The Physical Jew

[Alex K]

If you're not living in a cave hitting rocks against each other, you are using this guy's discovery.

Heinrich Hertz

He, of course, demonstrated the existence of electromagnetic waves. The fact that light is actually waves of electric and magnetic fields was predicted theoretically by J.C. Maxwell some years before (when he introduced the crucial part into the equations of electromagnetism which describes how electrical fields can create magnetic fields in mid-air without the presence of charges), and Hertz is the guy who showed the world that this is not only true, but that these waves can be easily created using electrical equipment. The rest is, as they say, history.