Can time be a generalized coordinate?

AI Thread Summary
Time is generally not considered a generalized coordinate in classical dynamics, as it functions more as a parameter that describes the evolution of a system rather than a quantity like position or energy. The mainstream view supports this notion, indicating that time cannot be treated as a generalized coordinate. Some literature explores the idea of time and energy as conjugate variables in extended phase space, but this approach is not widely adopted due to its complexities. The discussion emphasizes that unless specifically addressed in the context of extended phase space, time should not be treated as a generalized coordinate. Overall, the consensus leans towards the rejection of time as a generalized coordinate in classical dynamics.
Visceral
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The title pretty much says it. According to my book, Classical Dynamics by Thornton and Marion, generalized coordinates can be quantities other than position such as energy or length squared, but what about time?
 
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Visceral said:
The title pretty much says it. According to my book, Classical Dynamics by Thornton and Marion, generalized coordinates can be quantities other than position such as energy or length squared, but what about time?
I guess, time is not a quantity in the sense of your book. It is the parameter parameterizing the dynamics.
 
A. Neumaier said:
I guess, time is not a quantity in the sense of your book. It is the parameter parameterizing the dynamics.

I was just working on a problem the other day that had force as a function of position and time, and had to derive the potential and then the lagrangian and hamiltonian. So essentially, the answer is no?
 
nlsherrill said:
I was just working on a problem the other day that had force as a function of position and time, and had to derive the potential and then the lagrangian and hamiltonian. So essentially, the answer is no?
The main stream view is indeed ''no''. But there is a trickle of literature (I don't remember precise references now) which works in extended pase spase where time and energy are anotherr pair of conjugate variables. However, this approach has its own pitfalls and is not widely used because of that.
Certainly it is not meant in your case unless your book explicitly discusses extended phase space.
 
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