The Dark Forest

The population of earth now knows that the Tri-Solarans are approaching and will arrive within a few centuries. Some people initially plan on fleeing. However, that plan is quashed. The earth instead is focussing on plans to battle the invaders. Many of these plans rely on the people of earth taking advantage of not-yet-invented technology. The Tri-Solarans have sophons on earth that allow instant access to all human communications. However, their society doesn't have a difference between "thinking" and "saying". Can this help the humans?

Part of the plan is to have "wallfacers" who are given the power to do whatever they want. The hope is that they can create some plans to defeat the aliens without communicating it out loud. The Tri-solaran allies have "wall-breakers" that attempt to find the wallfacer plan. The wallfacers come up with some interesting plans - sometimes based on their particular interests.

The novel focusses primarily on a few periods of time. One is shortly after the earth knew about the impending invasion. Many of the main characters then enter hibernation and come back over a hundred years later. The earth has gone through a great catastrophe. However, now everyone is much more optimistic about the prospects of humankind. There is a large space fleet that humanity thinks will easily dispose of the invading force. Alas, things do not go according to plan and humanity becomes pessimistic. (We also wonder the role of a wallfacer innovation that can "imprint" beliefs on people - even something like "water is bad" can become a deeply held belief.)

In the end, it is social science that becomes the deciding factor. One planet is "cursed" and then later found to be destroyed. While this appeared to be magical, it just took advantage of interplanetary sociology. Social relationships also contribute to the fall of the Earth space fleet and the eventual fate of the earth. The vast amount of technology have their role, but without the understanding of how beings work together, they are of minimal use.