The S.I.U. station (the Search for Intelligent Universe station) was a Deep Space research station.
The scientists there believed in a theory that the universe itself is a sentient entity, and although most others in the Space Corps thought it preposterous, they attempted to contact it. However, the scientists died of old age whilst the station took centuries to undertake its trillions of calculations.
Eventually, the Nova 3 was sent out to locate the station, but crashed nearby, with the only survivor being a mechanoid named Butler. Over the next three million years, Butler immersed himself in research and became a learned polymath, and completed the original mission of his ship by locating the S.I.U. station.
When the Nova 3 wreck was visited by the Red Dwarf, Butler engineered events so that the Dwarfers would be redirected to the S.I.U. station, as he thought that would help with the mid-life crisis his fellow mechanoid Kryten was suffering from.
At the station, the Dwarfers found a telephone "on hold" and answered it, then communed with the entity which identified as "The Universe". Rimmer demanded to see proof that the entity was what it said it was, but this was not forthcoming.
Kryten then spoke with the entity, with the conversation having the outcome of resolving Kryten's emotional dilemma when Kryten spoke of how a Universe which contained love was worthwhile.