Why is momentum referred to as 'conjugate' in physics?

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Discussion Overview

The discussion revolves around the terminology of 'conjugate momentum' in physics, particularly in the context of classical mechanics and generalized coordinates. Participants explore the reasons behind the use of the term 'conjugate' and its implications in Hamiltonian mechanics.

Discussion Character

  • Conceptual clarification, Technical explanation

Main Points Raised

  • One participant questions the origin of the term 'conjugate' in the context of momentum, specifically in relation to generalized coordinates.
  • Another participant suggests that 'conjugate' describes the pairing of momentum with generalized coordinates, referencing a dictionary definition for support.
  • A third participant notes the need for a term to distinguish it from physical momentum and explains that the term 'conjugate' becomes more relevant in Hamiltonian mechanics, where phase space coordinates are treated as conjugate pairs.

Areas of Agreement / Disagreement

Participants express differing views on the terminology, with no consensus reached on a definitive explanation for why 'conjugate' is used.

Contextual Notes

The discussion does not resolve the underlying reasons for the terminology and relies on varying interpretations of the term 'conjugate' in relation to momentum and coordinates.

snatchingthepi
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So I'm studying for my CM final and in looking over the section on ignorable coordinates and generalized momenta I come across the definition for conjugate momentum p_{i} = \frac{\partial L}{\partial \dot{q_{i}}}

My question is simple - why is it called 'conjugate'? I just never really thought to question to the name.
 
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You need a word to differentiate it from a physical momentum, I guess "generalized momentum" might also work, but the "conjugate" part comes into play more when you move to Hamilonian mechanics where your phase space coordinates are these (p,q) conjugate pairs.
 
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Thank you both.
 

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