How Does Paul Stretch Work?

We've had lots of follow-up on super slow music. A few people have told us why this exists and a few people have sent us in some stuff that makes it. Xantor E on the Reddit has sent in a link to a software called Paul Stretch, which is free and the source code is available online. He also provided a explanation for how this works. I'm not even going to attempt it because it confuses me. Yes. It's math magic. The way you pronounce that word is not even, I was like Fourier. But, Fourier, how did you say it? I think it's Fourier. Fourier, Fourier,. Fou fancy