Other Side

The Other Side was an alternate dimension.

Time moved more slowly there compared to Earth's dimension. The inhabitants had no concept of death until the membrane between their dimension and Earth's was torn open when a dead baby was tossed through. More of Earth's physical laws bled through over time. Ultimately the inhabitants tried to destroy Earth in retaliation, but were stopped by the Fifth Doctor. He used the TARDIS to permanently seal the rift. (PROSE: Empire of Death)