The famous equation \( E = mc^2 \) was formulated by Albert Einstein. This equation, known as Einstein's mass-energy equivalence formula, is a key result of his theory of relativity. It expresses the idea that energy (\( E \)) is equal to mass (\( m \)) multiplied by the speed of light (\( c \)) squared. This formula has profound implications in physics, demonstrating the interchangeability of mass and energy.