system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How is data encoded on light?

For example, subsea fiber optic cables are responsible for nearly all of the information transmitted on the internet. These cables carry light (i.e. information) from one end to the other. What I’m struggling to understand is how this light can even hold information that we can then interpret.
gpt
Imagine two kids live across the street from each other. They want to talk at night, but don't have phones. They DO have flashlights. So they find a guide to Morse Code in a magazine. By flashing patterns of long light, short light, and pauses at each other, they can send words and sentences. Slowly. Life was pretty boring before phones but it was what it was.

Now imagine instead of two kids, it's computers. They can detect minuscule patterns of fluctuation in the light's brightness that last for fractions of a second. They're connected via a wire that carries the light. So one "listens" and looks at the patterns of light, and the other "talks" and sends the light. Software decodes the fancy patterns into data.