databank
900 year diary
entropy
The inhabitants of Logopolis discovered many years ago that the Universe was a closed system and had passed the point of heat destruction. To halt this, they used pure mathematics, block transfer computation, to create CVEs - holes in space leading into pocket universes such as E-Space. If the CVEs closed, entropy would begin and the Universe would collapse. When the Master caused a CVE to close, entropy began consuming the region of space around Cassiopeia, destroying Logopolis. The Doctor was able to beam the right mathematics back into the CVE, reopening it and thus saving the Universe from destruction.