Imagine molecules almost completely frozen in space. Theoretically, a short pulse (a delta kick) can reduce their thermal motion to picokelvin temperatures — as if a hurricane suddenly died down to a dead calm. This achievement rivals the records for atoms and promises ultra-precise tests, such as: does everything fall the same way?
A push at the right moment stops a swing. The delta-kick—a short laser pulse—was applied to a cloud of molecules, and it froze, like a swing after a precise kick. Molecules made of two different atoms, like a seat firmly locked to the swing’s bar, didn't fall apart during deceleration. The temperature dropped to picokelvins—trillionths of a degree above absolute zero, where motion nearly freezes and энтропия (a measure of disorder) becomes minimal. Even the internal jitter of atoms didn't disturb the stillness—like a passenger's slight swaying doesn't change the swing's motionlessness. An unexpected fact: at this temperature, the molecular cloud expands slower than grass grows. Now these nearly immobile objects are used to test the law of universal gravitation, which Галилей tested by dropping cannonballs from a tower, and Эйнштейн linked to кривизной пространства-времени. Based on them, scientists will build световую молекулярную интерферометрию—a device capable of detecting even the tiniest deviations.
🎯 At a temperature of one picokelvin, molecules move so slowly that crossing the width of a human hair would take them a full minute.