In quantum physics, “why” is a bit of a dirty word. You aren’t really supposed to ask why a wave can seem to bounce off itself in a classic two-slit experiment, why it can in fact be proven to bounce off itself, nor why particles can occasionally “tunnel” through insurmountable barriers as though they weren’t there at all. Quantum physics is great at describing such subatomic impossibilities and can even make useful predictions about how we could exploit them practically, but it says nothing about a principle that could actually explain them. Super-string theory is one possible answer, along with the perhaps more fantastical Many Worlds hypothesis. First popularized in the 1950s, this is the…