Space-time engineering involves using computer programming and electrical engineering to achieve transformations in space-time. The paper introduces concepts of space-time engineering and the principles of space-time programming using a computer program called J-Earth. J-Earth can request transformations from a host to produce expansions in space, such as creating portals and instantiating new dimensions. This allows limitless transformations without using real space, potentially enabling new universes to be programmed and useful applications to be developed.