Survey Finds No Hint of Dark Matter Near Solar System

Eponymous Hero writes "Does dark matter exist or doesn't it? It seems these results don't shed as much light as we'd hoped. 'Moni Bidin says he's not sure whether dark matter exists or not. But he says that his team's survey (PDF) is the most comprehensive of its type ever done, and the puzzling results must be reckoned with. "We don't have a good comprehension of what is going on," he says.' This has the smell of a Neutrinogate scandal, but at least we've been warned about the shoulder shrugging. 'As an example, Newberg notes that the researchers assumed that the group of stars they examined were smoothly distributed above and below the plane of the Milky Way. But if the distribution turns out to be lumpier, as is the case for stars in the outer parts of the galaxy, then the resulting calculations of dark matter density could be incorrect. Flynn agrees that there are a number of ways that the method employed by Moni Bidin and his co-authors "could get it wrong."'"

Comments

Of course it exists

[YA_Python_dev]

We have so much evidence about the existence of the dark matter that's not even funny: https://en.wikipedia.org/wiki/Dark_matter#Observational_evidence

Re:Of course it exists

[perles]

Yes, it exists. We sitting on one piece of dark matter!

Re:Of course it exists

[wisnoskij]

We have seen its effect on the solar system but I don't think we have any really evidence for what exactly Dark Matter is?
Is it matter? is it particles?
We have theories on what Dark Matter is, but those theories could be completely wrong.

So dark matter, as we know it, might not exist, all we know is that something is causing the effects that we see.

Re:Of course it exists

[Anonymous Coward]

But, but, but There is a consensus!

These people are just "Deniers".

Re:Of course it exists

[rainmouse]

We have so much evidence about the existence of the dark matter that's not even funny: https://en.wikipedia.org/wiki/Dark_matter#Observational_evidence

All indirect evidence. Personally the idea of an invisible, intangible, ethereal magical material that helps peoples sums add up is dubious at best. There are plenty of other good theories out there that do not include this populistic hypothesis.
such as http://www.springerlink.com/content/g332701735121773/

Re:Of course it exists

[Anonymous Coward]

Hey guys! By definition, black holes have large mass and don't show themselves. We can only count the ones that are actively pulling in gas that gets heated up, or the ones we see with gravitational lensing. There could be zillions that we are unable to observe, along with dead stars, proto-solar-systems, low density dust clouds, etc. Dark energy is the real mystery.

Re:Of course it exists

[CrimsonAvenger]

We have so much evidence about the existence of the dark matter that's not even funny

And now there's evidence that there's not any in our immediate vicinity (article I read mentioned 13000 ly).

Which means we need to come up with a reason why things work one way "way over there", and another way "right around here"....

Re:Of course it exists

[Normal Dan]

No, it does not exist. All of these effects that are attributed to dark matter are all actually due to the fact that gravity does not actually travel at the speed of light. In fact, gravity slows down as it travels. This is why there appears to be more gravity at the edges of galaxies, and even at the edges of galaxy clusters. I also explains why we have such expansive gaps between galaxy clusters.

Re:Of course it exists

[Anonymous Coward]

No, we have so much evidence that the model of gravitation on the scale of a galaxy is wrong. One explanation is dark matter, which leaves the model intact, but corrects the mass to match observed results. This is not the only possible answer for why our observations don't match the model's predictions.

Re:Of course it exists

[NemoinSpace]

The theory of overwhelming popular corroboration confirms it!

Re:Of course it exists

[buchner.johannes]

Dark matter is the name of the problem, not the solution.

It may not be particles, but the universe is very well described by the cold dark matter particle model (plus dark energy).

Re:Of course it exists

[jhoegl]

So dark matter is a filler. Much like religion.
Great! So, if I dont know about something and I dont believe in religious things, Ill call it Dark Matter.
Random person "What is behind the sun?"
Me "I dunno... dark matter?"

Re:Of course it exists

[Anonymous Coward]

We have an evidence that an effect exists. We have done our best to hypothesize as to what causes that effect and we have given it a name. Is the effect real? Yes. Is dark matter as we have hypothesized it the culprit? Maybe

Re:Of course it exists

[hazem]

that helps peoples sums add up is dubious at best.

I think it's a bit more than just coming up with stuff willy nilly.

We have these theories that work great for a lot of observations. They break down a bit for some observations, but can be "fixed" by adding dark matter. This either means the theories are wrong somehow, or there is something out there that's not been accurately observed, or maybe both. The key is to come up with experiments that can falsify the proposition that there is dark matter and that it's the cause of the aberrations.

A nice analogy is the discovery of Neptune. The theories predicted the planets would move in such a way. However they didn't quite do that. But by assuming another planet (which had not been observed), they could get their sums to add up. The testable part of it was when they said, "look here, and you should find a planet that's causing these deviations", and behold, they did.

The thing is, the current theories, even if they're wrong with dark matter, they're "close" to whatever the real situation is because they work so well in most cases. That means the "correct' theory won't be too extremely different, or must at least reduce to the current theories for the special cases we have observed.

If there are competing but "good" theories out there, the key is to find out what differentiates them in their predictions, then to devise experiments to observe what happens in those cases. If you can't devise and carry out such experiments, then it's all mere speculation.

Re:Of course it exists

[ankhank]

> Personally the idea of an invisible, intangible, ethereal magical material
> that helps peoples sums add up is dubious at best.

Yeah, prayer never helped me with math.

Re:Of course it exists

[Anonymous Coward]

Personally the idea of an invisible, intangible, ethereal magical material that helps peoples sums add up is dubious at best.

That's pretty much exactly how neutrinos were first theorized to exist by Pauli back in the 20s. It wasn't until the 50s that we actually observed them experimentally. The point being, we've found exactly what you're describing by looking for things that "help peoples sums add up" before.

Re:Of course it exists

[Hatta]

Awesome. Where's your paper?

Re:Of course it exists

[chuckinator]

The Earth is not dark matter. Even discounting the wide array of man made radiation that our species puts out, the Earth also puts out a considerable amount of detectable radiation. It's just an insignificant amount in comparison to the sun.

Re:Of course it exists

[buchner.johannes]

Dark matter is the name of the problem, not the solution.

It may not be particles, but the universe is very well described by the cold dark matter particle model (plus dark energy).

So dark matter is a filler. Much like religion.

Dark matter is the mismatch between observation and prediction in e.g. galaxy rotation curves. It looks as if there is additional matter there that doesn't radiate. "As if" is the key word here. What it actually is, is not explained by that name.

If you had x$ at the start of the month, and now you have x/3$, and you know where x/3$ went, but not the last third, you can call that "unknown expenses". Same thing.

Re:Of course it exists

[geekoid]

No.
There is an effect. This is known, Dark Matter is the name for that effect until it is solved.
The name is a place holder, not the effect. We measure and predict the effect. Something is impacting large bodies. We don't know what.

It's like hears a loud banging on your wall, You know something is there, you just don't know what until you figure out a way to look.

Religion has names for things that they can't show evidence for.

Re:Of course it exists

[Charliemopps]

Sorry, you're off base. Dark matter, whatever it is, has mass but does not interact with other matter or energy. This doesn't just mean that it doesn't give off or reflect light and radiation. It also means that it's transparent to light and radiation. Per observation, there are huge swaths of "dark matter" between us and other stars/galaxies. Yet we can see these radiation emitting bodies undistorted, so whatever is there generating the gravitational effect must be totally transparent to every form of radiation we can measure. "dark matter" was a poor choice in a name. It's not dark, and it very likely is not even matter.

Re:Of course it exists

[geekoid]

" Personally the idea of an invisible, intangible, ethereal magical material"

Like gravity? or solar wind?

Did you read the letter you linked to? You dio realize that he admits his proposal doesn't explain some effects we see? right?

There is an effect. We can make predictions about the effect.

SO something is happening. Proposed changes to the gravitation theory to explain the phenomena haven't played out.

Could it be some weird aspect of large scale gravity? lensing?

Sure, but the data for those ideas hasn't played out. New data will tighten up are understanding. That's how science works

SO, calling it populist is ignorant in the extreme.

Re:Of course it exists

[HiThere]

The thing is, the current theories, even if they're wrong with dark matter, they're "close" to whatever the real situation is because they work so well in most cases. That means the "correct' theory won't be too extremely different, or must at least reduce to the current theories for the special cases we have observed.

Well... that depends on what you mean by "too extremely different". If you accept that phlogiston was pretty close to the correct theory of combustion, then you are right. The predictions of the phlogiston theory were fairly close the the predictions of the current theory. But the mechanism was quite different. And in this case, also, the mechanism may well be quite different. Or maybe is *is* some undiscovered particle. But don't get fixated on that answer.

Re:Of course it exists

[CanHasDIY]

Which means we need to come up with a reason why things work one way "way over there", and another way "right around here"....

Would the existence of Kardashev Type 2 or 3 civilizations "way over there" present a valid hypothesis, or should I put the foil hat back on?

Re:Of course it exists

[Anonymous Coward]

to modify the theory of gravity you have to modify not only galaxies but how black holes work, how time works, how even motion works. I'm sorry but this still says dark matter exists, just not that form.

Re:Of course it exists

[HiThere]

There's this problem that we think we know the number of baryons that existed in the first few nano-seconds, because of the cosmic abundance of Helium and Lithium. Black holes aren't particular about not swallowing baryons (in fact, they rather prefer to), so this causes problems. If Dark Matter is matter, it must be non-baryonic matter, or we need to redo LOTS of calculations...which is going to mean a major theoretical shift, and nobody has come up with a reasonable theory to shift to. It's much easier if it's not matter at all, but some other effect. (Maybe gravity interacts with gravitational fields at long distances?) Otherwise Dark Matter needs to be non-baryonic matter, and then you've still got Dark Energy to explain.

Re:Of course it exists

[geekoid]

fact huh? care to cite? no? jeez, who would have thought. You're an ignorant egomaniac to self deluded to know when he is out of knowledge and into wild ass making shit up.

Re:Of course it exists

[Hentes]

The thing is, the current theories, even if they're wrong with dark matter, they're "close" to whatever the real situation is because they work so well in most cases. That means the "correct' theory won't be too extremely different, or must at least reduce to the current theories for the special cases we have observed.

They work in small scale, but most cases is streching it. Gravitational anomalies are pretty widespread, not just one or two special galaxies. Also, those 'theories' are without any predictive power, as they are mostly fit to existing data. In fact, "dark matter" itself is treated like a free variable in most of these theories, changing mass and distribution a hundred times to fit the observations. For the orbital speed of stars to be independent of their position in the galaxy, the distribution of dark matter would have to be very special, far more special than gravity alone could explain (as in most theories dark matter only participates in the gravitational interaction).

Re:Of course it exists

[Anonymous Coward]

He was talking about the skidmarks in his shorts.

Re:Of course it exists

[Black Parrot]

All indirect evidence.

Most of what we know comes from indirect evidence.

Personally the idea of an invisible, intangible, ethereal magical material that helps peoples sums add up is dubious at best.

For some reason the universe doesn't care what you're personally dubious about.

Re:Of course it exists

[Bengie]

Actually, there was a recent study showing the red shift of light escaping galaxies are with in 99.9% of the expected red shift for the calculated gravity-well. This means gravity does react as expected over large distances. The problem is any other forces we don't know about.

Re:Of course it exists

[CrimsonAvenger]

Which means we need to come up with a reason why things work one way "way over there", and another way "right around here"....

Would the existence of Kardashev Type 2 or 3 civilizations "way over there" present a valid hypothesis, or should I put the foil hat back on?

At this point, invoking Type2+ civilizations as the cause of the observations is effectively the same as invoking God - neither is testable, neither allows us to make predictions.

Re:Of course it exists

[ceoyoyo]

The problem with all the other theories is that they don't fit the data, all the data, as well as the cold WIMP dark matter hypothesis.

Personally I find postulating weird vacuum interactions more of a stretch than unknown particles with properties very similar to known particles (neutrinos) that we already suspected existed for other reasons. But to each his own.

Re:Of course it exists

[ceoyoyo]

Actually, you're both wrong. The dark matter most likely isn't normal matter because that doesn't agree with models of nucleosynthesis in the big bang. It probably is matter, because that hypothesis is the only one we've come up with that fits all the data reasonably well and doesn't require really weird new physics.

Dark matter is weakly interacting, but it probably does interact with normal matter, just like neutrinos do. It doesn't emit light (because it doesn't interact with the electromagnetic force), except perhaps when it annihilates.

Dark matter is an excellent name. It is dark, and it is very likely matter. And yes, it is transparent (non interacting) with the single type of radiation we can readily measure (electromagnetic).

Re:Of course it exists

[neonsignal]

so I guess we can't expect to shed much light on the matter? :-)

Re:Of course it exists

[wisty]

So, it could be that the laws of physics are slightly off, and Dark Matter is just an illusion we "see" because of the errors in physics.

Or Dark Matter could be actual matter, and is just ... dark.

Re:Of course it exists

[damburger]

There is more to it than that, and to be frank the 'alternative' theories are not good. To call the accepted theories 'populist' is, by the way, a red flag that you can kind of a crank.

This is a "hmm" results at best. What you have to understand is that this measurement is pretty local. They are very far from getting the big picture on this one despite being oversold in a press release.

Also, why rushing to break the consensus on dark matter might not be the best idea: http://edgepenguin.com/content/darkmatter.html

Re:Of course it exists

[Anonymous Coward]

Well, most particles are matter. Or have mass, which is what people usually mean when they say "matter".

Re:Of course it exists

[semi-extrinsic]

Then obviously you have never dabbled in quantum field theory, where praying away infinities is how we roll.

Re:Of course it exists

[semi-extrinsic]

I've always wondered why no sci-fi writers (that I know of) have used this as a plot device. "There are millions of aliens that cloak themselves from us, since we're not mature enough yet" seems to be a kick-ass sci-fi explanation of dark matter.

Re:Of course it exists

[Anonymous Coward]

We have only indirect evidence for radioactivity. Hell, we have only indirect evidence for the existence of atoms. Since the days of Galileo, most of our scientific evidence has been indirect.

Re:Of course it exists

[lgw]

Note that this is cosmologist-speak, and so "non-baryonic matter" in much the same way that everything but hydrogen and helium is a "metal". If not for neutron decay, simple neutrons would fit the observational evidence from dark matter faily well. Dark matter may very well be similar enough to known (uncharged) baryons under the covers that it's just a matter of convention - yes, we might then need to redo many calculations, but that's an area so inelegant that almost no one is satisfied with the Standard Model. I find it hard to decide which would be more convoluted - dark matter being made of quarks (which would clearly mean a new kind of quark that for some reason we can't make by smashing non-dark matter together), or made of something entirely new.

"Dark energy" has nothing whatsoever to do with "dark matter" beyond the name. "Dark matter" is dark because it doesn't interact with light, and is (almost certainly) matter. "Dark energy" is entirely a placeholder, the same as "cosmological constant" and "I don't know, but my math is wrong", and was so named to try to leech credibility from dark matter.

Re:Of course it exists

[Anonymous Coward]

If not for neutron decay, simple neutrons would fit the observational evidence from dark matter faily well.

Could you clarify/add to this?

Re:Of course it exists

[Raenex]

Dark matter is the name of the problem, not the solution.

No, it's a hypothesized solution to various problems seen in astronomy. You might have figured that out from the name itself.

http://en.wikipedia.org/wiki/Dark_matter

"In astronomy and cosmology, dark matter is a currently unknown type of matter hypothesized to account for a large part of the total mass in the universe. Dark matter neither emits nor absorbs light or other electromagnetic radiation, and so cannot be directly seen with telescopes.[1] Dark matter is estimated to constitute 83% of the matter in the universe and 23% of the mass-energy.[2]

Dark matter came to the attention of astrophysicists due to discrepancies between the mass of large astronomical objects determined from their gravitational effects, and mass calculated from the "luminous matter" they contain [..] Although the existence of dark matter is generally accepted by the mainstream scientific community, several alternative theories have been proposed to try to explain the anomalies that dark matter is intended to account for."

Re:Of course it exists

[lgw]

Here's what we know about dark matter from observational evidence:

* It doesn't interact with photons, even at the extreme energy levels of the early universe.
* It has mass, and interacts normally with gravity.
* It doesn't have friction or clump the way normal matter does at current energy levels (you'd expect this to be true from the first point, but it doesn't have an as-yet-unknown equivalent to baryonic friction).

There's nothing all that strange required here, it's just different from the matter that we see every day.

Re:Of course it exists

[justthinkit]

Thanks.

.
I took your first post to mean that dark matter and neutrons are very similar, except for the decay part so what if dark matter are neutrons that don't decay, outside of galaxies, the way they do on Earth?

My Thread Prediction

[Anonymous Coward]

Loads of buttmad.

Re:My Thread Prediction

[Anonymous Coward]

But not enough to account for the thread's rotational velocity.

Loonies

[Anonymous Coward]

Here come the electric universe looneys

I'm not surprised

[hort_wort]

I've never liked the theory of dark matter/energy. It always seemed to be a fudge factor thrown in to make the current theories work with what is observed. Astronomers have had good luck with that in the past, identifying planets and black holes based on gravitic effects, but they might have to a whole new approach to describe larger scales like this.

I truly hope it isn't dark matter. I *want* there to be a new theory. We'd end up learning so much more from it!

Re:I'm not surprised

[thegreatemu]

At first, maybe. Dark matter was proposed to explain the high velocity of stellar orbits, and dark energy to explain the redshift of distant stars. However, cosmologists later used dark matter and dark energy theory to predict the angular spectrum of the cosmic microwave background and the baryon acoustic oscillation peak in galaxy distributions.

Predictive power ftw!

Re:I'm not surprised

[Anonymous Coward]

It always seemed to be a fudge factor thrown in to make the current theories work with what is observed.

Not just seemed; is. Not that that's necessarily a bad thing, mind you.

Re:I'm not surprised

[Kjella]

Somehow I don't see the problem with either solution:

a) Dark matter is real. Then we have a whole new class of matter to investigate.
b) Dark matter is not real. Then we have a new understanding of the forces around us.

So what if it's real? The existence of dark matter particles would be a discovery about the size of finding the Higgs boson. It'd be way outside the Standard Model as we know it. We just need something more tangible on what exactly it is...

Re:I'm not surprised

[FrootLoops]

I understand that saying "we don't know what dark matter is" is unsatisfying, but some particles don't interact much with other particles. Neutrinos are a great example, since they only take part in the weak force and gravity (so not the electromagnetic or strong forces). Is it so hard to believe that some matter interacts solely through the gravitational force? That would mean no electromagnetic effects and almost no interactions with other forms of matter. Such matter would only be noticeable at gravity-dominated, cosmological scales.

Who knows? Maybe there's a whole segment of matter humans are unfamiliar with which interacts very little with the matter we know about but interacts with itself in complicated ways. Maybe there are dark matter solar systems populated by dark matter people who are just as confused as we are about the weird gravitational anomalies caused by our otherwise invisible existence. Communicating through gravity would certainly be an interesting challenge! I don't really believe this, but my point is basically the same as Hamlet's: "There are more things in heaven and earth than are dreamt of in your philosophy"--that is, it's arrogant to expect humans to be in a position to observe all the parts of the universe. Perhaps some things are just hidden.

Re:I'm not surprised

[hort_wort]

I didn't mean to imply that it wasn't possible because we couldn't see it. I was thinking about all the fudge factors from Newtonian mechanics that cleaned up once relativity was worked into it. Assuming that the fundamental rules we have are complete would also be arrogant, no? Rewriting equations for how spacetime works would be much, much more satisfying to me than identifying a new particle. I want warp drive.

Also, totally different topic, my online personas are usually associated with Toucan Sam, so I find this interaction between us quite amusing. :D

Re:I'm not surprised

[Anonymous Coward]

At what point does this "fudge factor" become something more in your eyes? When it's able to make successful predictions? When additional phenomena is observed that happens to support it?

Re:I'm not surprised

[s.petry]

I have been saying this for a long time. It's not logical that 80-90% of the Universe would be made up of something we have never seen or detected yet. The theory of course gives better credence to the current theories of Gravity and cosmology theories, but even when plugged in there is no consistent results.

Heavy matter, not a problem. We know from observation that most of an atoms size is empty space. I can see how in massive gravity situations, that space would compress making more dense atoms. But invisible stuff we can't see, detect, measure, or observe in any way other than a guess?

Have to give it to them though, they have made a lot of cash on that theory.

Re:I'm not surprised

[jd]

It's also not a universally-applied fudge factor - globular clusters show no evidence of dark matter around their edges, regardless of how you perform the analysis.

There's some good science indicating dark matter, but there's just as much that conflicts with it. Even if dark matter does turn out to exist, the fact that there's any conflict at all means that current dark matter theories are not merely a little too simple but have some facts plain wrong within the bounds for which they are defined.

Re:I'm not surprised

[damburger]

"Interesting" for the same old knuckle-headed response that any resident of mount stupid gives whenever the phrase "dark matter" is mentioned? Clearly the mods are fellow mountaineers.

Dark matter is not a 'fudge factor' to make the sums work. Dark matter is an interesting component of the universe we are only just learning about. Anyone who sits there and thinks that dark matter only exists to make rotation curves work clearly understands nothing about astrophysics.

Re:I'm not surprised

[hort_wort]

"Interesting" for the same old knuckle-headed response that any resident of mount stupid gives whenever the phrase "dark matter" is mentioned?

The knuckle-headed response is to wish for a more complete theory of the fundamental rules of the universe that would be the greatest thing to affect astrophysics since relativity? Dang. I'm terribly curious what the intelligent response would be! Please enlighten us, good sir!

Re:I'm not surprised

[FrootLoops]

Warp drive would be awesome. I'm not sure if a new particle (perhaps a new branch of particle physics?) or heavy revision to general relativity would be more satisfying to me as an explanation of dark matter / its purported effects. I'm not really knowledgeable enough in these matters to have a solid opinion either way. I just wanted to mollify what I see as a knee-jerk reaction against exotic dark matter and towards another Einstein-esque revision of previous notions about space and time

About my name, I think I was eating a bowl of Froot Loops when I made this account. Something about 4 o's struck me. I only later noticed the mild irony of a gay man picking a handle with "fruit" in it; it makes me smile from time to time :).

Re:I'm not surprised

[damburger]

You can wish all you like, but the Universe is not under any obligation to give you a neat solution.

The intelligent response is to be skeptical of anyone who comes out with some flashy bit of research claiming to have overturned the consensus. The moment you claim an entire field of natural science is suppressing some obvious insight, you are a conspiracy theorist.

Re:I'm not surprised

[lgw]

Dark matter yes, dark energy no. The CMBR data gave quite accurate measurements that confirmed the dark matter explanation for galaxy rotation rates, and not the other explanations. Dark energy had nothing to do with it, and it's just a more fashionable name for the same old "cosmological constant".

The CMBR data did suggest that the uniserve was at a more consistent temperature than it's age would suggest, but the "inflation" explanations of this were not existing theories, there was no pre-existing theory for the expansion of the universe that predicted the precise details of "inflation" to two significant digits, the way the dark matter theory was confirmed. Now, after the fact, people are trying to connect "inflation" with current universal expansion, but really there's not yet any actual confirmation for "inflation" to begin with, it's just an explanation for why temperatures were so nearly equal at the time of the Big Snapshot.

Re:I'm not surprised

[Troed]

The intelligent response is to be skeptical of anyone who comes out with some flashy bit of research claiming to have overturned the consensus. The moment you claim an entire field of natural science is suppressing some obvious insight, you are a conspiracy theorist.

A scientist should always be skeptical, sure. That includes being skeptical of "consensus".

http://randi.org/site/index.php/swift-blog/1506-skeptic-history-a-tale-of-two-scientists.html

Re:I'm not surprised

[damburger]

Being skeptical of the consensus doesn't mean throwing it away on one unconfirmed measurement.

Re:I'm not surprised

[Troed]

It only takes one successful challenge to refute a hypothesis. It takes a new generation of scientists to grow up before the consensus is gone, since us humans sometimes have a hard time changing our convictions (and scientists are no different).

"the hypothesis was generally met with skepticism from largely conservative scientists, who were resistant to any change in the status quo."

http://deskarati.com/2012/01/06/alfred-wegeners-continental-drift-hypothesis/

Re:I'm not surprised

[damburger]

This isn't a successful challenge. It isn't really a challenge at all. We are going to have to start thinking differently about how dark matter arranges itself in a galaxy, but the idea we are going to throw out dark matter is a fantasy coming straight from mount stupid.

Ugh, summary

[Anonymous Coward]

This summary is horrible. Not only do I not see anything in it about the headline (dark matter near the Solar System), but then it goes on about 'neutrinogate' (really?) without even mentioning why it might be controversial, or hell, what is controversial. What are the puzzling results? What constitutes being "near" the Solar System? What does this have to do with the existence/nonexistence of dark matter?

Re:Ugh, summary

[Anonymous Coward]

Couldn't agree more, it is doing science a disservice. We don't have to reiterate fundamentals of the scientific process here, do we? Let's just say that proving a theory wrong [against observation/data] is a perfectly valid and just as valuable outcome.

Re:Ugh, summary

[FrootLoops]

Agreed, atrocious summary and terrible title. Here's an alternate.

Survey Finds Too Little Dark Matter Near Solar System

The existence and approximate distribution of dark matter have become standard assumptions in cosmology. According to Nature, it "explains how structure arose in the Universe, how galaxies formed and how the rapidly spinning Milky Way manages to keep from flying apart." However, a paper recently accepted by the Astrophysical Journal studied stellar velocities in our part of the galaxy in an attempt to infer the amount of dark matter present near our solar system and came up with unsettling results. Moni Bidin, the study's lead author, concluded that "at most, only about one-tenth the amount of dark matter predicted by models could exist in the volume of space they examined." Astronomer Frederic Hessman, who is uninvolved in the study, put things bluntly: "If this is right, it turns everything totally upside-down." Physicists are calling for caution and several note the difficulty and sensitivity to error of the present results. Astronomer Chris Flynn, who approved Bidin's paper for publication, cautioned, "I wouldn’t throw out nearby dark matter quite yet” and “The measurement being made is very challenging, and there are a number of ways for it to miss the dark matter even if is there.”

Re:Ugh, summary

[Anonymous Coward]

Thank you. <3

It does exist

[Zharr]

You would think that with a planet named Uranus there would be some somewhere. Oh did I really type that? My inner child is acting out again.

That is so easily explained.

[140Mandak262Jamuna]

The dumb astronomers are looking in the outer space for it. No wonder they can't find it. All the dark matter in the solar system has coalesced into the form of Dick Cheney.

Re:That is so easily explained.

[Desler]

It's not very fair to leave out Karl Rove.

Re:That is so easily explained.

[Anonymous Coward]

Silly Mandak, Cheney's white, not dark.

Re:That is so easily explained.

[digitig]

Anyway, did they really expect dark matter to "shed light"?

Survey is biased...

[OakDragon]

...they never asked me!

They were looking for dark matter...

[clgoh]

...to shed light?

Dark matter exists

[Anonymous Coward]

Not only does dark matter exist, but I drink it regularly.

Who the hell is moni bidin?

[Anonymous Coward]

Gravatational lensing and dark matter.

I know where it is.

[Anonymous Coward]

It's the mass of the aether.

You'll kill me for this but...

[Anonymous Coward]

Dark Matter is just 21st century ether.

Dark Matter is there indeed...

[Anonymous Coward]

It's just that our solar system is poor in Eezo. Try in the Nemean Abyss.

Well duh

[Anonymous Coward]

The sun is RIGHT there. All they'd find is bright matter!

But seriously folks. I'd advise you not be too attached to the idea that dark matter does or does not exist. The moment you aren't willing to accept evidence (which I won't say this survey is or is not given the possible flaws) and use said evidence to change your views, instead fighting to cling to your old beliefs (wassup geocentric epicycles), is the moment you stop being a good scientist.

As always, I merely ask for more data.

An alternative to DM: MOND

[ArcSecond]

I like to think I have an open mind when it comes to cosmology, but I've never liked the Dark Matter "theory". If they ever find direct evidence, fine, but I will remain unconvinced until then.

My personal favourite alternative hypothesis is called Modified Newtonian Dynamics, which is based on the idea that gravity exerts a stronger pull between objects that are more or less in the same inertial frame (ie at very low relative accelerations, that "acceleration is not linearly proportional to force at small values").

http://en.wikipedia.org/wiki/MOND

Obviously, a lot of people find this blasphemy, but I don't see what is so bad with modifying the law of gravity as compared to invoking "ghost matter".

Re:An alternative to DM: MOND

[HiThere]

IIRC, MOND ran into some problems that it hasn't yet been able to solve. Doesn't mean some modified version won't work, of course.

FWIW, Dark Matter + Dark Energy seem to me to cry out for a different answer. But I'm not a cosmologist, so I don't feel obliged to come up with a new theory consistent with all extant evidence.

Re:An alternative to DM: MOND

[geekoid]

I would think the fact that the effect is not from a central point, but form many point is space substantially hinder the MOND theory, as well as the lensing issue.

NO one 'invoked nonluminal matter.

Re:An alternative to DM: MOND

[Bengie]

They think this ghost matter exists because there are large sections of seemingly empty space with gravitational lensing but no detectable matter in any frequency.

When "something" exerts HUGE amounts of gravity while being 100% transparent, we give it a generic name that that indicates that we don't understand it... "Dark Matter"

Re:An alternative to DM: MOND

[Anonymous Coward]

The quoted paper specifically assumes regular gravity and uses that as the basis of their model. Prof. Matt Strassler has an explanation: http://profmattstrassler.com/2012/04/20/dark-matter-now-you-see-it-now-you-dont/

Re:An alternative to DM: MOND

[semi-extrinsic]

There are problems with MOND indeed. Take a look at the predicted power spectrum of matter: http://i.imgur.com/Ouwin.png
Here the Cold Dark Matter model fits experimental results exactly, while MOND is way off.
(Stolen from http://arxiv.org/pdf/1112.1320v1 which is a good review of CDM vs MOND.)

Re:An alternative to DM: MOND

[damburger]

People who actually study this sort of thing don't find MOND to be "blasphemy" they find it to be "stupid".

The thing is, you've dismissed the dark matter theory (no, it doesn't need scare quotes) clearly without understanding it. You seem to be laboring under the delusion that rotation curves are the only evidence for this matter. They are not. Most aspects of large scale cosmology invoke dark matter in some way - and what is more, they do so in ways that cannot be predicted by your favorite hypothesis.

I suggest you actually learn some cosmology before making pronouncements on it, based purely on some wikipedia browsing.

lol

[Jessified]

Survey Finds No Hint of Dark Matter Near Solar System

Survey:

Earth: Anyone here composed of dark matter?
Pluto: Not me!
Saturn: Nay.
Mars: Nope. ...

Missing Mass goes missing again

[jurgen]

I just thought that would be a better headline. Dark matter is actually the hypothesized solution to the missing mass problem. And it was supposed to be "right here"...

Re:Umm yeah, Wikipedia

[wonkey_monkey]

So when's your Nobel Prize due to arrive?

And what Wikipedia actually says ("says" as in "reports", not "states as fact") is that

In 1959, Louise Volders demonstrated that spiral galaxy M33 does not spin as expected according to Keplerian dynamics

Dark Matter is just smoke screen used by Aliens

[danparker276]

Aliens don't want us to see them, duh... They put up these shielded areas where they can do all sorts of strange stuff that we can't see.

No MOND ?

[mbone]

It is disappointing that the original paper doesn't not appear to consider MOND (Modified Newtonian Dynamics) or TeVeS (a Tensor-Vector-Scalar theory of gravity, the relativistic version of MOND).

The way to think about Dark Matter is it represents a problem with physics, namely excess force in the dynamics of galactic sized and larger objects. We don't know if the problem is with quantum field theories or with general relativity. The first possibility leads to theories such as Cold Dark Matter (CDM) or Weakly Interactive Massive Particles (WIMPs); the second to something like MOND / TeVeS. As literally pretty much all we know about Dark Matter is that there is excess force, neither approach can be ruled out at present.

So, it's disappointing that they didn't consider the gravitational alternative. It's not clear from the paper whether or not MOND would survive this test. Unlike CDM or WIMP, MOND effects should be present at all places in the disk, so the real question is, are they compatible with these observations?

Re:No MOND ?

[Spinalcold]

both those theories still need to be consistent with the bullet cluster

Re:No MOND ?

[Black Parrot]

It is disappointing that the original paper doesn't not appear to consider MOND (Modified Newtonian Dynamics) or TeVeS (a Tensor-Vector-Scalar theory of gravity, the relativistic version of MOND).

From what I've read (e.g. this, MOND can be parameterized to explain galactic rotation curves *better* than the dark matter hypothesis does. However, there are a variety of other reasons to believe there's something out there that might be loosely described as "dark matter", and for all those other reasons, MOND doesn't work at all.

Re:No MOND ?

[mbone]

My understanding is that

- there is no completely satisfactory theory of the Bullet Cluster and friends (such as A520 and DLSCL J0916.2+2951, although I am sure there will be a lot more to come) using any model, so I think it is premature to say they are conclusive and

- The vector field in TeVeS may be able to explain the gravitational lensing of these clusters.

What is less clear is whether this can be done without some dark matter or some field that acts like additional Dark Matter (on extra-galactic scales). One of the attractions of MOND is that explains many galactic rotation curves with one free parameter (not one per galaxy, one). Requiring more parameters (or an additional role for some sort of actual dark matter) would be disappointing, but it will not by itself disprove the theory.

See Can Mond take a Bullet and Gravitational Lenses in Generalized Einstein-Aether theory: the Bullet Cluster for more. (That first title is a classic, BTW.)

Re:No MOND ?

[ceoyoyo]

MOND and relatives still require dark matter. The paper likely didn't consider them because their failure to keep up with cold dark matter in predictive power and simplicity really does put them in the long shot category, despite vehement defence by some people, most of whom seem to post on Slashdot.

Re:No MOND ?

[damburger]

Magic fairies pushing the stars around galaxies faster can be parametrized to explain rotation curves. You throw enough parameters at something, you are certain to get a solution.

Dark Matter a scientific Cul-de-Sac

[dgharmon]

A scientific cul-de-sac, in my opinion, like phlostigen, a faulty scientific theory ...

Alien race

[KnightBlade]

Has anybody considered that it could be an alien race making planets (and therefore mass) invisible and just fucking with us?

Are you sure?

[Tablizer]

Man, I was certain they'd detect Rush Limbaugh

It's depressing...

[StevenMaurer]

...to see so many ignorant posts following up yours, clearly having not even read the article, being modded up - while your reference is stuck at a "1". Just to correct rainmouse's claim of mere "indirect" evidence, here is a quote from the link you provided:

The most direct observational evidence to date for dark matter is in a system known as the Bullet Cluster. In most regions of the universe, dark matter and visible material are found together,[33] as expected because of their mutual gravitational attraction. In the Bullet Cluster, a collision between two galaxy clusters appears to have caused a separation of dark matter and baryonic matter. X-ray observations show that much of the baryonic matter (in the form of 107–108 Kelvin[34] gas, or plasma) in the system is concentrated in the center of the system. Electromagnetic interactions between passing gas particles caused them to slow down and settle near the point of impact. However, weak gravitational lensing observations of the same system show that much of the mass resides outside of the central region of baryonic gas.

In other words, gravitational lensing of light waves - which is 100% direct evidence of matter - shows a region where there is matter that is clearly non-baryonic (i.e. does not interact with the electromagnetic field, a.k.a. "dark"). This is not subject to dispute. The question of what, exactly, is dark matter - is indeed still a subject of scientific research. There are, however, a number of super-symmetric theories which posit super-partners for well known particles, the most stable of which turn out to have the exact characteristics we're noting observationally. It is important to note that these theories were not tailored to account for the dark matter, but seem to fit the observational evidence quite well so far. As with all science however, theories are subject to falsification at any times as soon as new evidence comes on the scene.

Re:It's depressing...

[Anonymous Coward]

... In other words, gravitational lensing of light waves - which is 100% direct evidence of matter - shows a region where there is matter that is clearly non-baryonic (i.e. does not interact with the electromagnetic field, a.k.a. "dark"). This is not subject to dispute.

Unfortunately, it is very common for cosmologists to claim gravitational lensing where there is none. Studies of quasars pairs have shown that the explanation of these pairs being an effect of gravitational lensing is statistically impossible. I have seen conferences where honest scientists presenting empirical data have been booed off the stage because it's obvious the data implies that a huge amount of the 'cosmology' currently being pushed is pure BS.

So... I'm saying dark matter is definitely subject to dispute and you should find more varied sources for you science education. ;)

Re:Umm yeah, Wikipedia

[geekoid]

"...Dark Matter nonsense ..."
you either don't know what 'Dark Matter' means, or you don't know what 'nonsense means'...or both.

Clearly it's QDM

[gstrickler]

It must be Quantum Dark Matter, it's only there when you're not looking for it. Attempts to observe it alter it.

"This has the smell of a Neutrinogate scandal"

[boristhespider]

No, it doesn't. Screw this, I'm done with shitty summaries and half-arsed ad-harvesting.

Re:"This has the smell of a Neutrinogate scandal"

[Anonymous Coward]

And why the hell does outrage still have to end in *gate these days? That's so last millenium.

Re:"This has the smell of a Neutrinogate scandal"

[Dachannien]

For that matter, "Neutrinogate" wasn't even a scandal. Yeah, it probably got more publicity than an unverified result merited, but the researchers did warn us that something could still be fishy, and that more work would be needed to see if something was wrong. They found a technical fault, fixed it, and are working on re-performing the tests. No big deal.

We know more about what Darkmatter is NOT.

[jd.schmidt]

Historically, Dark Matter meant any matter not contained in a star emitting light. It originally did not mean exotic material of any kind per se.

Now, the problem posed by Dark Matter is very real and valid. The issue is, as we get better at collecting accurate data about galaxies and better at detecting possible candidates, they all keep striking out. So, in order to match observed data, Dark Matter keeps picking up all of these exotic properties. On the one had this is progress, we are eliminating things. On the other hand, Dark Matter keeps getting stranger and stranger as we can’t yet find any way to “detect” it other than the gravitational effect.

To the best of my knowledge, Dark Matter only affect Galactic sized objects, and even then only beyond a certain size. I have been an “exotic material” skeptic for some time for a very simple reason. If that much of a Galaxy is exotic dark matter by mass, how is it possible to not be a prominent effect on local objects!

Worse yet the name is too Scifi, when the general public first hears about it they end up thinking it will be the next big thing after uranium.

Re:We know more about what Darkmatter is NOT.

[Anonymous Coward]

We know more about what Darkmatter is NOT.

Insert Borat here.

FTFY

[PPH]

Pluto: Piss off! I'm not even a real planet according to you big shots. Right?

[slams door]

Re:Umm yeah, Wikipedia

[gr8_phk]

So what makes anyone think stars in a galaxy should orbit according to Keplers laws? They assume a 2-body system. In the case of planetary orbits, we neglect the other planets and just consider 1 planet and the sun and Kepler works very well. How exactly is this supposed to work with a galaxy? If you show the reasoning, I'll point out the flaw.

Re:Umm yeah, Wikipedia

[gr8_phk]

you either don't know what 'Dark Matter' means, or you don't know what 'nonsense means'...or both.

Dark matter is some as yet unobserved (directly) stuff thought to interact with ordinary matter in some as-yet unexplained way. It's influence is gravitational, yet it is not influenced by "regular" matter in the same way because it is magically postulated to exist in a spherical halo around galaxies rather than have a distribution similar to all the visible matter. It's existence is required to explain phenomena like why galactic rotation curves don't follow Keplers laws - which is redundant because they shouldn't.

So yes, I know what Dark Matter "is" and I know what nonsense is. They are one and the same.

The way science works

[Livius]

People obsessing over whether dark matter is actually something like a material substance or really even a form of matter are missing the point. Dark matter is a hypothesis with explanatory power, and it very likely pointing to something that really exists. It may be many things acting together that are completely unrelated to the concepts of 'dark' and 'matter', or the current hypothesis might be a very natural explanation of what is causing the observed effects. The point is that there is a consistent theory which although not complete yet is helping us understand more about the universe.

Consider things like quarks and elections, where we talk about waves and particles. But the notions of 'wave' and 'particle' are merely metaphors we use because the human imagination fails us in trying to describe things which according to the mathematics are clearly neither waves nor particles.

Re:Umm yeah, Wikipedia

[Anonymous Coward]

The idea of 'Dark Matter' is due to the vast majority of cosmologists failing to take any plasma physics courses and/or understand the nature of what virtually the entire universe is made of. Simulations using the known laws governing plasma behavior (which we can directly measure in the lab) show the same rotation profile we see in galaxies!

So, which sounds more probable...

1) The laws of physics related to plasma and elecromagnetism which we have derived directly from laboratory measurements are applicable at galactic scales and predict what we see in galactic rotation profiles.

or...

2) The weakest known force in the universe is the only one that matters on galactic scales and the well understood forces of elecromagnetism which are over 30 orders of magnitude more powerful can be neglected, so... the galactic rotation curves we see must be due to some hypothetical, theoretical, unobserved, invisible, unknown, 'stuff' that permeates the universe (and still doesn't really explain the observations worth a damn at all).

I'll let you and Occam's Razor decide. ;)

IMHO, 'dark matter' is nothing but a load of BS, thought up by people who just don't have a good enough background in the right areas of physics to see the big picture.

I've also noticed that Wikipedia which used to be well known for its balanced articles has done a great job of purging radional ideas in this area of 'science'. These people are treating plasma physics as though it were fringe science when it's extremely well studied and the laws are well known and entirely reproducible. The progress is being made, but not by cosmologists but rather by electrical engineers who have to deal with the real world and make things that actually work! The current generation of cosmologists seems more interested in philosophy and self aggrandizement than with actually doing real science.

Just my $0.02

Did they look in...

[Anonymous Coward]

I bet they didn't look in my mom's garage. A fair % of the missing matter of the universe is is probably there. (She was a packrat).

words

[Tom]

Sometimes, not having english as your first language makes things funnier. The first meaning of the word "survey" that came to my mind this morning was 1 b) - "to query (someone) in order to collect data for the analysis of some aspect of a group or area" and I was wondering if they had sent questionaires to all the planets on one of the Voyagers. :-)
 

Dark Matter == Phlogiston

[Anonymous Coward]

There. I said it.

Does "gravity" exists ? If so then how ?

[Anonymous Coward]

All indirect evidence. Personally the idea of an invisible, intangible, ethereal magical material that helps peoples sums add up is dubious at best. There are plenty of other good theories out there that do not include this populistic hypothesis.

such as http://www.springerlink.com/content/g332701735121773/

In the link there it sais: "Recently, the gravitational polarization of the quantum vacuum was proposed as alternative to the dark matter paradigm."
Could this refer to my blog-posts in http://pushinggravity.wordpress.com/ ?

Re:Does "gravity" exists ? If so then how ?

[Anonymous Coward]

Here is the blog address as a link Gravity as a Pushing (not Pulling) Force for those of you who like to click :)

duh...

[cre_slash]

[quote]It seems these results don't shed as much light as we'd hoped.[/quote] It's not supposed to. It is dark matter