Does the mass difference between p+ and e+ explain differences wrt e- ?

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Discussion Overview

The discussion explores the differences between electrons and positrons in the context of their interactions with protons and the implications for atomic structure, particularly focusing on a hypothetical scenario involving a hydrogen atom with a positron replacing the proton. The scope includes conceptual reasoning and theoretical implications of particle interactions.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant proposes a Gedankenexperiment involving a hydrogen atom where the proton is replaced by a positron, questioning why the electron does not collapse into the nucleus as it would in a similar scenario with a proton.
  • Another participant clarifies that the electron and positron do not annihilate because they are not antiparticles, noting that the electron's wave function has a finite probability of being at the location of the proton.
  • A later reply acknowledges the contribution of the discussed effect in positronium, suggesting it helps explain the relatively long lifetime of positronium compared to other particles.
  • It is mentioned that if the electron and positron are spin aligned, the lifetime of positronium can be extended significantly.
  • One participant expresses appreciation for the insights shared in the discussion, indicating that the information is enlightening.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the implications of the mass difference between protons and positrons, and multiple viewpoints regarding particle interactions and lifetimes remain present.

Contextual Notes

The discussion does not resolve the assumptions regarding the nature of particle interactions or the specific conditions under which the described phenomena occur.

nomadreid
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My question is best explained by a Gedankenexperiment. First we have a hydrogen atom, with the electron not collapsing into the nucleus for the well-known reason of its minimum energy being above that needed to overcome the Coulomb force. Fine. Now replace the proton in the nucleus with a positron. Blip! the electron and positron annihilate. But the Coulomb forces are the same, the electron's energy is still quantised, so why doesn't the same mechanism work?
 
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The electron wave function does not vanish at the origin so the electron does have a finite probability of being at the location of the proton. They do not annihilate because they are not antiparticles.
 
Thank you, Meir Achuz. I had not considered this aspect. That puts a new light on the problem.
 
The effect you're talking about does contribute in positronium: in some sense it helps explain why positronium should live so long (0.1 ns). This is enormous in the sense that it is larger than the lifetime of some neutral mesons which can only decay through the weak force. (I'm thinking of the K short here).

If the electron and positron are spin aligned, you actually can have it live even longer: on the order of 100 ns
 
BHamilton: thank you for that information; it is very interesting and enlightening.
 

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