The "cookie dough theory," also known as the plum pudding model of the atom, was proved incorrect by Ernest Rutherford. Rutherford demonstrated this through his famous gold foil experiment in 1909, where he fired alpha particles at a thin gold foil and observed that some particles were deflected at large angles, indicating the presence of a small, dense, positively charged nucleus inside the atom. This finding disproved the plum pudding or cookie dough model, which posited that electrons were scattered within a diffuse positive charge. Rutherford's discovery showed that atoms consist mostly of empty space with a central nucleus, shifting the atomic model fundamentally.
