Deflating Claims That ESA Craft Has Spotted Dark Matter

Yesterday, we posted news that data from the European Space Agency's XMM-Newton spacecraft had been interpreted as a possible sign of dark matter; researchers noted that a spike in X-ray emissions from two different celestial objects, the Andromeda galaxy and the Perseus galaxy cluster, matched just what they "were expecting with dark matter — that is, concentrated and intense in the center of objects and weaker and diffuse on the edges." StartsWithABang writes with a skeptical rejoinder: There seems to be a formula for this very specific extraordinary claim: point your high-energy telescope at the center of a galaxy or cluster of galaxies, discover an X-ray or gamma ray signal that you can't account for through conventional, known astrophysics, and claim you've detected dark matter! Only, these results never pan out; they've turned out either to be due to conventional sources or simply non-detections every time. There's a claim going around the news based on this paper recently that we've really done it this time, and yet that's not even physically possible, as our astrophysical constraints already rule out a particle with this property as being the dark matter!

Comments

Dark matter and the sniff test

[bradley13]

I'm just a lowly engineer, but for me "dark matter" has never passed the sniff test. It's a kludge factor thrown in to make equations balance. And a kludge factor so huge that "dark matter" is supposed to outweigh all of the observable matter in the entire universe. The only reason this doesn't sound ridiculous is because we've been hearing it for so long.

If you need a kludge factor that big, it is far more likely that the equations are wrong.

There are other possible explanations. For example, if the speed of light were a function of space and time, then the situation changes completely. All observations of the distant/ancient universe are suddenly thrown into question; the interactions within that distant/ancient universe were also different from what we see locally, today. This particular theory (variability of C) is one that crops up periodically, most recently in 2013. It is difficult to prove, but really, it's no more unlikely than the existence of huge amounts of dark matter that stubbornly refuse to interact with the known universe.

Re:Dark matter and the sniff test

[Anonymous Coward]

There's a few scenarios were evidence of dark matter has been observed. All you have to do is smash two galaxies together and the non-interacting dark matter separates from ordinary matter. The separated dark matter then causes a gravitational lensing effect, which is displaced from the ordinary/visible matter in the galaxies.

It's possible that a modified theory of gravity (e.g. MOND) could still account for the behavior, but it puts requirements on the theory that (I am told) are difficult to accomodate. Sort of like how the Higgs boson discovery at 125 GeV puts requirements on supersymmetry that are hard to accomodate--it's still possible, but much less appealing.

This particular theory (variability of C) is one that crops up periodically, most recently in 2013 [livescience.com]. It is difficult to prove, but really, it's no more unlikely than the existence of huge amounts of dark matter that stubbornly refuse to interact with the known universe.

Considering it's 100% likely that there are particles which don't interact electromagnetically or via the strong force (i.e. neutrinos), dark matter isn't a stretch at all. It's strictly required to exist in most beyond standard model theories. And since the standard model sucks at explaining some observations (e.g. the maginitude of CP violation), we have reason to believe there's more physics going on than what we can currently observe.

Re:Dark matter and the sniff test

[wvmarle]

Smashing two galaxies together is not that easy :)

The thing that bugs me most with dark matter is that it is seemingly absent on small scales (e.g. the solar system), yet somehow shows up in immense quantities on large scale. It just doesn't add up to me.

Re: Dark matter and the sniff test

[Anonymous Coward]

Psst... Nobody tell him about dark energy, that'll really set him off...

Re: Dark matter and the sniff test

[Anonymous Coward]

You're already been given one clear proven kind of "dark matter"; the neutrino. This is incredibly difficult to spot; interacts very little; is almost absent from normal ("small scale") physics and yet it's existence is clear and well evidenced. It's really not that big a stretch that there is something else.

The thing is that if there isn't someone has to come up with really clever expansions for a whole load of other stuff. This would not be nearly the first time a physicist was wrong. In fact a truly dedicated physicist should try took be wrong several times a day. However strange and contrary to instinct would rule out relativity and quantum physics; in fact most of what we know to be true about the world. You have to find something more than gut instinct to oppose this with.

Re:Dark matter and the sniff test

[Dutch Gun]

Indeed there is probably something going on at large scales, where gravity doesn't work as it does on small scales.

I've often wondered about that. It's pretty well known that classical Newtonian physics tends to break down at the quantum level. I wonder if the same thing happens at the largest scales - galaxy-sized measurements. I'd never go so far as to argue against the prevailing theory with people that study these things their entire lives, but it does make for interesting reading and/or discussion to consider some of the proposed alternatives.

Re:Dark matter and the sniff test

[Dutch Gun]

It just doesn't add up to me.

"Not adding up" was the reason dark matter was invented. ;)

Re:Dark matter and the sniff test

[Anonymous Coward]

There are entire research groups dedicated to alternative gravity theories, but even their talks are often prefaced with the idea that dark matter does a better job of explaining the evidence in general. It would take several modifications to gravity to explain what could be explained by some dark matter theories. And for people who complain about dark matter being too arbitrary or just a fudge factor, several of the alternative gravity theories are literally fitted, arbitrary scales to just make it match the data. Yet most internet "scientists" don't seem to care in that case, because they spend so much time depending on a sniff test, going with their gut preferences instead of learning about the topic.

Re:Dark matter and the sniff test

[wonkey_monkey]

I'm just a lowly engineer, but for me "dark matter" has never passed the sniff test.

And yet it seems like most physicists - of whom I am not one - seem to think it is the simplest explanation for what we see.

The quote in the summary sums up, for me, the somewhat churlish attitude some people adopt when faced with dark matter:

There seems to be a formula for this very specific extraordinary claim: point your high-energy telescope at the center of a galaxy or cluster of galaxies, discover an X-ray or gamma ray signal that you can't account for through conventional, known astrophysics, and claim you've detected dark matter! Only, these results never pan out;

Of course they have never panned out - so far. If one of them had panned out, we would have stopped looking. Your keys are always in the last place you look.

Photons started out their theoretical life as a kludge factor to solve the ultraviolet catastrophe (great band), and people were appalled by the idea.

Re: Dark matter and the sniff test

[Anonymous Coward]

You can still do theoretical physics without any equipment. You only have to learn some math.
Unfortunately unverified theoretical physics is about as credible as astrology.

Re:Dark matter and the sniff test

[wonkey_monkey]

Compared to the galaxy as a whole, the solar system is very dense. That would (or so something I read said) made it harder to detect because the gravity of all the regular matter in the immediate neighbourhood swamps the signal.

Re:Dark matter and the sniff test

[Charliemopps]

I'm just a lowly engineer, but for me "dark matter" has never passed the sniff test. It's a kludge factor thrown in to make equations balance. And a kludge factor so huge that "dark matter" is supposed to outweigh all of the observable matter in the entire universe. The only reason this doesn't sound ridiculous is because we've been hearing it for so long.

If you need a kludge factor that big, it is far more likely that the equations are wrong.

There are other possible explanations. For example, if the speed of light were a function of space and time, then the situation changes completely. All observations of the distant/ancient universe are suddenly thrown into question; the interactions within that distant/ancient universe were also different from what we see locally, today. This particular theory (variability of C) is one that crops up periodically, most recently in 2013. It is difficult to prove, but really, it's no more unlikely than the existence of huge amounts of dark matter that stubbornly refuse to interact with the known universe.

Yes, but Variable c would open up many, far far more dire problems than Dark Matter.

Scientists aren't suggesting that dark matter is definitely a particle. That's one guess, but it could very well be some artifact of some underlying physical reality that we just don't understand yet just like you suggest. But the speed of light isn't variable.

Re:Dark matter and the sniff test

[wvmarle]

That it is the easiest explanation, doesn't mean it's the correct explanation, or that us non-believers so to say would support one of the other theories.

To me it's indeed very much a kludge, it seems to work, but I have the strong feeling that there is something else at play. Just no idea what that something else could possibly be.

Re:Dark matter and the sniff test

[wvmarle]

Yes, yes... and I took care already not to call it "massive quantities"...

Re:Dark matter and the sniff test

[Anonymous Coward]

I'm just a lowly engineer, but for me "dark matter" has never passed the sniff test. It's a kludge factor thrown in to make equations balance.

There are about 1e10 neutrinos flying through each square centimeter cross section of your body every second.
The chances of one of them interacting with your body is about once every 30 years or so.
Even our best neutrino detectors can capture only a small fraction of them every day (at best a few 100).
Given that, is it really hard to imagine there could be an even weaker interacting particle, that for current practical purposes was undetectable?

The reason we stick with dark matter as the best model, is because it seems to explain everything we observe: galactic rotation curves, distribution of clusters, Bullet Cluster like lensing, etc.
There are various models that all work well with dark matter, for example simulation of the evolution of our universe only work with 80% cold dark matter, calculations of the different ratios of atoms and isotopes also require dark matter to explain what we see today.
Everything we find seems to fit with dark matter, so what seems simpler: yet another neutrino-like particle, or some convoluted changes to our best formulas for spacetime?

Btw, the neutrino also started out as "dark matter". Experiments showed that something was carrying away momentum from other particles that could be seen. So they postulated there was an undetected particle. It took over 25 years to directly detect it.

Re:Dark matter and the sniff test

[EdgePenguin]

Dark matter is NOT a kludge factor. You should not make such strident pronouncements about a subject you clearly know nothing about. The existence of dark matter is not controversial amongst astrophysicists.

The fraction of deuterium produced by primordial nucleosynthesis, and the ratio between the acoustic peaks in the CMB, both require ~83% of the mass of the universe to be something other than baryons. Given that these two indicators are from entirely separate epochs (about a hundred seconds after the big bang for the former, and hundreds of thousands of years for the latter) this is a strong result.

Re:Dark matter and the sniff test

[Baloroth]

However, for some reason unknown to me, the visible matter in our solar system perfectly describes how the planets orbit the sun, how the moon orbits the earth, and how hard I hit the ground when I try to fly. So where is this dark matter, all this extra gravity? Shouldn't I hit the ground a lot harder than we can explain just based on the mass of our planet?

It's because dark matter only interacts gravitationally. See, normal matter clumps up into planets and stars because it sticks to other particles, and loses energy from collisions, causing it to collapse over time into locally dense spheres (planets, stars, black holes, etc.). But dark matter doesn't: it just passes through itself (mostly: it may interact through the weak force, but only very very very rarely if so, not enough to clump up). That means it doesn't form local regions of high density. On the other hand, an object immersed in a more or less uniform sea of matter (of any kind) won't notice any gravitational effects, because it's being pulled in all directions equally (for example: you'd be weightless at the center of the Earth. Dead from the pressure/heat/lack of air, but weightless). So, we can float through a sea, even a fairly dense one, of dark matter and notice nothing at all. Now, there is an non-uniformity in this dark matter "sea": there is more on the side of us towards the center of the galaxy than there is on the other side, but that pulls the entire solar system uniformly, accelerating it in it's galactic orbit, and that effect we do in fact see.

Re:Dark matter and the sniff test

[EdgePenguin]

Although you make the common error of thinking that the only requirement for dark matter is galaxy/cluster dynamics, you have stumbled on an interesting question; why is the Milky Way dynamically dominated by dark matter but the solar system is not. Fortunately, its easily answered.

Dark matter makes up most of the mass of galaxies, including the Milky Way. One of the best bits of evidence our own galaxy has dark matter is the rate at which M31 (Andromeda) is approaching us. The expansion of the universe drives galaxies apart, so the combined mass of the local group (basically just us and M31, M33 is next in mass but its much smaller than M31) has to be enough to pull the two galaxies together such that you would see M31 at the present distance and velocity. This is called the local group timing argument, and it shows that there is much more mass than can be accounted for with visible matter in the local group. This is not the only evidence for dark matter, but it along with the milk way rotation curve makes us confident that there is substantial dark mass in our galaxy.

As to the reason you don't see much dark matter impacting on the gravity of the solar system: that comes down to geometry. dark matter is arranged in a spheroidal halo whereas most of the visible matter is in a thin disk. The dark matter halo is much less dense in our galaxy than visible matter (and especially so in our solar system as for obvious reasons its got a higher density than the galaxy as a whole) but for large enough $r$, proportionality to $r^3$ always wins out over proportionality to $r^2$, which is why dark matter dominates the outer part of the rotation curve whilst at the same time being irrelevant for the internal kinematics of our solar system.

Re:Dark matter and the sniff test

[sconeu]

I believe that's "mass quantities".

https://www.youtube.com/watch?v=ygymejkA_CM

Re:Dark matter and the sniff test

[idji]

One of the consequences of Newton's Law of Gravity is that a spherically even distribution of matter behaves gravitationally as if it were all at the center http://en.wikipedia.org/wiki/S.... If you are INSIDE that sphere then you can IGNORE mass that is above you. Ie if you are in a hole 2000km into the earth you can ignore the outer 2000km of the earth. And so when you reach the center of the Earth you can ignore the Earth's gravity.


If you now apply this to Dark Matter and ASSUME that the Dark Matter in our part of the galaxy is evenly distributed then its gravitation effect upon is is effectively zero (or insignificant in terms of the Sun's effect on us). That is why we are unlikely to be able to measure local Dark Matter's effect on us, it is better to look outside of a Galaxy where it is less "spherical" or comparable to baryonic matter's influence
Also, since the baryonic matter INSIDE our solar system has MANY ORDERS OF MAGNITUDE of density higher than the Dark Matter INSIDE our solar system, Dark Matter is completely irrelevant for the orbits of solar planets, moons, etc..

Re:Dark matter and the sniff test

[budgenator]

However, for some reason unknown to me, the visible matter in our solar system perfectly describes how the planets orbit the sun, how the moon orbits the earth, and how hard I hit the ground when I try to fly. So where is this dark matter, all this extra gravity? Shouldn't I hit the ground a lot harder than we can explain just based on the mass of our planet?

I assume that because this so called dark matter, if it really exists, is pretty homogeneous at scales of planetary systems so all of the gravitational pulls at infinitely different angles just cancels out.

Re: Dark matter and the sniff test

[EdgePenguin]

I never said there was no other evidence for dark matter. The ratio of deuterium and the acoustic peaks of the CMB require most of the mass in the universe to be non baryonic. I simply stated the evidence that this non baryonic matter makes up most of the MW-M31 system. Your strident arrogance, coupled with your immense ignorance of the subject matter, would make a wiser person stay quiet.

Re: Dark matter and the sniff test

[EdgePenguin]

Stop. Really. You are embarrassing yourself. That is EXACTLY what you meant. You said I thought "the equations were off in two regards", so clearly you didn't know about any of the other evidence of dark matter. Now you are back-pedalling as you slowly realise you are not even vaguely qualified to be in this conversation.

Re: Dark matter and the sniff test

[EdgePenguin]

The claims are "extreme" because you don't like them, and the confidence of astrophysicists in this matter is a consequence of the overwhelming weight of evidence.

You have decided to take a position on a subject you are completely ignorant of, and that contrary positions to this are "extreme" and thus must be treated as fringe nuttery. Essentially, you think that your ad hoc guesses should be treated like the null hypothesis. You can try and dress it up in as much intellectual sounding language as you like, but you are being absolutely moronic and I'm done with you.

Re:Dark matter and the sniff test

[WillKemp]

[......] dark matter is arranged in a spheroidal halo whereas most of the visible matter is in a thin disk.

That sounds unlikely. How did it happen?

Re: Dark matter and the sniff test

[WillKemp]

Yeah, too right. If it wasn't for the meddling of a lowly patent clerk, we wouldn't be in this mess in the first place!

Re:Dark matter and the sniff test

[Anonymous Coward]

I mean sure there *could* be such a thing, it is much more plausible the equations are just wrong though.

You do realize that dark matter is an acknowledgement that the current theories are wrong and is a new theory to try to fix it right? It isn't any more or less of a new theory than other alternatives, but people try to act otherwise to support their gut feelings. Also your comment highlights one of the area that alternative gravity equations tend to fail, being able to explain only one short coming at a time, in a way often incomparable with other alternatives (you can't just pile up the effects) and with plenty of arbitrary factors to fit the data.

Re: Dark matter and the sniff test

[EdgePenguin]

Another good question. Gas can lose energy because it interacts with other radiation and matter, but dark matter cannot. The total angular momentum of the system must always be conserved, and a disk is the lowest energy configuration that does this. Both dark matter and gas start off in the spheroidal arrangement, and then the gas the cools to form a disk.

Re: Dark matter and the sniff test

[WillKemp]

Leave science to professionals.

The problem is that we've seen that shit before - it's called religion. Only a small clique of superior beings can actually know god's mind - and everyone else must just shut up and listen. If you can't explain this stuff in ways that non scientists can understand, then (a) you're not worth your wages, and (b) nobody's going to believe you.

Re: Dark matter and the sniff test

[WillKemp]

So does that mean dark matter is effectively a cloud of gas and its particles are constantly in rapid motion, but constrained in a spheroid by gravity? Or am i completely failing to grasp how it works?

Re:Dark matter and the sniff test

[WillKemp]

[......] theoretical physicists are typically far more intelligent than [engineers and computer scientists]

That depends on your definition of intelligence. But, whatever it is, all the intelligence in the world is worthless without the ability to communicate its products clearly in a way that lesser mortals can understand. Theoretical physicists, as a whole, do a very poor job of that.

Re: Dark matter and the sniff test

[EdgePenguin]

Thats right. Spheroidal systems in astrophysics are generally held up against gravity by such random motions, whereas flattened systems tend towards being help up by ordered rotation.

Re:Dark matter and the sniff test

[EdgePenguin]

Because the equations aren't "off" at all. They precisely predict the mass density of the universe and the baryon density of the universe from observations. The difference between these two values is very well established. Read the results papers from Planck and WMAP.

Re: Dark matter and the sniff test

[Rich0]

Don't waste your time arguing with trolls. It is a bit like somebody spending all day arguing that there are lots of things that could make a pendulum behave the way it does besides the earth turning.

Since the whole point of dark matter is attempting to account for phenomena which have no other explanation, it is entirely possible that all of physics is off the mark. However, to just dismiss the entire matter because any ONE specific issue is somewhat circumstantial is to miss the overall picture. There is certainly a lot of evidence that established theories are wrong, and there are a lot of independent constraints on what is going on.

Re:Dark matter and the sniff test

[Agent0013]

The very gasses that the say separated out from the galaxies have the ability to cause the bending of light also. It is just like refraction through a medium like glass, but there is no solid boundary that it passes through. Instead it has a varying index of refraction which leads to the very same bending of light that has been attributed to the dark matter that they keep saying is there. The bullet cluster isn't quite the nail in the coffin that the news will put it out as.

To me it sounds like a little circular reasoning. Physicists were looking for an aether and couldn't find one. Einstein comes along and explains that one isn't needed because of relativity. He first adds then removes the cosmological constant. We find things expanding too much so add the cosmological constant back in by the process of dark energy which supposedly involves vacuum energy of the aether, so we have added that back in also. And now we need dark matter to fix gravity also. So the need to get rid of the aether has led us around to putting it back in. Perhaps we went astray someplace back then and are heading off in the wrong direction.

I'm not trying to say I know more than the people working on this. I find it interesting either way though. But I have seen examples of scientists following the wrong trail for a while before it gets figured out. We are just starting to understand that the whole fat makes you fat thing was bad science and isn't really true. And we are all told the pyramids are tombs when no mummys have ever been found in one. No frescas or writing of the person buried there either like in all the other tombs of that time. Some guy in the past makes some claim and everyone buys it for quite a long time before it gets figured out that we took a wrong turn back then.

Re:Dark matter and the sniff test

[david_thornley]

Gasses do indeed have mass, and can cause gravitational lensing. However, we can detect them through other means, and there just isn't enough mass there by a long shot. In any case, the Bullet Cluster is an example of lensing happening where there is little or no gas. Gravitational lensing without matter we can detect does strongly suggest matter we can't detect.

Your second paragraph seems a bit incoherent, and ignores the fact that dark matter and dark energy are different things. We know there's dark matter already, since neutrinos qualify. Dark energy seems to this amateur somewhat more nebulous a concept, but the luminiferous aether has nothing to do with it. Nor did we drop it because of relativity. You seem to be confusing Michelson-Morley as an inspiration for relativity with some relevance of relativity to the aether idea. Michelson-Morley simply failed to detect and aether drift, suggesting that either we are the center of the Universe or light has a constant speed, the latter being a key factor in special relativity.

Dark matter doesn't fix gravity. It's an elegant and economical way to explain some gravitational effects we don't understand, and fits in with some particle physics stuff that I don't understand. Dark matter as a way of explaining galactic rotation curves is something like the discoveries of the outer planets from unexplained anomalies in their orbits. It's a way of explaining gravitational lensing when, as far as we can tell, there is nothing to create the gravitational field. Fiddling with gravitational theory to explain all the gravitational effects seems to me much like fiddling with it to explain the orbit of Saturn rather than hypothesizing a planet called Uranus.

Re:Dark matter and the sniff test

[david_thornley]

Until you can actually show us some

I'm going to ask for a definition of "show" here. By definition, dark matter is invisible, since it doesn't interact electromagnetically. What would constitute "showing" to you?

Dark matter isn't an idea that comes and goes each week. The theory has been around for a while, and scientists are currently attempting to discover what its other properties might be, and how else to detect it. Nobody is discovering or failing to discover dark matter itself.

Re: Dark matter and the sniff test

[beastofburdon]

I agree fully with your post. In fact there are many areas of science where the theory has become a religion and anything that contradicts the theory is derided as being "not scientific" or immediately "discredited" without any test of the data or new theory.
Even worse there is the medical field where the outcome of many studies is based solely on who is paying for it. Most of them being conducted in secret and the results only ever being published if the study supports the interests of the funders.

The current state of science is a disgrace!

Spammy submitter is spammy

[Anonymous Coward]

Moreso for spamming unreadable crap.

Kinda like the Gamma Bogon?

[Anonymous Coward]

And magnetic monopoles, when I was younger. I spent a fascinating class arguing with an MIT physics professor. His claim that "they must exist becase it makes Maxwell's Equations more electant and symmetrical" was like the the mathematics professor's claim that probabilities always being positive meant something subtle about how the universe works, and wasn't an artifact of how we chose to *)describe* probability.

I loved a great deal of both their teachings, but sometimes very smart people get very silly.

Do We Need Dark Matter?

[AbsoluteXyro]

As I understand it, dark matter is our best guess at explaining an observation of mass via gravitational lensing and other effects where there is not enough visible matter to account for it. What I never see mentioned, and perhaps there's a good reason for this unbeknownst to me, is the possibility that this phenomenon exists independent from any matter, just as we do observe it. It seems to suggest that without matter space time would be flat across the entire universe. Why isn't it possible that space time is inherently imperfect, with it's own curvatures independent of mass? I've never seen this question asked, or answered. Maybe I've been looking in the wrong places, though. Can someone enlighten me?

Wait Just a Second

[Anonymous Coward]

Time and time again when the subject GLobal (not) Warming comes up all we hear from the would be Slashdot PhDs is "Peer Review! Peer Review!"

But somehow now it's just fine to dump all over the findings of a group of scientists...real scientists, with degrees and shit, not just a Slashdot handle and low UID) and not a mention of peer review in sight.

Fucking hypocrites, the lot of you.

Science

[Livius]

Dark matter is a hypothesis. So far it fits the data, but new data may force modification or even rejection of the hypothesis. The reason it's an exciting area of research is exactly because physicist acknowledge that its an imperfect hypothesis.

All science works this way. The luminiferous aether hypothesis was not foolish or worthless - it was valuable science because when tested its limitations led to new insights. And while the materials science metaphor was eventually judged inappropriate, if "empty" space can have an energy density or a geometry, it may yet turn out that something about the basic idea of a luminiferous aether could be true.

Re:Science

[esperto]

Actually, from what I recall, dark matter, and dark energy, are just place holders for stuff that generate effects that we can measure but yet do not have an explanation for, we have a few hypotesis, some more likely than others, but no proof for any of those yet.
Basically we KNOW that our models are incomplete and that are stuff out there causing galaxies to rotate at a different speed than it supposed to be just by visible matter and that are other stuff making shit fly appart faster, but we don't have an actual clue of what they are.

Check out this unusual pattern of gamma rays!

[RevWaldo]

~ What do you think professor? Does it prove the existence of dark matter?

~ This? Oh, bless your heart, no, my young assistant. This is just chatter from some ancient interstellar civilization. Trade negotiations if I'm not mistaken.

~ Gosh, you're right, professor, I should have realized that myself.

~ Yes, completely useless I'm afraid. Fear not, we'll find the evidence someday.

.

Re:I'm also an engineer

[EdgePenguin]

You do not have a better theory. You have a hypothesis, posted on a webpage. This is timecube territory, sorry. Why is it that engineers make such laughably bad attempts to second guess scientists? And why do they insist on bothering actual scientists with mass emails about their crazy ideas?

Dark Matter is not a tweak to gravity

[EdgePenguin]

A lot of engineers and computer programmers seem to think that dark matter is just a fudge to make rotation curves fit, and that they being smarter than astrophysicists can see through this obvious error. This is profoundly irritating

Dark matter is required to explain the ratio of elements produced during big bang nucleosynthesis, the acoustic peaks of the cosmic microwave background, gravitational lensing, cluster dynamics, the Local Group timing and finally, yes, rotation curves. In the last application (which is bizarrely considered to be the only place dark matter is invoked), the most popular alternative hypothesis MOND, which has no theoretical basis and exists purely to fit rotation curve data, doesn't actually do that well on modern rotation curves.

You cannot offering any critical comment on dark matter that won't make you sound like a terminal case of Dunning-Kruger to an astrophysicist unless you understand all of the things I mentioned above.

Re:Dark Matter is not a tweak to gravity

[WillKemp]

Shoulda been first post!

Re:Dark Matter is not a tweak to gravity

[x_t0ken_407]

Perfect description of what goes on. Thanks for saving me the time on my rant, lol.

Re:I'm also an engineer

[EdgePenguin]

Yes, we are all Educated Stupid and thats why we don't believe in Timecube!