Fermat's Principle and Quantum Electrodynamics

In this short video I would like to tell you about the pioneering work of Pierre de Fermat, who discovered that light is the laziest object in the universe, always preferring to take the path that minimises the amount of time spent travelling between two points. But perhaps what is even more exciting is that Fermat’s principle lies at the heart of one of the most successful scientific theories ever created, quantum electrodynamics. In this video I would like to show you why light is so lazy, and how Fermat’s principle connects with our modern formulation of quantum electrodynamics. So, if you are ready for the ride, let's get started.

For an excellent non-technical overview of quantum electrodynamics, I highly recommend Richard Feynman's book QED: The strange theory of light and matter.

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Видео Fermat's Principle and Quantum Electrodynamics канала Physics Explained