Starfarers came out in 1998. I bought the hardcopy. Anderson’s strange prose style didn’t work for me and the book ended up in a box for ten years. I took it out again, and after struggling through the first third of its 494 pages, it picked up speed for me and I very much enjoyed reading it this time.
The book starts on earth in the nearer future. Astronomers noticed point-like sources of hard X rays with radio tails crisscrossing a region in the constellation Centaur. Parallax measurements taken across interplanetary spans showed that they were about 5,000 light-years away. Further analysis showed that they moved at virtually the speed of light.
Studying this phenomenon, scientists concluded that they must be spaceships, traveling at nearly the speed of light, something formerly thought impossible. The ultimate conclusion was twofold: There is intelligent life with technology out in the universe, and traveling at the speed of light is apparently possible – somehow. This knowledge spurned human scientists to invent the “zero zero drive”, an engine allowing human craft travel at virtually the speed of light.
Einstein’s physics states that when an object travels at relativistic speeds, those approaching the speed of light, the mass of the object approaches infinity (hence this is difficult to achieve) and time slows down. This is the technology that underlies the premise of the novel Starfarers. Earth evolves a society where crews on starships travel to distant stars, say 20 light years away, for exploration, eventual colonization of planets and finally trade.
The problem is that it takes, assuming travel at 99.9 percent the speed of light, 20 years to get to the destination. and another 20 to get back. When the travelers return, 40 years will have passed on earth. Due to time slowing down during the travel for the crew and ship, however, the crew will only age a few days during the 20 year trip there and finally a few more days traveling back home. All their friends on earth will be 40 years older, if still alive. It would be like leaving in the 60ies and coming back now.
Now imagine such a trip to a star 100 light years away. You travel a few weeks subjective, and you come back after 200 years. It’s like leaving on a trip when America declared its independence and coming back now, a month older.
Well, to visit the society in the Centaur region 5,000 light years away, earth built the starship Envoy, the most advanced vessel ever built. A crew of 10 people embarked on the trip of 5,000 years one way. For them, subjective, the trip took a year and a half each way.
Imagine what they found when they met the aliens whose starship trails they had detected 5,000 years before, which were then 5,000 years old already, or 10,000 years total before the time when they arrived. Was the civilization still starfaring then? Did it even exist anymore?
Imagine what they found when they returned to earth, approximately in the year 13,000?
Poul Anderson’s writing style is sometimes difficult to read. His plot development in this story is also somewhat clumsy. There are entire sections in this book that add some perspective, but don’t help the story along, so they really could have been left out. There are also some characters in the story that just don’t make sense. Why would Brent and Cleland board a starship to go on a 10,000 year journey, only to get antsy to go back home after 5,000 years have gone by? What’s another 5,000 years at that point.
While there are problems with this novel, the central idea of time dilation and the societal issues that arise from it are powerful and thought-provoking.
Time dilation speculation is almost as much fun as time travel rumination.