Only Quantum Gravity Can Entangle Masses ✎ express
Two massive spheres in the cosmic void. Push one, and the second will feel the push only after a moment: gravitational influence travels, like an echo of a shout in the mountains, with inevitable delay. This is how curved space transmits signals locally, step by step — predicted by Einstein long ago.
In the quantum world, the rules are different. There, particles can become "entangled": their states merge into one, even if separated by a chasm, like two dance partners mirroring each other's moves without music or touch. No waves, just direct correlation.
Some speculated that ordinary gravity could induce such entanglement between massive bodies simply by emitting a wave. But new calculations show: without quantum properties of the field itself, the trick fails. Wave-gravity can only deliver a delayed push, not a genuine quantum link.
The most striking conclusion: to entangle masses via gravity, spacetime at the microlevel must resemble not a smooth sheet but a fizzing foam, constantly changing. This foam, quantum gravity, is precisely what physicists are hunting for, including Penrose with his idea that gravity destroys uncertainty. While the search goes on, one can only marvel: ordinary gravity is simply not up to the task.
Einstein dubbed entanglement 'spooky action at a distance' and hoped that ordinary waves or particles were hiding behind it. Today we know: it's a purely quantum effect, with no hidden tricks.