In A Deepness in the Sky, the Arachnids discover diamond nano-tech particles mixed in with shale formations from the ancient past of the planet. When sifted from the surrounding shale, the nano-tech apparently reactivates and exhibits anti-gravity properties (becoming a material known as "cavorite").

However, in A Fire Upon the Deep, we are told that some technology, including agrav, can only be built in the High-Beyond and Transcend:

"The Beyond and below are like a deep of ocean, and we the creatures that swim in the abyss. We're so far down that the beings on the surface -- superior though they are -- can't effectively reach us. Oh, they fish, and they sometimes blight the upper levels with poisons we don't even understand. But the abyss remains a relatively safe place." She paused. There was more to the analogy. "And just as with an ocean, there is a constant drift of flotsam from the top. There are things that can only be made at the Top, that need close-to-sentient factories -- but which can still work down here. Blueshell mentioned some of those when he was talking to you: the agrav fabrics, the sapient devices. Such things are the greatest physical wealth of the Beyond, since we can't make them."

Not only can the only be created in the High-Beyond or Transcend, but they also apparently require being in those zones to maintain long-term functionality

In the Middle Beyond:

At Sjandra Kei the annual income of an academician might pay for a square meter of agrav fabric -- junk that might not last a year. Here there were millions of hectares of the stuff, supporting billions of tonnes. Just replacements for dead fabric required more High Beyond commerce than most star clusters could command.

In the Low Beyond:

It was a team game the two Skroderiders played. While Blueshell chattered, Greenstalk watched everything around them, running her skrode's recorders on all bands, trying to place this environment in the context of others they had known. Technology: What would these people need? What could work? In space this flat, there would be little use for agrav fabric. And this low in the Beyond, a lot of the most sophisticated imports from above would spoil almost immediately. Workers outside the long windows wore articulated pressure suits -- the force-field suits of the High Beyond would last only a few weeks down here.

And in the Slow Zone:

"That's only part of it. I think we Tines are more flexibly minded than the poor Two-Legs. Can you imagine what it will be like when we make more radio cloaks, when we make our own flying machines?"

Woodcarver smiled, a little sadly now. "Pilgrim, you dream. This is the Slow Zone. The agrav will wear out in a few years. Whatever we make will be far short of what you play with now."

How does the cavorite maintain its function in the OnOff system, which is clearly in The Slow Zone (and was, at one point, in The Unthinking Depths), despite the cavorite being millions of years old?

  • Can you give a location for the quote in AFUTD?
    – Sam
    Commented Mar 6, 2012 at 18:44
  • I can't remember from AFUTD, but in ADITSK, it's clearly stated that anti-gravity, AI, etc are "Failed dreams".
    – Benoît
    Commented Mar 6, 2012 at 19:06
  • @Sam It appears that my memory was slightly off... agrav and other High-Beyond tech will work in Low Beyond and the Slow Zone, but degrades quickly (a matter of years in even the Middle Beyond). I've added in references from AFUTD.
    – Beofett
    Commented Mar 6, 2012 at 19:18

1 Answer 1


Spoilers here, for A Fire Upon the Deep and "The Blabber" (which is a novella set in the Zones of Thought universe, or at least an earlier draft of it):

In "The Blabber" we are introduced to an artifact that works in the Slow Zone but exhibits functionality normally only available in the Beyond (FTL communication, albeit very slow). As a side-effect, it sucks enough energy from the local star to dim it by 0.5%. In A Fire Upon the Deep, Countermeasure produces Transcendent-level effects in the Beyond (continuing for a while into the Slow Zone), and temporarily extinguishes the light from the Tines World sun while doing so.

So I conclude that it is possible to operate and maintain higher-level technology in the Slow Zone as long as you have stellar levels of energy available, and that the OnOff star is Off for most of the time because its energy is being used to keep alive the Beyonder or Transcendent artifacts which are found on the planet in such profusion that they form geological strata.

  • 4
    Wow, interesting theory about the On-Off star Commented Oct 10, 2013 at 11:06
  • 7
    I always thought that the entire on-off system is some transcendent's version of a slow zone dredge. A purposfully constructed solar system that uses 200 years of solar energy to occasionally emit a superluminal ping. Commented Nov 23, 2014 at 7:41

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