Albert Einstein's formula "E=mc2" means energy equals the mass of an object multiplied by the speed of light squared. His theory means that the mass of an object, no matter how small, can be transformed into a tremendous amount of energy.
Nuclear energy proves this theory since it uses a small amount of mass and converts it into an enormous amount of energy that can be used to power millions of homes. Some of this energy can even be converted to mass to create a new particle. The speed of light squared is a large number, and it is the secret behind the power of this formula.