As my transport begins its final approach to the exit gate, I link into the external sensors and look back at the vastness I am leaving behind. Even across this distance, the world-disk fills the sky. Two billion kilometers in diameter and ten thousand thick, Discfinity dwarfs nearly every other structure ever imagined by Terragens. It fills my vision from end to end, our current heading placing it nearly face on to my perception. Here, on the edge of the system, the details of the disk are lost, the mountains, plains, and seas blurred together into a blue-green blankness. Yet, in the absence of hard detail, my mind's eye turns to memory to fill in the details.
There, that pale section just out from the glaring point of the central star (data-filters have automatically engaged to protect my vision) may be the deserts of the Crystal Plains, home to a silica-cybernetic ecology as complex as anything found on a carbon-based garden world. I remember walking across burning sands, clad only in an enviro-suite, as glass flutterbugs spun around me in scintillating clouds.
A hint of blue line in a section of dark green could be the Ringriver, a band of water as much as three thousand kilometers across and a full five hundred million kilometers long. A group of us spent a month on a home-made house-boat cruising down the river, swimming, fishing, drinking, and enjoying each other's company. Dozens of shore or water-dwelling sophonts visited in that time, often bringing local foods, drinks, and intoxicants of seemingly endless variety. Stored away in my personal files are memories, comm-codes, and images from that trip that I will enjoy for centuries to come.
Beyond the Ringriver, (tens of millions of kilometers beyond actually, although that is not apparent now) a darker line stands out more clearly, one of the few features clearly visible even from this distance. The Torus Range is really just an air barrier, separating one major region of the disk from another, and certainly the sculpting of such barriers into mountains is nothing new. But to climb the peaks of such a range, to stand atop it using only a thinsuit and air-dust, and to look out at a line of similar mountains extending off to the vanishing point in either direction is an experience I will not soon forget. No less the view of the Twilight, extending for tens of kilometers beyond. Hidden forever in the lee of the Range, the Twilight is never touched by the slow rise and fall of the central sun. It would have been easy enough to use orbiting flectors to illuminate it, of course, as has been done with some of the other air barrier mountains. But instead the Builders chose to weave a bio-system here. An entire ecology, bigger than worlds, entirely adapted to only the small bit of light that leaks over the Range or reflects from the normally illuminated lands beyond.
Walking through the Twilight is to enter a fantasyland of night-blooming flowers and bioluminescent organisms of all types. Sonar hunting Greatbats glide through the skies while songflowers use breeze driven sonic cries to repel insects and animals that would otherwise eat them. Through it all moves a multitude of dark adapted sophonts of all kinds. Some have merely modified themselves to thrive in the low light conditions but are otherwise found across the Civilized Galaxy. Others are entirely engineered for life in this surreal place and can be found almost nowhere else.
Thinking of the Twilight leads my thoughts naturally to the Underworld. Dwarfing even the Twilight as a place of darkness and wonders, the Underworld encompasses much of the internal volume of the great disk. A vast network of tunnels and caverns, some of them thousands of kilometers across, the Underworld is actually millions of worlds. Some are cloaked in endless darkness and silence like the cavern systems of Old Earth and other garden worlds. Home only to the slow pulse of geochemical processes and slow living microorganisms, they are subject to only virtual observation and very occasional visits by carefully screened petitioners. Yet other caves host ecosystems to rival those found on Labyrinth. Still filled with blackness or lit only by the glow of bioluminescent denizens, they nevertheless bustle with life and energy equal to that found in any surface dwelling biosphere. Finally, there are those caves engineered by the Builders, not as natural ecosystems so much as habitations or artworks for the use and delight of other sophonts, Discfinity natives and visitors alike.
Great light sources hang from rocky ceilings or float just below them. In their light can be found underground forests, lakes, rivers, and even seas. Great cities rise up from cavern floors to kiss the cave roof or cling to the walls of mighty tunnels extending for hundreds of thousands of kilometers in each direction.
A myriad of access points to the Underworld spot the giga-disks surface, most merely the size of great caverns, some so large that they literally punch through to the opposite face of the construct and void swarms and other tech must be used to manage the traffic and airflow as gravity does strange twists and turns as first one surface and then the other exercises its pull. Naturally, travelers can make such a journey in maximal comfort, barely noticing the switch from one face to the next. But far more commonly used are transport methods that do little or nothing to minimize the transition effects and which owe as much of their design to considerations of entertainment as practicality.
The transport orients for final approach to the gate and my view swings outward along the disk to the cold, dark realms of the Rim. Home to lifeforms whose need for light, warmth, and air is minimal, the Rim hosts thousands of cold adapted ecologies. Modeled on the frigid richness of Muuhhome, or the homeworld of the Soft Ones, or developed entirely from first principles, each ecology rivals the complexity of any world in the known galaxy. And most are homes to intelligence in one form or another. I remember icy cities and warm conversations with beings ancient and wise. Slow moving and thinking they might be, a natural consequence of their frigid metabolisms, but once I adjusted my own time rate to theirs, they proved as quick-witted as any being I have encountered anywhere else. And easily as charming.
The gate wells up around us and the transport shifts through. A moment of disorientation, two moments of blackness, and then I open my eyes to the sight of my study and the feel of the comfortable lounge that I habitually use for journeys into the local cybercosm. A servitor rolls forward with a glass of fruit juice, something I find perfectly refreshing and just what I would have ordered if given the chance (there are worlds that disdain the use of Environmental Optimization Protocols and their constant anticipation of one's every need or desire, but I am glad Eden is not one of them).
Rising, I dismiss the lounge and associated study surround back into house memory and manifest a door and balcony overlooking the nearby sea. The sun is setting and the evening breeze only adds to my feeling of relaxation. Although my visit to the Discfinity virtual environment took barely an hour of rl time, my memories of the visit encompass nearly a year of subjective experiences. It feels as if I have had a long and exciting vacation and I am ready now to resume my avocation of traveling across the Nexus and documenting my adventures. It is perhaps one of the little ironies of our modern age that, although I have already spent centuries engaged in such pursuits and have no intention of doing anything else for centuries more, all of the places I will ever travel to combined will never add up to even the smallest fraction of all the virtuals, surrounds, and environments that are instantly available just within the bounds of our local moon-node.