I recall Vinge saying something along the lines of “I needed an explanation for why everyone didn’t hit the singularity” in some interview or something, but I thought the zones were pretty clearly modeled on the complexity hierarchy.
Think of consciousness and FTL travel each needing certain algorithms to run. The local laws of physics bound what computing devices can be built, in a way that determines the algorithms that can be run. In the unthinking depths, no computing devices can exist on which consciousness algorithms can run. (Or maybe it just gets successively harder for consciousness algorithms to work.) I kept thinking of the transcend as where the algorithms were linear time, the beyond as polynomial with increasing exponents, and the slow zone (for FTL) or unthinking depths (for consciousness) as exponential.
The big idea behind A Deepness in the Sky was that with limits on computing power and other technology—the “failed dreams,” you’re caught in endless Motie-style cycles of collapse and recovery (or sometimes just collapse). All IMO. (Does Vinge ever comment on blogs?)
I keep thinking that in Dies the Fire (I’ve only read 1.5 books in the series), someone should start using compressed air tanks to store unlimited amounts of energy. I mean, the pressure gradient never gets above some maximum, right?
The interesting thing to me is the thought process here, as I also knew what was being tested and corrected myself. But the intuitive algorithm for answering the question is to translate “which of these statements is more probable” with “which of these stories is more plausible.” And adding detail adds plausibility to the story; this is why you can have a compelling novel in which the main character does some incomprehensible thing at the end, which makes perfect sense in the sequence of the story.
The only way I can see to consistently avoid this error is to map the problem into the domain of probability theory, where I know how to compute an answer and map it back to the story.