One of the simplest and most common physical objects is your average crystal, a collection of atoms arranged in an orderly, repeating three-dimensional pattern. Salt, snowflakes, and the quartz in your watch are all crystals. Earlier this year, the Nobel laureate and MIT physicist Frank Wilczek proposed that the fourth dimension can be crystallized, too: There can be space-time crystals. And now a team of physicists has proposed a way to build one.
This is highly strange, but the physics make sense, according to Wilczek’s theory, which he published on the arXiv server back in February. A spacetime crystal would simply be a physical object whose regular, periodic atoms move in a regular, periodic pattern. They would move forever, with no external input.