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Space Science

X Particle Might Explain Dark Matter & Antimatter 285

Posted by samzenpus
from the have-I-got-a-particle-for-you dept.
cold fjord writes "Wired Science has a story on a new theory that tries to explain dark matter, and the balance of regular matter with antimatter. This theory may even be testable. From the article: 'A new hypothetical particle could solve two cosmic mysteries at once: what dark matter is made of, and why there's enough matter for us to exist at all."
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X Particle Might Explain Dark Matter & Antimatter

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  • by Anonymous Coward on Wednesday December 08, 2010 @10:57PM (#34496522)

    What gives the X-Men their powers.

  • ArXiv link (Score:5, Informative)

    by Anonymous Coward on Wednesday December 08, 2010 @11:14PM (#34496616)
    The paper is also available at the arXiv [arxiv.org] if you don't have a subscription to Phys. Rev. Lett.
  • the paper (Score:5, Informative)

    by bcrowell (177657) on Wednesday December 08, 2010 @11:15PM (#34496618) Homepage
    Why, oh why can't people posting science stories on slashdot post links to the actual papers when they're publicly available? http://arxiv.org/abs/1008.2399 [arxiv.org]
  • by paiute (550198) on Wednesday December 08, 2010 @11:20PM (#34496654)

    "This theory may even be testable."

    To be a theory it must be testable.

    • by jfengel (409917) on Wednesday December 08, 2010 @11:48PM (#34496788) Homepage Journal

      There's a difference between "testable in theory" and "testable in practice". Science proceeds from both ends towards the middle, where theoreticians and experimenters meet.

      Theoreticians work on things that may not be testable in practice, now. They may be testable one day, and that actually happens: particle physicists build bigger colliders, astronomers get to see the views they couldn't before, paleontologists dig up the fossil they expected but didn't have.

      It leaves the realm of science utterly when it's not testable even in theory. Between the two there's a gray area, where something may not be practical in the forseeable future, or may require so much time and space and energy that it's absurd to think it would ever become practical. Theoreticians run a minefield here, but it would be invalid to forbid them from going there. They might well find a way to take something absurd and make it realistic; it happens.

      I'm glossing over a lot of epistemic niceties here, but the point is that a theory does not have to be testable at the moment to be science. If this one happens to be testable now or in the near future, yay; that lets us exclude a lot of territory that's currently in the mine field. But it likely would not have happened without other theoreticians having explored that space.

      • by IICV (652597)

        That's actually one of the major problems with many of the current formulations of string theory; they're testable in theory, but in practice by the time we can throw that much energy around we probably won't care about the answer any more, one way or the other.

        • by jfengel (409917)

          Very much so. On the one hand, it's not really correct to dub string theory "not science" just because it's so far from testable. They're doing what theoretical physicists down when presented with a conundrum: they formulate equations and push them around hoping to find something that does give them a testable result.

          The other hand, though, is that it's not anywhere near far advanced enough to merit the kind of attention it gets from the general public. There's a notion that they're looking for The Ultim

      • by stuckinarut (891702) on Thursday December 09, 2010 @03:30AM (#34497968)
        Well said sir! As an example, Frame-dragging was proposed as a theory in 1918 based on Einstein's theory of General Relativity but wasn't able to be tested until 1996 with a couple of special satellites and even then not accurately enough to be provable until 2006. Since we had barely left the ground let alone orbit the earth at that point I'm sure it must have seemed un-testable at the time.
      • Exactly!

        I hope, one day, I have enough money to test out the "Race Car on a Train" Theory - to overturn General Relativity.

    • by Drishmung (458368)
      That doesn't seem to have slowed String Theory down [columbia.edu] :-)
      1. Observe (the universe)
      2. Question (Where is the missing mass? Why is there more matter than anti-matter?)
      3. Hypothesize (X particles)
      4. Predict (X particles will do this thing which we have not yet observed)
      5. Test/experiment (Do they?)
      6. Analysis/Conclusion

      At the moment, they are at #3. Unless they can get to both #4 and #5 then the 'theory' is and will remain idle speculation, suitable only for prompting bad jokes in ./

    • Axiom of Choice?
    • To be a theory it must be testable.

      Can I jut say here for one moment that I have a new theory about black holes? What is it that it is - this theory of mine. Well, this is what it is - my theory that I have, that is to say, which is mine, is mine. What is my theory? This is it. My theory that belongs to me is as follows.

      This is how it goes. The next thing I"m going to say is my theory. My theory by MillionthMonkey Esq., Sir, brackets. This theory goes as follows and begins now. Black holes that swallow the earth can be made easily and for

      • by Unkyjar (1148699)

        I can't believe I got suckered into reading that whole thing. I tip my hat to you sir...I tip my hat to you.

    • by JustOK (667959) on Thursday December 09, 2010 @12:59AM (#34497172) Journal

      To be a theory it must be testable.

      Prove it.

    • by Eskarel (565631)

      I think the phrase should probably technically "This theory may even be testable with current knowledge and technologies for an amount of money which exists."

      You're right that all theories must be testable, but that doesn't mean we actually can test them.

    • They don't mean testable as in "the theory makes predictions that could hypothetically be distinguished via experiment" in this case. They mean in the sense of "we may be able to test it", like with existing technology.

    • by sjames (1099)

      There's testable in the sense of when I let go of this brick it will hit the ground in 1.3 seconds if my theory is correct and then there's testable in the sense of if we construct a 1000 mile high cylinder of neutronium and apply the entire industrial energy output of the earth to it for the next 10 years, this glass of water will boil if my theory is correct.

      The latter is testable in the sense that there exists an experiment that would unambiguously falsify it. It's just that we don't have the technology

      • > OTOH if the latter required a pegasus feather, it would not be testable.

        Sure it would. It would just have to wait until biology has advanced to the point where we can manufacture a pegasus.

    • by sg_oneill (159032)

      Normally, but there is a lot of theories in Physics that MIGHT or MIGHT NOT be true, but can't be tested YET, including most of String theory and its weird and wonderful offspring.

      Thats not to say they CANT be, but we dont know how to yet, and have to , for now, suffice with looking for mathematical models of string theory that fit with what we CAN observe.

  • Kindof Summary (Score:4, Interesting)

    by cosm (1072588) <thecosm3@@@gmail...com> on Wednesday December 08, 2010 @11:36PM (#34496738)
    Alright, so IANAPP, but, FTA:

    Equal amounts of X and anti-X were created in the Big Bang, and then decayed to lighter particles. Each X decayed into either a neutron or two dark-matter particles, called Y and . Every anti-X converted to an anti-neutron or some anti-dark matter.

    But the hypothetical X particle would rather decay into ordinary matter than dark matter, so it produced more neutrons than dark matter. Anti-X preferred decaying into anti-dark matter, and so produced more of it.

    Bold emphasis added is mine. Does this theory explain why "particle X" would rather decay into ordinary matter? Isn't that begging the question? How is that any different than moving to the larger set of all mass, and just saying "Hypothetical universe X would rather form more ordinary matter than dark matter". I understand they may be foregoing the DiffyQ's that perhaps stand behind their assertions for the word "rather" to provide for the layman, but this premise kills the theory for me unless there exist math/science/evidence/a reason besides the word "rather for this article.

    • by tylerni7 (944579)
      One step at a time. If it exists, then we can try to understand it more deeply.
    • Re:Kindof Summary (Score:5, Informative)

      by John Hasler (414242) on Thursday December 09, 2010 @12:08AM (#34496898) Homepage

      CP violation has already been observed. This theory provides a mechanism whereby it can account for both dark matter and the matter-antimatter imbalance.

    • by markov_chain (202465) on Thursday December 09, 2010 @12:10AM (#34496912) Homepage

      +1 Proper use of "begging the question"

    • by c0lo (1497653)

      Alright, so IANAPP, but, FTA:

      [...]

      Does this theory explain why "particle X" would rather decay into ordinary matter?

      Does the quantum therory explains why fermions would (never/rather) not share the same quantum state with others?

      • It seems it does, tough I didn't yet understand it enough to know.

        • by c0lo (1497653)
          Pauli exclusion principle [wikipedia.org] - being a principle, it is not demonstrated, just stated as true and verified by confrontation with the experience (sort of postulated). Pretty much like the Newtonian mechanics principles.
          • People versed in quantum field theory talk in a way that implies that it comes from the theory. I know that the spin, that was first postulated does come from the theory, that is certain, but I have never received a definitive answer from the exclusion principle. As I said, I don't know the theory to know the answer myself.

            By the way, are you a physicist? Is that a definitive answer?

  • The idea that a particle decays differently than its anti-particle is not something new ie Kaons so it is entirely possible from that end. And the Big Bang was dealing with energies much much higher than what we deal with even in the LHC so it is entirely possible to be made of quarks that are much much more massive than the ones we have currently discovered right?
  • From TFA:

    The signature of dark matter destroying protons “can be easily tested by the even bigger proposed underground detectors” planned to be built somewhere in Europe.

    Should anyone interested in science just move to Europe now? Seems to be the place in the world where people actually care about science these days.

    • In my opinion, the US doesn't have a whole lot to offer these days for lower level academics or grad level research. I love my home country and all, but as far as science goes, its all supporting the military and DHS. Additionally, you get paid crappy for doing it unless your an administrator or professor of some kind. To top it off, you get over-priced or crappy health care and you get indebted to the government for most of your life if you choose to go to college and happen to be one of the people that do
  • by Anonymous Coward

    God damnit, no, it doesn't explain all dark matter. It explains how some antimatter could appear in cosmological equations as dark matter.

    There's a lot of "dark matter" which really isn't all that dark (in the sense of "unknown") anymore. In cosmology, dark matter is just anything with mass which isn't conventionally visible from here. We can ballpark how heavy the universe should be based on the equations we've figured out for how the universe works in our neighborhood. Then we can turn around and observe

    • Didn't they also find more stars in galaxies recently, even lowing their dependence on "dark matter".

      • > Didn't they also find more stars in galaxies recently...

        Yes.

        > ...even [lowering] their dependence on "dark matter".

        No. The masses of galaxies are not determined by counting stars.

      • by Chris Burke (6130)

        Didn't they also find more stars in galaxies recently, even lowing their dependence on "dark matter".

        Well it means that we found a bunch of the 'normal' dark matter, as was expected to eventually happen, so in that sense yes we have less dependence on dark matter because some of it was only 'dark' as in 'unseen'.

        For the "weird" dark matter, WIMPs or whatever this theory predicts, there are separate predictions on the amount of that which should exist. There were discrepancies in this prediction, though, in

  • man 3 XInternAtom

  • Testable (Score:4, Funny)

    by Tablizer (95088) on Thursday December 09, 2010 @02:10AM (#34497616) Homepage Journal

    This theory may even be testable.

    Physicists going old-fashioned on us, eh?

  • wimps (Score:3, Funny)

    by CSMoran (1577071) on Thursday December 09, 2010 @04:47AM (#34498280) Journal
    From TFA:

    whenever two WIMPs meet up in space, they annihilate each other

    I'm trying to picture this in my head, and failing.

  • it's extreme... EXTREME!

  • /.'s summary calls it a theory, when the wired article uses hypothetical. From what i understand, it only becomes a theory once the scientists have run out of other options (meaning, they have failed at breaking the hypothesis).

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