ABSTRACT
As we learned in Chapter 7, light shows both particle and wave behavior. We have arrived at this conclusion through the attempts of twentieth-century physicists to understand the nature of matter. Some of the Greek philosophers believed that light consisted of particles that traveled in straight lines at high speeds and stimulated the sense of vision as they entered the eye. At the end of the fteenth century, Leonardo da Vinci speculated that light was a wave because of the similarity between the reection of light and the echo of a sound. In the seventeenth century, the Dutch physicist Christiaan Huygens also felt that light was a wave. However, his contemporary Isaac Newton thought that light was composed of particles. Newton’s corpuscular theory prevailed for about two hundred years, although by the eighteenth century many optical effects had been explained in terms of the properties of waves. In the early nineteenth century, Thomas Young in England and Augustin Jean Fresnel in France demonstrated in a series of landmark experiments that light showed interference and diffraction, phenomena characteristic of waves. In Scotland, Maxwell theorized that light was the propagation of oscillating electric and magnetic elds through space: an electromagnetic wave.
