In Maxwell's time, life was simple. These was two kinds of stuff--matter and energy. Matter was tangible and lumpy. The chemists were satisfied that matter was conserved in any chemical reaction. Energy was intangible. Energy existed as a wave and it too was conserved. Maxwell died in 1879, the same year Albert Einstein was born. By 1905, working as a patent clerk in Switzerland and aided by the work of others, most notably Max Planck, Einstein concluded that there were not two kinds of stuff (matter and energy) but rather one kind of stuff, mass-energy. The relationship connecting these two kinds of stuff is perhaps the most famous equation in the business E = m c^2. Einstein concluded that under the proper circumstances, matter could be changed energy and conversely.

Throughout the nineteenth century scientists were seeking to put order in the universe. Part of that order is symmetry. Planck had showed in his experiments that light (normally a wave) had a particle nature. The particles are bundles of energy called photons or quanta and the amount of energy each carries depends on the frequency of the wave. Arthur H. Compton was able to show that x-rays, normally waves with a short wavelength, also had a momentum.

If symmetry was to exist in earnest, should it be true that if light, which normally behaves as a wave, has a particle nature, then should not particles such as electrons have a wave nature. Should electrons have wave properties such as wavelength and exhibit diffraction, a wave phenomenon. The first person to suggest this gambit was Count Louis Victor deBroglie of France, who assigned a wavelength to the electron and made that wavelength conform to the Bohr model for the structure of the hydrogen atom. His conjecture was corroborated by electron diffraction patterns obtained by Davisson and Germer in 1923 in America and later by George Thomson in 1927 in England. Davisson and Thomson shared a Nobel prize in 1937 for their work on electron diffraction. It is ironic that J.J. Thomson spent much of his professional life showing that electrons were particles; his son George gained acclaim for showing those same electrons to have a wave nature.

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Last edited 10/18/07

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