Hertz lived from 1857 to 1894 and was the first to demonstrate experimentally the production and detection of Maxwell's waves. This discovery of course lead directly to radio, television, and radar. As interest in this phenomenon grew, a physical model to describe it was proposed. It was suggested that electromagnetic waves were like sound waves and that they propagated through some previously unknown medium (as sound waves propagate through air) that was called the luminiferous ether. Another scientist, Michelson, assisted by Morley, performed a remarkably clever experiment that proved the non-existence of this ether. What then were these waves which behaved like waves but yet were not like waves?
It is interesting to note that the photoelectric effect was first discovered by Hertz accidentally while carrying on these investigations in 1887.