Electromagnetic radiation — these interactions include the Faraday effect and the Kerr effect. In refraction, a wave crossing from one medium to another of different density alters its speed and direction upon entering the new medium. The ratio of the refractive indices of the media determines the degree of refraction, and is summarized by Snell's law. Light of composite wavelengths (natural sunlight) disperses into a visible spectrum passing through a prism, because of the wavelength-dependent refractive index of the prism material (dispersion); that is, each component wave within the composite light is bent a different amount. EM radiation exhibits both wave properties
James A. Abrahamson retrieval and repair mission. Abrahamson was appointed by President Ronald Reagan to be the first director of the Strategic Defense Initiative ("SDI") in April 1984. The "Star Wars" program, as SDI's detractors dubbed it, was initiated to develop a sophisticated anti-ballistic missile system that would prevent missile attacks from other countries, particularly the Soviet Union. Some countries opposed to U.S. missile defense efforts raised concerns about the program "contravening" the anti-ballistic missile (ABM) of the Strategic Arms Limitation Talks in years before the program was enacted. Ultimately, concerns about the objectives of SDI and fiscal budgetary constraints forced the Reagan