Ask a Physicist: Rudolph the Redshifted Reindeer

Visiting every house in the world in one night is a tough job, even when you don't count the difficulty of squeezing down a chimney after eating a few million Christmas cookies. Just from a logistics perspective, it's a nightmare: finding the most efficient route between a bunch of points on a map (the so-called "Traveling Salesman" problem) is such a notoriously difficult nut to crack that it seems we've got no shot at doing it efficiently without quantum computing.For a sense of scale, one of ...