>50 billion: Assuming both survive the Sun’s expansion, by this time the Earth and the Moon become tidelocked, with each showing only one face to the other.
100 billion: The Universe’s expansion causes all evidence of the Big Bang to disappear beyond the practical observational limit, rendering cosmology impossible.
450 billion: Median point by which the Local Group, the collection of ~47 galaxies to which the Milky Way belongs,[42] will coalesce into a single large galaxy.

(via Substack)

See also: Earth May Exist Forever and Matrioshka Brain.