Distinguishing electrons through spin

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    Electrons Spin
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Discussion Overview

The discussion centers around the concept of distinguishing electrons through their spin orientations in the context of Møller scattering in quantum electrodynamics (QED). Participants explore the implications of electron indistinguishability and the potential for spin state switching during scattering events.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether electrons can be distinguished by their spin orientations, suggesting that their indistinguishability complicates this notion.
  • Another participant clarifies that labeling electrons as A and B does not yield observable differences upon exchange, emphasizing their identical nature.
  • A participant expresses confusion about the possibility of electrons switching states through scattering, pondering if this is due to mixed wave functions in the scattering region.
  • There is a suggestion that while it is currently impossible to distinguish electrons, future methods may emerge to address this issue.
  • One participant asserts that the statistical properties of electrons confirm their indistinguishability, referencing the Gibbs Paradox as a supporting point.

Areas of Agreement / Disagreement

Participants generally agree on the indistinguishable nature of electrons, but there is disagreement regarding the implications of this for spin state switching and the potential for future developments in this area.

Contextual Notes

Participants express uncertainty about the mechanisms of angular momentum transfer during spin flipping and the implications of mixed wave functions in scattering events. The discussion reflects varying interpretations of indistinguishability and its consequences.

Josh1079
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Hi

I'm recently reading something about the moller scattering in QED, and I'm feeling a bit curious about how plane waves change their spin orientations (e.g. up to down)(I mean in the scenario that one is up and one is down). In the text it seems that it's because the electrons are indistinguishable, so it can end up in either final state. Therefore, I'm just wondering whether it is possible to distinguish the electrons through spin orientations. If this is not the case then I actually pretty curious about how the angular momentum is tossed between the two in order to flip the spin.

Thanks!
 
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That’s not what indistinguishable means. If you would label the electrons with A and B and exchange them (put A in the state of B and vice versa) you wouldn’t see a difference - because the two electrons are exactly the same particles. Of course you can say “I use the spin up electron to do X”, but you can’t say “I use electron A” because that doesn’t mean anything.
 
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Hi,

Sorry I'm still a bit confused about this. Does this mean that two electrons intially in different states can actually somehow switch states through scattering? Or is this because at the scattering region their wave functions are mixed so it becomes meaningless to say about which is which after leaving the scattering region?

Thanks for replying!
 
It is always meaningless to say that "this is electron A and this is electron B". Electrons are identical particles and there is no possible test you can make to check whether an electron is one or the other.
 
Josh1079 said:
If this is not the case then I actually pretty curious about how the angular momentum is tossed between the two in order to flip the spin.
Aren't we all... no one really knows. I agree it's not possible now, but I imagine there might be ways in the future...
 
jerromyjon said:
Aren't we all... no one really knows. I agree it's not possible now, but I imagine there might be ways in the future...
We can test if they are exactly identical and indistinguishable. They are.
 
jerromyjon said:
I agree it's not possible now, but I imagine there might be ways in the future...

That's simply untrue. (I note in passing you have been posting a lot of incorrect things lately. It is better to ask questions) The statistical properties of electrons are those of particles that are not distinguishable even in principle. See, for example these notes on the Gibbs Paradox.
 

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