What is the most general mathematical framework for quantum

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Discussion Overview

The discussion revolves around identifying the most general mathematical framework for quantum mechanics, examining various approaches such as Hilbert spaces, C*-algebras, and rigged Hilbert spaces. The scope includes theoretical considerations and the implications of these frameworks on the representation of states, particularly mixed states and unbounded operators.

Discussion Character

  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants argue that the Hilbert space approach does not adequately include distributions or mixed states.
  • Others suggest that the C*-algebra approach fails to account for unbounded operators.
  • One participant claims that the rigged Hilbert space approach also does not include mixed states.
  • Another viewpoint proposes that a comprehensive mathematical framework for quantum mechanics may not exist due to implications related to Gödel's incompleteness theorem.
  • Some participants propose that combining all three approaches could yield a consistent and rigorous framework for non-relativistic quantum theory.
  • A participant mentions the necessity of C*-algebras for dealing with infinite particle scenarios, particularly in the thermodynamic limit.
  • There is a challenge regarding the assertion that the Hilbert space and rigged Hilbert space approaches do not include mixed states, with a reference to the use of operators instead of vector space elements.
  • One participant recommends studying Ballentine's work as a powerful formulation of quantum mechanics.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the adequacy of different mathematical frameworks for quantum mechanics, and the discussion remains unresolved with no consensus reached.

Contextual Notes

Participants highlight limitations in the existing frameworks, including the treatment of mixed states and unbounded operators, but do not resolve these issues.

lfqm
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1.- The hilbert space approach does not include distributions (free particle, for example) nor mixed states.
2.- The C* algebra approach does not account for unbounded operators.
3.- Rigged Hilbert space approach does not include mixed states.

I'm not sure about path integral formulation... so I ask... What is the most general mathematical framework for quantum mechanics
 
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Maybe such mathematical framework cannot exist because it would imply the existence of number operators, hereby violating Gödels incompleteness theorem?
 
Lfqm, why do you think 1. and 3. don't include mixed states?
 
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I'd say all three approaches together make up a consistent rigorous mathematical framework for non-relativistic QT.
 
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I just started reading a bit on operator algebra's and apparently you need c*-algebra's to deal with situations where an infinite amount of particles are present, as in the thermodynamic limit. (http://www.springer.com/us/book/9783540170938)
 
George Jones said:
Lfqm, why do you think 1. and 3. don't include mixed states?

Off course it does. That's because states are not elements of a vector space but are operators.

Study Ballentine.

This book gives our most powerful, complete and rigorous formulation:
https://www.amazon.com/dp/0387493859/?tag=pfamazon01-20

In practice most physicists use Diracs formulation which is made rigorous by the rigged hilbert space approch.

Thanks
Bill
 

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