My book is about these explorers who travel throughout space searching for new planets to build on. Once they find a planet they build it up so it is liveable for other beings then they leave that planet to search for new ones. Once they leave a planet they cannot come back to it because the difference between space time and planet time is different. So when they leave they won't see those people anymore.
One of the major problems that they have aboard the Gypsy Moth is getting enough people to take the ship over in the future. So every once in a while they will have to steal or buy babies from certain planets. Becuase they cannot have babies themselves they are forced to do this. Some planets they cannot go to because they are known for sometimes stealing babies and they are hated by some beings because of it. When they do travel to other planets they travel in a transmitter. This is a way of transporting to other planets.