Light creates gravity and the greater the light's frequency the greater this gravitational effect is. It stands to reason then that light of different colors would react slightly differently to gravitational fields, namely bluer light would bend more than red light causing gravitational lenses to act like prisms.

Light creates gravity, and the greater the light's frequency, the greater this gravitational effect is. It stands to reason then that light of different colors would react slightly differently to gravitational fields. Namely, bluer light would bend more than red light, causing gravitational lenses to act like prisms.