The Long Earth by Terry Pratchett and Stephen Baxter

One day schematics for a simple device, called a stepper and powered by a potato, show up online. The device isn’t complicated. You could make it at home from spare parts or get the components from Radio Shack. It’s ease of construction isn’t what what makes it the latest fad among children and teenagers. What makes the device appealing to make is that it promises to send you to a parallel Earth. The scary thing is that it works, even though it shouldn’t. Soon kids are disappearing all over and the world is changed in an instant.

One young teen, Joshua, gains notoriety for finding and helping the missing children step back into the original Earth. As he grows up he realizes he doesn’t need a machine to step between worlds. He becomes a new type of explorer, one who journeys through countless different versions of Earth. What is immediately clear is that for some reason humanity is singular to our Earth. On no other reality is there signs of intelligent life, just pristine wilderness.

As people and corporations attempt to exploit all the new resources multiple earths represent Joshua is given a chance at exploring the Long Earth in style. A sentient computer named Lobsang whats to step millions of Earths away and he wants to take Joshua with him. They have an elaborate dirigible that lets the fly and step at the same time. Soon the exploring realities that no one ever dreamed could exist.  But out there in the wilderness of multiple realities lies something that waits. What it wants could put all the versions of Earth in mortal jeopardy.

The Long Earth is an adult sci-fi adventure novel that is an absolute delight to read. If you are a fan of alien worlds, computers, or just like to have fun then this book comes highly recommended. It is appropriate for ages 14 and up.