Once, we saw a large structure collapse like a stage prop, the debris slowly melting into the ground.
Buddha's Wheel was a meta-organism, constantly rearranging itself. It controlled its own matter to a degree that seemed almost magical.
The first artifact that seemed to break the laws of physics was a Constructor, which appeared without warning outside our mobile camp.
Described as hairy stick figures, they were not made of matter or any known form of energy. We soon learned they could be any size, but they all looked alike, from specks of dust to almost half a kilometer long. While they seemed to blur and shift as they moved, they were quite solid.
Working together, they could manufacture and assemble vast arrays of more complicated machinery in a matter of hours.
Our best guess is they were projections of the Wheel itself, remotely generated and controlled from somewhere within the endless tunnel network.
The total control of all matter inside Buddha's Wheel extended to the subatomic level. All its particles were like entangled gyroscopes that could coordinate their atomic spin. In theory, Buddha's Wheel could stop rotating, or even reverse its rotation instantaneously.
The interior activity increased hour by hour, but we never found evidence of any controlling intelligence, let alone intelligent aliens. Or an information kiosk, for that matter.
Buddha's Wheel was cycling through different configurations for no discernible reason. Was it a universal factory, an experimental laboratory, or a living museum?
Perhaps it was on a million-year mission to establish a new outpost in another galaxy. The Undergods may only settle remote areas, to avoid contact with radically different Others.
If so, its mission appeared doomed to fail.
There was never any doubt about Buddha's Wheel's immediate destination: it was on a direct collision course with Nemesis, also known as the Death Star.
It turns out that Earth's solar system has circled this 10-solar-mass black hole in a statistically unlikely, pseudo-stable orbit for half a billion years . . . still more evidence of destiny at work.
Arctica had to depart one week before impact. A trillion-ton alien starship mostly converted into energy would make quite a bright flash, even behind our layered mirror shields.
We watched the show from almost a billion kilometers away, having fallen far behind by then. We had no choice but to slow down, but at least it gave us time to map the environment around Nemesis. There was a thin accretion disk, with charged particle belts.
A few minutes before closest approach, our accompanying probes saw Buddha's Wheel make a ninety-degree angular-plane rotation.
The last thing the nearest probe saw was the Wheel seemingly becoming transparent. That was to be expected, as its matter stopped interacting with the rest of the universe.
Less than a second later, the black hole smoothly passed THROUGH the center of the great ring.
Traveling at near lightspeed, the inner rim spent only milliseconds in the danger zone, passing within fifteen kilometers of the event horizon. According to our current understanding of the laws of physics, the tidal forces should have instantly pulverized Buddha's Wheel to glowing plasma.
Maybe if it had been ten times wider, the ring might have survived.
At the moment of closest approach, the Wheel initiated an instantaneous acceleration maneuver, ejecting an enormous amount of unseen propellant matter.
Even this wasn't a complete surprise. We already knew from gravimetric analysis that an amount of dark matter equal in mass to the starship had somehow been stored in a compact ring (like a smaller wheel) around its center of mass, held there by what might as well be magic.
When the alien starship looped around the black hole, this invisible reaction mass was converted into a narrow beam of dark energy, blasted in the other direction.
We passed through the outer shell of the dispersal cone, and saw dim flashes of pair annihilations.
Buddha's Wheel also made a course correction during its close encounter.
Seconds later, it had climbed back out of the gravity well and was hurtling away at 15% of the speed of light, on a course that would take it just outside the plane of the galaxy. Its next plausible target was over a hundred thousand years in the future.
The acceleration should have been well nigh infinite, but apparently the force had somehow acted equally upon each particle of the starship. At least it didn't break the light barrier.
A few days later, we swung around Nemesis ourselves at a considerably safer distance, and performed our own acceleration maneuver on a rapid Earth-return trajectory.
For an instant, we glimpsed a majestic ring around Nemesis, perfectly aligned with the Wheel's new course.
Something that fragile shouldn't have survived that long.
Long ago, Nemesis "inadvertently" deflected a handful of ice mountains toward our dinosaur-infested planet.
If that hadn't happened, we would never have existed. Now we don't need to exist anymore.
At that time, Buddha's Wheel was moving through the intergalactic deep vacuum of the Local Group. It sure seems in a hurry all of a sudden.
Some say it's the end stage of a degenerate intelligence, without awareness, purpose, or meaning anymore. The optimists say it is fleeing from us, or what humanity is about to become.
More likely, it wants to spend as little time as possible in this particular quadrant of the galaxy.
Our solar system was just a passing speck in the night, unworthy of serious attention.
I don't think we should worry. We're not ready to worry.
We saw many inexplicable and seemingly impossible things, but all we learned during our time in Buddha's Wheel were our own biases, like ants investigating an airplane. It wasn't even a plausible psychology experiment, art project, or practical joke.
Which brings us to the very first mystery that was discovered about the object: until its rendezvous with Nemesis, it might not have been moving at all (in a way).
While it appeared to be passing Earth's solar system at a percent of the speed of light, it was completely motionless relative to the cosmic background radiation.
The unknowns are so vast they might as well cancel out.