Thousands of years earlier, Plato described something similar. Take a deep, dark cave and chain some prisoners at the bottom, so that they cannot move about or flex their arms or legs. Restrain them in a row, bolting them down so tightly that they cannot even move their heads, so that they have no choice but to all gaze upon the same cave wall. Build a fire behind them, to cast a steady light on the wall. And then march various objects past the light source, so that their shadows are cast on the wall where the prisoners may see.
Now imagine that the prisoners have been raised in this cave from birth. Because of the nature of their imprisonment, they would be unaware of any world other than the two-dimensional patterns of light and shadow on the wall ahead of them, and the sounds they heard (and, if they were permitted to talk, made themselves). They would be unaware that they even had limbs. If a dog was marched past the fire, and heard to bark, they would associate their word for "dog" not with what we know as a dog, but with what we would recognise merely as a dog-shaped shadow. For them, the entire world would be two-dimensional. Everything they knew would be thought of in terms of dark two-dimensional shapes and the sounds they appeared to emit. They would not know what movement is. Or what legs, arms, eyes and light truly are.
There are many possible interpretations which can be drawn from the allegory, especially when one considers the possibility of a prisoner breaking free and stepping out of the cave into brilliant, sunlit reality for the first time. But one of these is the ontological concept that the real world of three dimensions of space and one of time in which we live is, itself, not the whole thing. That all humans are still imprisoned in some fashion; that what is perceived is a literal or figurative shadow of the entire truth; that, in less flowery terms, there exist additional dimensions of spacetime which we are unable to perceive because we are not so free to move through them.
As the simulation burns its trail through his brain Ching feels like that freed prisoner.
Only, much more so. To make the analogy apply better, many additional directions of freedom would have to be stripped from the prisoners. Their senses of touch and hearing (and smell and taste if they had them) would be taken away, leaving only sight, and utter lack of sensation in/of the rest of the body. The full human body would then be cut down to a single eye, plus a brain and minimal biological support. Not even an eyelid to facilitate blinking, or muscles to allow it to move or focus. And the eye itself would not be permitted such luxury as a moving two-dimensional picture to look at, or even a line, but a dot, a single tiny dim grey pixel on a black background, not shining constantly but winking periodically, just to provide the absolute minimum of sensory input necessary to prove to the owner of the eye that he or she is not simply dead.
Even that would not be enough. To provide the true level of constrast Ching is experiencing, the world outside would have to be bigger, too, much bigger than a simple yellow Sun shining down on simple green grass. It would need to be created like a fractal, with intelligent patterns on every conceivable level, going up higher and higher into the sky, cut and carved into impossibly intricate shapes, with whole universes forming the building blocks of megaverses, themselves forming the foundations of still larger and more complex structures, with every tiniest component picked out in a unique and scintillating colour, voice, texture and emotion, and the whole thing extending upwards for hundreds and hundreds of dimensions, with no end to the wonder in sight.
This is approximately what Ching is seeing.
In reality, Ching claws at his skull, dazzled and nauseous with uncomprehension. In the simulation, a moment passes and then something up near the top of the structure ruptures open, and two dark dots shoot out of the hole like bullets. They decelerate and become caught in the pull of some other-dimensional gravitational force and go into freefall, descending together and eventually tumbling glacially slowly past Ching's point of view.
Ching watches them fall. He finds himself dragged down with them. He follows behind the two shapes as they plunge all the way back to ground level and into the black, engulfing cave, and down further still. And then the dull, winking pixel returns, and Ching opens his eyes to find himself face down on the edge of the United Kingdom Advanced Physical Laboratory Medium Preonic Receiver roof, clawing onto the concrete wall for balance while his ears stop spinning. His stomach convulses unpleasantly. "Was that for real?" asks a voice. Seph.
Ching stares at the grey concrete from a few centimetres away, trying to get his gut under control. He remembers that he hasn't eaten anything today. He feels shell-shocked and ill, and one thing that he now knows for absolute certainty is that there is something wrong, really catastrophically wrong with the world. It is as if something inconceivably important happened, and he wasn't there for it, or he wasn't ready for it, and now there are going to be terrible, costly Consequences. It is as if something is missing. No: more like something is there in the room who shouldn't be. A big, still, silent, threatening shape. Like a spider sitting on your pillow.
"He fell," stammers Ching, to whoever is listening. "And something went wrong."
"What did you see? Did we all just see the same thing?" Murphy.
"I don't know I just saw! I can't-- I can't even think about it properly!" Seph.
"What are you?" asks Tom Muoka. Ching turns around and looks up. It looks like a bomb hit the five of them. Muoka is sitting with his back against the dome, feet stretched out in front of him, leaning against the GEWR panels, head lolling as if half-dead, clutching one shoulder, panting, seemingly exhausted. Murphy is on his knees, struggling to get up. Seph is supporting herself on the wall around the edge of the Receiver building's roof, clutching her immense mane of hair with one hand.
Not five. Four. Ching looks up at the top of the dome and Mitch is not visible. "Where is he?"
"Describe what you saw," says Murphy. "Ching. Describe what you saw."
"I can't. Mitch fell. From somewhere else, to get here. There was a war or a fight or a battle or something and to stop it he came here. He killed the bad guy and he came here. And he's supposed to be dead."
At that moment Mitch flickers into visibility at the top of the dome. Flicker is the right word, different parts of his body jitter between being transparent and opaque, as if he is wobbling in and out of hyperspace. He is on his knees, almost in a foetal position. Multiple cross-sections move across his body like MRI scans. Mitch is apparently moaning or screaming but as different portions of his larynx and tongue disappear and reappear the sound is broken up with short, sharp edits of silence. There are curious discharges of blue light around his fingertips and the corners of his eyes.
Ching doesn't like what he's looking at. "We need to get out of here. We need to get away from him. He's waking up--"
"What's happened to him?" demands Seph.
"What in God's name are you?" demands Murphy.
Mitch looks up, still unable to fully tune in. His pupils are on fire and as his gaze sweeps across them it leaves spots in their eyes. "I d-- -ow! -- -on-- kn--!"
Seph climbs the dome and kneels in front of him, but is helpless for what to do other than shield herself from the light. "Don't touch him!" shout several people.
"Somebody call an ambulance!" suggests Seph.
"They couldn't help!" responds Ching, and then Mitch clonks back into real space and Seph catches him as he falls forward. She holds his head tight and murmurs calmly to him, lowering him to the floor. He holds onto her and just barely manages to stay real. A long moment of silence passes.
"I want to go home," is the first thing Mitch manages to say.
There's a pub in the village, the Hornpiper. Back during the A-LAY project, Seph, Ching and Murphy were regulars and it was also a decent place to drink: a twisty, low and claustrophobic pub with tables and chairs scattered off in dark corners and booths, separated off by black architectural beams, with friendly service and tatty furniture.
That all seems to have changed. The Hornpiper is now under the control of some impersonal corporate chain. The lighting is all bright, pleasant and wrong, and the bar staff are all clueless new youths. New seats. Lamentable range of drink on tap.
They bring Mitch in through the rear entrance and pick a table where any passing regulars aren't so likely to take notice of them. Mitch is still under the weather but the walk down the hill to the village has helped. He's had one bottle of water already. Murphy gets him some more from the bar. And some beer. And orders some food.
"He can move through 4D," states Muoka, pointing accusingly at Mitch, once Murphy returns bearing the first round of drinks.
"He can see and move through 4D," says Seph, who sits closest to Mitch. "That's what was happening. He came to me months ago, he said he had no idea what was happening to him. But that was it. He can walk through walls and see by superlight. And if he's from however many dimensions above us it would make sense that he can move through some of them."
"No, no, no," says Murphy. "One step at a time. Extraordinary claims demand more proof than just a shared psychadelic head trip."
"Assuming it was shared," says Muoka.
"I already told you what I saw," says Ching. "He was fighting someone, and they landed in this universe, and he killed the bad guy."
"And they were both locked in," says Seph.
Muoka and Murphy both come to agree with this outline of what was seen. But as for details, all four of them find the concepts strangely difficult to phrase. Simply trying to put words around them causes them to slip away, like dreams.
"I don't like this," says Murphy. "It's just too much like an environmental effect. Drugs in the air or ultra-low-frequency mood vibrations or something equally freakish."
"His head was glowing," says Seph. "I know what I saw."
"I know," says Ching. "The glowing thing was real."
"How do you know that?" asks Muoka.
"Because I have seen it before."
"What? Where? When?"
The conversation is silenced briefly when their food arrives, a big bowl of chips. Ching claims most of the chips and eats a few. The waiter leaves.
"You're the huge anomaly," says Ching to Mitch. "You're what's wrong with this whole universe. You're the reason why science has suddenly stopped working like science is supposed to work. Did you kill the teleporters?"
"No," says Mitch.
"What about the Powers? The flying people?"
"I don't know what that means." Nor does anybody else at the table.
"Why are you here?" Ching asks. "What's stopping you from going home?"
Mitch gulps some more water, then speaks.
"The place I come from is... bigger than this.
"I come from a long way up the chain-- that's the structure you all saw. The structure itself goes up a long way further still. I can't describe anything in the place I come from, outside of poetic terms. The words for it just aren't there.
"In the stack, everything is made up of smaller things and everything makes up something bigger. Universes combine to form multiverses, and they form rings which line up together to make strings, which are the building blocks of new, bigger universes. And because it's so large and complex, you can slice the entire mess up any way you like and find something living there. The whole place is alive. And intelligent life, too. You can't move for it. You're made of it, essentially. Like a human being is made up of individual living cells, only imagine each atom in the cell was a universe in its own right.
"It's not often that things move up the stack. An atom can't very well enlarge itself to human size. But things from up above can interfere below. Say a human started doing atomic experiments. Gets the cell under the microscope, starts bombarding it with protons or what have you. Interference. Only that picture doesn't really work, because the human can also actually descend to the level of the cell. He can climb into it and walk around.
"Dr Muoka was talking about information as substance. Well, it's true. Up there, much more so than down here. And if information can be pushed and shoved around and twisted, what do you call that?"
There's a long pause while they think about this. Then Muoka says, "Thought."
"Right. If information is a substance, then intelligent thought is a fundamental force. And it is. Up in the stack it's the dominant force. That's why intelligence shows up everywhere up there. Information clumps together like mass under gravity. And everything just wants to think."
"That's balderdash!" says Muoka. "This universe is empty!"
"I know. You're 3D. It's like you're under a microscope slide. Thought's a multidimensional push and it doesn't operate quite right down here. And the effects are very weak. But it's there, you've done the experiments yourself, with the teleporters. In principle, it's there. But here's why you're under this slide. This thing attacked my home. Intelligence can be moulded to different forms. It descended to my level and started using extradimensional power to destroy. I killed it, by shifting the playing field to a place where I could kill it. I blew a hole in the underside of my universe and dragged it down here, to your universe, three dimensions. And then trapped us both there, under this metaphorical rock, this prison wall. Where neither of us has any power. And I killed it. Right?"
All four of them nod.
"But I'm still here," says Mitch. "Because I had to be in the trap too. It was the only way to make sure. I can do this:" He puts out his hand and makes it vanish. "I can move a tiny distance up or down. That's me rapping my knuckles against the cell wall. But that's all."
"When did this happen?" asks Muoka.
"Where I come from we have five dimensions of time. It's complicated."
"And what's happened to Mitch?" asks Seph.
Mitch finishes his water and sighs. "I'm still here."