A long stand-by of science fiction is the generation ship. The core concept is that there is so much space between solar systems that a ship would need to be developed to last thousands of years. People (at present) don’t live for thousands of years. So, a generation ship might start with a small population that would be designed to grow over time.
Lots of science fiction writers over time have found the problems that a generation ship might encounter. One problem is that we never know how the next generation of humans will turn out. This problem is multiplied when talking about two generations. It boggles the mind how things might turn out on a generation ship where the people have hundreds or thousands of generations until they reach their destination.
One way to alleviate this generational problem which we encounter as much on Earth as we would in generation ships is to have a large population base in the beginning instead of only a growing population at the end. The more people there are and the more varied their ages (including the very old) the more likely inter-generational information will survive.
This might seem counter-intuitive; however, at least as far as knowledge is concerned a population needs to have more than one teacher in any subject. In order to have more than one teacher for each subject you have to have a need for more than one teacher in each subject. These teachers get together for meetings to figure out how best to teach their subjects, what are the best practices for teaching, and many other related topics.
The paradox is that a generation ship will have larger populations as the journey progresses. How do you manage a large population that then, in turn grows larger over time. Why do you need a growing population? Is it necessary to assume that a generation ship’s population grow over time?
Cultures that are thriving, living, and developing new concepts – are cultures that are growing in size. This is an assumption on my part. In addition, populations that are to remain exactly the same size require draconian measures in controlling individual crew member’s lives that inherently a very static, benevolent dictatorship style government (or not so benevolent) would necessarily develop.
What does this say about our generation ship? First, it has to be large. Greg Bear’s story “Eon” involves what appears to be an abandoned generation ship created from a large asteroid called “The Stone” or “The Potato”, but appears to have been the real-world asteroid Juno. In a funny twist like the Empire’s newest super weapon – you might needs to start with a hollowed out dwarf planet which when fully utilized can hold millions of people and start with a population of 200,000 (approximately). Then you have things like different schools, different school districts and, most importantly to our topic, multiple teachers for each topic. This counters the paradox of starting with a large population in a generation ship against spatial constraints.