A black hole is a whirlpool that not even light can escape. Its event horizon has been recreated in a superconducting circuit, where components form a wave trap. Nearing the boundary, signals get stretched, and the flow of time slows down. Schwarzschild and Hawking explained the nature of such objects.

New research, using methods from Penrose and numerical simulations, showed that any disturbances in this trap do not grow but give rise to a ring – not a musical tone, but a muffled thud, like a stone plopping into water and instantly falling silent. Measuring this ring will let us “hear” curved spacetime and build quantum amplifiers, turning the lab bench into a proving ground for gravity theories.

And if you connect two such circuits, you get an analog of a wormhole — a tunnel through space, bringing physicists closer to unraveling quantum gravity.