The Rosetta Stone and Quantum Waves

It was discovered in the early decades of the twentieth century that light and matter exhibit both wave-like and particle-like behaviour and this led to the development of quantum theory. Thomas Young demonstrated the wave-like behaviour of light 200 years ago. Thomas Young had wide-ranging interests and played an important role in deciphering hieroglyphic inscriptions. In 1905 Einstein showed that light also behaves like a stream of particles. Louis De Broglie suggested that particles such as electrons might also show wave-like behaviour and his prediction was soon verified in the laboratory. This led to the development of quantum mechanics, as well as important technological applications, such as the electron microscope.