Noether's theorem for finite Hamiltonian systems

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Discussion Overview

The discussion revolves around Noether's theorem as it applies to finite Hamiltonian systems, specifically focusing on how to derive first integrals from known symmetries. The scope includes theoretical aspects and mathematical reasoning related to symmetries and their implications in Hamiltonian mechanics.

Discussion Character

  • Exploratory, Technical explanation, Mathematical reasoning

Main Points Raised

  • One participant questions how to write the first integral if a symmetry is known.
  • Another participant suggests that if ##\mathbf{w}## is the vector field generating the symmetry, then it may be expressed as ##\mathbf{w}(f) = \{ f, P \}## for an arbitrary function ##f##.
  • A different participant expresses limited knowledge and describes their process of starting with the metric to write the Hamiltonian, then questioning if they can derive the field and subsequently identify a symmetry. They mention uncertainty about the application of Noether's theorem in this context.
  • One participant shares a link to a related thread, indicating a desire to connect the discussion to broader topics on Noether's theorem.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus, as there are varying levels of understanding and different approaches to applying Noether's theorem. The discussion remains unresolved regarding the specific steps to derive first integrals from symmetries.

Contextual Notes

Participants express uncertainty about the necessary steps and dependencies on definitions related to symmetries, Hamiltonians, and metrics. There are unresolved aspects regarding the application of Noether's theorem in their specific contexts.

thaalves
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TL;DR
How do I write a first integral knowing a symmetry?
The Noether's theorem for finite Hamiltonian systems says that:

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My question is: If I know a symmetry how can I write the first integral?
 
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If ##\mathbf{w}## is the vector field generating the symmetry then I think you can put ##\mathbf{w}(f) = \{ f, P \}## for an arbitrary function ##f##?
 
In fact my knowledge is very limited in this area, my situation is as follows...
I have the metric, with the metric I can write the Hamiltonian, with the Hamiltonian, can I write the field? if yes, after that do i have to look for a symmetry? Apparently once I have symmetry, Noether's theorem gives me the first integral (his proof in this case), but I'm not getting it.
 

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