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Anti-matter clumps

  1. Oct 4, 2004 #1
    anti-matter "clumps"

    I was recently reading an article about the US Air Force creating advanced weapons using anti-matter particles (positrons, specifcally). It got me to thinking...

    What I'm curious about is this: are there macroscopic "clumps" of antimatter particles? In other words, normal matter particles combine to create macroscopic things (i.e. normal particles combine to create atoms, which combine to create molecules). Are there particular anti-atoms and/or anti-molecules?

    Presumably this would be a manifestation of some kind of symmetry.

    Thanks for your input.
     
  2. jcsd
  3. Oct 4, 2004 #2

    mathman

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    Although anti-matter could clump just like ordinary matter, there is no evidence for any anti-matter other than at the particle level, such as created in labs.
     
  4. Oct 4, 2004 #3
    is that because:

    a) no theory predicts it?
    b) we haven't observed it?
    c) we can't observe it?
    d) we haven't tried to observe it?
     
  5. Oct 4, 2004 #4

    Nereid

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    Welcome to Physics Forums underworld!

    With 'it' = 'clumps of anti-matter',
    quite consistent with theory
    correct; no observations of such things (so far)
    we could certainly observe the 'death' of such clumps, e.g. as gammas! Indeed, we regularly observe particle-anti-particle annihilation events, in labs, in cosmic rays, and out in deep space.

    A curious observation about our universe is that it is comprised of matter, not anti-matter (nor a mixture). Indeed, in the concordance model of cosmology (the 'LCDM' models), all anti-matter in the early universe was annihilated, through collisions with matter (partly why there are so many more photons than baryons); all anti-matter in the nearby universe has been created recently, e.g. through particle collisions.

    IIRC, there are plans, at CERN, to create some atoms of anti-hydrogen, and test some theories (e.g. CPT symmetry breaking). However, these anti-atoms will be 'hot' - travelling at close to c - so testing their behaviour in gravitational fields may not be possible. :cry:
     
  6. Oct 4, 2004 #5

    pervect

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    Anitmatter should form anti-atoms and anti-molecules just like normal matter does, there should not be any difference in the physics of bulk matter vs bulk antimatter. I doubt that we have any experimental confirmation of this at this point, though.
     
  7. Oct 4, 2004 #6
    No one has even created a single atom of antimatter in the labs? I don't doubt it, but I find it curious. Is it a very difficult thing to acheive? Can't they slow down charged particles fairly easilly, and store them in magnetic or optical traps, and manipulate them at slow speeds that way? Is it a hard thing to achieve because the requirements for doing this with particles of such different masses and opposite charges like antiprotons and positrons are so different? Are there labs working on it, or is the experimental data an atom of anti-hydrogen would produce low in priority compared to other experiments?
     
  8. Oct 5, 2004 #7
    I never heard anything like this. Anti-matter better call them anti-particle are only created by using high energy particle colliders in labs. They are not so stable to be used in any form of macroscopic work. Untill now no bulk of anti matter has been created and is even unlikely in near future too.
     
    Last edited: Oct 5, 2004
  9. Oct 5, 2004 #8

    Nereid

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    correct (AFAIK)
    Yes, extraordinarily difficult! While it's relatively easy to create an anti-proton (and anti-neutron), and positrons are available by the bucketful (after all, what's the "P" in "PET", as in scan?), and 'cooling' anti-protons a challenge (but still do-able; cooling anti-neutrons? don't try it a home!), making anti-atoms ... well, how do you think it could be done?
    if only it were that simple!
    I think there are plans at CERN to make them; in terms of priority, my guess is they're not so important as to warrant spending €100,000,000 or more on!
     
  10. Oct 5, 2004 #9

    pervect

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    I seem to recall that someone, somewhere, created anti-hydrogen, but I strongly doubt any larger structures have been created.

    Google finds

    http://www.newscientist.com/news/news.jsp?id=ns99991957

    but

    is a little on the weak side of definite
     
  11. Oct 5, 2004 #10
    I remember some anti-hydrogen atom reports, too. However, it existed only for a fraction of a second.
     
  12. Oct 5, 2004 #11

    Nereid

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    Welcome to Physics Forums mwith!

    Do you happen to remember where you read/saw those anti-hydrogen reports? It'd sure be nice if we could show everyone a paper about it having been observed! :smile:
     
  13. Oct 5, 2004 #12
    anti-hydrogen atoms produced at CERN

    I found it... It was actually produced in my country :), at the "Centre Européenne pour la Recherche Nucléaire" (CERN) in Geneva.

    LINK
     
  14. Oct 8, 2004 #13
    so, the answer is that anti-particles can clump together to form anti-atoms at least.

    now, almost all of the replies to this thread seem to be narrowly defining these occurrences as man-made only. is there any reason why this shouldn't occur naturally as well? citing extreme difficultly is not a valid answer (i.e. it's extremely difficult to create a sun or black-hole - but those definitely occur naturally)...

    thanks for all the insightful responses.
     
  15. Oct 8, 2004 #14

    Nereid

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    Turn the question around ... since there is no anti-matter 'left over' from the Big Bang (at least, not baryonic matter, or perhaps no 'low mass' baryonic particles), how could such anti-matter clumps form? It's easy enough to describe situations in which anti-matter particles are formed, it's a different matter (pun unintentional, really) entirely for such to aggregate.
    Not at all ... a sun, a black hole, a galaxy, ... it's easy to describe how these objects can form, and to observe the processes of such formation at work throughout the universe.
     
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