World:Enter the Grey/Technology/Subspace
The 5th dimension, subspace was discovered during WWIII as a means of communicating secretly. It was found that "portals" could be created across vast distances, although the first portals were only permeable to energy- and specifically, to short streams of photons. This was enough to transmit data, and because the technology was not yet fully understood, such transmissions were completely secure.
Now, subspace research is a slowly growing field. Interplanetary communications via relay lines of buoys orbiting the sun at various distances are almost instant, though bandwidth is limited. Matter transportation is predicted within decades. In the meantime, subspace has provided a means of fast interplanetary transport. Subspace partial-shift drives allow vessels to fly through space at tremendous speeds, making the trip from Earth to Mars in a matter of days.