The World at the End of Time is a 1990 science fiction novel by Frederik Pohl

It follows the story of a young Earth-born human on a colony expedition to a faraway star system. Unbeknownst to the colonists, they have stumbled upon a massive battle between star-dwelling entities. These entities are all descended from one creature, Wan-To, who created his/its children out of loneliness, and now seeks to destroy them out of self-preservation. Manipulating star systems in ways humans cannot even speculate about, Wan-To and his children attempt to disrupt each other's lives through massive flares. Caught in the middle of this conflagration, the colony's entire star system is accelerated out of the galaxy.

With the sun dimmed through its efforts to create some kind of gravitational gradient, the colony world enters an ice age. Civilization breaks down into small, short-sighted tribes. The young boy, now a man, finds himself frozen and thawed several times trying to determine the nature of the events unfolding around him.

Eventually, Wan-To returns to the star system, this time as a refugee from the heat death of the universe. Unfortunately for him, humans have survived from the last encounter, and their technology now nearly matches his.