Szilard was appointed as assistant to von Laue at the Institute for Theoretical Physics in 1924. In 1927 he finished his habilitation and became a "Privatdozent" (private lecturer) in physics. For his habilitation lecture, he produced a second paper on Maxwell's Demon, "Über die Entropieverminderung in einem thermodynamischen System bei Eingriffen intelligenter Wesen" (On the reduction of entropy in a thermodynamic system by the intervention of intelligent beings), that had actually been written soon after the first. This introduced the thought experiment now called the Szilard engine and became important in the history of attempts to understand Maxwell's demon. The paper is also the first equation of negative entropy and information. As such, it established Szilard as one of the founders of information theory, but he did not publish it until 1929, and did not pursue it further. Claude E. Shannon, who took it up in the 1950s, acknowledged Szilard's paper as his starting point.