Javlon Rayimbaev

A superconducting contact is like a narrow bridge between two shores, carrying current without friction. Place such a bridge near a massive star, and it will feel time flowing slower near the star's surface. Clocks on the shores tick at different rates, and the current begins to oscillate differently. But if the star rotates slowly, the picture gets more complicated.

Drop a pebble into a well, and the sound tells you its depth. That's roughly how astrophysicists listen to black holes: after a merger or other disturbance, the hole vibrates, emitting gravitational waves. The frequency and damping of this 'ring' depend on what's inside the hole.