Least Action
Full Title
The Principle of Least Action in Quantum Mechanics[1] was Feynman's 1942 PhD thesis.
Context
This thesis introduced the ideas that came to be known as the [https://en.m.wikipedia.org/wiki/Wheeler%E2%80%93Feynman_absorber_theory Wheeler–Feynman absorber theory (also called the Wheeler–Feynman time-symmetric theory) ]derived from the assumption that the solutions of the electromagnetic field equations must be invariant under time-reversal transformation, as are the field equations themselves. Indeed, there is no apparent reason for the time-reversal symmetry breaking, Maxwell's equations and the equations for electromagnetic waves have, in general, two possible solutions: a retarded (delayed) solution and an advanced one. This symmetry can be viewed as the primary distinction between the laws of physics versus the common sense laws or time as we experience it.
The Principle
The principle of least action originates in the idea that, if nature has a purpose, it should follow a minimum or critical path. This simple principle, and its variants and generalizations, applies to optics, mechanics, electromagnetism, relativity, and quantum mechanics, and provides an essential guide to understanding the beauty of physics.[2]
References
- ↑ Richard P. Feynman, The Principle of Least Action in Quantum Mechanics, Princeton University 1942, reprinted in Feynman's Thesis, Ed Laurie M. Brown, 2005 ISBN 9789812563804
- ↑ Alberto Rojo and Anthony Bloch, The Principle of Least Action = History and Physics Cambridge UP (2018-04) ISBN: 9780521869027
Other Material
- See wiki page on the Eventful Universe
- You Tube Video for novices.
