Two nuclear missiles
When you read a Larry Niven novel, you shouldn’t expect memorable characters. You should expect big-picture science fiction concepts, with characters who serve as vehicles to carry you through the sci-fi landscape. I’m OK with that; I think there’s a place for stories focused on ideas and locations rather than characters. Niven’s signature novel, Ringworld, is a story about an artificial structure (with the mass of Jupiter) that encircles a star at about one earth orbit. A World Out of Time is also huge in scope, but in terms of years rather than miles.
It’s been a while since I read the book, so it’s possible I’ll get a detail or two wrong, but I think I can paint a reasonable overall picture. To me, the novel breaks into three separate parts:
The beginning of the book was once published as a (pretty good) standalone short story. The main character allowed himself to be frozen (the standard reason for this would be an incurable disease) and is woken up hundreds of years later. He finds himself on an overcrowded Earth with absolutely no privacy (not even for sexual activities or going to the bathroom). None of Earth’s population is psychologically capable of being alone, so the frozen new guy is an ideal solo pilot for a spaceship flying out to distant planets to seed them with algae or whatever as the first step in terraforming. Because he wasn’t treated very nicely, or possibly because he doesn’t want to see other planets turned into hives of humanity, the frozen new guy dumps his algae and goes off exploring.
In the middle part of the book, he decides to return home. A combination of suspended animation and time dilation means that he returns millions of years after he left. He barely recognizes the solar system, and lands on an Earth that is mostly too hot for human life. He encounters an evil old woman who’s in a situation somewhat like his own, and spends a good bit of the book trying to dodge her using various forms of advanced public transportation. I felt that this part of the book dragged a bit.
The last part of the book was a little more interesting. The main character learns that humanity invented a treatment which has to be administered before puberty, freezing the person in a pre-pubescent physical state and preventing any further aging. The Earth was run by ancient people in pre-pubescent bodies, who kept a small population of breeder humans to replace their own losses from accidents and such. At some point, the ‘boys’ and ‘girls’ went to war against each other. At first, the girls won, exiling the boys to Antarctica. Then, by screwing around with planetary orbits, the girls made the Earth too hot, leaving Antarctica as the only inhabitable part of the planet, and causing their own extinction.
The main character wanders around Antarctica, which is populated by dwarf versions of African savannah animals and some friendly housecats which don’t have legs and move around like snakes. He encounters the ‘boys’, who take him to one of their breeder colonies. There, he participates in an orgy, which is only a small part of the book, but is a little gross.
I must have found the ending of the book underwhelming, as I truly don’t remember it. I remember that the main character had a plan to help the breeder colony escape to a refuge in the Himalayas which the ‘boys’ weren’t aware of, but I can’t remember whether this was successful, or whether the book ended on some other note.