Iv'e done some calculations and found a potential error in E=mc^2.
Lets take an object with the mass of 1 kg and accelerate it to .866% of
c where gamma equals 2, the total energy or mass of this object would now be 2 kg in accordance with relativity.
Now assuming that the 1kg mass is moving in a striaght line at .866% of c in the +x direction,at a constant velocity, a constant force in the +y direction
is applied to the 1 kg moving mass.
According to E=mc^2 any small change in the velocity in any direction
of the 1 kg mass moving at .866% of c will appear like a mass of 8 kg's to a force acting on the moving mass. Note this force is acting on the the moving mass from a stationary position relative to the moving mass. Also the 1kg moving mass acting like a 8kg mass, is derived from the acceleration rate of the 1 kg mass acted on by a constant force, measured from a stationary position.
Iv'e looked up 2 different beam deflection equations at relativistic velocities and rearranged the equations and in both equations, Iv'e found that if the
equations are to work the 1kg mass, moving at .866% of c, would have to
appear like a mass of 2 kg's to a stationary deflecting force, not the 8 kg's that is required by E=mc^2. This would mean that E=mc^2 is wrong, or the beam deflection equations are wrong and could also bring into question the
valitity of shrinkage of space at relativistic velocities. Could someone
double check this work.