The requirement that the above integral be minimized is called the “Principle of Least Action” 1 , and is thought to be the fundamental principle that describes all of the laws of physics. Thus, in th...The requirement that the above integral be minimized is called the “Principle of Least Action” 1 , and is thought to be the fundamental principle that describes all of the laws of physics. Thus, in the Lagrangian formulation, one first writes down the Lagrangian for the system, and then uses the Euler-Lagrange equation to obtain the “equations of motion” for the system (i.e.
