Louis de Broglie

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   If light, which we thought was a wave, also comes as particles, perhaps particles such as the electron also behave as waves. Louis de Broglie proposed this in 1924, and in 1927 electrons did in the lab exactly what waves do.

   The wave nature of the electron (prelegerea Nobel, 12 decembrie 1929) · 1929

   Every object has a wave, but the heavier and faster it is, the shorter and harder to see that wave becomes.

   After Einstein, light had two faces: wave and packets. A young French prince, Louis de Broglie, turned the question around. If light, thought to be a wave, also has a particle face, why shouldn't particles such as the electron also have a wave face? In the doctoral thesis he defended in Paris in November 1924, he even gave a rule: the heavier and faster an object is, the shorter its wave. The idea seemed so bold that his examiners asked for Einstein's opinion. Einstein replied that de Broglie had lifted a corner of the great veil. The proof came in 1927. At Bell Laboratories in New York, Clinton Davisson and Lester Germer sent electrons at a nickel crystal. The electrons did not scatter at random; more of them came out in certain directions and almost none in others, exactly like light passing through a fine grid of lines. At almost the same time George Paget Thomson saw the same thing by sending electrons through thin metal foils. So why don't we see a football making waves? Because its wave is unbelievably short, far smaller than a proton. To notice a wave, it has to meet obstacles or gaps about its own size. For the electron, the spacing between the atoms of a crystal is right. For the ball, no goal is anywhere near narrow enough. De Broglie received the Nobel Prize in 1929, and the electron microscope, which sees viruses and atoms, relies precisely on the electron's wave.

   “For both matter and radiations, light in particular, it is necessary to introduce the corpuscle concept and the wave concept at the same time.”

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