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Space Science News

LHC Research May Help Explain the Universe's Matter/Antimatter Imbalance 113

suraj.sun sends this excerpt from the BBC: "Particles called D-mesons seem to decay slightly differently from their antiparticles, LHCb physicist Matthew Charles told the HCP 2011 meeting on Monday. The result may help explain why we see so much more matter than antimatter. The team stresses that further analysis will be needed to shore up the result. At the moment, they are claiming a statistical certainty of '3.5 sigma' — suggesting that there is less than a 0.05% chance that the result they see is down to chance. The team has nearly double the amount of data that they have analyzed so far, so time will tell whether the result reaches the 'five-sigma' level that qualifies it for a formal discovery."
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LHC Research May Help Explain the Universe's Matter/Antimatter Imbalance

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  • Observable universe (Score:4, Interesting)

    by Lord Lode ( 1290856 ) on Friday November 18, 2011 @07:39PM (#38104632)

    What we see is just the observable universe. What if all this missing antimatter happens to be in a non-observable part? You'll never be able to see that! Unless those faster than light particles end the theory of observable universe of course.

  • by Surt ( 22457 ) on Friday November 18, 2011 @08:54PM (#38105148) Homepage Journal

    The unobservable universe is the infinite portion beyond the light speed horizon.
    If you really want to be depressed, think about future civilizations in our galaxy for whom all other galaxies will have retreated beyond the light speed horizon. They will have a much harder time figuring out how the universe works.

    Now realize that we may already be one of those future civilizations from the perspective of the lucky folks who got to see the universe early on.

  • by Anonymous Coward on Friday November 18, 2011 @08:59PM (#38105170)

    The assumption is- if the universe had a fair amount of both, we'd see the gamma radiation leftovers from collisions, and we don't...

    That's not a great assumption. Contrary to popular belief, when random matter and antimatter collide, they don't always create gamma radiation. Anything is possible that still is consistent with a conservation of energy, momentum, and quantum number(s). Although the most likely result of a electron/positron collision is 2 gamma ray photons, it is not impossible that there is some other "light-weight" particle is formed (say like a neutrino/anti-neutrino or some unknown ligher particle or even whatever people might be calling dark matter that is not easily detectible). It may be that there is some unknown field/symmetry that favors the create of something else on the "lightweight" side instead of a photon. Or perhaps there is something that somehow segregates matter from antimatter (like dark energy with negative pressure) to prevent large scale production of gamma radiation.

    However, the current wisdom is that antimatter just doesn't exist in large quantities in the universe because the cosmic radiation which is detected in our neck of the woods is mostly of matter origin (high energy protons, electron), and not of the anti-matter origin. If there were large amounts of anti-matter galaxies, and such, there probably wouldn't be this type of bias in cosmic radiation...

  • by izomiac ( 815208 ) on Friday November 18, 2011 @09:40PM (#38105386) Homepage
    As I understand it, the theory is that anything galaxy-sized or smaller must be almost completely composed of either matter or antimatter since otherwise it'd destroy itself. But, if you had antimatter galaxies then you'd expect to see gamma particles created when they interacted with matter galaxies.

    That hasn't been observed, so the prevailing theory is that the whole universe is almost exclusively comprised of matter, thus there must be some preference in the laws of physics for matter. Personally, I suspect we'll discover an alternate explanation for the missing gamma rays that doesn't require an asymmetry in physics, such as your idea, but I'm certainly not an expert on the topic ("neophyte" would be generous).
  • by Anonymous Coward on Friday November 18, 2011 @10:58PM (#38105748)

    Posting anonymously because I've moderated in this discussion, but the quick answer is no, probably not - we know the signatures of matter/anti-matter annihilations very well, and they simply don't describe gamma ray bursts well enough.

    Interestingly off-topic but I once entertained myself in an astronomy project filling in a cloudy night by calcuating if gamma ray bursts could possibly be accounted for by tightly-collimated electron/positron annihilations. My conclusion was that if they *weren't* collimated, it would involve almost as many electrons as seem likely to be in the universe, while if they were collimated it was possible... but you'd have issues with the red- or blue-shifting.

    Now, I wouldn't actually *trust* those results since I did them in my second year of university, but they were interesting nonetheless. From people I'd actually trust who do this, it doesn't seem too likely that gamma ray bursts are caused by matter/anti-matter annihilations. But hell, it's physics, you never actually know.

The IBM purchase of ROLM gives new meaning to the term "twisted pair". -- Howard Anderson, "Yankee Group"