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Dwarf Galaxies Dim Hopes of Dark Matter

Posted by samzenpus on 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.

23 of 137 comments (clear)

  1. Aether by frovingslosh · · Score: 3, Interesting

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

    --
    I'm an American. I love this country and the freedoms that we used to have.
    1. Re:Aether by Anonymous Coward · · Score: 2, Interesting

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

    2. Re:Aether by amaurea · · Score: 2

      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.

    3. Re:Aether by Attila+the+Bun · · Score: 5, Interesting

      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.

    4. Re:Aether by Anonymous Coward · · Score: 4, Insightful

      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.

    5. Re:Aether by Archangel+Michael · · Score: 2

      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.

      --
      Agent K: A *person* is smart. People are dumb, stupid, panicky animals, and you know it.
  2. statistically by lkcl · · Score: 2

    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...

    1. Re:statistically by Bengie · · Score: 5, Interesting

      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".

  3. The three most beautiful letters by Intrepid+imaginaut · · Score: 5, Interesting

    WTF

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

  4. Dwarf Galaxies Dim Hopes of WIMPS by mbone · · Score: 5, Informative

    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.

  5. Hardly Either Or by Crashmarik · · Score: 2

    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.

    1. Re:Hardly Either Or by Attila+the+Bun · · Score: 2

      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 could be developed more cheaply without the involvement of particle physics research, but so far nobody has figured out a way to make that happen.

    2. Re:Hardly Either Or by Crashmarik · · Score: 2

      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

    3. Re:Hardly Either Or by Attila+the+Bun · · Score: 2

      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 superconductors, or RF generators, or ion sources, or ultra-high vacuum techniques? All technologies which have been heavily developed for particle physics, and which have already found their way into industry. Even if you came up with a figure for the value of those technologies up to now, there's no way you can measure their future value. Yet future progress without them is unthinkable. All our technology is built on fundamental research, so if technology (and by extension, civilisation) is to advance so must fundamental research.

      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.

  6. We don't know anything is weird here by fyngyrz · · Score: 5, Insightful

    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.

    --
    I've fallen off your lawn, and I can't get up.
    1. Re:We don't know anything is weird here by Artifakt · · Score: 5, Interesting

      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.

      --
      Who is John Cabal?
    2. Re:We don't know anything is weird here by Roger+W+Moore · · Score: 4, Interesting

      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 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.

    3. Re:We don't know anything is weird here by PvtVoid · · Score: 3, Insightful

      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.

    4. Re:We don't know anything is weird here by Roger+W+Moore · · Score: 2

      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 tuned that nobody believes them because there is no evidence to support them over the far simpler model that there is some undiscovered particle out there.

  7. Not really that wierd at all by Roger+W+Moore · · Score: 2

    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.

    If the LHC sees nothing in the next few years though it does tell us something: Dark Matter is unlikely to be a a massive particle which interacts with matter via the weak force. At LHC energies we can pretty-much exclude the mass range consistent with thermal production in the Big Bang for this class of particle. There are ways around this e.g. exotic production mechanisms or multiple types of particle contributing to Dark Matter but the simplest models for weak particles will be gone and axions might start to look even more attractive as an explanation.

  8. Norm makes the original argument with his data by stevez67 · · Score: 2

    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.

  9. Re:Scientists obsessed with exotic explainations by aXis100 · · Score: 3, Interesting

    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...

  10. Re:wrong by TheTurtlesMoves · · Score: 2

    There is as much evidence of dark matter as there is of climate change. Quite a lot. Just because you are ignorant of that evidence does not make such evidence disappear.

    --
    The Grey Goo disaster happened 3 billion years ago. This rock is covered in self replicating machines!