Cosmic Fuggedaboudit: Dark Matter May Not Exist At All

A once-improbable theory is challenged by a new, even less probable one

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ESA / Hubble / NASA

The dwarf galaxy NGC 5477

When the idea of dark matter first pushed its way into astronomers’ consciousness a few decades ago, the primary reaction was: “Seriously? There’s a mysterious, invisible substance out there, with a mass six or more times greater than that of the visible stars and galaxies, only we have no way of detecting it, but really, it’s there? OK then.” Or something like that, albeit in more formal scientific language.

These days, dark matter is a firmly established principle of cosmology; most of the questions now focus on how the stuff is distributed through the universe, and which of many possible subatomic particles it’s made of.

Most of the questions, but not all. Ever since the early 80’s, a competing theory has been struggling for acceptance. Known as MOND, for Modified Newtonian Dynamics, it posits that dark matter’s main effect — allowing galaxies to spin faster than they should — isn’t caused by extra stuff, but instead by a change in how gravity works under certain conditions.

(MORE: Telescope to Hunt For Missing 96% of the Universe)

That underdog theory has now gotten a boost: using MOND-based models, and assuming no dark matter whatever, astronomers have successfully predicted the orbital speeds of stars in 15 faint dwarf galaxies that hover around the nearby Andromeda spiral galaxy. MOND can already explain galaxies that spin like the Milky Way — not surprisingly, since the theory was invented to do just that. But this is its first test in galaxies that aren’t spinning as a whole, but whose individual stars are instead following their own random orbits. MOND predicted how fast those stars should be moving, and, says Stacy McGaugh of Case Western Reserve University, lead author of a paper on the predictions, “It’s spot-on.”

Whether this will change the minds of mainstream cosmologists about the existence of dark matter is another question entirely. McGaugh himself was completely dismissive about MOND when he first heard about it. “Who wants to waste their time hearing about that crap,” he recalls thinking when MOND’s creator, the Israeli astrophysicist Mordehai Milgrom, showed up to give a presentation many years ago. McGaugh went to listen anyway. His reaction afterward? “This is crazy talk.”

But maybe not. Gravity weakens rapidly the further you move from the attracting body — the Earth say. Milgrom’s idea is that at very low intensity, like out at the edges of galaxies, that weakening should slow. If that were true, the attraction produced by visible matter at those great distances would be greater than current estimates suggest — perhaps enough to allow the edges of galaxies to rotate unexpectedly fast, without the help of any invisible, unknown matter holding them together. The same phenomenon would allow galaxies in clusters to orbit one another other at surprisingly high speed without the distances among them steadily widening.

(MORE: Solved: How Cosmic rays Are Made)

This alone wouldn’t make MOND a competitor to conventional dark-matter theory, which explains those high speeds equally well. But the mainstream theory does have some shortcomings that MOND avoids. Conventional theory predicts, for example, that there should be thousands of small clumps of dark matter floating around in the so-called Local Group of galaxies, and that these clumps should have formed the seeds for thousands of dwarf galaxies. But in fact, the Local Group has only a few dozen dwarfs — at least, that anyone has found so far.

Numbers aside, the theory says that any dwarf galaxies we do see should have dense knots of dark matter at their cores. But as far as anyone can tell by carefully measuring the orbital speeds of individual stars, they don’t. MOND, on the other hand is agnostic on how many dwarf galaxies there should be; it’s fine with just a dozen. It’s also better than conventional dark-matter theory at explaining the mass-to-light relation in so-called low-surface-brightness galaxies, another class of objects that are dim, like dwarfs, but not especially small.

(MORE: Discovered: The Most Adorable Planet Yet)

That’s what eventually won McGaugh over. “I bothered to learn about MOND,” he says. “Many of the more vocal critics choose to remain willfully ignorant.”

But at least one subscriber to the mainstream theory who has taken a serious look at MOND remains unconvinced. “If MOND were purely a theory of modified gravity, that would be one thing,” says Avi Loeb, chair of the astronomy department at Harvard. But even MOND requires some sort of dark matter to explain such crucial phenomena as evolution of structure in the universe — why and how galaxies have been pulled into huge clusters, for example, rather than being smoothly distributed through space. MOND enthusiasts, he says, call on the gravity exerted by giant clouds of neutrinos — a type of fleet, lightweight elementary particle so ethereal that it could zip through a chunk of lead a trillion miles thick without even noticing – to accomplish that feat.

While neutrinos are known to exist, however, it’s not clear they can do what MOND supporters claim. Dark matter, by contrast, explains both cosmic structure and the behavior of individual galaxies in a much simpler way. “With [the extra factor of neutrinos], MOND loses its appeal,” says Loeb, “because it is no longer purely a modified theory of gravity.” For his money, that’s just too speculative.

That doesn’t make MOND crazy, though. As physicist Anthony Aguirre, of the University of California, Santa Cruz, wrote a few years ago, “MOND is out of the mainstream, but it is far from wacky.” That’s more than many astrophysicists would have said for dark matter a generation ago.

PICTURES: Deep-Space Photos: Hubble’s Greatest Hits

117 comments
Ugebig
Ugebig

Hi, I am from South Africa and I have a theory about why the universe is expanding and accelerating. I don't really want to blurt it out on this blog, I'd rather publish something so that somebody else doesn't steal my discovery. It is very simple and I am driving my wife mad because she simply can't grasp it. We are so blinded from the trees that we cannot see the forest. I'm not a scholar of quantum physics, nor do I have any qualifications, I am a builder, a jack of all trades and master of one - the one that disproves dark matter. They all dance around and suppose, but the secret sits on the OUTSIDE and knows...
can anybody direct me to a place where I can publish something?


captmurphysealab
captmurphysealab

As a pure novice, I have never liked dark matter. It smacked of being deus ex machina. I think the fact that we don't properly understand gravity is a far more logical and likely case than some mysterious unseen, (but more importantly) unprecedented stuff floating around that happens to solve all of the cosmological problems we have encountered.

RickGillespie
RickGillespie

I have a short paper on ResearchGate.net  that goes over an error in the interpretation of a galactic speed limit of the velocity of the speed of light. (https://www.researchgate.net/publication/236212521_There_is_a_Fundamental_Error_in_Limiting_Travel_to_c) And even though I agree that e=mc2 has been proven, I do not believe "c" should be read as a velocity as opposed to the transformation that is described which is actually an acceleration.  So the real problem is now taking that to the cosmic level of E=Mc2 that implies there was just one transformation of all Energy to Mass at the Big Bang. e=mc2 is a transformation that is going on in both ways all across the universe. Stars are created and black holes are converting mass back to energy.

RoccoJohnson
RoccoJohnson

These things never cease to convince me how closed-minded the scientific community can be. I'm making no statement about a particular position regarding black hole theory or any other cosmological or scientific position, other than to say that far too many of these researchers take their entrenched positions and defend them to the death, without sincere consideration of other ideas. 

Stacy McGaugh's statement “Who wants to waste their time hearing about that crap” is a perfect example of this. When a researcher has built an entire career on one position their objectivity goes out the window, as they now have a vested interest in ensuring they're not wrong. 

Science without honesty has no integrity, and the respected scientific community lowers itself to the level of wacko pseudo science mongers.

tfdrumm
tfdrumm

When there is a massive shortage of something your theory absolutely needs to remain current--and you haven't thought of a theory to replace it, GO DARK!

mariodesouza.ufs
mariodesouza.ufs

Yes, Dark Matter does not exist at all. At the APS April 2013 meeting I'll present the paper: A new model without dark matter for the rotation of spiral galaxies which shows that Dark Matter does not exist in spiral galaxies.

RogerE.Clairborne
RogerE.Clairborne

 If you take the elements of differing solar systems as a whole, or maybe just their outer most polar charged layer, I suspect their net charge of either predominately negative elements or positive elements are opposites and thus lock each solar system in a positive to negative layered alignment; a trailing chain like formation similar to a string of beads being swung from one end in a circle over your head.

Now it has been noticed that sometimes the centers of Galaxies spin faster than the outer bands rotate around them. Yet the outer bands don’t seem to be pulled in and wrap around the hub like a string of beads would under such unsynchronized speeds. There are various energy wave theories proposed but I think the solution to this problem is much simpler and more logical than all that. First visualize the positive to negative chain of solar systems locked together on a single string. Next try to visualize if you will different layers of strings swinging side by side. Finally imagine the positive to negative net charged solar systems being lined up just enough with positive beads swinging next to repelling positive beads on the next string to keep each string and solar system from crashing into each other. If you add the net charges of clusters of these solar system string of beads together, eventually you will get even wider repelling gaps between clusters as the opposing net charges increase with the mass and density between clusters.

akbmuruhan
akbmuruhan

If space can exert gravity,  the gravitational force does not fade farther from celestial objects, because of the presence of space. This goes with what MOND expects.

middleroad
middleroad

i'm an engineer not a scientist and I have never believed in 'dark matter', 'time travel', 'wormholes', 'big bang', 'space/time continum' or any other of these 'theories'. While theories are very important, today's scientists are far too interested in getting their 'theories' published to the world that they perform very poor science, ignore variables and other procedural techniques that years ago would have gotten you tossed out of the scientific community. Its a battle for funding, so if you don't come up with an 'advancement' you get no more money, so by default you need to rig your experiment to 'conclude' something. As for dark matter, we don't even understand why gravity exists so pretending there is a 'magic' matter that exudes this force that we don't even understand is pretty silly. My answer, "we simply don't understand the system nor do we have tools capable of detecting what we need to detect in an accurate manner, so there is obviously something going on with planetary movement we don't understand." not very sexy but it covers the issue. why is it so hard today to admit you don't know?

NathanielGatewood
NathanielGatewood

I'm not a physicist (just an admirer).  But, dark matter has always seemed a little to..convenient for me.  I've never liked the idea.  It doesn't really seem..creative enough of an answer; it seems too simplistic (if that makes sense).  to me, we're thinking too human. "Oh, the mass doesn't add up?  There must be an invisible, undetectable particle that takes up most of our universe."

Like I said, I'm not a physicist.  And I understand.  We tend to always gravitate to the simplistic answer.  Most of the time, that's the correct one.  But what if our understanding of gravity over large distances is flawed?  What if there's a large chunk we're leaving out?

Honestly, I really don't know.  The math adds up for dark matter, so that's what we need to go with.  But, I welcome all theories like MOND (working, theories..not just anything) to throw a monkey wrench in our science.  Sometimes, I think we get a little too comfortable with the status quo; even in science.

ReidBarnes
ReidBarnes

Yet the article says there seem to be problems with this new theory, MOND, also: "But at least one subscriber to the mainstream [dark matter] theory who has taken a serious look at MOND remains unconvinced. 'If MOND were purely a theory of modified gravity, that would be one thing,' says Avi Loeb, chair of the astronomy department at Harvard. But even MOND requires some sort of dark matter to explain such crucial phenomena as evolution of structure in the universe — why and how galaxies have been pulled into huge clusters, for example, rather than being smoothly distributed through space." On the other hand, it escapes me why dark matter proponents would cling to relativistic theories flawed by self-contradicting non-Euclidean geometry. We seem to be ignoring the prospects of plasma models and also the prospects of something called Zero Point Energy, a term actually coined by Einstein. I tend to think Einstein was wrong about space curvature (because of the flawed non-Euclidean geometry) but right about dice.https://www.facebook.com/notes/reid-barnes/not-the-god-particle-the-god-field-if-you-must-call-it-that/519767374742508

stacy.mcgaugh
stacy.mcgaugh

I agree with some of what ialsoagree says, but some of it is wrong.  MOND is not contradicted by many observed facts.  There are indeed claims to this effect, which I have reviewed extensively - most recently in a review invited by the journal Living Reviews in Relativity: http://relativity.livingreviews.org/Articles/lrr-2012-10/fulltext.html.  Very few of these claims hold water, and I am disturbed by how readily some of the more absurd claims are accepted uncritically.  The sociology seems to boil down to: if it supports dark matter, it must be right; if it supports MOND, it must be wrong.

I do not understand why ialsoagree asserts that there would be no cosmic microwave background (CMB) in MOND.  This is not the case.  I correctly predicted the amplitude ratio of the first to second peak in the power spectrum of the CMB using a model motivated by MOND.  Nobody else got that right ahead of time.  The same model fails to get the third peak right (this debate would be over if it had), but by some strange coincidence the first-to-second peak ratio is still measured to be exactly what I predicted ahead of time.

So yes, MOND has a ways to go, but it has already come farther than seems to be appreciated.  ADS: http://adsabs.harvard.edu/abstract_service.html - use it to search the literature.

I do agree that MOND suffers problems in clusters, and have said so many times.  It is not the only piece of evidence.  Some evidence favors LCDM (our current standard cosmological model), some favors MOND.  What conclusion you come to depends on how you weigh the evidence.  See http://astroweb.case.edu/ssm/mond/LCDMmondtesttable.html.  You don't have to agree with my evaluation of the evidence, but I have considered all the things people seem to be fond of asserting automatically exclude MOND.  It just isn't that clear.

LCDM has enormous trouble doing the things MOND does easily.  Where MOND explains galaxy dynamics with a single free parameter per galaxy, the unavoidable conversion from measured starlight to the mass of the stars producing it, LCDM requires a minimum of three parameters.  That doesn't really work, so we invoke "feedback" which brings at least another three free parameters  Even then it still doesn't manage as well as MOND.  I'm sure we can keep adding free parameters until we get it right, but this is a pretty blatant violation of Occam's razor.  If I were to adopt the same attitude as MOND's critics, I would assert that it is impossible for LCDM to do what the data require and therefore it is falsified.  That is no less fair a statement than the legitimate complaints about MOND.  So again, I don't think it is that easy to choose.

And yes, MOND is a scientific theory, in the same sense that Newton's Law of Universal Gravitation is.  MOND is an extension of that theory.  In the modern parlance, it can be derived from a Lagrangian.  What MOND is NOT is an extension of General Relativity.  Reconciling the two is a big challenge for theorists.  So far we haven't been able to reconcile General Relativity with the other fundamental forces in a would-be theory of everything, or even quantize gravity satisfactorily.  So I hesitate to say there can be no surprises in gravitational theory.

Dark Matter is a concept, not a theory.  We can develop specific hypotheses for what the dark matter can be, and construct legitimate theories therefrom.  But "dark matter" by itself could be just about anything, and is not subject to falsification.  Didn't see enough brown dwarfs?  Must be WIMPs.  No WIMPs? OK, Axions then.  If not that, we can always make up something else.

This subject always brings out the big questions.  All we said in the paper (and the press release) was that we applied MOND to the newly discovered dwarfs of Andromeda, and it seems to work.  It didn't have to be so.  We also make some a priori predictions that have yet to be tested, so maybe it will still fail.  It that not interesting?

ialsoagree
ialsoagree

Just to clarify, as some people seem confused.

MOND is not a scientific theory, it is a hypothesis, and a hypothesis that is contradicted by many observed facts (gravitational lensing, general relativity, cosmic microwave background radiation, models for the formation of cosmic bodies).

Dark matter is a scientific theory, and it is not contradicted by any observed phenomenon.

That doesn't gaurantee that dark matter is correct and MOND wrong. But when cosmologists have to use a model for the universe, the only model that makes logical sense to use at this time - and the only model that will lead them to conclusions that are supported by observation - is a model of the universe containing dark matter.

Is MOND worth further exploration? Of course!

But that doesn't mean it's ready to compete with dark matter as a valid explanation - at least not yet.

CloudZ1116
CloudZ1116

So basically what MOND is saying is that the 1/r^2 law for gravity doesn't hold over long distances? Would be very interesting if it were true. There are some guys at the University of Washington who have been looking for deviations from the 1/r^2 relationship with a fine tooth comb, since any variation would have huge implications for string theory. However, they haven't turned up anything... yet.

CharlesBoyer
CharlesBoyer

With both theories, the details (i.e. the math) are what matters, and that is far beyond the scope of a general-science article in mass-media.  It is, however, an interesting discussion about two competing theories, and a good jumping off point for those it interests to do more learning about MOND and the state of the art of dark matter research.  

It is amusing, however, for people who have no idea of how research into physics works to say that it is bunk.  Einstein, for example, was well known for his thought experiments that he used to suss out relativity, and they had nothing to do with direct observation.  From there, he used mathematical modeling and once he had that working to his satisfaction, direct observation to finally prove or disprove what he was working on.  Obviously, it worked as Relativity is a foundational theory yet to be credibly disproven while it has been confirmed many times over.  In terms of cosmological theory such as dark matter or MOND, we are still in the first two stages and eventually there will be confirmation or repudiation by observation...and none of it is bunk.  Science is a means, not an end.


cronenborrough
cronenborrough

I love how science can propose its own idea, and then punch the numbers into a "model", and then its proves thesis.   Where else can that happen?  Gee, I have 3 dollars and I'm going to put it in this hat and pull out eleven...  Clearly there are things that we don't know, and possibly can't  Making up theories about things with no evidence is like writing a novel.  No matter how great our technology we can't know anything without actually touching or measuring it.  Ever stood on the top of the Eiffel Tower?  No?  Then on what basis are you going to describe the view and the smell and the experience of actually being there?  Impossible. 

acwhitney
acwhitney

This seems to be a simpler explanation of many of the phenomena attributing to dark matter.  I find it hard to believe any credible scientist would say a simpler explanation that has been observed in experiment would not be worth more research.  Science makes its biggest leaps when we find out what we know is wrong.  If anything the community would be excited about the possibility of designing new experiments to try and prove/disprove the new theory.

JamesSavik
JamesSavik

I'm not burning the physics book yet.

Common sense tells you that there has to be a whole lot of "dark" matter in the universe. It doesn't have to be exotic. 

It is simply matter that is not blazing away in a star.


JoshEison
JoshEison

This is definitely surprising news. Does that mean that the lack of matter affects gravitational fields? Would that mean the "arms" of galaxies such as spiral and bar galaxies are some kind of indicator of a large scale gravitational field? A "standard" gravitational field on a local level has magnetic field lines that protrude from the source in circular patterns. The arms of galaxies don't appear to have the same patterns. Does this mean the gravitational fields of large mass objects behave differently in vacuums than small gravitational fields do? 

papakojo
papakojo

It seems that anytime a scientific theory is not being accepted by the 'mainstream' , the 'believers' resort to trying to disprove valid scientific theories. All the Newtonian and Relativity math back the existence of dark matter so no need for this sensationalized propaganda 


RickFromTexas
RickFromTexas

I happen to know that they prefer to be called little people galaxies rather than dwarf galaxies.

LelandWilliamsJr.
LelandWilliamsJr.

Keep sending your tax money to the National Science Foundation to keep these Physics PHD's from getting a real job.

BrianMathies
BrianMathies

@NathanielGatewood 

I don't know that its explanation is too simple. After all, E=mc^2 is a pretty simple equation, but it holds up pretty well.

Hadrewsky
Hadrewsky

@ReidBarnes 

Space curvature like gravitic lensing doesnt exist? So going back to the 30s when Eisenstein's solar eclipse demonstrated space being warped is all in the mind?


What are you smoking?

workingracket
workingracket

@ialsoagree - when the observed phenomenon requires the mathematical creation of dark matter, it is no different than the cart in front of the horse.  under this understanding, to call dark matter a theory is completely bogus.  it is a mathematical explanation to correct equations that could not predict reality.   maybe the base equations were wrong from the get go.  applying some mathematical hocus pocus in no way validates them

workingracket
workingracket

@CloudZ1116 what about the instantaneous action of gravity... if it was we would be attracted to were a body was and not where it is ... this would result in everything spiralling together, which is opposite of what we may think we see

ialsoagree
ialsoagree

Just to clarify, this is not "two competeing theories." Dark matter is a theory. It has predictive value. It is consistent with all known observations. And there have been significant observations that only dark matter explains (see: bullet cluster).

MOND is not a theory, it is a hypothesis. MOND is inconsistent with observation. MOND predicts that there is no general relativity, but we have observed general relativity. MOND perdicts no cosmic microwave background radiation, but we have observed the CMBR. MOND predicts no gravitation lensing, but we've observed gravitational lensing. MOND predicts that the cosmic bodies we observe - such as galaxies - cannot form in the ways or time period that are consistent with the observeable universe, and consistent with the predictions of dark matter.

MOND has seriously flaws, and while that doesn't mean it's wrong, it means it has a *long* way to go before it can seriously be considered competition for dark matter as an explanation.

Einstein had one thing going for him that MOND doesn't. His thought experiments didn't contradict known fact. MOND does.

BrianMathies
BrianMathies

@cronenborrough 

O ye of little brains. Who said anything about making a theory with no evidence? The evidence is all around us. The question is, how exactly do we interpret what we see?

TimeTraveler28
TimeTraveler28

@cronenborrough You just demonstrated that you don't know the first thing about how science works. And it does work. The device and the infrastructure you're using to post these comments is evidence of that.

Hadrewsky
Hadrewsky

@acwhitney 


seems that you need +10 light years to even think about an experiment.

That is a long way to walk between two objects.

workingracket
workingracket

@JamesSavik - there is always the aether that we are now calling something like the cosmic flux....  once you realize the politics that played into eddington's observations, you will realize that science is as corrupt as any other aspect of human nature

TimeTraveler28
TimeTraveler28

@JamesSavikDark matter is not that simple. It's not like any kind of matter currently known or detectable. It is not "simply matter that is not blazing away in a star". It is not gas and dust. Literally NOTHING is known about dark matter. It's just a name for a placeholder. Something that is *supposed to* exist, but has never been detected.

JoshEison
JoshEison

Well, not so much "objects" but rather, large mass "areas"?

ErikButler
ErikButler

@LelandWilliamsJr.You probably should shy away from articles like these to avoid hurting your wittle brain.  Go read fairy tails in the bible or something.

DouglasRutledge
DouglasRutledge

Yeah, you clearly don't want to compete for a job after dumping several thousand highly competent, highly professional and hard working individuals on the job market.

ReidBarnes
ReidBarnes

@Hadrewsky @ReidBarnesIt seemed Einstein had the measurements to prove relativity.  He predicted a different measurement for the perihelion of Mercury and predicted light bending around the sun, famously measured by Author Eddington during a solar eclipse, all based on his space-time curvature.  Eddington’s explanation was that space is curved by gravity, according to Einstein’s general theory of relativity, an explanation invalidated because of the self-contradicting non-Euclidean geometry in the theory.  This is explained in my Facebook Note:  Are We Clinging to Relativistic Space-Time Concepts that Distort Reality?   https://www.facebook.com/notes/reid-barnes/are-we-clinging-to-relativistic-space-time-concepts-that-distort-reality/505042069548372

workingracket
workingracket

@BrianMathies @cronenborrough - how about you quit being a jerk.  instead of implying that this evidence is everywhere, how about you man up and present it?  talk is cheap and deriding commenters is a sure-fire way to get you ignored.  but then again, you really don't have anything to say.

workingracket
workingracket

@TimeTraveler28 @cronenborrough - actually, at a simple level, this is exactly how the theory of dark matter was arrived at....  it was a vain attempt to support a broken model by mathematical patchwork that had very little to do with observing reality....  also, deriding commenters that bring valid points only proves that science is just a fundamentally challenged as religion.

workingracket
workingracket

@BrianMathies @NathanielGatewood = also E=mc^2 was derived mathematically whereas dark matter is a mathematical addition to fix faulty equations.. it is, in essence, science trying to tell us how reality should be...  nothing arrogant about that (sarcasm off)