Sartorius is the name of a character from both the Polish science fiction novel Solaris by Stanislaw Lem and the Russian science fiction film of the same name (d. Andrei Tarkovsky.) In the book, Sartorius is a physicist. In the film, he is an astrobiologist, and played by Anatoly Solonitsyn, one of Andrei Tarkovsky's favorite actors, with whom he worked on many occasions. In both works, the character provides a sort of antagonistic cynicism as a counter to Kris' increasing emotional attachment to his mysterious visitor. An interesting note is that Sartorius is absent in the American film version of Lem's novel, replaced by Helen Gordon (Viola Davis.) Helen Gordon provides the same cynicism and scientific detachment as Sartorius; the change (from a white, middle aged man to a younger black woman) to me seems to be one not of story revision or political correctness but simply translation. The novel Solaris was a Polish novel with Polish characters. The first film was a Russian film, and had very Russian characters. The latest film is an American film, and as such has American characters, and that does mean adding diversity to the cast.