Book Review: Probability Moon

Nancy Kress
2000
Rating: ★ ★ ★ ★ –

This book did not win any of the major science fiction awards, but it is the first book in the trilogy that includes Probability Space, which won the Campbell. And it should have won an award, because it is way, way better than either Harry Potter and the Goblet of Fire, which won the Hugo that year, and The Quantum Rose, which won the Nebula. With the minor exception of the ending, it is a well-paced, accessible, engaging, relatively original story; almost a cross between an Ursula Le Guin alien-planet story and a Jack McDevitt space adventure novel. And it is quite effective in making you want to read its sequel, Probability Sun.

In the near-future setting of Probability Moon, humans have expanded throughout the solar system with the help of a series of wormholes connecting various parts of our galaxy, which were put there by some vanished ancient alien race as yet unknown, and whose technology is still not really understood.

These wormholes have led human explorers to hundreds of habitable planets and several sentient alien species. Most of these species are humanoid and peaceful, and one, the Fallers, is definitely neither humanoid nor peaceful. The Fallers simply want to exterminate us, without negotiation or diplomacy. Humanity is now in a constant low-level war with the Fallers, with each side trying to upgrade their weapons technology as fast as possible and thereby gain military advantage over the other.

Probability Moon opens after an initial human (Terran) recon team has returned from their investigation of a new planet recently discovered via the ancient wormholes. The team reported that the inhabitants, which call their planet “World,” are peaceful and have organized their entire economy and social culture around the cultivation and worship of flowers. They also reported that of the planet’s seven moons, one is not actually a moon, and may be of intense interest to the military.

This intrigues the Terran government, which sends a larger exploratory crew to investigate World at greater length. Half of the crew—the purported reason for the mission—is a natural science team, including an anthropologist, a biologist, and a geologist. They are deployed to the surface of the planet to learn as much as they can about the native culture. The other half of the crew—the real reason for the mission—is a military astrophysics team sent to investigate the “moon” of interest.

The surface team quickly discovers that the planet’s natives have an unusual characteristic: they share a common reality. All of them understand a single, uniform truth in any situation. If someone questions that truth, it gives the natives severe head pain, sometimes to the point where they cannot function. And if someone reveals that they do not share the same common reality with the others, that person is declared “unreal.” The best that can happen to an unreal person is that they are shunned by society until they have served some sort of penance; the worst that can happen is that they are condemned to death.

The surface team ingratiates itself into the household of one of the wealthier inhabitants of World, and becomes particularly close to one of the servants, Enli, who has been declared unreal for having killed her brother, and who is serving her penance by spying on the Terrans. This outreach goes relatively well at first for the team, but gradually their position becomes more and more dangerous, since it’s obvious they do not share the same reality with each other, much less the natives, and are increasingly at risk of being designated as unreal and being condemned to death.

Eventually they do have to flee to the comparative safety of a highly radioactive mountain range where they hope to be rescued by the spacebound half of their crew—and where they discover what just might be the source of the natives’ shared reality.

The problem is that while the ground team was involved with the natives on the surface, the spacebound team was getting itself in even deeper hot water in orbit. First, they discovered that the planet’s seventh moon is not, in fact, a moon at all, but a piece of technology left there by the original wormhole builders. Then, their testing revealed that it is a weapon: a powerful one that could potentially serve to turn the tide of the war with the Fallers. And then, of course, the Fallers show up, and there is a terribly tense game of cat-and-mouse as the humans and the Fallers both try to gain control of the moon-sized weapon.

Probability Moon is somewhat unsatisfyingly unresolved at the very end. And the characters aren’t terrifically charismatic; none of the aliens really caught my interest, even Enli, and neither did most of the humans. My favorites were Bazargan, the leader of the on-planet surface team, and Gruber, the surface geologist, who were the most individual and appealing; the others were either undistinctive or creepy.

But, in general, this book is fun. It has a plausible galactic political and military structure, a well-developed alien planet ecosystem, and a non-human sentient species with a unique social structure. The Faller threat adds dramatic tension. And although the surface plot gets much more narrative time than the space plot, both are well-paced and build up nice lines of parallel suspense and then intertwining action.

And it could be that the ending is ambiguous because Kress is setting us up for the sequel, Probability Sun—so I won’t judge too harshly until I have read that one.