A plot-enabling device in the DoctorWho story ''Logopolis.'' Apparently, the Universe has long passed the point of natural heat death, so the Logopolitans opened up something called a Charged Vacuum Emboitment to allow our dying universe to exchange entropy with a Universe in hopefully better health. The job was carried out by a process called Block Transfer Computation, in which calculations actually change reality. Apparently this is best done by abacus rather than with a computer, as the computer would be changed by the computation.