Is E=mc^2 correct?

E=mc² is not incorrect. But it is incomplete. It only works for things at rest. It fails where p (momentum) is non-zero. It is a clipped version of Einstein’s original equation E²= (mc²)²+ (pc)².

Popularizers of Einstein’s work get the blame for the inaccuracy and the credit for correctly guessing that the short version would catch on better with the public and politicians. No physics equation is more often quoted.

A great video explaining the full equation can be found at https://www.youtube.com/watch?v=NnMIhxWRGNw 

Also, Einstein may be getting too much credit for the equation.

♦ 1889 ─ (4/3)E=mc² was applied by Oliver Heaviside to a sphere’s electric field.

♦ 1895 ─ E=mc² was applied by Henri Poincaré to electromagnetism in general. 

♦ 1905 ─ Einstein asserted that the laws of physics are the same from the perspective of any inertial reference frame. So, E²= (mc²)²+ (pc)² in all cases.