The motion relativity of the magnetic field

The motion relativity of the magnetic field means that neither the observer nor the detection instrument moving at the same speed as the field source can measure the magnetic field generated by the moving field source, but the magnetic field of the field source can be measured when the speed is different from that of the field source. For example, in the earth's surface reference system, we determine that the electrons stationary on the earth's surface do not generate a magnetic field, but the electrons stationary on the earth's surface are constantly rotating with the earth's surface and revolving around the sun. As another example, the current that causes the wire to generate a magnetic field is the result of the directional movement of a large number of electrons. When the current-carrying wire generates a magnetic field to the outside, each moving electron in it is not disturbed by the magnetic field of other electrons in the same line, because all the electrons in the line have the same magnetization and cannot feel the existence of the magnetic field of other electrons.