Consider 2 dipoles separated by a distance of atleast 2 light minutes or so . we can call the 1st dipole A . the distance btw the opposite charges is small so the field strength is weak same for the other dipole B . Now we increase the distance btw the charges in dipole A so the field strength increases and it travels to B. at the exact time it reaches B we increase the distance btw the charges of the dipole B . so due to the Field which has reached B it statrs accelerating let's say in the positive x direction. Now due to the increase distances btw the charges at B the filed generated by B starts travelling towards A . BUT if we combine the charges at A effectively Neturalising it there won't be any charge for the field to act on . BUT MOMENTUM is not conserved in this case cuz only b is moving and nothing is moving in the opposite direction.????????????????