Psi: What's the inner astral for?

[Gef]

Thanks for the responses. Sir Pudding, you've reminded me of several ways I can coerce PCs to go there, but my question is really toward routine utility. RPK's answers likewise go to reasons of plot, and the specific examples fit a fantasy idiom more than scifi, even soft scifi. Looks like the utility depends solely on how the GM develops it. Alas, I was hoping to avoid having to map a world that's bigger than the world. -GEF