A black hole doesn't just swallow everything around it: it also slowly evaporates, like a chunk of ice in the sun. As the hole shrinks, the quantum fields around it start behaving unusually. In a new study, physicists traced how entanglement, a special kinship between particles that persists even when they are far apart, changes.
In an ordinary world without black holes, entanglement between distant patches of a field can flare up again and again, like an echo that returns after many steps. But when an evaporating black hole is nearby, that echo begins to fade. The reason lies in how the hole scrambles information. If the scrambling is slow, the entanglement surges are still visible. If it's fast, they smooth out and disappear. The authors found the point where the surges vanish completely: at that moment, the size of the region covered by entanglement grows exponentially with the scrambling time.
The work connects two extremes: the world of free particles, where entanglement spreads like a wave, and the world of maximal chaos, where any memory of the past is erased almost instantly. It turns out that you can smoothly transition between them just by changing the speed at which the black hole entangles information.
In the quantum world, entanglement doesn't weaken with distance, unlike a radio signal: two particles can fly to the edge of the universe and still remain a single whole.
In Robert Charles Wilson's novel Spin, an alien veil around Earth acts as a giant filter that alters the flow of time — somewhat like how the black hole here filters and quenches quantum memory.