It was generally accepted by the Minds, drones and even humans who cared about such things that, with the space between the stars being so vast, any technically advanced artefact that wanted to stay undetected had a very good chance of remaining so, especially if it refrained from doing anything conspicuous that might advertise its presence. Even so, interesting things – often, very old interesting things – were discovered from time to time.
So, as a matter of course, there were numerous vague suggestions and a myriad of low-probability contingencies included in the voluminous briefing that the General Contact Unit Xenagogue received from the General Systems Vehicle What’s Not To Love? and the contingent of Contact Minds that took it upon themselves to orchestrate explorations in this particular region of space.
It was just another wandering rock tumbling slowly in the vast quiet dark spaces between the stars. It was previously unknown, quite possibly, to any species now living, or at least any who were prepared to talk about such things. It might, also quite possibly, have remained unknown if, by a spectacularly huge piece of luck, it had not been encountered by the Xenagogue taking an eccentrically circuitous route from one star system to another.
[tight beam, M8, tra. @n188.8.131.529]
A great many civilizations, at a relatively early part of their evolution, perfected virtual reality, allowing citizens to experience any number of real and imaginary environments and scenarios in a truly immersive way. Most civs, at roughly the same point in their development, developed reliable ways of copying a person's thought processes onto machine substrates of various kinds, allowing the recorded person to appreciate simulated situations, or be transcribed into suitably enabled machines or bodies - there was often little difference between these, at this level of technology - to continue to experience the Real.
Inevitably, the Culture made considerable use of these technologies. Everybody had access to immersive VR for games, education, travel and, of course, sex. Brain-state copies allowed people to be backed up before attempting dangerous activities, although this - like everything else in the Culture - was entirely optional. The Culture had its fair share of immortals - people who wanted to live forever and enjoy every moment of it - but the prevailing fashion was for people to age and die, after three or four hundred years, having seen and done and experienced everything they desired. Some asked to be Stored, inactive, to be woken - and perhaps revented into a new body - when some specific event had occurred, or when something interesting happens - content to leave that judgement to others - or perhaps just at periodic intervals. A few entered Group Minds, where one's personality gradually merged with that of others.
The one thing the Culture did not do, as a rule, was to use these abilities to create Afterlives: perfect simulated Heavens for its dead citizens to enjoy for as long as they want. The prevailing view was that one was either dead, completely and irrevocably, or alive - even if only potentially - and capable of being returned to the real in any of innumerable forms.
There was a moral issue too, which left many Minds and the few people concerned about such things in conniptions: if it was possible to create Heaven, it was equally possible to create Hell.