Measuring spin of a free electron

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    Electron Measuring Spin
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Discussion Overview

The discussion revolves around the possibility of measuring the spin of a free electron without the necessity of interacting it with a magnetic field. Participants explore theoretical approaches and implications related to the measurement of electron spin, referencing the Stern-Gerlach experiment and related concepts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant asserts that measuring the spin of a single electron without interaction is not feasible, as any measurement would inherently involve interaction that could alter the spin state.
  • Another participant suggests that while measuring a single electron's spin may not be possible without interaction, one could infer properties of a group of electrons by demonstrating their fermionic nature and observing interactions with known spin states.
  • A different perspective proposes that it might be possible to change the orientation of the spin through a sequence of accelerations, implying a method to measure the spin directly.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of measuring electron spin without interaction, with some agreeing on the necessity of interaction while others propose alternative methods. The discussion remains unresolved regarding the practicality of these approaches.

Contextual Notes

Participants mention specific theoretical concepts such as the Pauli exclusion principle and Thomas precession, but the discussion does not resolve the implications of these concepts for measuring spin without interaction.

Frank Einstein
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Hi everybody. I have been reading about the Stern Gerlach experiment lately and a doubt has came to my mind.
Is there any way to know the spin of an electron without forcing it to interact with a magnetic field?

Thanks for reading.
 
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If you're sticking to the spin of a single electron, I'd say no.
Theoretically, to measure the spin of an electron would require interacting with it in a way that can in principle (however slightly) change its spin state.
As far as I know, the only interactions capable of changing the spin-state of an electron are magnetic.

However, if you're going to measure the spin of a whole bunch of electrons, you could at least narrow it down by showing that they are fermions (i.e., half-integer spin particles obeying the Pauli exclusion principle).
For example, since a pair of electrons cannot occupy the same state, you could try to bring other electrons with known spin states close, and see how the repulsion between them changes depending on the spin state of the known electron. Ideally, the electron in a spin state most closely resembling the spin state of the unknown electron would have a maximum repulsion.

There may also be quirks of statistics that will distinguish a bunch of spin-1/2 particles from a bunch of spin-3/2 particles, but I don't know enough to say just what that would be.
 
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Thank you very much for your anwser. That's pretty much what I thought that would happen.
 

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