We know from elementary physics that if a point charge is moving in the X direction, in an area where there is a magnetic field in the Z direction, the charge will move in a circle because of the lorentz force. Now, lets say that the charge has zero velocity, and an observer moving in the -X direction is looking at our point charge. He will see the charge moving in the +X direction, inside the magnetic field, in a straight line. How is this possible in light of the lorentz force?
