According to Einstein's theory, Earth's rotation drags space-time itself along — like a spoon dragging thick honey. This effect is incredibly weak: about one revolution in billions of years. But it can be caught. Scientists propose a tabletop experiment: a sensitive detector is placed in superfluid helium — a liquid that flows without any friction. The rotation creates microscopic quantum vortices in the helium, and the device counts them with fantastic precision. Calculations show it will notice even a turn lasting four billion years — almost as long as Earth has existed. Such precision will allow testing gravity theory right in the lab, not just in space.

The device's sensitivity is such that it captures rotation trillions of times slower than the movement of a clock's hour hand. For comparison: around black holes, this same drag effect accelerates matter to near-light speeds.