The Second Law, formulated by Sadi Carnot and Rudolf Clausius, states that the total entropy (a measure of disorder or randomness) of an isolated system always increases over time. This law explains why spontaneous processes, such as heat transfer and chemical reactions, occur naturally in one direction but not the other. The Second Law has far-reaching implications, governing the direction of spontaneous processes, the efficiency of energy conversion, and the ultimate fate of the universe.