Alain Aspect, Philippe Grangier, and Gérard Roger conducted an experiment to test realistic local theories using Bell’s theorem. They measured the linear polarization correlation of photons emitted in a radiative atomic cascade of calcium, achieving high statistical accuracy. The results strongly violated generalized Bell’s inequalities and ruled out realistic local theories. No significant changes were observed with source-polarizer separations up to 6.5 meters. The experiment used a high-efficiency source and a variety of polarizer orientations, providing a valuable test of local realistic theories. The authors concluded that their results, in excellent agreement with quantum mechanical predictions, strongly support the nonlocal nature of quantum mechanics and rule out realistic local theories.Alain Aspect, Philippe Grangier, and Gérard Roger conducted an experiment to test realistic local theories using Bell’s theorem. They measured the linear polarization correlation of photons emitted in a radiative atomic cascade of calcium, achieving high statistical accuracy. The results strongly violated generalized Bell’s inequalities and ruled out realistic local theories. No significant changes were observed with source-polarizer separations up to 6.5 meters. The experiment used a high-efficiency source and a variety of polarizer orientations, providing a valuable test of local realistic theories. The authors concluded that their results, in excellent agreement with quantum mechanical predictions, strongly support the nonlocal nature of quantum mechanics and rule out realistic local theories.