughly the acceleration that will take an object from rest to the speed of light in the lifetime of the universe. It is also of the order of the recently discovered acceleration of the universe.” ”
Another way of looking at a possible deeper phyiscal meaning of MOND is at the very centre of modern physics:
What is inertial mass? What is gravitational mass? And, why should they be equal?
Inertial mass: take a perfect ball in free space, push it and you feel resistance. This resistance is governed by “inertial mass”. The larger the inertial mass, the more difficult it is to push the object. This is why an astronaut would be squashed by a space shuttle but not by a ping-pong ball even if both travel at the same speed.
This ball also curves space time about it (according to Einstein’s ideas) which we interpret as the force of gravitation. This force depends on the mass of the ball, its “gravitating mass”.
One way of looking at MOND is as follows:
When the gravitational field becomes extremely weak, inertial mass and gravitational mass are not equal any longer. If this were the case, then this would revolutionise physics at a most fundamental level.
How can this come about? Again, Milgrom has a suggestion which is summarized in the appendix of this paper by Kroupa et al.: http://adsabs.harvard.edu/abs/2010A%26A…523A..32K
Take the ball in completely empty flat space and push it. As it gets faster, as it accelerates, it begins to “see” the vacuum in front of it getting hotter (the energy fluctuations in front of it get blue shifted). This exerts a force against the ball (Unruh radiation) and may be related to what we feel as the inertial mass.
The same ball, if it is pushed extremely weakly but now in curved space will additionally “see” a radiation field which comes from the cosmological horizon (the Gibbons & Hawking radiation). This radiation is basically the same radiation you would observe coming from a black hole as the energy vacuum fluctuations at its event horizon get split to a part that ends up in the hole and a part that is left in our universe. That is, we can think of our universe as being the inside of a black hole.
When the push on the ball is extremely weak, the Unruh and the Gibbons & Hawking radiation cancel, such that pushing the ball gets easier.
The ball can then move faster more rapidly, and this is exactly what we see in those regions of all stellar systems where the gravitational pull is very weak.
That is, MOND emerges from the quantum mechanics of the vacuum plus the whole universe.
This is why MOND is so amasingly exciting.
And it is so painful to see the constant misunderstanding, misinterpretations, misrepresentations and barking and biting at what is probably one of the most significant physics discoveries (by Milgrom) of the second half of the 20th century!
For our sun MOND like effects should appear at ~0.1 light year, or ~10^15 m, if the sun’s gravitational field dominates. It is interesting that the acceleration to the sun from the Milky Way is about 10^-10 m/s^2 or about a_0. I think any stars in the vicinity of our solar system will have much weaker accelerations than a_0 at 0.1 light years so only the sun and the galaxy dominate acceleration (about equally but not necessarily in the same direction) at 0.1 light year. But we also need to keep in mind that 3.3 lbs held at 1 meter has the same acceleration!
HXPPE,
The conventional answer to your question is basic to the theory of structure formation in cosmology. If you consider an overdensity in an expanding universe, a spherical shell of matter at some radius sees both the expansion and the gravitational attraction of the overdensity. There is a turnaround radius which depends on the mass of the overdensity, redshift and so on. A shell of matter at the turnaround radius will begin to fall back onto the overdensity, so it transitions from expansion to belonging to a gravitationally bound object. As this continues, the overdense mass grows with time. The growth rate depends on the cosmology, including the values of Omega_matter (mass density) and Lambda (cosmological constant).
Note that I didn’t mention dark matter. This structure formation theory is based on matter and standard GR gravity (Friedmann cosmology) but it doesn’t depend specifically on the matter being dark. Dark matter is something incorporated into it from observational motivations. This part of structure formation has been worked out for a long time (Press and Schechter 1974; White and Rees 1978; etc).
In my opinion, MOND gets about the correct amount of attention. It is not suppressed – people can publish papers on it in mainstream journals. MOND is sort of a pain to work with on large scales because it violates the strong equivalence principle, and since it’s not 1/r^2, far-field effects are not zero. That means, in Newtonian gravity if you sit inside a spherical shell of matter, you feel no force, but in MOND this is technically no longer true.
One needs to remember that the vast majority of astronomers are not working on dark matter cosmology. For someone working on, say, star formation or quasars or dust in galaxies, as long as MOND reproduces Newtonian gravity on small scales and TeVeS can be tweaked up to produce the right rate of structure formation, it doesn’t make a difference to their research. It’s the places where it doesn’t reproduce the current standard model that are going to matter, so making testable predictions (for say the mass spectrum of bound structures in the universe) is important.
Athinkingscientist,
“The same ball, if it is pushed extremely weakly but now in curved space will additionally “see” a radiation field which comes from the cosmological horizon (the Gibbons & Hawking radiation). This radiation is basically the same radiation you would observe coming from a black hole as the energy vacuum fluctuations at its event horizon get split to a part that ends up in the hole and a part that is left in our universe. That is, we can think of our universe as being the inside of a black hole.
When the push on the ball is extremely weak, the Unruh and the Gibbons & Hawking radiation cancel, such that pushing the ball gets easier.”
Unruh radiation during acceleration is on firm theoretical ground. However, one can’t just say a body far removed from any gravitational attraction is receiving the same effect as Gibbon & Hawking radiation. Just because someone noticed and published somewhere that this “might” be able to counteract and neutralize hawking radiation induced inertia does not make it true. To me it is just wild speculation that an object far on the perimeter of a galaxy would see the same effects as one near a black hole. Why would that have any credibility beyond pure speculation?
Thanks Ben and ATSS for the replies. ATSS your response has much to consider as you are contemplating the origin of inertia itself. Ben, I think I follow what you say and it makes sense as there are models of the structure of the universe in terms of mass distributions that fit observations into deep space. These models must incorporate expanding space and clumping matter. I would like to understand that boundary better especially when considering the acceleration of the expansion, does the boundary of expansion to clumping move deeper into the clumping matter to pull more matter away? If so, how does that appear in terms of dynamics from the reference frame of the earth?
At any rate, if I’m thinking about this right, if MOND is at all related to the expansion of space then it does so within the local overdense portion (as opposed to the overdense boundary because that is too far away) and appears to enhance the local gravity slightly.
Hi all,
Just wanted to pointed out , since Sean also had a recent post on LIGO, coincident gravity
wave observations(and photons) from a GRB or supernova, once they are observed should be able to settle the dark matter vs MOND debate definitively with a much more stronger case
than the bullet cluster. See arxiv.org/abs/0804.3804
@Eric Habegger(#90):
Sure, it is speculation to a certain degree. Better refer to it as a theoretical proposition.
But it is noteworthy that Milgrom was able to derive the MOND transition function, which defines how the dynamics changes from the Newtonian regime to the MONDian regime, from this proposition. The coincidences between this critical acceleration a_0, below which either cold dark matter appears or effective gravity becomes MONDian, and the cosmological parameters is also tantalizing.
So MOND might be giving us astronomical hints on the connection between inertial mass and gravitational mass and the vacuum. It might also just mean that Einstein’s field equation is not complete.
Note that we might also think of Planck’s introduction of the new constant h as pure speculation (which it was at that time). It’s relation to energy quantisation was realised much later.
I don’t think there is any difference between inertial mass and gravitational mass. Mass responds the same in both circumstances. An everyday example is when people try to bury old tires at garbage dumps. Because tires are voluminous but not dense they are very susceptible to a field density gradient of the dirt, just like helium balloons on the atmosphere. Tires just keep popping to the surface because there is a density gradient in the dirt moving towards the less dense at the earths surface. You must expend a small constant force to keep old tires buried underground.
Gravity works the same but with the force exerted on it in the opposite direction to the example given. Gravity is a force that is only due to a gradient in the field, not absolute values. That gradient is equivalent in action to a force. At the edge of galaxies the gradient “should” diminish to practically zero. That is, a value low enough for massive objects there to not remain in orbit around the galaxy.
People assume the gravitational gradient does not diminish like it should to keep massive objects orbiting. One theory for this is modified gravity, Mond, which says the gradient doesn’t diminish below a certain level basically because that is what we observe. But it is a curve fitting formula used to closely match observations and so far, from what I can see, it is curve fitting only with no good physical arguments for it besides speculation. Plus, as Sean said, the math is ugly. If you could think of GOOD reasons for the formula besides curve fitting I’d be more convinced.
There is also problems with the conventional particle theories, so Mond isn’t alone in being inadequate. Things like reasons for the odd distribution of massive particles near the the perimeter of of galaxies. I think people tend to implicitly assume that gravity is keeping those perimeter objects in line, even if the gravity is coming from new particles. It may not be gravity that is keeping those objects in orbit. People Should start thinking about analogues of confined objects that do not use gravity. There are plenty of examples in the quantum world and in the macroscopic world also. They should also start combining those thoughts with the fact that space itself is a lot bigger and a lot colder than when baryons and later atoms were formed. Atoms are hugely bigger than baryons and they formed when when space was colder. There is no good reason to say this process of particle formation isn’t still occurring and that it scales with the changing volume and temperature of the
universe. Scientists need to be a LOT more imaginative than they have been up to now.
“One needs to remember that the vast majority of astronomers are not working on dark matter cosmology. For someone working on, say, star formation or quasars or dust in galaxies, as long as MOND reproduces Newtonian gravity on small scales and TeVeS can be tweaked up to produce the right rate of structure formation, it doesn’t make a difference to their research. It’s the places where it doesn’t reproduce the current standard model that are going to matter, so making testable predictions (for say the mass spectrum of bound structures in the universe) is important.”
—
I’ll take epicycles for $500, Alex. I’m intrigued reading the deeply theoretical pugilistics here. It reminds me of some other famous bouts in 20th century physics, much of which involved the alleged existence of elementary particles first required by theory and only confirmed later by experiment. Absent confirming data, it does kind of gravitate toward theoretical aesthetics. Do we patch up the hole in the boat with a new particle or by tweaking a fundamental law? Either way there’s still a hole in the boat. Which is good. It would be terribly boring if we found we had discovered everything.
@Douglas Watts(#95):
Indeed, holes there are. A historical review:
There were 2 instances when unknown matter was postulated, on the basis of existing theory, to exist and then discovered: Neptune and the neutrino.
There are at least 3 cases, when unknown matter was postulated, on the basis of existing theory, to exist and then falsified: Phlogiston (solved by thermodynamics and atomic physics = new physical laws)
aether (solved by special relativity = new physical laws)
a planet within Mercury’s orbit (solved by general relativity = new laws of physics)
There might have been more.
The case with phlogiston is an interesting parallel, because well before modern concepts were in place discrepancies had arisen within the phlogiston framework such that it became untenable centuries before quantum physics allowed oxidization for example to be understood at a fundamental level.
Concerning cold dark matter, we already have exactly this same situation at hand: within the LCDM framework insurmountable discrepancies have been arising despite a practically fantastic effort to solve these, only one of them being the Fritz Zwicky Paradox. For me this is the clear signal that LCDM is not viable, and we need to move on, whereby the success of MOND is giving essential clues.
“For me this is the clear signal that LCDM is not viable, and we need to move on, whereby the success of MOND is giving essential clues.”
Whoever wants to “move on” now should do so. You really don’t have to wait for everyone else.
#97: Good hint. And yes, they are … But, I happen to know that there is unfortunately significant hindrance from the traditionalists… Surely this hindrance is not in the best interests of the taxpayer who are lead to believe, employing scientific tricks, that the traditional picture works perfectly well.
Great discussion – lots of information and insight.
Here is another pertinent link:
http://scienceblogs.com/startswithabang/