1Two racers leave at the same time
One is lightning-fast. One is a slowpoke.
Every bolt fires off two things at once: a flash of light and a clap of sound. Watch how fast each one crosses the same little lane:
Light — the flash
Crazy fast. Light crosses a whole room before you can blink. Over a storm, it reaches your eyes almost the instant it's made.
Sound — the boom
A slowpoke. Sound ambles along about as fast as a jet plane — roughly 1 kilometer every 3 seconds. Way slower than light.
2Two kinds of storm
Right on top of you, or far away
Here are the two cases at the heart of the puzzle. The dots show when each racer reaches you — see how big the gap is in each one:
The close storm
Flash and boom arrive almost together — there's barely any distance for sound to fall behind.
The distant storm
The flash is long gone before the boom shows up — a big gap opens between them.
3Your turn — fire the bolt
Race the flash and the boom to you
The bolt is at the top, you're at the bottom. Hit Strike! and watch the gold flash zoom down while the orange boom crawls. The timers show when each one reaches you.
4Now the real question
What happens to the gap as you move away?
You start standing right under the storm. Now you back away from it, step by step. Before you try it — make a guess.
Guess before you find out
The flash and the boom are born at the same instant in the bolt. As you drag yourself farther from the storm, what happens to the gap between seeing the flash and hearing the boom?