ABSTRACT
Change is essential to light, and indeed any other ‘electromagnetic’ wave, like radiowaves or microwaves. And so, although it seems unlikely, to investigate light, we begin by making an imaginary wave machine. It consists simply of a rectangular magnet and a wire spiral. According to the nineteenth-century experimenter James Clerk Maxwell, it is change in a magnetic field that creates an electrical field, and change in the electrical field that creates magnetism. Sometimes electrical waves create a magnetic field that creates an electrical field that creates …. The wave that travels through an electromagnetic field at a constant velocity of 186,000 miles per second (300,000 km/s), oscillating between being electrical and magnetic all the time, is the one we know as ‘light’.
