Does the Failure to Find Dark Matter Prove the Existence of Dark Matter?

I admit the title is a little click-baity, but open your mind for a moment to consider if the possible answer to this seemingly absurd question might actually be "yes" or at least "maybe". The latest discovery seems to disprove the alternative hypothesis to dark matter.

Some recent interesting research is discussed in a video by physicist Matt O'Dowd at PBS spacetime:

No Dark Matter = Proof of Dark Matter?

We’ve been failing to detect dark matter for decades. Finally, the latest failure to detect dark matter may have actually proved its existence. One of these is true: either most of the matter in the universe is invisible and formed of something not explained by modern particle physics OR our understanding of gravity is completely broken. The debate over which is true has raged for decades, but may finally have been resolved in an unlikely way: the proof that dark matter exists, and really is an exotic, unknown substance, may have come from the discovery of two galaxies that appear to have no dark matter at all. Today on Space Time Journal Club we’ll look at the papers that reveal this discovery

I copied the video synopsis which sums up the idea but I'll explain a little more.

The two alternative ideas being debated to discuss observations have been these. Either:
A. There some kind of matter we can't see causing galaxies that are rotating so fast they would fly apart without it, or
B. Our model of gravity which seems to work at the scale of our solar system is completely broken at larger scales like galaxies.

Can anybody think of a third option? It's critical if you can because the premise of this discussion is that those are the two options. They are certainly the two options which I've seen discussed in the scientific literature.

Since there is some distress because of the failure to find what dark matter really is, let's first of all say that you're standing on a type of dark matter called "baryonic dark matter". So we know the earth exists and thus there's no doubt this type of dark matter exists, the problem is all of our estimates suggest that there can't be enough of this type of dark matter to explain observations. If it was in the form of gas or dust we would see it block starlight and while that happens in limited regions, it's not enough to explain galaxy rotation curves. Also gravitational microlensing observations failed to find a sufficient number of black holes to account for it. And Primordial black holes have been hypothesized which could be too small for gravitational microlensing observations to detect, but our theories say those should "evaporate" and release a lot of energy in a certain type of signature which we haven't observed.

So the idea scientists have is that only a small fraction of the dark matter could be "baryonic" dark matter made of "ordinary stuff" like the Earth, and the rest needs to be made of something else which is hard to detect.

Since we haven't detected it despite extensive searches should we give up and re-invent gravity theory to explain observations? Some scientists have certainly tried to do that and papers have been published suggesting it, an idea called MOND, short for "MOdified Newtonian Dynamics".

MOND has some advantages, since tweaking the parameters can make it fit some galaxy rotation curves pretty well. But before you jump to the conclusion that "Aha I knew dark matter was a fantasy, that must be the answer", MOND is not without some serious problems, even before the latest discoveries, which might be the final nail in the coffin of MOND.

The problems with MOND already known were that most scientists seem to think it can't explain observations in the bullet cluster, where the dark matter seems separated from the luminous matter, which already questions whether any modification of gravity can explain what is seen there. But the MOND supporter wrote a paper saying that maybe MOND can explain the bullet cluster. My take is many scientists don't buy that explanation, but that's not the only problem.

Next, is the problem that MOND can't explain gravitational lensing observations, but dark matter can. Relativity says a lot of matter can "magnify" the images of more distant objects and this is what we observe, and MOND can't explain it. So this is a big reason why MOND has not been widely accepted.

There is also a more subtle problem with MOND in that it can't explain the evolution of the universe like dark matter can.

But now to discuss the latest research which may be the final death of MOND:
Two galaxies have been discovered that appear to have no dark matter at all! This is the "failure to find dark matter which might prove there is dark matter" or it might be more correct to say it proves the alternative hypothesis of MOND can't be correct. If it was our understanding of gravity that was wrong as MOND suggests, then there should be no way we would observe galaxies which appear to be following the traditional gravity models. There would seem to be no way to tweak the parameters of MOND to explain how some galaxies can rotate really fast without flying apart, and others rotate "normally". The presence or absence of dark matter in various galaxies could however explain this, so should this research hold up, MOND is definitely falsified and the only alternative we have left is the dark matter hypothesis unless you or someone else has a better alternative.

In that sense I think the answer to the question "Does the Failure to Find Dark Matter prove the existence of Dark Matter?" is "sort of". It does seem now that the only other alternative hypothesis with any credibility in the mainstream has been MOND and that would seem to be falsified at this point (even more so than it was already by lack of ability to explain a number of things like gravitational lensing and the evolution of the universe). But I don't think we can answer a confident "yes" until we figure out what dark matter is.

While dark matter searches have been extensive, not all of the "parameter space" has been searched, and so searching will probably continue until more of the parameter space has been searched. One problem I see is that observations of our own solar system seem to indicate there's not a significant amount of dark matter in our solar system, since the motions observed locally follow the predictions or relativity well without adding dark matter, but it appears to be around in the larger scale of the Milky Way galaxy, and other galaxies, except not in the two recent discoveries which didn't appear to have any dark matter.

So in summary, it's more intense than a Sherlock Holmes mystery that we don't know what 95% of the universe is made of. I see a lot of comments from laypeople like "scientists don't know what they are doing" and so on but following this research has been a hobby of mine and I can't say I've found fault with scientists observations and they admit we can't really explain them definitively. But we never claimed to have all the answers and even if the dark matter mystery is solved we still won't have all the answers, there will always be mysteries to explore, and solving mysteries can be fun. This mystery is taking a long time to solve though, but perhaps the latest findings discussed in the above video put us a step closer to letting us know which track to follow in trying to solve it.

a reply to: Arbitrageur

I can't find a million dollars in my bank account. Does that mean it is there? I hope so.

a reply to: Arbitrageur

Dark matter is a place holder term. According to our understanding of the size of our universe, the amount of matter that we have calculated to exist, and the speed at which objects are moving away from the center, there should be far more stuff there. Like 95% more stuff in the universe. We don’t know if it is a problem with our calculations, or if there is stuff there that we can't see. We know that we don’t know, so they made up the term to describe that we know we are missing something. Maybe. This has always just been a hypothesis.

originally posted by: Woodcarver
a reply to: Arbitrageur

Dark matter is a place holder term. According to our understanding of the size of our universe, the amount of matter that we have calculated to exist, and the speed at which objects are moving away from the center, there should be far more stuff there. Like 95% more stuff in the universe. We don’t know if it is a problem with our calculations, or if there is stuff there that we can't see. We know that we don’t know, so they made up the term to describe that we know we are missing something. Maybe. This has always just been a hypothesis.

The interesting thing about this latest research though, is the discovery of 2 galaxies where unlike most other galaxies, nothing seems to be missing. There doesn't need to be any more stuff there! So some models or ideas of what is going on with observations we can't explain seem to be eliminated by this discovery.

originally posted by: Arbitrageur

originally posted by: Woodcarver
a reply to: Arbitrageur

Dark matter is a place holder term. According to our understanding of the size of our universe, the amount of matter that we have calculated to exist, and the speed at which objects are moving away from the center, there should be far more stuff there. Like 95% more stuff in the universe. We don’t know if it is a problem with our calculations, or if there is stuff there that we can't see. We know that we don’t know, so they made up the term to describe that we know we are missing something. Maybe. This has always just been a hypothesis.

The interesting thing about this latest research though, is the discovery of 2 galaxies where unlike most other galaxies, nothing seems to be missing. There doesn't need to be any more stuff there! So some models or ideas of what is going on with observations we can't explain seem to be eliminated by this discovery.

I fell for the click bait thread title, but I was just reading that some scientists once thought that tiny black holes was the stuff that we could not see.

a reply to: InTheLight
There is a whole list of dark matter candidates that have been/are being researched, and those are on the list. They are called "Primordial Black Holes" (PBHs). There is an excellent Sixty Symbols video which does a nice job of explaining what they are hypothesized to be, and what kind of observations should result, and what constraints our observations have put on their prevalence.

So there's a lot of information about primordial black holes in the video, but what I think may be even more interesting to some people who aren't that familiar with the scientific process is Professor Copeland's explanation of how the scientific process works, to establish a model, test it against observations, and then use the observations to put constraints on the model. It can be an interactive process to refine the model based on new observations. I think the video contains some very interesting insights into not just PBHs but also how the scientific process works.

Primordial Black Holes - Sixty Symbols


Dark matter is probably not just one thing, it could be composed of several things. It can't be mostly baryonic matter, and according to Dr Copeland it can't be mostly PBHs, but it could consist of some small portion of baryonic matter (black holes are often lumped in this category even though technically they probably aren't strictly baryonic) and several other things.

ErosA433 is a physicist and ATS member who has worked on Dark Matter projects and he posted a graphic showing many different candidates for dark matter, re-posted below:

www.abovetopsecret.com...

originally posted by: ErosA433
It is an open question. Though with any open question complex stipulation should be done with some caution. It is true that dark matter can be more than one form of matter, it in truth could be many things. It however isn't the truth to say we have no idea about it for example.

From our observations we have the following phenomenological understanding or knowledge, presented with evidence

1) It has electrostatic neutral charge.
Evidence - We do not observe its presence in the EM spectrum
We do not observe any drag effect indicative to a high strength interaction such as with the EM spectrum... - Bullet Cluster)
2) It interacts gravitationally
Evidence
- We observe large lobes of matter in gravitational lensing far beyond the observable stars in galaxies
- We observe universal rapid rotation out to large distances in spiral galaxies
- We have observed Galaxies with very very few stars, but significant mass... so called Dark matter galaxies in which the stars rotate around a central point but there doesn't really appear to be enough stars or gas in that galaxy to support it at all in comparison to say... the milky way
- Clusters of galaxies move too quickly to be bound. This would mean that when we look into the sky, we should not see any observable families of galaxies, and more just a totally random distribution. Again, something is holding it all together in a gravitational well.
3) - Tenable statement - It is probably particulate in nature. This means it could be a particle of some kind rather than a weird field or simply a force.
Evidence
- Objects like the Bullet cluster show how the matter concentration of a cluster can be separated from the particle concentration. This object is two clusters that have passed through each other. The result from gravitational lensing places the centre of mass ahead of the observable mass from optical and X-ray measurements. Optical measures show how hot gas stripped from the clusters drags behind in a shock front structure. What this suggests is that Dark Matter is some kind of particulate matter that experiences gravitation but not electrostatic effects. If it did, it would be dragged back similarly to the hot gas stripped from the clusters.

SO what are the candidates?

Well again we can imagine many, here are a few models...

I don't see PBHs listed perhaps for the reasons Dr Copeland explains or maybe I don't recognize what they are called. The PBH research already done seems to place a constraint on how much of dark matter can be accounted for by PBHs and it's not enough which is why we need all these other candidates to explore.

a reply to: Arbitrageur

The fact dark matter is needed to make the stupid equations work is evidence for the existence of God.

Dark energy is even more fun because more of it is being created ALL the time.

a reply to: dfnj2015
So are you saying God does not exist in the "Fritz" galaxy (what Matt O'Dowd calls it) since dark matter is not needed to make the equations work in the Fritz galaxy?

MOND can adequately account for all observations if it makes logical leaps about fundamental physics that current dark matter models make, when considering quantum behaviors.

That being, the existence of something outside of space-time having an influence on observations within space-time.

If there were pre-existing energy or force parameters scattered across the Highs fields of our universe, MOND can be valid, AND we have the observations mentioned in the topic post.

Ok here it is...
Dark matter does not really exist in a state as matter in this dimension, however this matter from another dimension is a force in this dimension and is a lot like two magnets repelling one another as it interacts with matter here...
It’s like nothing and everything because nothing we know would be as it is without it. For it’s the very fabric of space and time...

a reply to: Arbitrageur

bare with me, I have few basic questions, so I can understand it better:

1. Can we detect "dark matter" in any way ? Is it based solely on calculations or is there any kind of observation that lends credence to the idea ?
2. If we cant detect it, how do we know these two galaxies dont have any ?
3. If dark matter theory is correct and universal, should there be "exceptions" ?

You said:

One problem I see is that observations of our own solar system seem to indicate there's not a significant amount of dark matter in our solar system, since the motions observed locally follow the predictions or relativity well without adding dark matter

As a layman, this is something that sticks to my childish mind. Observations of our own solar system should be the default starting point. If other systems, galaxies dont follow suit, one of these should be true:

1. our "long range" observations are wrong because of lack of understanding or limits of technology or...
2. dark matter is not needed to explain the motion or...
3. it is needed for some parts of the universe, but obviously not universally.

Could it be, that the there cant be a single theory that explains it ? Could it be that different parts of the universe have different "laws of physics". There may be a larger truth, and our standard model is just a subtheory that explains a fraction of what we can see or understand.

It seems to me that we have made many assumptions about the Universe, and then we are trying to cram everything to fit our theory, but these assumptions are actually slowing us down. Pointing to a fake trail, a dead end.

These comments are made strictly based on your post. Havent had time to check the video yet, but defo will later in the day. Excuse if some of these questions are covered by the video or are stupidly uneducated

All I know or have read is every attempt has been unable to detect Dark Matter no matter how many years or how much money on test equipment is spent... So... Maybe the universe is much more dusty than anyone has accounted for or maybe the Plasma universe guys and gals are more right all along.. Some intriguing stuff has and is being done based on an electric/plasma universe theory; which the old guard hates.. I figure if it works there might be something there to look at..

I doubt everything will be ironed on anytime soon unfortunately..

a reply to: Arbitrageur

From my understanding there is still a mass window for PBHs of sublunar mass 10^20 - 10^22 g as a possible dark matter candidate. They are too light to be detected by micro lensing but heavy enough to not have evaporated.

If one questions the Hawking radiation prediction, one would get a much broader mass range starting from Plank mass BHs, which would probably not be directly detectable at all.

My theory is that the universe was a primordial soup and it was a series of Bangs, like a gunpowder circle lit from the center. That is best I can explain. I think the many Blackholes are an example of many different ignition points. I think it could explain why we see the many different make up and combinations of Planets. It may explain that the mass was there but now exploded.


It is a theory based on thought no maths.

On a side not if every planet contained a black hole would that make the math add up? (impossible question I guess)

a reply to: Arbitrageur

The PBH is a very interesting theory, but I find this one more intriguing and it keeps Einstein's theory of relativity intact too.

Abhay Ashtekar and Javier Olmedo at Pennsylvania State University in University Park and Parampreet Singh at Louisiana State University, Baton Rouge, have taken a step toward answering this question [1]. They have shown that loop quantum gravity—a candidate theory for providing a quantum-mechanical description of gravity—predicts that spacetime continues across the center of the hole into a new region that exists in the future and has the geometry of the interior of a white hole. A white hole is the time-reversed image of a black hole: in it, matter can only move outwards. The passage “across the center” into a future region is counterintuitive; it is possible thanks to the strong distortion of the spacetime geometry inside the hole that is allowed by general relativity. This result supports a hypothesis under investigation by numerous research groups: the future of all black holes may be to convert into a real white hole, from which the matter that has fallen inside can bounce out. However, existing theories have not been able to fully show a way for this bounce to happen. That loop quantum gravity manages to do it is an indication that this theory has ripened enough to tackle real-world situations.

physics.aps.org...

originally posted by: MarioOnTheFly
a reply to: Arbitrageur

bare with me, I have few basic questions, so I can understand it better:

1. Can we detect "dark matter" in any way ? Is it based solely on calculations or is there any kind of observation that lends credence to the idea ?

Detection methods are referred to as "direct detection" and "indirect detection".
All direct detection experiments have failed so far.
There are several types of indirect detection I mentioned in the OP:

Galaxy rotation curves
Gravitational lensing

Other reasons why dark matter seems to fit observations better than other alternatives is because it is consistent with observations related to the evolution of the universe, though these concepts are a bit difficult for a layman explanation. The galaxy rotation curves and gravitational lensing should not be too hard to understand though. If you want an in-depth look at all of these, I suggest this article though it gets a bit deep for a layman:

What Astronomers Wish Everyone Knew About Dark Matter And Dark Energy

Among the general public, people compare it to the aether, phlogiston, or epicycles. Yet almost all astronomers are certain: dark matter and dark energy exist. Here’s why.

2. If we cant detect it, how do we know these two galaxies dont have any ?

The indirect detection method of galaxy rotation curves.

3. If dark matter theory is correct and universal, should there be "exceptions" ?

That's a valid question for any conceivable explanation of observations. The state of affairs now is that of the two main lines of thought to explain observations, at least it's possible to say the amount of dark matter can vary but it's much more difficult to explain these observations by saying gravity of ordinary matter has different effects at larger distances than what Einstein's model predicts.

You said:

One problem I see is that observations of our own solar system seem to indicate there's not a significant amount of dark matter in our solar system, since the motions observed locally follow the predictions or relativity well without adding dark matter

As a layman, this is something that sticks to my childish mind. Observations of our own solar system should be the default starting point.

We have not ruled out the possibility of dark matter in our solar system but even if it's at the expected density it's too small to detect because on a galactic scale, the 93 million mines from Earth to the sun is a tiny distance and cosmically speaking it contains a tiny amount of dark matter. On a human scale the 93 million mile radius around the sun could be expected to contain a "large" amount of dark matter, something like 2.3 billion tons! That sounds like a lot, so how could we not detect that? The reason is because the mass of the sun is roughly a billion times a billion times larger than that and we don't have any measurement methods precise enough to detect something that's a billionth of a billionth of the sun's mass, considering all the other uncertainties and error bars that result when calculating orbits. If we ever can make such precise measurements or calculations to measure a billionth of a billionth in this context which significant above the error bars, that would be a great accomplishment, but we are probably a factor of 100,000 away from being able to do that, so not even close.

This link has some more precise numbers:

Do we measure any gravitational effect of dark matter in our solar system?

Havent had time to check the video yet, but defo will later in the day.

I thought the video was good because it went beyond just discussing the latest research and covered the reasons why even before the latest findings, alternatives to dark matter didn't seem to fit observations as well.

originally posted by: 727Sky
All I know or have read is every attempt has been unable to detect Dark Matter no matter how many years or how much money on test equipment is spent... So... Maybe the universe is much more dusty than anyone has accounted for or maybe the Plasma universe guys and gals are more right all along..

If you are referring to Thornhill and other electric universe guys, they don't have any model so it's impossible to say their model is right if they don't have one.

originally posted by: moebius
a reply to: Arbitrageur

From my understanding there is still a mass window for PBHs of sublunar mass 10^20 - 10^22 g as a possible dark matter candidate. They are too light to be detected by micro lensing but heavy enough to not have evaporated.

If one questions the Hawking radiation prediction, one would get a much broader mass range starting from Plank mass BHs, which would probably not be directly detectable at all.

Thanks, I'm always impressed by your comments as I am with these and as usual I agree. While many generally assume that Hawking's model for black hole evaporation is likely to be true, it's not substantially proven by observation, so it's certainly fair to question the Hawking predictions until they are observationally confirmed. Dr. Copeland does say that PBHs are candidates for dark matter so that is not a question, the question is, how much dark matter could such objects account for? As you suggest the answer to that could depend on whether or not Hawking's model is correct. If Hawking's model is correct, I think PBHs are not the answer:

Now We Know That Dark Matter Isn’t Primordial Black Holes
That conclusion is based on assuming Hawking's model is correct, but I think questioning Hawking's model is a valid thought.

Here's another analysis which doesn't rely on Hawking's model as much as it does gravitational lensing if I understand it correctly:

Black holes ruled out as universe's missing dark matter

Based on a statistical analysis of 740 of the brightest supernovas discovered as of 2014, and the fact that none of them appear to be magnified or brightened by hidden black hole "gravitational lenses," the researchers concluded that primordial black holes can make up no more than about 40 percent of the dark matter in the universe.

So apparently they don't rule out that PBHs can explain some portion of dark matter observations, but it's not enough, which is along the lines of what Dr Copeland says in the PBH video in my previous post.

a reply to: InTheLight
I think white holes are speculative and I've never seen any evidence for them. In the case of "dark matter" we have observations that beg to be explained, a far more interesting topic to me than speculative hypotheses with no observational evidence and it sounds like it's impossible to observationally confirm that speculation in your link.

I was not referring to Thornhill but to some of the latest papers published. Go to the 2:50 minute mark or on youtube there is a link to a PDF. youtu.be...


Ben is very interested in dark matter and on his channel he seems to always mention the latest university/lab findings..... which in the dark matter quest seems to be like looking for WMDs in Iraq.

No argument from me either way as others I just find it interesting.

originally posted by: 727Sky
I was not referring to Thornhill but to some of the latest papers published. Go to the 2:50 minute mark or on youtube there is a link to a PDF. youtu.be...

The only pdf link I see is for "Dust Grain alignment and magnetic fields", is that what you're talking about?

JCMT BISTRO Survey observations of the Ophiuchus Molecular Cloud: Dust grain alignment properties inferred using a Ricean noise model

I don't know what that paper is supposed to have to do with the topic of this thread and I don't have any arguments with that paper, but I don't consider Ben a reliable source of information at all. I seem to remember debunking some of his ill-informed claims before on ATS and here is a video which also does the same with some specifics:

WRONG BEN - Stop Misleading People!

As that video shows, Ben has taken things which he doesn't really understand and tried to portray certain implications which are not true because his interpretations are not true, and I don't think those are isolated examples.

a reply to: 727Sky

All I know or have read is every attempt has been unable to detect Dark Matter no matter how many years or how much money on test equipment is spent...

Well, here's something more for you to read then...

Gravity lens reveals dark matter

How Gravitational Lensing Shows Us Dark Matter!

There are quite a few articles about this. Click here for more

Assumption is that gravity alone is prime mover of stars orbiting within a galaxy. Is it not possibility that a spinning supper massive black hole producing large clouds of axions could also dictate the speed of rotating mass. With speed of rotation dictated by a vortex of flowing axions created by a spinning central supermassive black hole.