Action (physics)

In physics, the action is a particular quantity in a physical system that can be used to describe its operation in an alternative manner to the usual differential equation approach. The action is not necessarily the same for different types of system.The contemporary action approach for physical systems yields the same results as those found using differential equations to describe the system, but only requires the states of the physical variable to be specified at two points, called the initial and final states. The values of the physical variable at all intermediate points may then be determined by 'minimizing' the action.
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