Many movies and television shows these days offer some specific scientific elements. Consultants are called in for everything from cooking to historical information as well as period costume dress and set design. It pays to specialize, as far as Hollywood is concerned. War movies hire experts in battlefield technology and maneuvers, martial arts movies almost always have real martial artists choreographing the actor’s moves. Writer Tom Clancy has provided information related to espionage and ‘war games’ for more than one big budget film. It is also common place for actors to train in a specific skill before filming their roles. For instance, Mila Kunis and Natalie Portman trained extensively for their roles as ballet dancers for the recent blockbuster movie Black Swan, and still talented body doubles were used for the trickier dance routines.