Two particles can become linked so that a nudge on one instantly reverberates in the other, even if they are separated by galaxies.
Physicists wondered: can gravity itself, a simple mutual attraction, create such a connection? Experimenters plan to bring two microscopic diamonds close and check if they become entangled without any intermediaries.
But calculations show: classical gravity is deaf to quantum effects. The authors used a theory combining Newton’s attraction with spacetime curvature and concluded — gravity alone is not enough to generate entanglement. It's like a deaf conductor trying to lead an orchestra: synchronization is impossible without a hidden prompter.
Earlier, scientists hoped that catching entanglement would prove the quantum nature of gravity. Now it's clear: if entanglement occurs, it means someone else stepped in. Perhaps dark matter particles or unknown fields. The experiment turns into a hunt not for quantum gravity, but for something more mysterious.
as written by the authors arXiv:2511.19242
Once again, dispute has arisen over the interpretation of proposed quantum information theory experiments to probe the quantum nature of gravity by testing for gravitationally induced entanglement (GIE) between two spatially separated massive particles ([2] vs. [16, 17]; further contributions in [11, 13]). The confusion appears to reside in interpreting applications of a Hamiltonian formalism. But classical gravity cannot mediate entanglement on independent grounds. A Newton-Cartan analysis shows that if gravity is classical, a mediator, and entanglement is observed as an outcome of performing a GIE experiment, something other than gravity must have supplied the (virtual) force needed during the experiment to produce the effect.
Entanglement is so strong that measuring a particle in one galaxy theoretically affects its partner in another instantaneously — faster than light. But you can't transmit information this way, as it violates the theory of relativity.
In Carl Sagan’s novel 'Contact,' travelers use gravitational waves to communicate through wormholes. Here, gravity itself becomes a testing ground for quantum reality, blurring the line between fiction and science.