Paul put down the knife. He didn't want to perform that experiment. Not yet.
+ + +
Outside his own apartment, everything was slightly less than convincing; the architecture of the building was reproduced faithfully enough, down to the ugly plastic potted plants, but every corridor was deserted, and every door to every other apartment was sealed shut -- concealing, literally, nothing. He kicked one door, as hard as he could; the wood seemed to give slightly, but when he examined the surface, the paint wasn't even marked. The model would admit to no damage here, and the laws of physics could screw themselves.
There were pedestrians and cyclists on the street -- all purely recorded. They were solid rather than ghostly, but it was an eerie kind of solidity; unstoppable, unswayable, they were like infinitely strong, infinitely disinterested robots. Paul hitched a ride on one frail old woman's back for a while; she carried him down the street, heedlessly. Her clothes, her skin, even her hair, all felt the same: hard as steel. Not cold, though. Neutral.
The street wasn't meant to serve as anything but three-dimensional wallpaper; when Copies interacted with each other, they often used cheap, recorded environments full of purely decorative crowds. Plazas, parks, open-air cafes; all very reassuring, no doubt, when you were fighting off a sense of isolation and claustrophobia. Copies could only receive realistic external visitors if they had friends of relatives willing to slow down their mental processes by a factor of seventeen. Most dutiful next-of-kin preferred to exchange video recordings. Who wanted to spend an afternoon with great-grandfather, when it burnt up half a week of your life? Paul had tried calling Elizabeth on the terminal in his study -- which should have granted him access to the outside world, via the computer's communications links -- but, not surprisingly, Durham had sabotaged that as well.
When he reached the corner of the block, the visual illusion of the city continued, far into the distance, but when he tried to step forward onto the road, the concrete pavement under his feet started acting like a treadmill, sliding backward at precisely the rate needed to keep him motionless, whatever pace he adopted. He backed off and tried leaping over the affected region, but his horizontal velocity dissipated -- without the slightest pretense of any "physical" justification -- and he landed squarely in the middle of the treadmill.
The people of the recording, of course, crossed the border with ease. One man walked straight at him; Paul stood his ground -- and found himself pushed into a zone of increasing viscosity, the air around him becoming painfully unyielding, before he slipped free to one side.
The sense that discovering a way to breach this barrier would somehow "liberate" him was compelling -- but he knew it was absurd. Even if he did find a flaw in the program which enabled him to break through, he knew he'd gain nothing but decreasingly realistic surroundings. The recording could only contain complete information for points of view within a certain, finite zone; all there was to "escape to" was a region where his view of the city would be full of distortions and omissions, and would eventually fade to black.
He stepped back from the corner, half dispirited, half amused. What had he hoped to find? A door at the edge of the model, marked exit, through which he could walk out into reality? Stairs leading metaphorically down to some boiler-room representation of the underpinnings of this world, where he could throw a few switches and blow it all apart? He had no right to be dissatisfied with his surroundings; they were precisely what he'd ordered.