Poisson brackets and classical conserved observables
In canonical coordinates, {A,B}=Σ_i[(∂_q_iA)(∂_p_iB)−(∂_p_iA)(∂_q_iB)] and dA/dt={A,H}+∂_tA.
Key knowledge
In canonical coordinates, {A,B}=Σ_i[(∂_q_iA)(∂_p_iB)−(∂_p_iA)(∂_q_iB)] and dA/dt={A,H}+∂_tA. A time-independent A with {A,H}=0 is conserved; a cyclic coordinate has conserved conjugate momentum, while H is conserved when it has no explicit time dependence.
Values and equations
{A,B}=Σ_i(∂_q_iA ∂_p_iB−∂_p_iA ∂_q_iB); dA/dt={A,H}+∂_tA
- A,B
- Phase-space observables; their own units
- q_i,p_i
- Canonical coordinates/momenta; product has action unit J s
- H
- Hamiltonian J
- t
- Time s
- i
- Coordinate index
Conditions and scope
- Smooth regular finite-dimensional canonical Hamiltonian system; generalized momentum units correspond to action divided by coordinate units.
- H need not equal physical total energy in time-dependent coordinates. Explicit time dependence of A must be retained.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Quantum Mechanics (2013): Classical Poisson brackets: Equations 92–101: canonical evolution and bracket; explicit ∂_tA restored to source's time-independent expression.
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Entry details
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- physics-poisson-bracket-dynamics
- Revision
- university-core.1
- Structured reference record
- University core expansion