Dear Trinity (uber cool name). On behalf of Blast Science, thanks for writing in, and sending in your very excellent question. Invisible stuff is really difficult to see, much less explain, so how do we know they are there? It makes perfect sense that it doesn't make sense. The name is in the answer. Hertz. Heinrich Hertz. Lydia's super smart dad, Alex Nicholls helped us with this one. Read on. Read out-loud if it helps. It always helps me.
Radio waves are a type of electromagnetism. Radio waves have frequencies, and like all other electromagnetic waves, they travel at the speed of light. Radio waves happen naturally, google "listening to space" sometime. Sound from Space, waves making sound. It blew my mind the first time I heard it. Artificially generated radio waves are used for radio and TV, and navigation and communications systems, like airports... the military. .So, real waves, fake waves.
Now, Different frequencies of radio waves have different characteristics in the Earth's atmosphere; long waves may cover a part of the Earth very consistently, shorter waves can reflect off the ionosphere and travel around the world, and much shorter wavelengths bend or reflect very little and travel on a line of sight. Sound is pressure and has to push air molecules out of the way. Light shines right through. Quickly. Have a look at the difference between the speed of sound, and the speed of light...you'll see what I mean.
All electromagnetic radiation is light, but we can only see a very small portion of this radiation—the portion we call visible light. Infra-red light is off the spectrum on the red side of light. If you ever shine a light through a prism, the wavelengths separate into the colours of the rainbow because each colour IS a different wavelength. Another weird name to remember, Roy G. Biv. They are the colours of the rainbow. (red orange yellow green blue indigo violet). Thirdly, another name to remember is Newton.
Isaac Newton's experiment way back in 1665 showed that a prism bends visible light and that each colour refracts at a slightly different angle depending on the wavelength of the colour. Read that sentence again if you have to, it's important. He was amazing. Each colour in your rainbow corresponds to a different wavelength of the electromagnetic spectrum. And lucky ol radio waves have the longest wavelengths in the electromagnetic spectrum.
So, Heinrich Hertz proved the existence of radio waves in the late 1880s. They were already there, just like Gravity was to Newton. But he explained it with an experiment. He used a spark gap attached to an induction coil and a separate spark gap on a receiving antenna. When waves created by the sparks of the coil transmitter were picked up by the receiving antenna, sparks would jump its gap as well. Hertz showed in his experiments that these signals possessed all the properties of electromagnetic waves. A radio of phone tower is a massive antenna for transmitting radio waves.
When you tune a radio to a specific wavelength—or frequency—and listen to your favourite music, I like Absolute 80's when I'm cooking dinner... The radio "receives" these electromagnetic radio waves and converts them to mechanical vibrations in the speaker to create the sound waves you can hear. A Hertz (his namesake) is a unit of frequency, written Hz. Bingo The truth....Hertz. (sorry, I couldn't pass up that joke). Keep it real, and keep in touch, Trinity. Thank you for your question.