  Penrose then directly applied this to the problem of the Szilard engine. The insertion of the partition corresponds to a macroscopically indeterministic process. After the insertion the molecule is in one of two possible macrostates, in either case reducing the Boltzmann entropy by k ln 2. However, this reduction cannot be directly exploited to extract k T ln 2 heat and leave the molecule in a macrostate occupying the entire box again.  If there was a process which could directly exploit this reduction, it could combine with the insertion of the partition to be a macroscopically deterministic process that reduces the Boltzmann entropy (via the extraction of heat from the heat bath). Penrose had already argued, from first principles, that a macroscopically deterministic process cannot reduce the Boltzmann entropy.