Hubble Builds 3D Dark Matter Map 177
astroengine writes "Dark matter can't be spotted directly because it doesn't interact with electromagnetic radiation (i.e. it doesn't emit any radiation and reflects no light). However, its gravitational influence on space-time can bend light from its otherwise straight path (a phenomenon known as 'lensing'). Using a sophisticated algorithm to scan a comprehensive Hubble Space Telescope survey of the cosmos, astronomers have plotted a map of 'weak lensing' events. Combining this with red shift measurements from ground-based observatories, they've produced a strikingly colorful 3D map of the structure of dark matter."
Shiny and beautiful... (Score:5, Interesting)
I agree it's a nice picture but there seems to be no explanation as to what these colours actually mean, let alone any kind of conclusion drawn from what I presume to be "pockets of dark matter".
Anyone care to enlighten me?
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Every map needs to have a scale bar at the very least. We need something to tell us where this thing is and what all the colors mean. Also, there is nothing 3D about it.
Re:Shiny and beautiful... (Score:4, Funny)
Re:Shiny and beautiful... (Score:5, Informative)
From TFA, the closest hint we get to the 3D nature:
By combining the Hubble observations of gravitational lenses with spectroscopic red shift observations from telescopes on Earth, the 3D location of clumps of mass (dark matter, galaxies, black holes etc.) can be found. In this case, the white, cyan, and green regions are closer to Earth than those indicated in orange and red.
but yes, the rest is pretty awful... it's just a starfield without any context with blotches of colour randomly scattered over it.
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Wait, I thought the whole story was about someone getting a bunch of grant money to make a starfield without any context with blotches of colour randomly scattered over it.
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X = X
Y = Y
Z = RGB
FTFA: "the white, cyan, and green regions are closer to Earth than those indicated in orange and red."
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Re:Shiny and beautiful... (Score:5, Informative)
...but I fail to see the 3D that was promised by TFA.
Yeah sadly it's the data that's 3D, not the presentation. They located the dark matter in three dimensions, the 3rd being distance according to red shift which is how it's colored. I can see how it's hard to find the explanation, too, what with them breaking up the story every couple paragraphs with a giant bold link to something else. I thought those were different news items at first!
Bad presentation in the article aside, this is pretty amazing work. What a phenomenal instrument we have in Hubble.
The article on the the Hubble site [spacetelescope.org], while similarly lacking a good explanation for the image, actually talks about dark energy more than dark matter. Apparently this data also indicates a universe expanding outward from every point, corroborating that theory, along with some GR experimental validation as well. Not bad for a days work.
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I guess this is the first time scientists were able to actually go from saying "There's dark matter 'somewhere'" to "Look at this data, we were able to indirectly locate some of it".
They have been able to locate some of it before, just the scale here is unprecedented. It was previous discoveries of dark matter outside colliding galaxies that put dark matter well ahead of alternative explanations.
Cool thing, it might just get us a step closer to understanding the whole subject better.
Indeed.
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Your link was busted, had an @ at the end which I got too when trying to copy the link. :(
But who cares about that! We've been searching for likely dark matter candidates in deep dark holes with ultra-sensitive detectors, when this whole time it's been posting to slashdot!
Sorry couldn't resist. ;)
Re:Shiny and beautiful... (Score:4, Informative)
The image doesn't really help me visualize the concept, but it attracted me to the article. That's probably the intent of these kind of images, grab people's attention and explain the findings when they want to know what the hell they're looking at.
Here's the explanation (Score:2)
http://www.spacetelescope.org/goodies/printlayouts/html/heic1005.html [spacetelescope.org]
More on how it was done (Score:2)
And a little more about how they did it:
http://www.spacetelescope.org/images/html/heic1005c.html [spacetelescope.org]
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You have to stand about 3 feet away, and let your eyes go fuzzy. It's a cute picture of a unicorn.
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Do yourself a favor and don't let that bastard of a horse talk you into making the "magical mayonnaise".
Zetarians? (Score:3)
FAKE (Score:2, Funny)
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Troll? Looks like a badly done Photoshop to me as well.
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Well, it is, technically. They didn't just save the pictures directly off Hubble and post them on the internet, you know.
Nice pretty picture (Score:4, Insightful)
There isn't any "scale bar" because you are not looking at something at any fixed distance! You are looking at (theoretically) blobs of stuff at various distances.
Re:Nice pretty picture (Score:5, Informative)
...especially when you consider it's a picture of something that very possibly doesn't even exist.
It exists. Educate [wikipedia.org] yourself [wikipedia.org].
Re:Nice pretty picture (Score:4, Informative)
Thanks. It's worth noting that the Bullet Cluster results you linked to are only the most recent development in dark matter's nearly 80 year history:
1933 - Zwicky studies the Coma cluster of galaxies and is surprised to find that these galaxies are orbiting each other much faster than he predicted based on their visible mass. He proposes that each galaxy actually contains much more mass than is visible.
1959 - Measurements of galactic rotational velocities conflict with expected velocities based on the amount of matter observed to be present. The dark matter concept proposed by Zwicky is found to solve this problem too.
1970s - Big Bang nucleosynthesis has trouble reconciling observations of high deuterium density with the expansion rate of the universe. Non-baryonic dark matter solves this problem as well.
At this point, dark matter was simply an hypothesis. MOdified Newtonian Dynamics (MOND [umd.edu]) was another hypothesis with equal weight. But then in 2006 measurements of the Bullet Cluster supported the dark matter hypothesis over the MOND hypothesis.
Simultaneously, WMAP [wikipedia.org] (2001-present) measured the microwave background radiation and independently confirmed the existence of dark matter. It also revealed an even larger amount of "dark energy" which confirmed the 1998 discovery [arxiv.org] that the expansion of the universe is accelerating.
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At this point, dark matter was simply an hypothesis. MOdified Newtonian Dynamics (MOND [umd.edu]) was another hypothesis with equal weight. But then in 2006 measurements of the Bullet Cluster supported the dark matter hypothesis over the MOND hypothesis.
I don't think you could really say MOND had equal weight until 2006. I got my physics degree in the late 80's/early 90's and while MOND was often mentioned along with dark matter, it was usually as a footnote of other possiblities. Very few considered it a
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Gotta keep up with the news, man!
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Educate yourself. It's still just a theory.
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Why was this modded down? Mendel was in fact ignored, for decades, and the primary reason was that his ideas conflicted with mainstream theory!
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Actually, Mendel may have cheated, or his assistant may have arranged the results to match what he knew Mendel wanted. The problem is that, statistically speaking, Mendel's results are too good to be true. There is some controversy about this. I'm not taking sides--just pointing it out, e.g. http://www.ayubmed.edu.pk/JAMC/PAST/19-3/22%20Faraz.pdf [ayubmed.edu.pk]
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So are Relativity and Quantum Mechanics.
You say "theory" as if it's a bad thing, while it's the highest you can hope to achieve in science.
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So you think the Universe cannot go beyond the bounds you can easily imagine? That it can't contain anything new and fascinating?
In what way is dark matter stranger than quantum physics or relativity, except for the fact that we've had about a century to get used to those?
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>>It exists.
What are it's properties then? All we've observed are anomalies in gravity and space-time. Positing some mysterious form of invisible matter isn't an explanation at all - all we still know is that there's these weird things going on with gravity and spacetime, and that our current theories are incomplete.
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You present as evidence exactly the same sort of imaging techniques that were used to make the image in question? That's really lame.
That's like trying to prove that a photograph of a ghost is real by producing more photographs of the ghost. Hint: it doesn't work.
There are alternative theories, such as MoND, that might explain this (since it explains the apparent gravitational anomalies in spiral galaxies, it is possible that it could explain this kind of gravitati
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You present as evidence exactly the same sort of imaging techniques that were used to make the image in question? That's really lame.
No it isn't. It's incontrovertible evidence. Or do you have proof that the methodology is faulty (despite the results agreeing with other sorts of data, such as WMAP)?
There are alternative theories, such as MoND, that might explain this
No, there aren't. Even MOND proponents have admitted that *some* form of weakly interacting matter is *required* to explain the galaxy colli
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If you had bothered to read my other comments, you might have found out something yourself.
And yes, other than this, which does appear (without having researched it fully) to support the existence of dark matter, most of the evidence I have seen that was supposedly "evidence of dark matter" was pretty equally evidence of some of the alternative theories. Just how much do you know about the evide
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If you had bothered to read my other comments, you might have found out something yourself.
I've read those comments. None of them appear to provide any evidence to either invalidate these and related findings, or provide a mechanism by which MOND or other theories could be altered to fit current observations.
Just how much do you know about the evidence I have seen anyway? You seem to believe you are an expert on the matter.
Well, judging by your comments, you certainly are. So, please, explain to me how t
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Your supposed expertise in physics aside, you seem to need reading and logic lessons.
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And yet, for all that you know about the evidence that you have seen, you still haven't explained how MOND or other alternatives to dark matter can explain the results that I've cited, results which are accepted by most of the physics community as supporting dark matter while ruling out MOND. I mean, it's not like you can just cherrypick the results to fit your theory. You gotta explain them all.
So please, if you have citations or other references which explain how MOND can be altered to fit the latest re
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If you read more of my statements, not just the one you have been obsessed with, you will see that I was not saying that MoND could explain this... simply that (I am repeating myself here) most of the evidence that I have seen does support alternate theories at least as well as dark matter. I have already stated (as you would know, if you had actually been reading) that it might not apply here.
All I have said here, given the whole of my statements, is that -- contrary to yo
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It is nothing of the sort. You may know a lot about current physics but you obviously know squat about logic and evidence. You offered the wikipedia link as evidence that OP's picture is correct... yet they used exactly the same techniques (having to do with gravitational lensing) to produce the pictures.
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See the AC. He explains it very nicely, so I won't bother.
Honestly, how stupid do you think physicists are? They came up with the idea of dark matter *specifically* to deal with galactic rotational curves. You really don't think they put a little thought into local effects? Please...
This is just classic Slashdotter arrogance. You somehow think you've achieved a brilliant insight that people who've spent decades specializing in the field somehow failed to notice.
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Hmm. First, you seem to have taken an inordinate interest in me. Why is that? Especially considering how often you seem to disagree. Is it possible I have an evil stalker? Why else would he
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Thanks. I think this would've been impossible if I'd logged in.
It wasn't. Starting scores for users and ACs are different.
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get your ass down to the IEEE who actually have an idea of whats really going on
LOL.
Yeah right. The IEEE know that Electric Universe is a bunch of horesshit, because they understand how electromagnetism actually works, which cannot be said of any of the EU idiots. EU proposes that the solar wind - which is a quasi-neutral plasma consisting of equal amounts of positively and negatively changed particles -- is created by an electric field emanating from the sun.
Q.E.D. They're idiots.
My little pony (Score:2, Funny)
That explains.... (Score:3, Funny)
Cool picture! (Score:4, Funny)
So luminiferous and aethereal! Almost magical like!
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So, are you trolling, or are you really not aware that the jury is in and that dark matter has been [wikipedia.org] confirmed [wikipedia.org] (and more importantly, that MOND without any kind of weakly interacting matter has been ruled out)?
Old news? (Score:3, Insightful)
I actually submitted a story [slashdot.org] on this exact same topic back in 2007. The only thing new they seem to have now is a nicer picture, the article seems much lighter than the original article [bbc.co.uk] I linked to three years ago. The new article doesn't seem to indicate any new science that has developed since then, not even links or mentions of any new publications updating the findings in 2007, or even mentions of the scientists who are behind this work...
The data was old, the analysis and imaging is new. (Score:3, Informative)
The article dated "March 26, 2010":
http://news.discovery.com/space/hubble-3d-map-universe-dark-matter.html [discovery.com]
has a source dated 25-Mar-2010::
http://www.spacetelescope.org/news/html/heic1005.html [spacetelescope.org]
with this quote which explains everything:
Star Trek TOS (Score:3, Insightful)
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YES!!!!
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We have no reason to hate humans!
Could it be that dark matter.... (Score:3, Interesting)
So when I saw this documentation I always wondered, when 'our' gravity migrates into other universes, shouldn't also migrate gravity from other universes into ours? I wondered if this theory was true, how would a black hole in a parallel universe look like here?
So maybe, if we had the ability to fly to those places where hubble located the 'dark matter', we would find nothing. The space is curved there for no apparent reason. It is actually because of normal matter in a parallel universe.
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Re:Could someone explain... (Score:5, Informative)
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Sorta. As the earth goes around the sun, we do in fact get enough parallax to determine the distance to nearby stars. On the galactic scale, though, this doesn't work. The way they find lensing artifacts is that lensing doesn't just skew a single flat image of what we see, it might bend the same light source so it comes at us from different angles, producing multiple images of a single event. Something like this: http://en.wikipedia.org/wiki/Einstein_Cross
If they have good enough images with spectral plots
Re:Could someone explain... (Score:4, Interesting)
(To me still a imaginary excuse, based on the arrogance of not being able to admit that the math is wrong, but instead calling the universe wrong! ^^ [But a good {and compact!} explanation will of course change my mind.])
That might be something similar to what they told Einstein when he used his math to explain characteristics of nature that no one had witnessed.
I find the possibility of dark matter and energy kind of fascinating. Maybe it just a problem with their math - but then again, having huge amounts of mass in the universe be something other than what we experience every day adds a little mystery to it all.
Re:Could someone explain... (Score:5, Insightful)
The bottom line remains what osgeek above me said: it's easy for you to call the scientists who postulate dark matter "arrogant" considering it's something that has about as much impact on our daily lives as Einstein's Theory of Relativity does (which, when it was being proved, required very specific measurements to be taken, measurements that could only be gathered in a solar eclipse...how's that for completely unnecessary to quotidian life?).
No, right now we can't definitively prove that the 3D image referenced in TFA is indeed dark matter. But within the parameters of the current hypothesized model, that is what scientists believe to be pockets of dark matter.
Re:Could someone explain... (Score:5, Informative)
Exactly! Dark matter and dark energy are just tags for unexplained phenomena that appear to have similar properties to matter and energy. They are not simply mathematical entities, they are phenomena that can be observed but cannot (yet) be explained with our mathematical models. This is no different to any other physics, Newton didn't discover gravity he discovered it could be described with maths.
Just a nitpick on relativity and normal life (Score:2)
Re:Could someone explain... (Score:5, Informative)
...how they know it’s lensing, and that the stars aren’t just positioned like that?
Sounds to me like you could never prove, which one it really is, until you fly behind that “dark matter”. (To me still a imaginary excuse, based on the arrogance of not being able to admit that the math is wrong, but instead calling the universe wrong! ^^ [But a good {and compact!} explanation will of course change my mind.])
When you see multiple images of the same object, it's lensing. This is, in fact, how gravitational lensing was first discovered. Check out this great wikipedia image of the effect: http://en.wikipedia.org/wiki/File:Einstein_cross.jpg [wikipedia.org]. This is actually called strong lensing. TFA discusses weak lensing, which is a much smaller effect. That's detected by looking at very distant galaxies. Lensing changes the shape of galaxies such that there is a preferred orientation. If this orientation is statistically significant, i.e., too many galaxies are stretched in the same direction to be caused by normal physics, then it tells us that the weirdness is likely caused by lensing. Thanks to Hubble's ability to paint an incredibly dense picture of background galaxies, our statistics are based on a huge number of samples and we can trust them pretty thoroughly.
Awesome, right?
Re:Could someone explain... (Score:4, Interesting)
I'll go farther than that: I can remember how before the Hubble was launched, scientists didn't think we'd ever actually be able to observe the effect because it was too small to be imaged from any ground-based telescope.
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how are we sure it's gravity producing the lensing effect and not some other force?
Because gravity is the only force we know that is capable of doing so.
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...how they know it’s lensing, and that the stars aren’t just positioned like that?
I think it's because, in a perfectly flat space-time, only light that starts out coming directly at us will reach us. However, in our universe, heavy stuff can make light reach us that did not originally start coming at us. Also, when this bent light hits us, it appears to be coming from a direction that is not its true starting point.
Now, here's the key: Two photons starting at a star going in slightly different directions can both reach us, due to the heavy stuff out there bending space-time. When they
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Much like with regular lenses, there's more to it than just a change in apparent position.
To me still a imaginary excuse, based on the arrogance of not being able to admit that the math is wrong, but instead calling the universe wrong! ^^ [But a good {and compact!} explanation will of course change my mind.]
Once we discovered extra-galactic dark matter, it became really hard to find a different explanation. Coming up with a
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You are mistaken. Parallax only works for nearby objects (basically the nearest stars).
Here's how it was done:
http://www.spacetelescope.org/news/html/heic1005.html [spacetelescope.org]
Also look at each of the descriptions on the image links on the right hand side.
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The language was asking for it.
Re:Maybe, but not very promising (Score:5, Informative)
IANAAstrophysicist, but my understanding is that a point source, such as a black hole, would create a strong lensing effect. These observations are of a weak lensing effect that indicates a diffuse source of gravity.
The dark matter doesn't bend light. The gravity from the dark matter bends light.
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or put another way, the dark matter doesn't bend light -- it bends space. (!)
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Re:Dark matter doesn't exist. (Score:4, Informative)
Actually, it does exist. Frankly, I'm fucking sick of posting the same links over and over, so why don't you just go to Wikipedia and read about the Bullet Cluster. There is simply no question, now, even among MOND proponents: there is weakly interacting matter out there, and we have no idea what it is.
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It's the aether, of course. =^)
--
Toro
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And yet the very notion of "non-baryonic matter" challenges laws as fundamental and thoroughly-established as laws of gravitation
Since we already know lots about non-baryonic matter it's a little hard to see how the very notion challenges any laws of physics. Massive neutrinos, for example, are non-baryonic matter, and dark matter too. They exist. They don't account for the greater part of the dark matter that is inferred from observations, but they do exist.
The question I have is why so many people are so antagonistic to the very notion of dark matter, routinely calling the people who suggest it as an obvious and minimal move to
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The question I have is why so many people are so antagonistic to the very notion of dark matter, routinely calling the people who suggest it... "arrogant" and the like.
Personally I think the AC (perhaps unintentionally) nailed it -- it's part of a larger anti-science movement that considers the conclusions of science confusing, uncomfortable, or politically unattractive, and therefore seeks to discredit not just the particular theories but science in general. They do this by dressing up their ignorance wit
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Isn't doubt what got us science in the first place?
Only when done sincerely, and with an understanding of the existing theories and the evidence for them, and thus their actual flaws.
We call those people "scientists". There are plenty of them who are exercising legitimate doubt yet following the evidence.
A "doubter" shares none of these aspects with scientists except for the doubt, and even then calling "doubt" is inaccurate because they are so often already convinced that the science is obviously wrong,
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And yet the very notion of "non-baryonic matter" challenges laws as fundamental and thoroughly-established as laws of gravitation.
Uh no it doesn't. Why do you think that? Who told you that? Gravitational theory itself has nothing to say on the subject of baryonic vs non-baryonic matter, and another thoroughly-established theory, the Standard Model, has predicted non-baryonic matter which has also been subsequently verified to exist (google up neutrinos, W and Z gauge bosons).
As the more detailed link on
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My mistake. It was my understanding that non-baryonic matter was still strictly theoretical and basically precluded its interaction with other matter except in gravitational terms. It may have been explained incorrectly to me, or I may have misunderstood. Thanks for clearing that up.
For future reference, when someone says that Hypothesis A is clearly contradicted by Theory B, when Theory B is something that anyone working on Hypothesis A would obviously be familiar with, and indeed requires to formulate the
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Dark energy/matter are the names of the observed phenomena just as energy/matter are names for similar phenomena. If they are (as you claim) the names of specific hypotheses then what are the phenomena called?
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"I'll note: this has nothing to do with dark matter. As it happens, 90% of the matter in the Universe is in a form that emits no light, but affects other matter through gravity. We know it exists ... locally, in nearby galaxies and clusters of galaxies, too. This new result doesn't affect that, since the now un-hidden galaxies are very far away, like many billions of light years away. They can't possibly affect nearby galaxies, so they don't account for dark matter."
Citation (Score:2)
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Dark matter being simply regular matter that is hard to see was in fact one of the first hypothesis put forward and of course hugely favored for its simplicity, and to this day it is believed to account for some dark matter.
However further observation has largely ruled out this possibility for the majority of dark matter. The large halos of dark matter surrounding galaxies should be absolutely flooded by the light from said galaxy. It's not like the lights in your room are off, it's like you've got a 10-b