Han Yan

The Moon is not just a rocky sphere, but a giant bell. Passing through it, gravitational waves cause it to vibrate almost imperceptibly. This tremor was predicted by Einstein, and Weber was the first to try to hear it with Earth-based detectors.

Gravitational waves are ripples in spacetime curvature that imperceptibly stretch and squeeze everything around. But the Moon, like a bell, catches these waves: as a gravitational wave passes through it, it makes our satellite vibrate.

A magnetic material can be compared to a crowd of tiny compasses. In an ordinary magnet, all the needles point in the same direction, and turning them all at once is no easy feat. Physicists have found a way to do this with an electric current.

Back in the 1960s, physicist Joseph Weber tried to catch gravitational waves using aluminum cylinders: they were supposed to tremble like tuning forks from the ripples of spacetime.