Slow ship

From Wiki

A slow ship is called a generation ship in some science fiction. Generation ship provides a human perspective on the time it takes a slow ship to travel between stellar islands. In the Red Galaxy biological life is rare, and in any event, sapient lifespans tend to be long by early twenty-first century standards, so most beings that are on are in a slow ship can expect to reach their destination in their lifetime.

Slow ships vary in size from large to massive, though they are minuscule compared to the total ecological-economy active mass of a stellar system. Slow ships form a critical part of the communication network between stellar islands. Slow ships carry parcels and even entire atomic components of Dyson swarms between star systems. A few slow ships are permanent wanderers. These ships tend to be made of compartmentalized intelligences. They are at once beings and cultures. Most systems welcome visits from wandering slow ships.

Slow ships are propelled by ion drives, particle drives, or laser drives powered by fusion reactors or antimatter reactors.