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Thread: Antimatter => Negative mass => Antigravity?

  1. #1
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    Antimatter => Negative mass => Antigravity?

    Hi,

    I just saw this article (sorry it is in French):
    https://www.pourlascience.fr/sd/phys...haut-16638.php

    And they never tested antimatter to figure if it falls down or up yet?


    Regards,
    philippeb8


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  2. #2
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    Quote Originally Posted by philippeb8 View Post
    ... And they never tested antimatter to figure if it falls down or up yet?
    That is a fairly difficult test to make. The forces in the trap are so much stronger than gravity. It is hard to turn them off without giving some impetus to the few atoms in the trap.
    That being said, I will be *very* surprised if antimatter has negative mass.
    Forming opinions as we speak

  3. #3
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    Quote Originally Posted by antoniseb View Post
    That is a fairly difficult test to make. The forces in the trap are so much stronger than gravity. It is hard to turn them off without giving some impetus to the few atoms in the trap.
    That being said, I will be *very* surprised if antimatter has negative mass.
    Interesting... thanks!


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    Quote Originally Posted by philippeb8 View Post
    Hi,

    I just saw this article (sorry it is in French):
    https://www.pourlascience.fr/sd/phys...haut-16638.php

    And they never tested antimatter to figure if it falls down or up yet?
    They are working on it with the ALPHA experiment at CERN: http://alpha.web.cern.ch

    (Edit: I see the ALPHA experiment gets a mention in the article. My French isn't good enough to comment further on the article!)

  5. #5
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    Quote Originally Posted by Strange View Post
    They are working on it with the ALPHA experiment at CERN: http://alpha.web.cern.ch

    (Edit: I see the ALPHA experiment gets a mention in the article. My French isn't good enough to comment further on the article!)
    Thanks!

    (If people think French is hard to read or speak, wait until they have to correctly write it down!)


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  6. #6
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    Also, my recollection (told to me by an antimatter researcher) is that observations support that antimatter experiences gravity in the normal way. The problem is that the error bars are very wide, so it is not possible to rule out the opposite. It's kind of like the measurement is that it is 1 +/- 2. So it could be anything from -1 (reverse gravity) to +3 (very strong gravity experience). So the intuitive conclusion is that it is +1.
    As above, so below

  7. #7
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    There are also some pretty sound indirect arguments (backed up with measurements) that antimatter should respond to gravity normally.
    Conserve energy. Commute with the Hamiltonian.

  8. #8
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    Quote Originally Posted by Grey View Post
    There are also some pretty sound indirect arguments (backed up with measurements) that antimatter should respond to gravity normally.
    For example: Electromagnetic energy is expected to curve space-time as much as its equivalent mass. If antimatter behaved opposite to matter gravitationally, pair production would take a positive gravitational mass and transform it into a net zero gravitational mass, and annihilation vice versa. The net mass of a system could vary back and forth. You could make an overbalanced wheel from a ring of magic boxes that just convert back and forth between energy and equal quantities of matter and antimatter.

    Or do something more direct: once separated enough that their mutual charges don't pull them back together, gravity would pull a particle and antiparticle apart, increasing their electrostatic potential energy. You could build a free energy machine that uses gravity to separate particles and antiparticles.

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