Gravitational force between matter and antimatter

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Discussion Overview

The discussion centers on the gravitational force between matter and antimatter, exploring whether this force is attractive, repulsive, or non-existent. Participants examine theoretical predictions, experimental challenges, and the current state of research in this area.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire about the scientific consensus regarding the gravitational interaction between matter and antimatter, questioning if it is repulsive, attractive, or zero.
  • One participant suggests that the antiparticle of a photon is itself and posits that photons attract.
  • Another participant states that general relativity predicts the gravitational force between matter and antimatter to be attractive, arguing that a different interaction would violate conservation of energy.
  • Several participants agree that it is predicted to be attractive, but note that this has not yet been experimentally tested.
  • Concerns are raised about the experimental observation of antimatter's gravitational behavior, particularly regarding the challenges posed by electromagnetic fields affecting charged antimatter.
  • One participant mentions that while neutral antimatter has been produced, its gravitational properties have not been studied yet.
  • A participant references potential upcoming experiments that may measure the gravitational properties of antimatter with good accuracy, citing a specific article for further information.

Areas of Agreement / Disagreement

Participants generally agree that the gravitational force between matter and antimatter is predicted to be attractive according to general relativity, but there is no consensus on the experimental evidence, as it remains untested. Multiple views exist regarding the challenges in measuring this force.

Contextual Notes

Limitations include the dependence on electromagnetic fields affecting charged antimatter and the unresolved status of gravitational studies on neutral antimatter.

Delta2
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What is the current scientific consensus on the gravitational force between matter and antimatter. Is it repulsive, attractive or zero?
 
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Antiparticle of photon is itself and photons attract.
 
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It is a prediction of GR than it is attractive. If it were not (and indeed, not the same as for matter) it violates conservation of energy.
 
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Yes, it is clearly predicted to be attractive, but this has not been experimentally tested yet.
 
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Dale said:
Yes, it is clearly predicted to be attractive, but this has not been experimentally tested yet.
But, we've made antimatter... didn't anybody notice if the stuff tended to fall down, or up ?
 
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hmmm27 said:
But, we've made antimatter... didn't anybody notice if the stuff tended to fall down, or up ?
No. The antimatter that we have made is charged and it is hard to get a region where the EM field is so small that you can see which way it falls under just gravity.
 
Dale said:
No. The antimatter that we have made is charged and it is hard to get a region where the EM field is so small that you can see which way it falls under just gravity.
Actually, we have made neutral antimatter, but I think that their gravitational properties haven't been studied yet.
 
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If one believes the press releases, various experiments might be getting close to measuring the gravitational properties of antimatter (compared to matter) at good accuracy. Check out the following article:

AEgIs -- Cern Courier Feb 2021
 
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