Physics
Inverse Square Law
Quick fact
The inverse square law is why a planet's orbital speed decreases with distance from the Sun – a key insight that helped Newton deduce gravity's nature.
Why this is interesting
You can feel the warmth of a fire from close up, but step back a few feet and it's much weaker. Why does the heat drop off so quickly? The answer reveals a hidden pattern that runs from the smallest atoms to the largest galaxies.