The Triumph Of Time

James Blish's The Triumph Of Time is cosmological fiction on two or maybe three levels. First, it is set entirely outside the Milky Way. The characters are all human beings but have permanently left their home galaxy. One group, the Hevians:

travels through four other galaxies, Andromeda, M-33 and the Lesser and Greater Magellanic Clouds;

considers the million light year journey to NGC 6822;

instead travels to the centre of the universe, here called the Metagalactic Centre.

Thus, they have freedom of movement in the three spatial dimensions of one four dimensional continuum.

Secondly, the characters freely theorise about a much vaster realm. Having detected in intergalactic space both the continuous creation of material hydrogen atoms and the arrival from elsewhere of anti-material hydrogen atoms, they postulate an anti-matter universe with a reverse arrow of time, although perhaps both arrows point the same way, downhill? Further, an astronomer postulates sixteen dimensions to contain both universes.

Thirdly, by occupying the Metagalactic Centre at the moment of the collision between the two universes, the members of one group each enter a different space within which they are able to create new universes from their own bodies so that the novel ends, "Creation began." (Blish, The Triumph Of Time, London, 1981, p. 596).