Emergent long-range couplings in arrays of fluid cells.

We present a system exhibiting extraordinarily long-range cooperative effects, on a length scale far exceeding the bulk correlation length. We give a theoretical explanation of these phenomena based on the mesoscopic picture of phase coexistence in finite systems, which is confirmed by Monte Carlo simulation studies. Our work demonstrates that such action at a distance can occur in classical systems involving simple or complex fluids, such as colloid-polymer mixtures or ferromagnets.