electromagnetic spectrum

The electromagnetic spectrum is the full family of light — not just the light you can see, but every kind of electromagnetic wave, lined up from the longest, laziest waves to the shortest, most energetic ones. Radio waves sit at one end, then microwaves, infrared (heat you feel), the rainbow of visible light, ultraviolet, X-rays, and gamma rays at the other end.

What makes them all the same thing is that they're all waves of electric and magnetic energy moving at the speed of light. The only real difference is the size of the wave: a radio wave can be longer than a building, while a gamma ray is smaller than an atom. Shorter waves pack more punch, which is why X-rays can pass through you and gamma rays can be dangerous.

Here's the humbling part: the colors your eyes can detect — red, orange, all the way to violet — are a razor-thin sliver of the whole spectrum. Almost everything around you is glowing in light you simply can't see, from the WiFi in the air to the warmth of your own body.