There is no inherent mistake in Einstein's equation E=mc². It is one of the fundamental equations in physics and is a cornerstone of Albert Einstein's theory of relativity.
The equation relates energy (E) to mass (m) and the speed of light (c), stating that the energy of an object at rest (rest mass energy) is equal to its mass multiplied by the square of the speed of light. This equation demonstrates the equivalence between mass and energy, suggesting that mass can be converted into energy and vice versa.
Einstein's equation has been extensively tested and verified through various experiments and observations, such as nuclear reactions and particle physics. It forms the basis for understanding phenomena like nuclear energy, the behavior of particles at high speeds, and the mass-energy relationship in general.
If you have a specific concern or criticism regarding the equation, please provide more details, and I'll do my best to address them.