Túnel no céu de Robert Heinlein!
A Malthusian catastrophe on Earth has been averted by the invention of teleportation, called the "Ramsbotham jump", which is used to send Earth's excess population to colonize other planets. However, the costs of operating the device mean that the colonies are isolated from Earth until they can produce something to justify two-way trade. Because modern technology requires a supporting infrastructure, more primitive methods are employed — for example, horses instead of tractors.