One could instead argue that an entangled object releases an unknown particle or some other signal at high speeds to influence its partner, giving the illusion of a simultaneous reaction.

In the past, experiments have ruled out any suspects for such hidden signals from the realm of classical physics. Still, one exotic possibility remains — that such x-factors instead travel faster than the speed of light.

To investigate this possibility, scientists at Geneva in Switzerland began with entangled pairs of photons, or packets of light. These pairs were then split up and sent over fiber optic cables provided by Swisscom to stations at two Swiss villages some 11 miles (18 kilometers) apart from each other. The stations confirmed that each pair of photons had remained entangled — by analyzing one, scientists could predict aspects of its partner.