A black hole's horizon is not a wall but rather a one-way membrane. Anything that crosses it disappears forever. Stephen Hawking showed that this boundary should glow faintly, emitting particles. But catching such radiation from a real black hole is impossible: it's too far and too dim.

Physicists have found a workaround: build a "toy" black hole out of magnetic atoms. In a chain of atoms, each resembling a tiny magnet, you can write down equations nearly indistinguishable from those describing a black hole. By changing how you describe space, like a cartographer choosing a map projection, you get different arrangements of atoms. But on large scales, they all merge into the same physics: a semblance of general covariance, the key principle of Einstein's theory of gravity.

Such an experiment is within reach of modern laboratories. It requires no space telescopes, just a cooled crystal and precise measurements. For the first time, there's a chance to see particles born from the void, curved by gravity, without leaving Earth.