Every time a car reverses, those little bumps on the bumper switch on and start doing something remarkable.

Daniel noticed the beeping getting faster as Mom reversed into a parking spot. So he asked what was actually happening.

The answer turns out to be something bats figured out millions of years ago.

Parking sensors work through a process called echolocation — the exact same principle bats use to navigate in the dark. The sensors send out high-pitched sound waves, far above the highest sound a human ear can hear. Those waves travel through the air, hit whatever is behind the car, and bounce straight back. The sensor measures how long the echo takes to return. A long return time means the object is far away — slow beeps. A short return time means it's close — faster beeps. When something is very close, one continuous tone. Sto ...