Why does this count? Because the cutoff isn’t arbitrary. Sellke’s team showed that no matter how you cut the deck, seven shuffles force randomness. Their method tracked individual card movements, eliminating guesswork.

This matters for fields relying on randomness, from cryptography to statistical physics. The findings also resolve a long-standing debate. Earlier, Steven Lalley suspected cold spots would vanish at a cutoff, but couldn’t prove it.

Sellke’s binary labels provided the proof. The result is elegant: a single number (seven) governs chaos across systems. Diaconis, who once ran away to learn card tricks, now calls it ‘brilliant mathematics.’ The work isn’t just academic.

It could refine algorithms for secure data shuffling or model how disorder spreads in networks. For now, though, it’s a triumph of pure math—showing that even messy processes have hidden order until a critical point.