IT was as if some ghostly bridge across the city of Geneva, Switzerland, had permitted 2 photons of light nearly seven miles apart to respond simultaneously to a stimulus applied to just one of them.
The twin-photon experiment by Dr. Nicolas Gisin of the University of Geneva and his colleagues last month was the most spectacular demonstration yet of the mysterious long-range connections that exist between quantum events, connections created from nothing at all, which in theory can reach instantaneously from one end of the universe to the other.
In essence, Dr. Gisin sent pairs of photons in opposite directions to villages north and south of Geneva along optical fibers of the kind used to transmit telephone calls. Reaching the ends of these fibers, the two photons were forced to make random choices between alternative, equally possible pathways.
Since there was no way for the photons to communicate with each other, ”classical” physics would predict that their independent choices would bear no relationship to each other. But when the paths of the two photons were properly adjusted and the results compared, the independent decisions by the paired photons always matched, even though there was no physical way for them to communicate with each other.
Albert Einstein sneered at the very possibility of such a thing, calling it ”spooky action at a distance.” Scientists still (somewhat shamefacedly) speak of the ”magic” of ”quantum weirdness.” And yet all experiments in recent years have shown that Einstein was wrong and that action at a distance is real.
The idea behind Dr. Gisin’s experiment was not new. Since the 1970’s, physicists have been testing a prediction of quantum theory that ”entangled” particles continue to communicate with each other instantaneously even when very far apart.