Time for the Stars

Time for the Stars is a science fiction novel by Robert A. Heinlein published by Scribner's in 1956 as one of the Heinlein juveniles. The basic plot line is derived from a 1911 thought experiment in special relativity, commonly called the twin paradox, proposed by French physicist Paul Langevin.

Plot summary
The Long Range Foundation (LRF) is a non-profit organization that funds expensive, long-term projects for the benefit of mankind. It has built a dozen exploratory starships (torchships) to search for habitable planets to colonize. The vessels can continually accelerate but cannot exceed the speed of light, so the voyages last many years. Each starship has a much larger crew than necessary to maintain a more stable, long-term shipboard society, as well as provide replacements for the inevitable deaths.

It is found that some twins and triplets can communicate with each other telepathically. The process seems to be instantaneous and unaffected by distance, making it the only practical means of communication for ships traveling many light years away from Earth. Before announcing the discovery, the foundation first recruits as many of these people as it can. Testing shows that teenagers Tom and Pat Bartlett have this talent and both sign up. Pat, the dominant twin, manipulates things so that he gets selected as the crew member, much to Tom's annoyance. However, Pat does not really want to leave and his subconscious engineers a convenient accident so that Tom has to take his place at the last minute.

On board, Tom is pleased to find his uncle Steve, a military man, has arranged to get assigned to the same ship. The trip is fraught with problems as trivial as an annoying roommate and as serious as mutiny. The ship visits several star systems. Due to the nature of relativistic travel, the twin who remained behind ages faster and eventually the affinity between them is weakened to the point that they are no longer able to communicate easily. Some of the spacefaring twins, including the protagonist, are able to connect with the descendants of the Earthbound twins. Tom works with his niece, then his grandniece and finally his great-grandniece.

The last planet scouted proves to be particularly deadly...


 * The Jailbait Wait and Wife Husbandry: The story uses relativity to accomplish both this and dilute enough genes to avoid incest charges.
 * Population Control: Mentioned in the backstory. Each family on Earth can have three children. Extra children are taxed and the family doesn't receive government financial help for them. Families can trade for each other's unused child slots or apply for reclassification for more children.
 * Subspace Ansible: Played with, in that the FTL communication is telepathic rather than technological.
 * Telepathic Spacemen and Twin Telepathy: The plot revolves around these tropes.
 * Time Dilation: Played straight, and the ramifications are explored during the story.
 * Time Dilation: Played straight, and the ramifications are explored during the story.