Prove P=h/i(d/dx) from Axioms: Get an Answer

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Discussion Overview

The discussion revolves around the proof of the equation P=h/i(d/dx) based on a set of axioms in quantum mechanics. Participants express interest in understanding the derivation and the rationale behind choosing this specific operator among others.

Discussion Character

  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant requests a proof that the axioms dictate P=h/i(d/dx) and questions the choice of this operator.
  • Another participant mentions that the proof is lengthy and can be found in standard quantum mechanics texts, referencing the fundamental commutation relations.
  • A participant expresses difficulty in locating the proof in Cohen-Tannoudji's work and asks for specific keywords or phrases to aid their search.
  • One participant provides a link to a document and specifies page numbers where relevant information can be found.
  • A later reply raises concerns about the definition of momentum in the provided document, questioning the use of a Fourier Transform to represent linear momentum.
  • Another participant briefly mentions that linear functionals are involved in the discussion.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the proof or the rationale behind the operator choice, with ongoing questions and concerns about the definitions used in the context of linear momentum.

Contextual Notes

There are references to specific texts and documents, but participants express uncertainty about the definitions and representations of momentum, indicating potential limitations in understanding the axioms and their implications.

Palindrom
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O.K.

So we have a list of axioms.
Could someone please prove to me that these axioms dictate
P=h/i(d/dx)?
I'm interested in a proof, and if there isn't, why choosing this operator of all the operators that could keep the axioms?
Thanks!
 
Last edited:
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The proof is pretty long,it can be found in any book on QM (Cohen-Tannoudji,Sakurai,...),i believe i typed it once (search for it),ain't going to do it again.It comes naturally,yes from the axioms and from the coordinate representation of the fundamental commutation relations:
[tex][\hat{x}_{i},\hat{p}_{j}]_{-}=i\hbar \delta_{ij} \hat{1}[/tex]

Daniel.
 
I looked in Cohen Tanoudji, didn't find it.

Could you give me a key word or phrase to find the proof you wrote?
 
Tom Mattson said:
See pages 59-61 of the following document:

http://fafalone.hypermart.net/lectures.pdf

edit: Use the page numbers on the actual pages, not Adobe's page numbers.

First of all, thank you.

Now, we're getting to what's bothering me. In this doc., they simply define <p| as some kind of twisted Fourier Transform, which is what we did in our course as well.
Why? Why this? This is supposed to represent the old and familiar linear momentum.
 
Thanks, I'll go over it all and come back if I have complains... :smile:
 

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