Radio
From Slackerpedia Galactica
Part of the electromagnetic spectrum in the frequencies below that of visible light. Humans on the planet Earth tend to waste it by transmitting mindless television, brain-dead corporate music, and boring talk shows to each other. Astronomers on Earth can use it more productively to look at the universe. What any (hypothetical) aliens use it for is unknown to us.
External Links
Radio on Wiki.
