Time for the Stars is a book about two twins, Tom and Pat, who are telepathic. They can communicate with each other in their minds without speaking out loud. Scientists have discovered that some twins have this ability, and they believe it can be useful in space exploration.
The problem is that space exploration takes a long time, and the further away you go, the longer it takes. The scientists can't send a message back and forth between Earth and the spaceship quickly enough. So, they decide to send one twin into space while the other stays on Earth. They will communicate through their telepathic abilities.
Tom is chosen to go to space, while Pat stays on Earth. Tom is sent on a spaceship to explore a distant planet. He travels at an extremely high speed (close to the speed of light) which slows down his perception of time.
On the other hand, Pat, who stays on Earth, experiences time normally. He goes to school, grows up, gets a job, gets married, and has a family. Meanwhile, Tom ages very slowly because of his high-speed travel. When Tom returns to Earth, he is only a few years older, but Pat has grown into an old man.
This concept is called time dilation. In a nutshell, it means that time passes differently for objects moving at different speeds. The faster an object moves, the slower it experiences time.
The twins in Time for the Stars experience this phenomenon firsthand. By using their telepathic abilities to communicate over long distances, they help humanity explore the depths of space in a way that we never thought possible. It's a fascinating concept that will make you think about time, space, and how they're all connected.