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.
Related Stories
Last month, a team of scientists led by Stacy McGaugh at Case Western Reserve University determined from observations of 153 galaxies that the dynamics of galaxy rotation seems to depend solely on the normal, visible matter in it (SN coverage here). It was a strong argument that rather than hypothesising dark matter to explain the oddities in galactic rotation, it may instead be necessary to modify the laws of gravity.
However, two scientists from McMaster University, Ben Keller and James Wadsley, have just recently examined the results of a detailed simulation of dark matter in galaxy formation previously done known as the McMaster Unbiased Galaxy Simulations 2 (MUGS2). The simulation was a sophisticated one that took into account various other factors such as gas dynamics, star formation, and stellar feedback, but incorporated no new physics beyond that of the standard Lambda-Cold Dark Matter (ΛCDM) cosmological model. They found that the relation that McGaugh et. al. discovered from observations of real galaxies was reproduced just about exactly by the simulation. Their paper is here. Their abstract states:
Recent analysis (McGaugh et al. 2016) of the SPARC galaxy sample found a surprisingly tight relation between the radial acceleration inferred from the rotation curves, and the acceleration due to the baryonic components of the disc. It has been suggested that this relation may be evidence for new physics, beyond ΛCDM. In this letter we show that the 18 galaxies from the MUGS2 match the SPARC acceleration relation. These cosmological simulations of star forming, rotationally supported discs were simulated with a WMAP3 ΛCDM cosmology, and match the SPARC acceleration relation with less scatter than the observational data. These results show that this acceleration law is a consequence of dissipative collapse of baryons, rather than being evidence for exotic dark-sector physics or new dynamical laws.
So now it seems that the earlier troubles with dark matter were actually the result of too naïve a simulation, and by taking into account additional known, relevant physics, the troubles disappear.
Further coverage and commentary by astrophysicist Ethan Siegel here (archive.is).
Related: Study Casts Doubt on Cosmic Acceleration and Dark Energy
(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
(Score: 2, Insightful) by Anonymous Coward on Friday September 30 2016, @05:38PM
Now this is interesting. Something that challenges the current understanding.
Go science, venture forth!
(Score: 4, Informative) by frojack on Friday September 30 2016, @05:40PM
For those not familiar:
Wiki has a good explanation of rotation curve: a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's centre. It is typically rendered graphically as a plot.
https://en.wikipedia.org/wiki/Galaxy_rotation_curve [wikipedia.org]
No, you are mistaken. I've always had this sig.
(Score: 5, Interesting) by Anonymous Coward on Friday September 30 2016, @05:41PM
Here is how I'm interpreting this. The rotation differentials between the inner and outer part of galaxies STILL don't appear to follow Newtonian physics: the outside rotates faster than "Newton" predicts. However, the differential rates are consistent with the volume and distribution of visible (normal) matter. Thus, distribution of normal matter appears to be a near perfect predictor of rotation rates even though it doesn't follow Newton. But, perfect prediction is not necessarily an explanation.
Thus, there's still a mystery of the "flat" rotation, but there's no evidence the deviation from Newton is caused by dark matter because variations in normal matter between galaxies match tightly with observed rotation rate curves. The "news" here is that dark matter doesn't explain the Newton deviation, and not that the mystery is solved.
But I wonder if dark matter is not attracted to and/or repelled by normal matter based on normal matter's mass. Thus, more normal matter in the outer part of a given galaxy could be proportional to the amount of dark matter. The original dark-matter assumption was its relation to normal matter with semi-independent. Maybe on a galactic scale they are tightly dependent such that if Galaxy B has 60% more normal matter in its outer edge than Galaxy A, then B also has 60% more dark matter in its outer edge, explaining the difference from Newton predictions for visible matter AND the tight relationship between rotation rates and visible matter. No?
(Score: 2, Insightful) by frojack on Friday September 30 2016, @06:00PM
So then you reject the finding that explains why dark matter might not exist at all, and you turn that finding inside out to explain an imaginary property of dark matter?
No, you are mistaken. I've always had this sig.
(Score: 3, Insightful) by Anonymous Coward on Friday September 30 2016, @09:48PM
Dark matter "explains" other things besides galaxy rotation. And we still haven't solved the flat-rotational-curve mystery itself, only de-linked it directly from dark matter as previously modeled.
Either way, there is something odd about gravity over longer distances. Whether it's dark matter, gravity being an inconsistent force, entanglement, and/or something else, we don't know yet.
(Score: 0) by Anonymous Coward on Friday September 30 2016, @06:46PM
What about dark matter attached to strings? I posit there is as much evidence for this as the current theory!
Throw a few strings in there for tensioning and I am sure the theory will appear to match the data!
After all, nothing but quality science comes from just adding on ethereal bits and pieces to your theory until it by chance matches a set of data!
As long as the maths works out, you will get a paper out of it!
(Score: 2) by Gaaark on Friday September 30 2016, @09:59PM
but if you attach dark matter to strings, you need over 40 new imaginary dimensions that ARE there, we just have to find them. Yeah.
But they ARE there! Yep yep yep!
Because they solve problems!
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 0) by Anonymous Coward on Friday September 30 2016, @10:27PM
I think we are just missing an important piece in our theories of gravity. That's it, no invisible stuff necessary.
(Score: 0) by Anonymous Coward on Saturday October 01 2016, @12:29AM
As a thought experiment, what kind of force-by-distance curve of gravity would match observations for the three "categories" of distances: solar-systems (traditional Newtonian), galactic level (explaining the "flat" spin curve), and the inter-galactic distances, such as Hubble's gravity lenses? And maybe even the accelerating expansion of the universe.
Rather than looking at many simple forces, we can explore a complicated single force (gravity with a "weird" curve).
(Score: 3, Insightful) by bradley13 on Friday September 30 2016, @06:03PM
I'm not an astrophysicist, but an interested layman with an engineer's instinct. Dark matter stinks of "kludge" and it always has.
There is clearly some aspect of the universe and its laws that we have failed to understand. Saying that up to 90% of the mass of the universe is undetectable except for gravitational effects? And yet doesn't affect gravitation anywhere close, where we could see it? Bollocks.
Who says that the measurements we can make locally can be extrapolated by dozens of orders of magnitude? Just as a very minor example: We think that the inverse-square law applies to gravitation, but we can only accurately measure this on the order of a few AUs. The first problems with this theory occur on a galactic and intergalactic scale.
On top of that, when we look into galactic space, we are seeing the past. We may think that physical constants are unchangeable, but...maybe they aren't? Maybe they drift over the course of billions of years?
The point is: there are alternative explanations. The fact that astrophysics converged on dark matter was always a bit weird, because it's no more likely, and no less arbitrary than any of a dozen alternative explanations.
Everyone is somebody else's weirdo.
(Score: 3, Informative) by turgid on Friday September 30 2016, @06:28PM
Many years ago when I was studying space, one of the most important points that they kept making was that we don't know how much baryonic matter we can't see. In those days, the HST had only just been launched, and there were a couple of infrared observatories (important for seeing through dust) but you really can't see much through the Earth's atmosphere, since about all it lets through is visible light and radiowaves. It's pretty opaque to infrared. We really do need better space telescopes, as well as the huge ones on Earth.
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 2) by bradley13 on Friday September 30 2016, @06:53PM
"We really do need better space telescopes, as well as the huge ones on Earth."
Absolutely. And not just telescopes in the sense of visible light, infrared, etc.. We need all sorts of scientific instruments up in space, measuring all sorts of things. Aside from measuring Pioneer's course, what gravitational measurements do we have outside of a few AU? None!
We're like a bunch of bacteria, supposing the whole universe is just like our little petri dish.
Everyone is somebody else's weirdo.
(Score: 3, Informative) by tangomargarine on Friday September 30 2016, @07:16PM
You're probably thinking of Voyager 1, not Pioneer 1, if you're talking about the farthest manmade thing from Earth.
With a bit of googling I'm getting ~126 AUs out. One AU is from Earth to the sun.
93 million miles = 1 AU
Voyager is 11.7 billion miles
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 3, Informative) by turgid on Friday September 30 2016, @07:58PM
What's really cool is that you can see the comms to the spacecraft in realtime [nasa.gov] -- Voyager 1:-)
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 1) by nitehawk214 on Friday September 30 2016, @09:44PM
Currently transmitting at 159 bytes/second.
I didn't know comcast could communicate in deep space.
"Don't you ever miss the days when you used to be nostalgic?" -Loiosh
(Score: 0) by Anonymous Coward on Saturday October 01 2016, @04:17AM
The speed is a bit too fast for it to be comcast, but the lag is about right.
(Score: 1) by In hydraulis on Friday October 07 2016, @01:54PM
No, he means Pioneer.
https://en.wikipedia.org/wiki/Pioneer_anomaly [wikipedia.org]
(Score: 2) by tangomargarine on Friday October 07 2016, @02:44PM
Except it says communication with the Pioneers was lost in 2003. The Voyagers are expected to still have limited functionality (including communications) until at least 2020.
2020 Start shutdown of science instruments (as of October 18, 2010 the order is undecided but the Low-Energy Charged Particles, Cosmic Ray Subsystem, Magnetometer, and Plasma Wave Subsystem instruments are expected to still be operating)[82]
2025–2030 Will no longer be able to power any single instrument.
- Wikipedia [wikipedia.org]
Suzanne Dodd, the Voyager project manager at NASA's Jet Propulsion Laboratory, says the Voyager spacecraft are powered by a couple of nuclear reactors sitting on the back of the probe, but they will soon run out of steam. "The nuclear power sources lose about 4 watts of power a year," she says. At this rate, Dodd says, Voyager should have enough power to communicate with Earth until 2022 or maybe 2025.
- Popular Mechanics [popularmechanics.com]
Although I believe it's inaccurate to refer to the RTGs [wikipedia.org] as "reactors." They just feed off the heat produced by the nuclear material sitting there and gradually decaying.
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 2) by tangomargarine on Friday October 07 2016, @02:53PM
Saying the "reactors" will "run out of steam" is particularly wince-worthy since there's no steam involved in the process, unlike real nuclear reactors.
Apparently the RTGs themselves last surprisingly well vis-a-vis power generation: it's the thermocouples degrading that will cause the probe to die first. In 2011 with fresh thermocouples it would've been at 76% power; with the initial ones it's only at 57%.
https://en.wikipedia.org/wiki/Voyager_program#Power [wikipedia.org]
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 4, Interesting) by turgid on Friday September 30 2016, @07:17PM
We have the first direct measurements of gravitational waves now, from LIGO and LISA Pathfinder is up and has proved that that particular technology will work too. If the full LISA mission gets the go-ahead, that will be great. A lot of new technology will have to be developed for that.
The problem with infrared space telescopes is that their lifetime is limited by how much coolant you can put in them, but the astronomy they do is particularly valuable. In order to reduce thermal noise in the detector, they have to be cooled, and I think they use liquid nitrogen or something like that (can't remember - is it even helium?) so they only last a few months or a couple of years.
Better, cheaper access to space would be an advantage, obviously. And the Moon would be an excellent place for telescopes...
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 0) by Anonymous Coward on Friday September 30 2016, @07:14PM
Whichever it is, that kind of makes it harder to find out which one is true :).
(Score: 3, Informative) by Anonymous Coward on Friday September 30 2016, @10:08PM
Because we've never seen any of the other forces deviate from simple formulas over scale. If gravity follows a VERY predictable curve (pattern) for the size of the solar system and multi-star systems/clusters (based on our observations so far), but THEN goes bizirk beyond say 100 light years of separation between objects, that would be a fantastic and revolutionary discovery.
But we can observe various stages of the past and see the same patterns and arrangements. We have spectrums (chemical signatures), and things like Cepheids and Type Ia supernova that act as cosmic rulers. You cannot tweak too many cosmic parameters without screwing these yardsticks up.
Uniformity is a realistic assumption at this point and just because gravity on a large scale doesn't fit our current models is not by itself reason to discard the uniformity assumption.
There are still many great mysteries to be solved.
(Score: 0) by Anonymous Coward on Saturday October 01 2016, @12:17PM
Because we've never seen any of the other forces deviate from simple formulas over scale.
What do you mean by that? The nuclear forces seem to have something I'd call a crazy-ass wtf discontinuity over certain scale.
If "gravitons" had a half-life of few hundred million years, you'd get exactly such "deviation from simple formulas". (not that the results of such would be necessarily consistent with observations)
(Score: 5, Insightful) by stormwyrm on Friday September 30 2016, @11:28PM
This is not true. Astrophysics and cosmology converged on it precisely because it appeared more likely and less arbitrary than the other alternatives that were postulated, since agreed with all the available observational data better than any other alternative theory. Postulating dark matter allowed cosmological theory to explain a whole slew of observations, such as the large-scale structure formation of the universe, the observed fluctuations in the cosmic microwave background, the observed element ratios of primordial nucleosynthesis, galaxy clustering, cluster collision phenomena, and many other things besides. None of the other alternative explanations were able to do that, which is why they converged on it. Postulating, say, a modification to general relativity (e.g. TeVeS) to explain the phenomena that have been attributed to the presence of dark matter yields a far more complex solution.
Now, this new discovery can be thought of as a refutation of dark matter, but it can also be construed as further evidence of the physical properties of dark matter. It might show that dark matter is strongly self-interacting [wikipedia.org]. It could have weak interactions with normal matter. It could have polarisation or condensation properties.
Numquam ponenda est pluralitas sine necessitate.
(Score: 4, Interesting) by opinionated_science on Friday September 30 2016, @06:38PM
I am following this chap
https://physicsfromtheedge.blogspot.com [blogspot.com]
His published work of MiHSC (an extension to theory of gravitation) is far more compelling because it is not parameterised , as the dark matter fudge is.
As dogmatic stances go, physics can sometimes have a real problem adapting to new evidence. Hence, the echo chamber here is the accidental correlation of MOND and other approved theories.
I recommend reading this guys papers/blog, it is far more credible. Oh and provides a physical explanation of the EM drive that is testable.
(Score: 0) by Anonymous Coward on Sunday October 02 2016, @01:26AM
Thanks for letting us know that crackpot is still around. Somebody needs to post a link to an Electric Universe next time, it's funnier.
(Score: 4, Funny) by takyon on Friday September 30 2016, @06:45PM
Dark matter doesn't real!
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 0) by Anonymous Coward on Friday September 30 2016, @09:34PM
McGaugh already published this 12 years ago:
https://arxiv.org/abs/astro-ph/0403610 [arxiv.org]
(Score: 0) by Anonymous Coward on Friday September 30 2016, @09:57PM
http://scienceblogs.com/startswithabang/2016/09/29/dark-matter-faces-its-biggest-challenge-of-all-synopsis/ [scienceblogs.com]
Also, this argument is great. The way dark matter works is you put an arbitrary amount of invisible mass in a unique spheroid around each galaxy.* That is one all powerful ingredient that happens to sound exactly like epicycles in 3D.
*https://en.wikipedia.org/wiki/Dark_matter_halo
(Score: 0) by Anonymous Coward on Saturday October 01 2016, @12:35AM
Shhhhhh, Newton 2.0 ain't born yet. We gotta wait and keep everyone happy until then.
(Score: 0) by Anonymous Coward on Friday September 30 2016, @10:47PM
It looks like Milgrom himself feels the same way:
https://arxiv.org/abs/1609.06642 [arxiv.org]
(Score: 3, Interesting) by migz on Saturday October 01 2016, @08:12AM
Whoa! If this is correct then ...
Galaxies rotate faster than predicted by gravity, but in direct proportion to the non-dark matter.
So I wonder, perhaps this is just because we are assuming a flat universe, rather than a relativistic one.
It's not the stars moving, its space being warped. Look at this from the outer edge of the galaxy as stationary, the stars closer to the centre move at a certain velocity predicted by gravity up to a point, then they move too fast. So just before they cross that "threshold" move to that ring and look at the next level in. The stars on the outside ring appear to be moving faster the same speed as this ring did from the other side. Look towards the centre, repeat. Eventually you land up in the middle, and at no point have you seen stars in the previous or next ring moving too fast.
The stars don't move they twist space, they are limited in how much they can twist space by the speed of light, but that limit is relative. The next lot of stars can twist it again.
It's a galaxy sized warp drive.
(Score: 2, Informative) by Fauxlosopher on Saturday October 01 2016, @04:41PM
Rather than the current/traditional view that gravity is the primary force acting upon matter in the universe, and all the problems that stem from such a view (dark matter, supermassive mathematically-impossible black holes, sunspots being cold and dark, etc.), some folks have been investigating plasma physics and the possibility that electric and magnetic forces play the major role in our universe's matter interactions.
Significant findings from NASA cometary missions have supported this "electric universe" theory, notably that NASA probes have discovered the comets they flew by to be solid rocky bodies rather than the expected "melting snowballs". Further, the surface details of such comets show remarkable similarities to material being ablated by electric arcs.
It's exciting to see some really convincing data in support of a theory which has the potential (eh heh heh) to lead to another "world isn't flat" moment.
https://www.thunderbolts.info [thunderbolts.info]
https://www.thunderbolts.info/wp/about/syn/ [thunderbolts.info] (general overview)
https://www.youtube.com/watch?v=34wtt2EUToo [youtube.com] (cometary info)