  The magneto-optic effects and electro-optic effects are the essential optic
effects, although their theoretical explanations are not unified in the
classical electromagnetic theory. Describing with the algebra of octonions, the
electromagnetic theory can derive the magneto-optic effects and electro-optic
effects from the same one force definition in the paper. As well as the
magneto-optic effect is deduced from the known force term, the electro-optic
effect is from the new force term in the octonion space. This description
method is different to that in the quantum theory as well as the index
ellipsoid approach for the electro-optic effect. One more significant inference
is that the gravitational field has an impact on the rotation of linearly
polarized light, and then results in the similar birefringence for the
transmitted light in the cosmic matter.
