Why does Ushas need the White Fountain?

At 02:27 PM 7/6/98 -0400, you wrote: Ok, all this discussion of the black hole/white fountain has made me realize that, although I thought I understood, I still don't get it. Urth's sun is dying for some reason. Severian goes to get a White Fountain, but brings it back to a different universe, to Ushas, whose sun is, as far as I know, doing just fine. How does this action help either Urth or Ushas? I imagine I'm missing something obvious that re-reading Urth or the archives might answer, but would someone mind explaining it one more time? -Rostrum

Urth's sun is dying for some reason. Severian goes to get a White Fountain, but brings it back to a different universe, to Ushas, whose sun is, as far as I know, doing just fine. How does this action help either Urth or Ushas?

Ushas is Urth post-White Fountain. The White Fountain is the new sun of the same universe that Urth was in.

At 04:12 PM 7/7/98 -0400, you wrote: I asked:

Urth's sun is dying for some reason. Severian goes to get a White Fountain, but brings it back to a different universe, to Ushas, whose sun is, as far as I know, doing just fine. How does this action help either Urth or Ushas?

On Mon, 6 Jul 1998, Marc Coleman answered:

Ushas is Urth post-White Fountain. The White Fountain is the new sun of the same universe that Urth was in.

So Ushas and Urth are in the same universe? Ushas is simply Urth some years later when the newly restored sun has melted the ice? Somehow I thought it was more complicated than that. -Rostrum