Here’s a frequency fact that hits all the right notes: the unit “Hertz” (Hz) is named after Heinrich Hertz, the physicist who first proved the existence of electromagnetic waves in the late 1800s. But here’s the kicker—when asked about the usefulness of his discovery, Hertz famously said it was of “no use whatsoever.” Fast-forward to today, and we use Hertz to measure everything from Wi-Fi signals to your favorite tunes.

And for a quirky twist: some turtles communicate from inside their eggs using ultra-low-frequency sounds to coordinate hatching. Nature’s got rhythm too!