The secret is in tiny localized time variations, possibly caused by neutrinos. The theory is far out, but the findings will help other scientists. test a quantum theory that flips our understanding of time on its head. Physicist Joan Vaccaro first articulated the divisive "quantum theory of time"—that "dynamics may be a phenomenological consequence of a fundamental violation of time reversal symmetry," in her words—a few years ago. But now, researchers can use neutrinos and antineutrinos to measure the passage of time within a powerful nuclear reactor. Vaccaro has been open about the theory as a far-out educated guess rather than a sure thing, and the findings should be interesting to other scientists either way.