Cowl (novel)

Cowl is a 2004 science fiction novel by Neal Asher. It tells of an epic time war between two factions from the 43rd century.

Setting
Time travel is a reality with the exception to more common theories that there is only one main time line. Whenever a time line is distorted a parallel universe is created that branches off. The more the sub branch differs the more energy is required to travel back to the main time line. Getting stuck in an alternative universe without the required energy to return is the fear of every time traveler.

Plot summary
The first part of the story is set in the 23rd century describing a western civilization that made little technological progress and is on the edge of collapse due to genetic decline.

The second part of the story is set in the 43rd century where the Heliothane are the dominant force. Technologically they are not as advanced as one might think since the western civilization collapsed and a new civilization had to be rebuilt without abundant natural resources. To avoid another collapse eugenics was practiced, as a result the Heliothane can no longer be classified as Homo sapiens since they are several times stronger, faster, and more intelligent.

The third part revolves around Cowl, a being genetically designed by an evolutionary simulator in an attempt to create the ultimate product of natural selection. Cowl, who seems mainly interested in his own survival, blows up Callisto and uses the released energy to take himself and his followers two billion years into the past to the paleoproterozoic. The Heliothane don't have the resources to follow him there and Cowl's followers, who name themselves the Umbrathane, fight a guerrilla war from this fortification.

The Heliothane fear that Cowl is trying to push them from the main time line, and try anything in their power to stop him.