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What we observe is not nature itself, but nature exposed to our method of questioning. Werner Karl Heisenberg (1901- 1976)

Wave Mechanics; Prince Louis de Broglie - WAVE MECHANICS. Prince Louis de Broglie.

—————(1892-1987)—————. In 1923, while still a graduate student at the University of Paris, Louis de Broglie was able to rethink the basics of our existence. The ageless concept of a particle world (Newtonian) was well accepted at the turn of the century. The only exception was light, in that 19 century experiments (Young) showed strong evidence that light is a wave. At the energy the experiments were conducted, light had a vary wavy distribution. But then, by the discovery of the photo electric effect and the eventual explanation found by Planck and Einstein - that at this energies light is a quanta, a localized object. The old Foundations were crumbling.

Prince Louis de Broglie, with the new knowledge of the light quanta behavior assumed that the wave and the particle are two sides of the same coin - an observable (or a wavicle). As such they share the same energy and from there the math follows:

The wavelength for the associated wave is proportional to 1 / (momentum) of the associated particle.

With the constant of proportionality being the famous Planck Constant - h

This duality, the relationshp between momentum and wavelength was tasted countless times since its discovery and is still unshaken. Carefullness must be taken when interperating this relationship. The variations in the momentum will determine - with the aid of the Heisenberg Uncertainty Principle - a finite width to the position eigenstate (a fancy word for a function that describes the state of the system - wavicle). This width in position will also be connected to the way we will measure the position of the wavicle. Thus it was posible for two distinct experiments to give different answer to the old question: What is Light.