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Space Science

Dwarf Galaxies Dim Hopes of Dark Matter 137

Posted by samzenpus from the nothing-to-measure-here dept.
An anonymous reader writes Once again, a shadow of a signal that scientists hoped would amplify into conclusive evidence of dark matter has instead flatlined, repeating a maddening refrain in the search for the invisible, omnipresent particles. The Fermi Large Area Telescope (LAT) failed to detect the glow of gamma rays emitted by annihilating dark matter in miniature "dwarf" galaxies that orbit the Milky Way, scientists reported Friday at a meeting in Nagoya, Japan. The hint of such a glow showed up in a Fermi analysis last year, but the statistical bump disappeared as more data accumulated. "We were obviously somewhat disappointed not to see a signal," said Matthew Wood, a postdoctoral researcher at Stanford University who was centrally involved the Fermi-LAT collaboration's new analysis, in an email.
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Dwarf Galaxies Dim Hopes of Dark Matter More

Dwarf Galaxies Dim Hopes of Dark Matter

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  • or can know....or something like that.

    • We don't know anything is weird here (Score:5, Insightful)

      by fyngyrz ( 762201 ) on Sunday October 26, 2014 @07:30PM (#48237137) Homepage Journal

      Dark Matter and Dark Energy are not terms that should conjure up weirdness in your mind. Not at this point, anyway.

      Neither concept has a shred of evidence behind it indicating that anything exotic is going on. If you really want a good handle on the terms, just think of them as "We hope some sources of energy and matter we can't detect are out there because otherwise, the math behind our hypotheses doesn't work."

      It's a limitation of trying to figure out what's going on incredible distances -- and times -- from us with a combination of barely functional tools, our (decent, I'm guessing) grasp of science, and the participant's intuitions.

      • Re:We don't know anything is weird here (Score:5, Interesting)

        by Artifakt ( 700173 ) on Sunday October 26, 2014 @07:56PM (#48237281)

        I suspect we should have avoided terms like "Dark X', in favor of something that sounds more neutral and less dramatic. (I know, 'dramatic' sells research programs, especially to congress...).

                    Linguistic problems have happened frequently in Physics and particularly Cosmology. After all, "Big Bang" was a term made up to poke fun at the idea it described, coined by Fred Hoyle, who wanted to defend the alternative ""Steady State" theory and thought "Big Bang" would sound rediculous. The phrase "Collapse of the state vector" in Quantum Mechanics has a similar problem, in that 'collapse' itself has a negative connotation, and makes it sound to some people like the Quantum state is superior to the Classical state, like some sort of 'fall from heaven' occurs when the vector reifies. "Reification" was a more neutral term that many people such as Dirac and Minkowski liked, but which died out in use by the 1970's. A lot of the Depak Chopra sort of writing on QM seems to stem from seeing the process of quantum probabilities becoming classical events as a fundamentally negative thing, and the Quantum "Realm" as somehow closer to God than the regular realm we experience, and calling it a collapse certainly encourages that view.

                      Dark Matter and Dark Energy may be causing something of the same effect, where a more neutral term, such as "Undetected Matter", or "Unknown Force" might not.

        • Re: (Score:2)

          by Z00L00K ( 682162 )

          Dark Matter and Dark Energy may be causing something of the same effect, where a more neutral term, such as "Undetected Matter", or "Unknown Force" might not.

          May the Force be with you.

        • Re: (Score:2)

          by Livius ( 318358 )

          I think some people are simply objecting to the name but expressing themselves poorly and objecting to the science. Since matter (in the ordinary sense) can be dark (in the ordinary sense), it is perfectly valid to point out that 'dark matter' is a truly terrible name, and hopefully whoever discovers it will name it something better.

          (It's much worse than, for example, calling quarks red, green, and blue, since you can't reflect visible light off a quark and therefore in that context colour must take on a m

        • I suspect we should have avoided terms like "Dark X', in favor of something that sounds more neutral and less dramatic.

          Isn't this exactly what we want?? Seriously, name one thing that is wrong with people seeing science in a dramatic, exciting perspective which draws more interest and funding?

          One of the greatest motivations in human advancement has been a curiosity in the unknown, and giving it an intriguing name and surrounding it with mystery is just us doing our thing.

        • Re: (Score:2)

          by Sique ( 173459 )
          But dark in this case is completely cromulent, as dark implicitely means no light, and in fact, dark matter (and also dark energy) doesn't emit any light or even interact with light. This matter really is dark in the original sense of the word, all later connotations not withstanding.
        • dark roast...

      • Re:We don't know anything is weird here (Score:5, Interesting)

        by Roger W Moore ( 538166 ) on Sunday October 26, 2014 @09:43PM (#48237733) Journal

        Neither concept has a shred of evidence behind it indicating that anything exotic is going on.

        It depends on what you mean by 'exotic'. In physics we usually reserve this term for 'new physics that we do not yet understand'. In these terms Dark Matter is "exotic". There is a huge amount of evidence (from galaxy rotation curves, cosmic microwave background and gravitational lensing) indicating that there some sort of mass which is not made of atoms. Since all the matter we have a handle on is made of atoms (or, if a plasma, parts of atoms) 'exotic' seems like an appropriate description at least until we figure out what it is exactly.

        Your suggestion that the "maths does not work" has been tried. Modified Newtonian Dynamics (MOND) models essentially died with the Bullet Cluster [wikipedia.org] because this showed that there was a gravitational field (it lensed the galaxies behind it) where there was no atomic matter. Effectively when this pair of galaxies collided the atomic matter in each interacted with each other and slowed down and the Dark Matter passed through each other without interacting. It is very hard to explain this with anything other than some type of 'exotic' form of matter not made of atoms.

        • There is a huge amount of evidence

          IANAP but wouldn't you phrase this somewhat differently? I wouldn't be able to decide between the theory hypothesising the extra matter being wrong and the existence of some invisible and so far undetected source of mass. I understand why physicists don't want to throw General Relativity away of course.

          • Re:We don't know anything is weird here (Score:4, Insightful)

            by PvtVoid ( 1252388 ) on Monday October 27, 2014 @08:18AM (#48239675)

            There is a huge amount of evidence

            IANAP but wouldn't you phrase this somewhat differently?

            Why should he phrase it differently? There is a huge amount of evidence. As in, multiple, independent measurements that all point in exactly the same direction:

            - Galactic rotation curves
            - Gravitational lensing
            - Cosmic Microwave Background acoustic oscillations
            - Cluster baryon fractions from X-ray measurements
            - Large-scale structure

            All of these things require something like dark matter to make any sense at all.

            • All of these things require something like dark matter to make any sense at all.

              They do within the existing framework of physics. But you're not giving both sides of the story here. There's no evidence of dark matter in our local vicinity yet theory suggests our galaxy must be composed of at least 80% dark matter. The gravitational effects of such a huge amount of invisible mass should be obvious to us. So far no evidence for its existence has been found, despite increasingly accurate measurements (ra

              • The gravitational effects of such a huge amount of invisible mass should be obvious to us.

                Not necessarily - Dark Matter is so far only obvious at the galactic scale and above. This might be because its distribution only varies on such large scales. If this is the case then DM within the solar system would have no gravitational effect because the density of DM would be approximately uniform throughout it.

                As for redefining the physical laws on a large scale these models have a lot of trouble explaining all the observed effects but in any case these are still 'exotic' physics and, if anything,

        • Please, can we forget the Bullet Cluster as the holy grail for Dark Matter? Even the wikipedia page mentions the alternative interpretations.

          • The point of the bullet cluster is not that it is the "holy grail" for Dark Matter - all the other evidence provides that - it is that it really kills the MOND interpretation which was pretty much already dead and gone before hand in any case. The 'alternative explanations' part of the wikipedia article refer primarily to an *online refutation*, not a refereed journal paper. However I'm sure that you can come up with models that make the bullet cluster work it is just that they are so convoluted and fine tu

      • Re: (Score:2)

        by Z00L00K ( 682162 )

        According to some it's an electric phenomenon. Ever seen the effect static electricity have? If the center of the galaxy has a different potential than the outer parts it could be the answer.

        But unless we can measure the potential difference we won't know.

        • Such an electric field would be trivially detectable. The currents the electric universe would need would also be trivially detectable. And then on top of all that, the electric universe explains a very good approximation of absolutely nothing about the universe we observe (Red shifts for example but plenty of other examples)

        • Re: (Score:2)

          by Bengie ( 1121981 )
          If there was something electric, it would interact with light. Light is the carrier of electromagnetism.
    • It is very easy to imagine models for Dark Matter where the DM cannot annihilate with itself. In such cases there are only two ways to detect it: create it in high energy collisions such as those at the LHC or detect it bouncing off an atomic nucleus in extremely sensitive experiments placed deep underground to shield them from cosmic rays. The fact that there is no evidence of annihilating Dark Matter does not "dim hopes of Dark Matter" it just dims hopes of one particular class of model of Dark Matter.

  • Aether (Score:3, Interesting)

    by frovingslosh ( 582462 ) on Sunday October 26, 2014 @06:29PM (#48236863)
    Dark Matter is the Aether of the 21st century. Eventually we'll stop wasting money on finding it.

    • Re: (Score:2, Interesting)

      by Anonymous Coward

      Well, while the Dark Matter theory sucks I doubt the hunt for it will stop until someone suggest a better theory.

      • Ok, Ill suggest a better theory.

        In the void between galaxies particles and anti-particles are created as they cross the planck barrier as wave forms. In most cases they annihilate each other. However there are slightly more anti-particles created. These anti-particles have a negative mass and repel most normal particles. Thus the space between galaxies is filled with anti-particles that force the galaxies into areas and account for the missing mass, the unexplained reason that the galaxies remain together,

        • Ok, Ill suggest a better theory.

          In the void between galaxies particles and anti-particles are created as they cross the planck barrier as wave forms. In most cases they annihilate each other. However there are slightly more anti-particles created. These anti-particles have a negative mass and repel most normal particles. Thus the space between galaxies is filled with anti-particles that force the galaxies into areas and account for the missing mass, the unexplained reason that the galaxies remain together, and the reason that the galaxies are moving apart at accelerated speeds. :P

          Fine. Now please get back to us after you quantitatively calculate how this affects gravitational lensing by galaxies and clusters, and Cosmic Microwave Background acoustic oscillations. Also, we'll need a prediction for the two-point correlation function of galaxies, compared to the Sloan Digital Sky survey. If you want anybody to take you seriously, you will have to do these things at a minimum. The data are public.

          • Funny as it sounds, it was a theory that was put forward by an astrophysicist. I read about it just over a year ago.

            I found it interesting namely because he used the gravitational differences and negative mass to account for the lensing effect by taking the fact that time moves differently based on mass.

      • There are alternative theories, such as mulch-dimensional time, which actually works. The problem with Dark Matter, is that it is basically Sciency version of "Magic". Unknown, UnSeen, magical force that explains what we don't know. We dress it up in Science terms to reflect that we just don't know, so it becomes acceptable.

    • Your comment is a bit terse. Would you mind elaborating on why dark matter is like the aether? In particular it would be great if you could summarize the different lines of evidence that make astronomers think there is a lot of dark matter, and how you think each of them is being misinterpreted.

      • Re:Aether (Score:4, Insightful)

        by Anonymous Coward on Sunday October 26, 2014 @08:12PM (#48237361)
        In particular, it is like the Luminiferous Aether because it is a hastily invented answer to something we've observed when the problem is we don't properly understand the question.

      • Re: (Score:1)

        by Anonymous Coward

        IAATP (in training, PhD Candidate)

        The Luminiferous Aether was something that *HAD* to be there under the experimentally very well justified assumption that Maxwell's electrodynamics and Newton's mechanics were the correct description of reality.

        Likewise, Dark Matter is something that *MUST* be there under the experimentally very well justified assumption that Big Bang Nucleosynthesis, Isotropy and Homogenity, and General Relativity are the correct descriptions of reality.

        What frovingslosh is saying is that,

        • The Luminiferous Aether was something that *HAD* to be there under the experimentally very well justified assumption that Maxwell's electrodynamics and Newton's mechanics were the correct description of reality.

          Are you sure about that? It is my understanding that Maxwell's Equations specifically deny a preferred frame of reference which is what a Luminiferous Aether would be. Is that not so?

          • My understanding is that Maxwell's equations were assumed to apply in an at-rest condition, which is why people expected Michelson-Morley to get indications of Earth's motion through the aether. Once that failed to turn up, people started asking themselves all sorts of questions.

    • Yea because another turning point like Wave-particle duality is going to come around without funding.

      • Re: (Score:2)

        by flyneye ( 84093 )

        We could have a public access telethon with topless chicks and beer and stuff.
        You just have to be more clever about fundraising.

    • Re:Aether (Score:5, Interesting)

      by Attila the Bun ( 952109 ) on Sunday October 26, 2014 @07:06PM (#48237039)

      Dark Matter is the Aether of the 21st century. Eventually we'll stop wasting money on finding it.

      ...and the enlightened explanation for galactic rotation curves will be, what?

      There's strong evidence for the presence of unseen stuff in galaxies. It shows itself in its gravitational effects on the way stars orbit around galaxy centres. Either our understanding of gravity is wrong (an option on which money has also been "wasted"), or there is some invisible "dark" matter out there. Figuring out what that matter is will mark a huge advance in cosmology and likely determine the future direction of particle physics too.

      If you feel that understanding our universe and our origins is wasted effort, then we will never see eye to eye.

      • If you want to be technical about it, you are creating an excluded middle.

        Thinking that the current search for dark matter is wasted effort hardly makes you anti science. It just means you don't like a particular line of research. I happen to be very pro physics research but very anti spending on ever larger accelerators. While they do get results we haven't been getting very much in spinoff from them for a very long time.

        • Frovingslosh is saying dark matter doesn't exist. He's wrong. He's saying the effort devoted to finding out what it is is fruitless. He's wrong on that too.

          The question of priorities is much more complex, and everybody has their preferences. As it happens large accelerators are delivering more and more-useful spinoffs than ever before: the technologies developed to build the most recent generation of accelerators have direct applications in industry and medicine. Some people claim the same technology

          • Frovingslosh is saying dark matter doesn't exist. He's wrong.

            That's a very strong statement. I personally would say no more than "Something we don't fully understand is causing an effect".

            it happens large accelerators are delivering more and more-useful spinoffs than ever before

            You spend 8 billion to get 100 million worth of R&D it's not a great use of funds. It's not the first time this debate has come up. I doubt it will be the last. The space program is probably the best example, 100 billion for the research and spinoffs ? Really bad investment. 100 billion to win the cold war ? cheap at 100 times the price.*

            * which is actually less than what it cost

            • Re: (Score:2)

              by Bengie ( 1121981 )
              And that "something" is Dark Matter. No matter what it is, something is causing unaccountable effects. Since we know those effects are facts, we can say with 100% certainty that Dark Matter is real. It is whatever is causing those effects. It could be something we know, but not very likely.

              It's like saying we fall towards the Earth, so we're going to give that force a name of "Dark Force". Some time later, we call it gravity. As far as I care, from a hypothetical standpoint, it could have been almost anyt
              • But the "effects" of which you speak aren't "effects" are such. They're deviations from current theory. That is to say, theory and observation do not match at these very large scales. The orbit of Mercury deviated from the predictions of Newtonian mechanics etc. Was it being perturbed by another body in the inner solar system that we haven't yet managed to see?

                • Re: (Score:2)

                  by Bengie ( 1121981 )
                  We clearly see the distortion of space time with nothing detectable there. You are wrong is your assumptions.

            • Frovingslosh is saying dark matter doesn't exist. He's wrong.

              That's a very strong statement. I personally would say no more than "Something we don't fully understand is causing an effect".

              Our statements are almost identical. The term "dark matter" is just shorthand for "something we don't understand, exerting a gravitational effect". There's also the possibility that there is no "something" and our understanding of gravity is wrong, but that has now been all but ruled out.

              You spend 8 billion to get 100 million worth of R&D it's not a great use of funds.

              This is a separate argument, but I'll answer it with two important points:

              1. You can't put a value on fundamental research. The Higgs Boson in unlikely to have any direct application in the near future, but what about s

              • Re: (Score:2)

                by Cabriel ( 803429 )

                2. Could you develop the same technology more cheaply, without building huge science experiments? No. Of course not. Who would spend their whole career perfecting some obscure device if there wasn't a chance of participating in a great discovery? Industry just can't generate that kind of motivation.

                To agree with you, I would say we've seen the example of Industry's idea of advancement in the automobile industry: The major manufacturers kept making almost solely gasonline-only vehicles with only minor incremental advancements until they were required by legislation to make alternatives available to the public, and when they whined about how much it would cost, the (North American) governments gave them subsidies for these new lines of vehicles...

                ...That is, until an outsider decided to enter the market

            • Re: (Score:2)

              by Livius ( 318358 )

              "Something we don't fully understand is causing an effect".

              And it's name is 'dark matter'.

              We have to call it something.

              • The language you use, can easily define and limit your thinking. Calling this dark matter really seems to be a good example,

              • What if it isn't matter at all. By calling it Dark Matter, you have lead yourself and everyone else looking for answers down the wrong dead end. I have yet to see an reasoning that says it isn't just the different speeds of time through the gravity well of the galaxy. Time passes slower when in a stronger gravity field. So the stars near the core will appear to be moving more slowly to us who are well outside of that galaxy. In relation, the stars out at the edge will have faster clocks and will therefore b

                • Re: (Score:2)

                  by Livius ( 318358 )

                  Calling an apparent effect of time some sort of mysterious matter would be a large mistake

                  Actually it would be general relativity.

                • It has mass, and doesn't move very fast, so it's reasonable to call it matter. It doesn't interact electromagnetically, so it's reasonable to call it dark.

                  In the meantime, I suspect astrophysicists have already calculated the effect of mass on passage of time. Moreover, while that could conceivably explain the galactic rotation curves that were the first problem (I'm not a physicist), how would it explain other evidence of dark matter?

          • Frovingslosh is saying dark matter doesn't exist. He's wrong. He's saying the effort devoted to finding out what it is is fruitless. He's wrong on that too.

            And you know this how?

      • There is no doubt that there is a dark matter "effect", it is just that we don't really know we will every find a particle that is "Dark Matter". I kind of dislike the name for that reason, maybe scientist are affected by this but your common layman seem to think one day we will have bottles full of "Dark Matter" we can use in some future technology. We simply know very little about what is causing the dark matter effect and we have much more knowledge about what it isn't than what is might be. The key i

    • Re: (Score:2)

      by Livius ( 318358 )

      The search for the aether led to special relativity and general relativity. That doesn't sound like a waste.

    • Why would you think that? Nobody was really comfortable with the aether, but dark matter is perfectly understandable. It's a variety of matter that does not interact electromagnetically. We already know one form of matter like that (neutrinos), so what's the problem with thinking there might be things like massive, slow, neutrinos?

  • statistically (Score:3)

    by lkcl ( 517947 ) <lkcl@lkcl.net> on Sunday October 26, 2014 @06:39PM (#48236915) Homepage

    i think at some point some scientists somewhere will work out that the statistical evidence is growing to show, more and more, that dark matter *doesn't* exist...

    • I believe that all the words you used do, in fact, exist, and you used them in an order that implies meaning, but I don't think you wrote anything meaningful at all, because it doesn't appear you know anything substantive about the research. You might as well be leaning on the water cooler, saying, "Them fancy scientists! Pshaw!"

    • Re:statistically (Score:5, Interesting)

      by Bengie ( 1121981 ) on Sunday October 26, 2014 @07:08PM (#48237059)
      Then we need someone else to explain the excessive spacial distortion. We assume it's matter, but no matter what it is(pun), it does not fit anything we currently know about. I guess something other than matter could distort space time like matter, but we'd not quite sure yet. But as it stands currently, the only thing that can distort space is something that has mass, and anything with mass is "matter".

    • Re: (Score:2)

      by Livius ( 318358 )

      *Something* exists. If the dark matter model doesn't fit the evidence, then scientists will abandon it, but don't be surprised if the new explanation is something even stranger and less to your liking.

    • For a long time much of the community also didn't like dark matter... But as we collect more data, we get *more* statistically evidence that dark matter indeed exists. Dark matter is non baroynic matter that interacts with everything else with gravity only.

  • The three most beautiful letters (Score:5, Interesting)

    by Intrepid imaginaut ( 1970940 ) on Sunday October 26, 2014 @07:07PM (#48237049)

    WTF

    I love it when science can't explain something yet, it means we have so much more to learn.

  • Dwarf Galaxies Dim Hopes of WIMPS (Score:5, Informative)

    by mbone ( 558574 ) on Sunday October 26, 2014 @07:09PM (#48237061)

    The Dark Matter is still there, as something (we don't know what). This doesn't "dim" the existence of DM as an effect* at all. What this does is (again) dim some faint hopes it might be WIMPS. It doesn't constrain other models / theories at all.

    * : even if the DM is MOND, or some other gravity correction, it might not be matter, but the effect would still exist.

    • Yep. If dark matter only interacts via gravity, and not via any of the other forces, then these results wouldn't constrain it. It would also mean that it's not going to be directly observable any time soon, so most scientists hope that's not the case, but it's certainly a possibility. Sterile neutrinos are one possibility for this.

      • Re: (Score:2)

        by mbone ( 558574 )

        There are other possibilities that are in principle quite observable. I would actually favor either condensed matter nuggets or axions to WIMPS, but that may be just me.

  • There is no dark matter... it's a glitch in the machine.

    That's not a bad thing; a glitch can be exploited.

    • Re: (Score:2)

      by Bengie ( 1121981 )
      Just wait until they "fix the glitch" in accounting, without telling Dark Matter. He'll be back for his stapler.
  • It doesn't matter what you call it ... declining or dilution ... the end result is fewer women in CS career fields than men. The effect is less a less robust CS field and the resulting negatives that come along with a technology field operating with blinders.
  • Why are scientists obsessed with finding the most exotic explanation of Dark Matter without first exhausting the more prosaic explanations? It is Occam's Razor upside down. I think that the reason is there there is a Nobel Prize and fame if Dark Matter turns out to be a particle, but there is no glory if it turns out to be something more ordinary such as neutral hydrogen, dust, etc. Even a modification of Newtonian laws at a distance to explain Dark Matter is not exotic enough.....so we have to endure C

    • Re: (Score:3, Interesting)

      by aXis100 ( 690904 )

      Plenty of scientists have tried to use simpler explanations but there is evidence that rules them out. The best example is the bullet cluster - two galaxies collided and the various components of the cluster - stars, gas and dark matter - all behaved differntly during the collision. The gravitational lensing effects cannot be explained by theories that dont include dark matter.

      http://en.wikipedia.org/wiki/B... [wikipedia.org]

    • What's so exotic about matter that doesn't interact with anything except gravitationally (and possibly by the weak force)? It isn't anything we've seen, but there's a selection bias in there.

      In the meantime, people have looked extensively for dust and gas and other things, but these in the quantities necessary would have effects we can see. People have tried modifying Newtonian gravity (those theories have a name, so people have been considering them), but they don't account for all the effects.

  • Don't know much about physics, but Newton's laws of motion were good and still work on a small scale for most practical purposes. Then we had the theories of general and special relativity, which work on larger scales and describe spacetime. Further we have quantum field theory, which describes interactions at an extremely small scale and apparently has yet to be unified with the G/S theories of relativity. The lack of unification leads me to believe that we're either too stupid to discover the missing link

  • I don't know... I kind of like the fact that the universe is still such a mystery to us. With the large hadron collider there was almost a sense of let down that nothing exotic or unexpected appeared. That everything went according to our models.

  • Of course (Score:1)

    by Anonymous Coward

    Of course it flat-lined, they were using the Fermi Large Area Telescope (FLAT)!

    • When you can't explain unusual gravitational attraction you write it off as DM (doesn't matter).
      When you can't explain unusual gravitational repulsion you conclude it's DE (downright evil).

  • If you look for the golfball particles, perhaps you can find the Dorf galaxies?

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