For more than a century, the zipper has stayed more or less the same: two interlocking rows of teeth, a sliding pull, and the fabric tape that holds it together. It’s one of those inventions that conquered the world by blending into it. Billions are used every day, yet few people ever stop to think about how they work.Now, after a hundred years of stasis, YKK, the Japanese company that makes roughly half the world’s zippers, has decided it’s time to rethink the mechanism that holds much of moder...