Nature: Quantum mechanics suggests that entangled particles share the same states and can communicate with each other instantaneously, regardless of the distance that separates them. Albert Einstein rejected that idea, which he labeled "spookiness," and proposed instead that perhaps entangled particles have a predefined set of hidden properties that determine their later behavior. In the 1960s John Bell proposed that hidden variables could explain only a certain level of correlation, and several tests of that proposal have all favored spookiness. Those tests, however, had loopholes, either because too many of the entangled particles weren't detectable or because the particles were too close together to tell if the "communication" between them was faster than light. Now, Ronald Hanson of Delft University of Technology in the Netherlands and his colleagues have performed the first Bell experiment that closes both loopholes. They used entangled photons to entangle electrons that were separated by 1.3 km, far enough apart to detect a time delay. When they measured the electrons, they detected enough of the entangled particles to surpass the threshold that Bell set. And the overall result of the experiment confirmed the standard quantum mechanical view of spooky action at a distance.
