Temporal tipping point

The Eleventh Doctor identified the 2020 Cwmtaff incident as a "temporal tipping point", explaining that it was not a fixed point in time. He claimed that such a tipping point would "change future events, create its own timeline, its own reality." (TV: Cold Blood)

The Doctor also identified 26 January 2011, the night of the National Television Awards, as a temporal tipping point; "millions of people are going to be making vitally important decisions, and if they make just one tiny mistake the entire universe will be destroyed." (TV: Dermot and the Doctor)

Similarly, the Seventh Doctor identified the Wenley Moor Affair as a crucial nexus-point in Earth's time stream such that a countless number of futures could be claimed from that moment with near-endless divergent realities. (COMIC: Final Genesis)