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The hypothesis of dark matter has proved incredibly successful in explaining the overall large scale structure of the universe and in interactions on the level of galactic clusters, which competing hypotheses such as modified gravity have failed to adequately explain. However, on the relatively smaller scales of individual galaxies, hypothesising dark matter shows some problems. In a paper recently accepted for publication in Physical Review Letters, astronomers Stacy McGaugh and Federico Lelli of Case Western Reserve University, and Jim Schombert of the University of Oregon, have made observations of 153 different galaxies with a wide variety of shapes, masses, sizes and amounts of gas. They have found a strong relationship between how quickly the galaxy rotates and the presence of normal (baryonic) matter alone. From an article on Case Western Reserve University's Daily:
[...] A team led by Case Western Reserve University researchers has found a significant new relationship in spiral and irregular galaxies: the acceleration observed in rotation curves tightly correlates with the gravitational acceleration expected from the visible mass only.
"If you measure the distribution of star light, you know the rotation curve, and vice versa," said Stacy McGaugh, chair of the Department of Astronomy at Case Western Reserve and lead author of the research.
The finding is consistent among 153 spiral and irregular galaxies, ranging from giant to dwarf, those with massive central bulges or none at all. It is also consistent among those galaxies comprised of mostly stars or mostly gas.
[...] "Galaxy rotation curves have traditionally been explained via an ad hoc hypothesis: that galaxies are surrounded by dark matter," said David Merritt, professor of physics and astronomy at the Rochester Institute of Technology, who was not involved in the research. "The relation discovered by McGaugh et al. is a serious, and possibly fatal, challenge to this hypothesis, since it shows that rotation curves are precisely determined by the distribution of the normal matter alone. Nothing in the standard cosmological model predicts this, and it is almost impossible to imagine how that model could be modified to explain it, without discarding the dark matter hypothesis completely."
[...] Arthur Kosowsky, professor of physics and astronomy at the University of Pittsburgh, was not involved but reviewed the research.
"The standard model of cosmology is remarkably successful at explaining just about everything we observe in the universe," Kosowsky said. "But if there is a single observation which keeps me awake at night worrying that we might have something essentially wrong, this is it."
Additional coverage and commentary by Ethan Siegel and Brian Koberlain. It seems that the universe has just thrown us yet another curve ball. This kind of correlation is just the sort of thing that modified gravity such as MOND and TeVeS predict. However, they fail miserably in explaining the large scale structure and evolution of the universe, which the dark matter explains admirably.
(Score: 4, Funny) by fishybell on Friday September 30 2016, @05:38PM
Look! Scientists completely fail to understand the universe in the is one aspect! We can't believe them about anything now!
(Score: 2) by frojack on Friday September 30 2016, @05:45PM
I'd comment on that, but Muphry's Law [wikipedia.org] would strike me.
No, you are mistaken. I've always had this sig.
(Score: 0) by Anonymous Coward on Friday September 30 2016, @07:06PM
At least it's a law and not a theory.
(Score: 2) by Gaaark on Friday September 30 2016, @09:52PM
It's more a of thoery than.
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 4, Insightful) by The Mighty Buzzard on Friday September 30 2016, @05:46PM
I was thinking more along the lines of "Good, now maybe they'll stop using Fucking Magic as an explanation for things and actually figure out why." Dark Matter is a shit term and always has been. If you don't fucking know, just say you don't fucking know and get to finding out. Don't give what you don't know an important sounding name so it looks like you know more than you actually do.
My rights don't end where your fear begins.
(Score: 5, Insightful) by Zz9zZ on Friday September 30 2016, @07:21PM
Who cares what the general public thinks? Seriously, the physicists know what's up and anyone who cares to research will realize they have no idea what it is. It isn't a secret. But being human we need names for things, it would get pretty tiresome to refer to it as "whatever is causing these observational errors in the standard model" and so we get "dark matter" and "dark energy" to represent the additions that "fix" the equations. Hell, they even use "dark" to imply that we can't see it / don't know what it is, however I will agree with you that quite a few physicists/astronomers started behaving like Dark Matter/Energy is a given truth but they are just lazy :)
~Tilting at windmills~
(Score: 2, Flamebait) by Nerdfest on Friday September 30 2016, @08:34PM
I'm actually a little surprised we haven't heard wailing from the SJW crowd about that one yet.
(Score: 2, Touché) by ikanreed on Friday September 30 2016, @08:39PM
That's because the strawman that lives only in your head doesn't care.
(Score: 0) by Anonymous Coward on Friday September 30 2016, @08:45PM
What??
(Score: 2) by Gaaark on Friday September 30 2016, @09:55PM
If you add dark numbers, 1+1=42.
Because i said so.
See, 1 + 1 + some dark numbers i've just come up with = 42.
See? See?!
Yeah. Told you.
--Physicists who know shite.
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 4, Informative) by HiThere on Saturday October 01 2016, @12:12AM
Unfortunately, our words tend to channelize our thought processes. When you call it "dark matter" you may *know* that this just means you don't know what is going on, but your thoughts tend to turn to WIMPs, Axions, sterile neutrinos, etc. I.e. to MASS rather than to anything else.
Similarly with "dark energy". Only a few people think of non-energy possibilities, even though anybody who seriously thinks about it knows that it's another label for "something that we don't understand is being shown by the experiments".
Now admittedly "dark matter" could, in principle, be explained by the appropriate massive particle. And "dark energy" could in principle be explained by something feeding energy into space-time. So the terms aren't really arbitrary. But they act to channelize the thinking on the subject. E.g. dark energy could be explained by particles with negative mass showing up somehow.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 3, Insightful) by Zz9zZ on Saturday October 01 2016, @02:00AM
Yeah, language is a bitch! If its some other dimension like string theory goes for, then wtf do we know? 4D is the pinnacle of our general mental modes...
~Tilting at windmills~
(Score: 1) by fustakrakich on Friday September 30 2016, @07:27PM
Don't give what you don't know an important sounding name so it looks like you know more than you actually do.
Scientists are advertising geeks too. Even NASA does their click baiting with *Big Announcement!... Coming next week!* And then the big letdown. It's the internet's fault.
La politica e i criminali sono la stessa cosa..
(Score: 0) by Anonymous Coward on Friday September 30 2016, @10:00PM
I was thinking more along the lines of "Good, now maybe they'll stop using Fucking Magic as an explanation for things and actually figure out why." Dark Matter is a shit term and always has been. If you don't fucking know, just say you don't fucking know and get to finding out. Don't give what you don't know an important sounding name so it looks like you know more than you actually do.
My understanding is that "Dark Matter" (and "Dark Energy") are exactly what you describe, placeholders to say "we don't know what this is, we should (and are) researching it."
If they were instead to call it "TSUF" (the stuff unaccounted for), it would be exactly the same. Dark Matter is just the label for the unknown, as much as "x" in algebra.
So they are doing exactly what you are suggesting, unless I am misunderstanding something... and this discovery is just one more small step into transforming "Dark Energy" from a meaningless placeholder name into a poorly-named scientific phenomena, like the "God" particle, "weak" force, and the various strange names of quarks.
(Score: 2) by fido_dogstoyevsky on Friday September 30 2016, @10:21PM
If they were instead to call it "TSUF" (the stuff unaccounted for), it would be exactly the same.
Except that there are many "stuffs unaccounted for" so we'd need to use TSUF_1, TSUF_2,... so we may as well use "dark matter", "dark energy", "dark coolness" etc
...the various strange names of quarks...
But some of those strange names are so charming.
It's NOT a conspiracy... it's a plot.
(Score: 3, Funny) by The Mighty Buzzard on Friday September 30 2016, @10:43PM
I'm personally in favor of Buzzard's WTF_a and Buzzard's WTF_b. They don't prima facie presume, like dark matter/energy, that some unknown form of matter or energy exists.
My rights don't end where your fear begins.
(Score: 2, Insightful) by khallow on Friday September 30 2016, @10:03PM
Dark Matter is a shit term and always has been. If you don't fucking know, just say you don't fucking know and get to finding out.
What makes you think they haven't done that? Ever wonder why they have more than one term for stuff they don't know? Here, we have both "dark matter" and "dark energy" which represent different parts of that unknown respective to a gravitation model that seems close to reality. Further, a short, memorable name is vastly better than some lengthy, neutered term which ends meaning the same thing, even if it's not entirely accurate in meaning.
Finally, what is so "important sounding" about "dark matter"? These are the people who came up with "big bang", MACHOs and WIMPs, and a variety of other whimsical names for things.
(Score: 2) by The Mighty Buzzard on Friday September 30 2016, @10:34PM
The main problem is that even some scientists have taken the fact that it's been given a cool enough name to be ripped off by science fiction and let it trick their brains into thinking this meant it was A) an actual thing instead of an error in understanding B) caused by one thing instead of multiple sources. If you don't understand it, don't go giving it a name like you do. Call it George's Weird Phenomenon and you'll accomplish the same goal without the unscientific lameness.
Dark Matter/Energy are today's Aether. If you use the words without scorn, you're probably wrong.
My rights don't end where your fear begins.
(Score: 3, Insightful) by khallow on Friday September 30 2016, @11:21PM
George's Weird Phenomenon
Instead of "dark matter"? I don't think that is even remotely a better choice.
B) caused by one thing instead of multiple sources.
Note that for "dark matter" most of these explanations are dark and massive. Fits with the name. Dark energy is far more tenuous since it can just mean a space-time with a little bit of curvature and/or inflation neither which makes sense until you learn that the "dark energy" comes from a negative energy term in the flat space approximation of curved space-time. Even then, the name's better. I don't buy that science is better served by coming up with obscure, stilted names.
I used to work in mathematics which has a huge problem with such things, just because there is far more stuff to label than there are nice names to label them with. But then maybe it's obvious to you that Nevalinna theory means figuring out how fast complex functions grow in a particular way (just to mention an example I hope to write about some time).
Dark Matter/Energy are today's Aether.
Except of course, they label phenomena we actually observe. And despite its cool name, we don't see scientists defending any theories of aether.
The main problem is that even some scientists have taken the fact that it's been given a cool enough name to be ripped off by science fiction and let it trick their brains into thinking this meant it was A) an actual thing instead of an error in understanding
Which if you think about it, just aren't serious problems. I think we have better things to do with science than protect scientists from snappy names.
(Score: 0) by Anonymous Coward on Friday September 30 2016, @10:19PM
Scientists only put forth models and let observations and scrutiny select the best KNOWN model. It's perfectly well known among cosmologists that existing "best fit" models may turn out to be wrong. They never claimed "dark matter" was gospel truth. It was merely a suggested explanation comparable to "Ether" in the late 1800's as a rough idea to explain certain observations.
Science is basically an algorithm:
1. Observe
2. Propose new models
3. Compare and contrast candidate models to observations
4. Best-fitting and simplest model(s) is the current "best explanation so far"
5. Test models against yet more observations
6. If the models fail to match observations, Go To step 2
7. Profit! (Okay, I made this step up)
(Score: 1, Interesting) by Anonymous Coward on Friday September 30 2016, @10:21PM