Entropy

Entropy, represented by the second law of thermodynamics is the slow, irreversible process of breakdown and decay.

Because of entropy, N-Space, the main universe, had a finite lifespan and would have "died" some time prior to the 20th century had the Logopolitans had not siphoned entropy out from it into E-Space, another universe via the CVE's which they created (DW: Logopolis, NA: Timewyrm: Apocalypse)

In N-Space and in E-Space, the entropy appeared as a green tint seen both in the sky of planets and in space itself. (DW: Full Circle, State of Decay) In 1981, the Master interfered with the Logopolitans and closed CVEs. A wave of entropy destroyed most of the universe. On the planet homeworld of the Logopolitans], machines affected by entropy would cease to function and then crumble. Parts of [[the Monitor, the Logopolitan leader, dissapeared unevenly, piece by piece and then he vanished. Whole stars and galaxies and most of the universe vanished, such as the Traken Union. (DW: Logopolis)