A common misunderstanding about wave-particle duality

‘Particles caught morphing into waves’ was how a recent preprint from researchers in France was widely reported. The timing could not have been better, for this year is the centenary of Louis de Broglie’s remarkable and bold thesis – presented at the Sorbonne in Paris, where some of the team responsible for the new work are based – proposing that matter can behave like waves. De Broglie’s idea was dismissed at first by many of his contemporaries, but was verified three years later when Clinton Davisson and Lester Germer at Bell Laboratories in New York, US, observed diffraction of electrons – an unambiguously wave-like phenomenon – from crystalline nickel. Such waviness became enthroned as a central concept in the newly emergent quantum mechanics under the now famous rubric of ‘wave-particle duality’.