Physicists at NYU have discovered a new type of time crystal—an exotic state of matter whose particles rhythmically “tick” while levitating on sound waves.

A strange form of matter called a time crystal has fascinated physicists for about a decade. These systems move in repeating cycles, even without a steady external push.

A team at New York University has discovered a new form of time crystal that hovers using sound waves. Unlike ordinary matter, these crystals seem to behave in ways that don’t align with Newton’s ...