After Leonard Susskind proposed the black hole complementarity conjecture for black holes in quantum gravity, he realized it would also apply to a de Sitter universe with a positive cosmological constant with the cosmological horizon in place of the event horizon.
The region within the horizon is the causal patch,[1][2] and it is self-contained.
This means we may neglect what happens beyond the cosmological horizon.
A consequence of this radical conjecture is that the total number of states of the universe is finite.
This relativity-related article is a stub.