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Lagrangian and Hamiltonian. What are these in layman terms?

  1. Jul 1, 2015 #1
    All I know is that Lagrangian is kinetic energy- potential energy and Hamiltonian is kinetic energy + Potential energy.

    Why do we calculate the lagrangian or hamiltonian?
  2. jcsd
  3. Jul 1, 2015 #2
    When the Lagrangian is maximised it gives equations of motion.
  4. Jul 1, 2015 #3


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    Why do we do anything in physics? We do it because it gives a good description of what we can observe.
    No, when the action is extremised (i.e., maximised, minimised, or finding a saddle point) we find the equations of motion. The action is the time integral of the Lagrangian.
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