Bell's inequality

Bell’s inequality is a test in quantum physics that shows how particles like electrons or photons can become linked, or “entangled,” in ways that classical physics can't explain. It compares the results of measurements on these particles to what’s expected if they behaved like independent, classical objects. If the inequality is violated—as experiments often show—it indicates that the particles' states are connected through quantum entanglement, implying that information about one instantly influences the other, no matter how far apart. This challenges traditional ideas of locality and suggests that the universe operates with inherently quantum, interconnected properties.