While the theremin was the favorite instrument of 1950's and 60's science fiction, it was not, as is often reported, played in the theme song to Star Trek.
In 1927, the inventor of the theremin, a Russian physicist named Lev Sergeyevich Termen, played his instrument in London to a crowd that included George Bernard Shaw among others. Thermen changed his name to Leon Theremin and boasted that one day every home would have a theremin. One of the early theremin enthusiasts was a kid named Robert Moog. He began building theremins and would later developed the synthesizer often called the Moog. Today Moog's company not only sells synthesizers, but one of its best sellers is the theremin.
Theremin was an interesting cat! With all the repetitive biopics out there, one would think that Theremin's story is ripe for the picking. Theremin might have been a Soviet spy. He was madly in love with Clara Rockemore who refused to marry him. He later married Lavinia Williams, a prima ballerina with the American Negro Ballet. Williams believed that he was kidnapped by the Soviet Union and spirited out of America, but the actual reason he left abruptly has been greatly disputed.
As for Rockmore, her performance of Camille Saint-Saëns' The Swan is considered one of her finest.
If you want to here more of Rockmore, might I suggest her CD, The Art of the Theremin.
Now click on that doodle and practice, practice, practice.