principle of least action(redirected from Least action principle)
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principle of least action[′prin·sə·pəl əv ‚lēst ′ak·shən]
The principle that, for a system whose total mechanical energy is conserved, the trajectory of the system in configuration space is that path which makes the value of the action stationary relative to nearby paths between the same configurations and for which the energy has the same constant value. Also known as least-action principle.