Abstract

Article 1 and article 6 point out that principle of constancy of the light velocity is deficient. The conclusion of this paper is that light velocity has superposition feature: in the vacuum, light wave has no oscillating medium to propagate, and the mass of light field is zero, motion of field does not need the action of force, so the motion of light is a radiation, and it is a vector c₀ which is relative to the radiation velocity of light source, this is a relative velocity which is relative to the radiation source, but not the absolute velocity, and it obeys superposition principle of velocity vector, when the relative velocity v exists between light source and observer, the relative light velocity that observer measures is c = c₀ + v, and such conclusion indicates: light velocity obeys Galilean principle of relativity.