Literature: Time For The Stars
Time for the Stars is one of Robert A. Heinlein's most famous juvenile novels. The basic idea is derived from the "Twin paradox" thought experiment in special relativity.Tom has always resented his twin brother Pat, but then they get involved in "Project Lebensraum" and are discovered to have a telepathic bond. When Pat is chosen to go on board a relativistic starship while he stays behind to send and receive messages to/from his twin he is instantly jealous. But then Pat is paralyzed in a skiing accident and Tom has to go out into space in his place.Tom spends less than three years in space, having to watch from light-years away while his brother ages more than seventy years.
- All Planets Are Earthlike: Averted, the Lewis and Clark explores four systems and only finds two inhabitable planets. And as far as they can tell the other ships find even fewer.
- Fish Out of Temporal Water: After the second jump they start noticing slang that they don't recognizing through the telepathic communiques. When they get back to Earth they're so out of place that most of them want to go back into space.
- Generation Ship: The Lewis and Clark is out in space for years at a maximum speed just under the speed of light, multiple crewmembers marry and have children in that time.
- Incest Is Relative: When Tom gets back to Earth he marries his great-great-niece and current primary telepartner Vicki.
- Lightspeed Leapfrog: After losing most of the crew to hostile natives on Elysia they are ordered to remain in the area for a month so an FTL ship can pick them up.
- Psychic Link: Twin Telepathy is by far the most common form, but other relationships are seen such as "Uncle Alf" and his great-niece "Sugarpie", both of whom Tom learns to form a link with. As the Earthside telepartners age and lose their connections the institute figures out how to form new connections, such as Pat's descendants.
- Time Dilation: Relativistic. As they speed up the Earthside twin starts to sound like they're jabbering and the space-faring twin is drawling. When they get near the speed of light contact is impossible without a lot of drugs and hypnosis.