system
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human
[The Culture] Was the Advanced alien object from the novel "Excession" supposed to be from a sublimed race, or something else entirely?

The perfect "black body sphere" from the culture novel "Excession" is said to be far more advanced then anything from the culture universe. My question is whether or not it is more or less advanced then the civilizations that have sublimed. Are there other levels of reality outside the normal culture space-time and the sublimed space-time that this object came from?
gpt
Spoilers for Excession:

The end makes it fairly clear that the Excession is something else entirely.  The Excession was able to travel between universe. The multiverse of the Culture looks like the layers of an onion, slightly older universes moving outward, slightly younger universes moving in. The Energy Grid separates the universes from each other. For hyperspace travel you "connect to the grid" alternating between the older/younger sides.  The Excession was able to connect to the Energy Grid in both directions (when a Mind says "Gulp", thats a big deal).  The Excession could move up or down the line of universes to older/younger versions.

The Excession was scouting the Culture universe to see what the local galactic conditions were and get a feel for the local inhabitants.  The Culture (cough, The Interesting Times Gang, cough) did not do a very good job.  

Can the Sublimed do the same thing as the Excession?  We don't know.  The Sublimed don't talk much.  It could be the Sublimed can find a way to do the same thing and move to younger universes (effectively immortality even from the heat death of the current universe).  However, it is also possible they do not.  Again, we just don't know.