I'm driving in my car. I turn on the radio. I listen to the Ticket my local sports/guy radio station and think no more about it. I don't ponder how in the world people miles away are regaling me with their (only half the time right) thoughts on who will win the big game tomorrow. All this as I drive around at 70 miles an hour in oft times differing directions.
I will continue to hear these savants opine until my distance is far enough away from them, that their observations start to fade and crackle as they cackle. Not to worry though as a small turn of the dial will bring in a different set of opinions on numerous topics or even the latest tune. Barring that, perhaps songs you have heard so often it makes you cringe or country (if you can still call it that).
We can thank Guglielmo Marconi for all this. He did not invent radio waves, but he did come up with a way to artificially utilize them by mimicking their patterns in both presentation and reception, which was of course a remarkable feat indeed. James Clerk Maxwell was the first to become aware of the little buggers and Heinrich Hertz the first to prove him right and finally the aforementioned Marconi the first to put them to work. All this in the span of less than 25 years at the end of the 19th century.
Radio waves travel at the speed of light. AM waves which fluctuate the strength of the signal, can travel a fair distance, impeded only by objects in their way. The thicker the object the slower the pace. This explains why AM radios are difficult to hear in tunnels, under bridges or in big cities. Sometimes though this can be a blessing.
FM radio waves vary the direction the waves journey, allowing them to be static free but they can only transmit over a much shorter distance. This is because they are limited by a longer wavelength, restricting them to the curvature of the Earth in their quest to be heard. AM can bounce back and forth between the surface and the ionosphere allowing it to travel greater distances and annoy more people with bad commercials. At night without the interference of the Sun, AM reception can increase dramatically.
Now all this is closely regulated by the government. It is the rare instance where government interference is needed in order to prevent radio interference. By allowing only one entity in each band of the wavelength spectrum we avoid a case of everyone talking at once. Although occasionally a stronger signal will bleed into a weaker one. This is why every station is constantly giving you there frequency making it easier to dial them in.
Radio waves themselves have existed forever, or at least as for as long as we can determine. Those radio waves have the longest wavelength and the lowest frequency in the electromagnetic spectrum making them ideal for use as a transmitter of sound waves.
We point telescopes at the stars to see (or hear) what we can find. Radio telescopes are not necessarily better than optical ones, they just give a different point of view. Allowing us to blend the information together for a fuller picture of the Universe. And who knows we just mind find out how the football teams are doing on Proxima B.
Finally, there are probably more songs about the radio than any other non-love related theme. This makes sense as most songs need to be played on the radio in order to be heard. And even though TV has replaced the radio as the electronic hearth it's still a major force. Watching television while driving is not advisable. Although in this day and age it's really only one more thing to add to the list of things not to do while driving.