Quote - Earlier he denied the importance of relativity in Cathode-Ray tube calculations.
Kawecki - do you know the speed of the electrons in a CRT? Does 1 * 10^8 m/s sound fast or what? It's 1/3 the speed of light. At such speeds, the mass of the electron is increased by 25%, and if you do not consider this in deciding how much force is needed to deflect it into the right position, it does not go into the right position.

Did you know that magnets around a CRT have not an uniform magnetic field, magnetic materials used for the magnets are non-linear ? All these errors make electrons go to other place that is not the correct one, so we need to put auxiliary magnets and adjust then manually to make electros go to the right place. Any error introduced by the electron mass increase with speed is insignificant compared to the errors introduced by the real world magnetic field. Perfect magnetic fields only exist in books and are for academics and not engineers.

The second point is that the increase of electron mass with speed was not discovered by Einstein and his Theory, this was afact known many years before Einstein. Also Einstein based his theory on Lorentz's work that has nothing to do with Relativity and it was an aether theory.

Stupidity also evolves!