> It's also worth noting that this hypothesis is not an original idea of Liu's Yes, Greg Bear explores the concept in Forge of God (1987) and Anvil of Stars (1

> It's also worth noting that this hypothesis is not an original idea of Liu's Yes, Greg Bear explores the concept in Forge of God (1987) and Anvil of Stars (1992), twenty years before Liu. David Brin also covered it. Anvil of Stars really explores the moral quandary from the perspectives of a civilisation that can take revenge in such an environment.