Rigged Hilbert Space Φ ⊂ H ⊂ Φ'

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Discussion Overview

The discussion revolves around the concept of Rigged Hilbert Spaces, specifically the relationship between the subspace Φ, the Hilbert space H, and the dual space Φ'. Participants explore the implications of these relationships, including theorems and examples related to quantum mechanics and the behavior of wave functions in various potential scenarios.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants question how H can be a subset of Φ' given that Φ' relates to Φ, and they seek clarification on this relationship.
  • Others propose that since H is its own dual, it must also be included in the dual of Φ, suggesting that H is a subset of Φ'.
  • A participant suggests a theorem Φ⊂H ⇒ H' ⊂ Φ' and discusses the implications of this relationship.
  • Concerns are raised about the application of the momentum operator in the context of a square well potential, indicating potential issues with boundary conditions.
  • Another participant discusses the behavior of expectation values for different potentials, suggesting that a mathematically smooth potential may resolve divergence issues seen in the square well case.
  • There is a discussion about the differences between finite and infinite square wells, with participants noting that these cases cannot be rigorously connected through limits.
  • One participant shares detailed calculations related to the wave function of a square well potential and its implications for expectation values.

Areas of Agreement / Disagreement

Participants express differing views on the relationships between the spaces Φ, H, and Φ', with some agreeing on certain theorems while others question the implications. The discussion remains unresolved regarding the application of operators and the behavior of expectation values in specific potential scenarios.

Contextual Notes

Some participants note limitations in their understanding of the mathematical details and the need for further exploration of the concepts discussed, particularly regarding the application of theorems and the behavior of wave functions in quantum mechanics.

Who May Find This Useful

This discussion may be useful for those studying quantum mechanics, particularly in the context of Rigged Hilbert Spaces and their applications in theoretical physics.

  • #61
sweet springs said:
Another idea to remove for the difficulty is modification of energy eigenfunction; [...]
It is usually more profitable to study thoroughly what other people have already achieved before constructing one's own theory.

In this vein, it may be helpful to study distribution theory more deeply. I found Appendix A of Nussenzveig's book on "Causality and Dispersion Relations" quite helpful.
 
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  • #62
Thanks for your comment.
I am excited to know that the square well potential that appears n many QM textbooks seems to have something more to be explored.
I agree with you that I should learn more.
 

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