Natalie Wolchover profiles the work of Swiss physicist Nicolas Gisin, who challenges the Einsteinian “block universe” model where time is a stubborn illusion. Gisin argues that the deterministic view of physics relies on a mathematical fiction: “real numbers” with infinite strings of pre-existing digits, which implies infinite information in a finite volume. By applying “intuitionist mathematics”—a century-old framework where digits are constructed sequentially rather than existing simultaneously—Gisin suggests that the future is mathematically open. This approach treats time not as a dimension already laid out, but as a process where new information is genuinely created, offering a potential bridge between the determinism of General Relativity and the randomness of Quantum Mechanics.