Mathematics
Fast Fourier Transform (FFT)
Quick fact
The FFT algorithm was popularized by James Cooley and John Tukey in 1965, but the core idea was actually discovered by Carl Friedrich Gauss in 1805, over a century before the age of computers.
Why this is interesting
You know how Shazam can identify a song from just a few seconds of audio? That magic relies on a clever mathematical shortcut called the Fast Fourier Transform—how can a simple algorithm unmix sound so quickly?