The empirical facts are that an World is always surrounded by Grandmist, and this continues to be the case no matter how much the World expands. There are no cases of something being "found" in receding Grandmist, whether that be another actual World or the scars of a collapsed World.I'm really confused about how grandmist works. Like, you dispel it but then when your inner world is destroyed what happens to that hollowed out space? Or is it impossible to know because no one has successfully make inner worlds close enough to interact with each other?
There are two main theories in-setting to explain this.
- Some reason that the creation of a Dantian literally creates an infinite sea of Grandmist as well. Then, when a world collapses, said infinite sea disappears with it. This fits the empirical evidence perfectly, but leaves people questioning how the creation of a Dantian can create an infinite world. Normally, any creation is supported by Qi, so an infinite creation doesn't seem possible - and of course, normally a creation can only return the Qi invested in making it, so it seems absurd that the birth, growth, and death of an inner world somehow generates Qi overall.
- Others argue that the Grandmist Sea actually exists somewhere; it is just unfathomably large, to the point where collisions between worlds have negligible probability. This fits the data as well, though it leaves open the question of where the Grandmist actually is and what kind of scar is left in it after a world dies.
So your question doesn't really have a knowable answer in-setting.