ABSTRACT

In 1924 a young PhD student submitted a thesis containing the germ of an idea that would revolutionize our understanding of the material world.3 e student was Louis De Broglie4 (pronounced De Broy), and for a while he had been meditating on the wave/particle nature of light. In a moment of insight he suddenly realized that the odd behavior of light might extend to other aspects of nature as well. Perhaps particles, such as electrons, could have a wavelike nature to balance the particlelike

nature of light, which had been thought of as a wave. Echoing the Planck-Einstein formulas for photons, De Broglie proposed that electrons should have a ‘pilot wave’ with frequency ( f ) and wavelength (λ) given by

h mv

f E h

His thesis also contains an explanation for Bohr’s quantized orbits in hydrogen. If an orbiting electron had a ‘corresponding’ wave, it would have to close on itself around the circular arc of the orbit. is forces the circumference of a satisfactory orbit to be a whole number multiple of the wavelength (see Figure 18.1).