Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Antiparticles and gravitation

  1. Sep 13, 2010 #1
    Can someone tell how antiparticles affected by gravitational force? The same way as particles or opposite? Thanks.
  2. jcsd
  3. Sep 13, 2010 #2


    User Avatar
    Homework Helper
    Gold Member

    Antiparticles have the same mass as their particle counterparts. Antimatter theoretically attracts matter and antimatter particles in the same way that matter attracts matter.
  4. Sep 13, 2010 #3
    If antimatter particles were to repel each other by gravitation, then all Majorana (neutral) particles would have to be unaffected by gravitation - what is proven false.
  5. Sep 15, 2010 #4
    Ok, what is confusing to me is that the very name “antiparticle” sounds more important than it actually is. Antiparticles are made of ordinary matter and have ordinary mass affected by the gravitation the same way as “normal” particles. So the only difference between “normal” and “anti” is charge? That’s it? Electron and positron are the same in all but one property?
    Then how do we even distinguish which particle is “normal” and which is “anti”? We can’t do it by charge’s sign because though electron has negative charge and positron has positive, we see other examples, namely, a proton has positive charge - then why don’t we call a proton an antiparticle?
    Let me clarify. When a negative electron and a positive positron meet - they annihilate. Why then electron doesn’t annihilate when it meets a proton? The charges are opposite, and though proton has bigger mass, the annihilation must still take place. They are “anti” to each other.
    And this reminds me of that problem of “missing antimatter”. By established theories, at the Big Bang there were equal amounts of matter and antimatter created. But we only see matter in our observable Universe. Now – returning to the definition of antimatter above – we can consider protons being “antimatter” and then the math might become valid again – antimatter is not missing if we sum all electrons as matter and all protons as antimatter.
    Anyway, there must be an error somewhere in my thoughts. Can someone clarify what the antimatter is if not all those particles that charged positively? Thank you.
  6. Sep 15, 2010 #5


    User Avatar
    Gold Member

    Being an anti-particle is far more involved then just having opposite charge. A particles anti-particle has all of its intrinsic quantum numbers flipped in sign. When a proton and electron meet, they will not annihilate, one is not the others anti-particle.
  7. Sep 15, 2010 #6
    perhaps there is here a misunderstanding

    an ANTIPARTICLE does NOT have NEGATIVE mass.. its mass is POSITIVE

    another example would be particles with NEGATIVE ENERGY ¡¡ so its rest mass and so on becomes more and more NEGATIVE

    in this case perhaps they would have anti gravitational properties ,
  8. Sep 15, 2010 #7
    Whenever this subject comes up nobody references any experiments, any propsed experiments or any thought experiments.

    There was previously talk about collecting anti-matter that occurs naturally in the Van Allen belt?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook