For years, scientists have been trying to discover the size at which solid materials could change their internal structure in a single, swift step, like molecules do during isomerization. This unanswered question has been the missing link in scientists’ quest to map and understand the crossover from molecular isomerization, such as those that make eyesight possible, to bulk phase transitions, like the transition of graphite into diamonds. If understood, these processes could be useful for applications such as energy harvesting or quantum computing. In their recent paper published in Science (DOI: 10.1126/science.aau9464), Professors Tobias Hanrath and Richard Robinson finally reveal that a “magic size cluster” bridges this divide between how matter rearranges in the small scale of molecular isomerization and in large, solid bulk matter phase transitions.