Uncertainty Principle & Non-Commuting Observables

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Discussion Overview

The discussion revolves around the relationship between non-commuting observables and the uncertainty principle in quantum mechanics. Participants explore whether all non-commuting observables generate an uncertainty principle and the implications of this relationship.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • Some participants question if all observables that do not commute necessarily generate an uncertainty principle.
  • One participant asserts that the uncertainty principle applies to all observables, suggesting that knowing the non-commuting nature of observables introduces uncertainty about their values.
  • Another participant elaborates that non-commuting observables indicate a dependence between them, which can lead to various forms of generalized uncertainty relations, not limited to the standard position-momentum case.
  • A later reply presents a mathematical formulation of the uncertainty principle, relating the uncertainty to the commutator of the two observables.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether all non-commuting observables generate an uncertainty principle, with multiple competing views expressed throughout the discussion.

Contextual Notes

The discussion highlights the variability in interpretations of the uncertainty principle and the dependence on the specific observables being considered. There are unresolved aspects regarding the nature of the generalized uncertainty relations mentioned.

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Do all observables which do not commute generate an uncertainty principle ?
 
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The uncertainty principle applies to all observables. The act of knowing that the object does not commute makes you unsure about where it is.
 
Anupama said:
Do all observables which do not commute generate an uncertainty principle ?
Yes you can put it like that, depending on what mean by uncertainty principle.

That observables does not commute simply means that they aren't independent. The details of this dependence can vary depending on what observables we talk about. "Conjugate variables" are related by means of the Fourier transform and is what one most commonly refers to. But in principle one can imagine any relation between independent variables that will imply some kind of "generalized uncertainty relation" that described a relation that constraints their mutual possible values, but not necessarily a simple one like for the case of x and p.

/Fredrik
 
Anupama said:
Do all observables which do not commute generate an uncertainty principle ?

Yes, the general uncertainty principle relates the uncertainty to the commutator of the two observables:

##\sigma_A^2 \sigma_B^2 \ge (\frac{1}{2i}\langle [\hat{A}, \hat{B}] \rangle)^2##
 
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