In A Deepness in the Sky, the OnOff star and the spider's planet both exhibit unusual properties. The star itself spends most of its time essentially dark; while the planet contains minerals which seem to have antigravity properties.

These are not characteristics typical of the slow zone, and seem like they could result from the system being located in a higher zone of thought. However the human fleets which reach the planet are clearly comprised of slow zone ships.

What zone of thought is the OnOff system in?

Edit / Notes:

In Deepness the concept of zones of thought is apparently unknown to all the characters (and I think not even mentioned in that book itself). However, that doesn't mean that they haven't stumbled in ignorance out of the slow zone or perhaps into a region which oscillates between zones.

Also we learn in A Fire Upon the Deep that Pham Nyguen (or his body anyway) ends up in a higher zone of thought. This also tends to suggest that the region that the Qeng Ho operate in or where he went after On/Off could be at least relatively near (on a galactic scale) to the zone boundary.

  • Possible duplicate/answer: scifi.stackexchange.com/questions/12556/…
    – DavidW
    Commented Jun 3, 2019 at 17:54
  • 4
    The OnOff system is pretty canonically in the slow zone, though. (Don't have the book handy as a reference unfortunately.)
    – DavidW
    Commented Jun 3, 2019 at 18:03

4 Answers 4


It's been a while since I read it, but my memory is that within the Deepness in the Sky setting, there are no zones other than what is referred to as the "Slow Zone" in Fire Upon the Deep. That is:

  • There is no mention of the Zones, let alone of the characters being aware of them.
  • All of the travel is sublight speed.
  • At the end of Deepness in the Sky, Pham Nuwen embarks on a journey to the center of the galaxy. As detailed in Fire Upon the Deep that this put him in the "Unthinking Depths". If humanity had been aware of The Beyond and how the Zones work, surely Pham would have wanted to go to The Beyond, not the Unthinking Depths.

We also have the Emergents using people as makeshift AI, and if there were in the Beyond, they would just use actual AI.

wikipedia has this to say:

A Deepness in the Sky takes place in the Slow Zone, though Vinge does not explain the connections, and the characters in the story remain unaware of the zones' existence. The sun's inexplicably strange behavior, the unusual planetary system (with only a solitary planet and several asteroid-sized diamonds), and the discovery of "cavorite" on the planet may indicate the system originated in the Transcend, though it is currently moving outward from the Unthinking Depths. Vinge's characters speculate that the Spiders descend from an ancient star-faring civilization, and that the anti-gravity material and other strange artifacts have connections with that civilization. Unfortunately, they guess the structure of the Zones (though not the actual properties) backwards, coming to the conclusion that the bright center of the galaxy is the most likely location for advanced civilization. This leads Pham on his path inwards to the Unthinking Depths, and his eventual resurrection.

The implied sequence of events is this: The Spiders' planet was originally in the Beyond, on the other side of the galaxy from where the Qeng Ho and Emergents found it. It then traveled into the Slow Zone, eventually passing through the lower portion of the Slow Zone and possibly the upper edge of the Unthinking Depths, causing a collapse of the civilization. It then came out the other side, continuing on back toward The Beyond. Eventually, its increased distance from the galactic core, along with time for its inhabitants to rebuild, resulted in the Spiders reaching a 20th century Earth level of technology, and the radio emissions of their civilization alerted the Qeng Ho and Emergents to their presence. Pham Nuwen, seeing that the planet had signs of previously advanced technology, and observing it traveling away from the galactic core, incorrectly surmised that the galactic core was a region of advanced technology.

  • 2
    @DaveInCaz Yes, but it's corroborated by the other points that I made. Commented Jun 3, 2019 at 22:26
  • 1
    @RLH The snippet starting "Pham Nuwen embarks on a journey" is clearly from the point of view of Nuwen's personal timeline, in which the events of AFUtD followed ADitS, so the existing wording is correct.
    – DavidW
    Commented Jan 25 at 17:53
  • 2
    @RLH Why the insistence on publication order? Would you also claim that all references to A New Hope must state that it came before Revenge of the Sith?
    – DavidW
    Commented Jan 25 at 18:39
  • 1
    @DavidW: Because Vinge wrote Deepness as a flashback-sequel/prequel for an audience who he expected had read Fire, has not indicated that Deepness should be read first and uses the reader’s knowledge of the Zones to create narrative tension. The SW canon is a mess that I try to avoid touching, but I would certainly object to a statement that the meaning for something that happens in Rogue One is “later revealed” in A New Hope.
    – RLH
    Commented Jan 25 at 18:49
  • 1
    I’ll just say that you’re the one who rolled back an approved edit that was a softening of a previously approved edit.
    – RLH
    Commented Jan 26 at 5:54

The OnOff system is in the Slow Zone but there are artifacts from other Zones in the system, including the OnOff star itself:

  1. The system is in the Slow Zone

Paleontological evidence on the Spider world indicate no external visitation for millions of years - if the planet were in the Beyond, it would have been colonized by one of the millions of civilizations that inhabit the Beyond, and travel freely in it.

  1. The On-Off Star may be an artifact

2a) Beyond artifacts can survive in lower Zones

From A Fire Upon the Deep

Relay was in Middle Beyond; the Organization’s only export was the relay function and access to the local archive. Yet they imported the finest biologicals and processing equipment from the High Beyond. ... But the Docks were in no orbit. They floated a thousand kilometers above Groundside on the largest agrav frame Ravna had ever seen. 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.

2b) the On/Off star is such an artifact.

In Deepness in the Sky, the Focused scientist Wen says

“Things are happening that we can’t see. Relight, a light curve vaguely like a periodic Q-nova, settling over a few Msecs to a spectrum that might almost be an explainable star riding a fusion core. And then the light slowly fades back to zero…or changes into something else we cannot see. It’s not a star at all! It’s magic. A magic machine that now is broken. I’ll bet it was a fast square-wave generator once. That’s it! Magic from the heart of the galaxy, broken now so that we can’t understand it.”

It is a bit of irony that Vinge has a near-madman reporting a distorted version of the truth, and not being believed.


The Qeng Ho fleet was first to arrive at the OnOff star. That might not matter. For the last fifty years of their voyage, they had watched the torch-plumes of the Emergent fleet as it decelerated toward the same destination.

A Deepness in the Sky, Chapter One, opening sentence


... S.J. Park was smiling, too, probably with as much sincerity as Tomas Nau. Fleet Captain Park had not been popular with the Triland Forestry Department; that was partly because he cut their pre-Flight time to the bone, even when there had been no evidence of a second fleet. Park had all but fried his ramjets in a delayed deceleration, coming in just ahead of the Emergents.

A Deepness in the Sky, Chapter One

Both fleets, especially the Qeng Ho, using ramships to get there despite the immediate attraction is required by the target system being in the Slow Zone.

  • 2
    Humans were still using ramships when they first left the Slow Zone (else how would they have gotten out?); Deepness seems to be set before humanity found its way out. There's more evidence of this in A Fire Upon the Deep.
    – Zeiss Ikon
    Commented Jun 3, 2019 at 18:41
  • @ZeissIkon I didn't think it was clear that humanity had never left the Slow Zone at that point. I thought that the Qeng Ho at least had traded across the boundary already by this point, and could have routed a faster expedition that way if the OnOff system had been in the Beyond. I've only just found my copy and browsed the first chapter so far, so I could be mis-remembering.
    – DavidW
    Commented Jun 3, 2019 at 18:50
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    As I recall from the two books, humanity was exploring the wrong direction -- hence why Pham Nguyen was found, during Fire, at the bottom of the Slow Zone, near the Unthinking boundary -- he'd never have gone there if he'd had word from Beyond first.
    – Zeiss Ikon
    Commented Jun 3, 2019 at 18:53
  • 1
    @ZeissIkon right. And how would they even know if they had crossed the boundary when they didn't know such a thing even existed? Commented Jun 4, 2019 at 10:06
  • @Zeiss Ikon: moreover, there was some rumination about the galactic orbit of the OnOff which mostly lies in (or close to) the Core (that is, in the Unthinking). If Ī̲ remember correctly, Qeng Ho even discovered some enigmatic artifacts which Pham conjectured to originate from central regions of the Milky Way. Commented May 18, 2020 at 12:06

There is also the possibility that the on-off star is the source of the Surge triggered by Nuwen/Old One/Countermeasure at the end of “Fire”:

In “Fire,” it is implied that whatever made Countermeasure is something “beyond the Powers” that came from the Depths, not the Transcend. This would be consistent with on-off having originated in the Depths.

The source of the Surge is clearly beneath Tines’ World, i.e. in the Slow Zone (or deeper).

The motif phrase “So high, so low” can be read as a reference to the Surge which leaps from the depths to the Transcend.

I’m currently 1/4 way through rereading it, years after my first time, and I remember thinking there was plenty more detail to support this theory, first time round!

  • 2
    Hi, welcome to SF&F. Do you have any evidence for this? IIRC the quote from AFUtD is "Powers beyond the Powers" which is to say unknown entities even further removed from the Transcend than the Transcend is from the Beyond. Can you quote any passages that situate the source of the Zone shift in the galaxy at all? When Pham Nuwen says he's focusing Countermeasure, he talks about signaling entities far outside the galaxy.
    – DavidW
    Commented Jan 24 at 22:13

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