Gold is an element, which means you can't make it through ordinary chemical reactions — though alchemists tried for centuries. To make the sparkly metal, you have to bind 79 protons and 118 neutrons together to form a single atomic nucleus. That's an intense nuclear fusion reaction. But such intense fusion doesn't happen frequently enough, at least not nearby, to make the giant trove of gold we find on Earth and elsewhere in the solar system. And a new study has found the most commonly-theorized origin of gold — collisions between neutron stars — can't explain gold's abundance either. So...