Exploring the Quantum Formulation of String Theory

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Discussion Overview

The discussion centers on the exploration of a quantum formulation of string theory that does not rely on a classical Lagrangian. Participants examine the implications of such a formulation and its relationship to traditional quantum mechanics and established theories.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions whether a purely quantum formulation of string theory exists that does not begin with a classical Lagrangian.
  • Another participant points out that specifying a Lagrangian and quantizing it is standard practice in quantum mechanics.
  • A participant mentions that, to their knowledge, such a formulation does not exist but references Witten's talk on the topic.
  • One participant defines "pure quantum" as a formulation using operators and wave functions, seeking a model that operates entirely within the quantum realm.
  • Another participant expresses that their ideas for a quantum formulation involve adapting wave functions to quaternion functionals and modifying gradients, aiming for applicability to vibrating strings.
  • One participant finds Witten's talk enlightening and suggests it aligns with their inquiry, although they acknowledge their ideas are not yet a self-consistent model of quantum gravity.
  • Another participant notes that Witten's ideas could lead to a new interpretation of quantum mechanics.
  • Concerns are raised about reconciling a new formulation with the correspondence principle, which expects that new theories should reproduce known results in certain limits.
  • One participant argues that a new formulation is necessary to describe both h and alpha deformations simultaneously.

Areas of Agreement / Disagreement

Participants express differing views on the existence and nature of a purely quantum formulation of string theory. There is no consensus on whether such a formulation can be achieved without starting from classical mechanics, and the discussion remains unresolved.

Contextual Notes

Participants reference the correspondence principle and its implications for formulating new theories, indicating a dependence on established theories and limits. The discussion includes speculative ideas that have not been fully developed or validated.

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String theory is what I'm currently studying. The dominant form is the action formulation of it. A classical string Lagrangian is submitted and quantized to produce the equations of motion of a string. Is there a purely quantum formulation of string theory that doesn't start with a classical lagrangian?
 
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What do you mean by "pure quantum"? Specifying a Lagrangian and quanising is the standard also in normal quantum mechanics.
 
AFAIK such a formulation doesn't exist, but Witten mentions this issue briefly in this talk,



probably somewhere at the end.

ps for future topics you could make your topictitle a bit more specific ;)
 
I mean by pure quantum the traditional style of quantum mechanics. The use of operators and wave functions to do calculations. Now my question is ; Is there a formulation that doesn't start in classical mechanics, but purely in the quantum realm? Now the reason why I'm asking is this formulation ,puts quantum mechanics at a less than fundamental role in calculations. Also I do agree the formulation is a large part of traditional quantum mechanics to and all of quantum field theory. My ideas behind such a quantum formulation are that the wave functions are changed into quaternion functionals, that gradients are converted into total derivatives ect. This adaptation to standard quantum mechanics makes it applicable to vibrating strings.
 
The talk was very enlightening and is exactly what I was aiming for in my question. The thoughts listed in my last message are a long way from a self consistent model of quantum gravity, but possibly in the direction of Edward Witten's talk.
 
As Witten said it could very well lead to a new meaning of quantum mechanics.
 
Yes, but i don't know how to reconcile this with the correspondence principle.
 
What do you mean?
haushofer said:
Yes, but i don't know how to reconcile this with the correspondence principle.
 
Well, somehow you expect that such a formulation should be able to reproduce known theories in certain limits, say h --> 0 ( or alpha' --> 0, if you want to obtain point particle results ). This is the correspondence principle. So I would expect then that one would be able to obtain such a formulation also by quantizing a classical theory.
 
  • #10
But that's precisely why we need another formulation to describe h and alpha deformations simultaneously.
 

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