"What kind of explosion?"
Filatov waved off her question in frustration. "It's a term from mathematics. To do simulation, the computer has to 'can' responses to keep ahead of the processing demands of the experience. It has to anticipate all the things you could possibly do, and then prerecord them for playback to you. You might pick up a Coke, for instance, and take a drink, so the computer stores a simulation of you doing that in a cache. It'll then feed it back if that's in fact what you do. You might, on the other hand, choose to shake the Coke vigorously, and so the geyser from the carbonation is another possibility."
"But there must be millions of things you can do, or ways you can do them."
"Combinatorial explosion — like I said! Two raised to the n minus one — where n is the number of options available. In a class-one simulation — a complete, real experience — the number of basic options available to the user at any given moment might be as high as eighty or so. Two raised to the eightieth power minus one is over one trillion, a trillion variations which the computer stores away on the off chance that you might pick one of those branches. The only way the simulation is possible at all is that the computer is so damn fast. It can limit the number of options to eighty only by being able to react so quickly to whatever you do. The feedback has to be instantaneous. Studies have shown that the mind monitors the results very carefully."
"Cognitive carousel tests!" Laura interrupted. "You know, where you attach electrodes to people's scalps and give them a clicker to advance slides. Once the computer figures out which brain impulse signals the thumb to press the button, it bypasses the clicker and advances the side directly a few dozen milliseconds ahead of when the subjects expect it to. They report seeing the picture change just before they 'decide' to move on to the next frame. It really freaks them out."
"Ready, Dr. Filatov," one of the operators said.
A hatch in the wall opened with the squeaking sound of rubber on rubber. The door was several feet thick, and inside; the black room was cylindrical like the other workstations, but larger.
Laura felt a sense of dread. There were too many strange happenings and errors.
"Go on in," Filatov said, motioning for her to enter.
Laura climbed slowly through the opening — through the portal to another world.
The workstation wasn't large but it was roomier than the cramped chambers of the older models — maybe ten feet or so in diameter with a ceiling about the same height above. She felt less claustrophobic even if she was no more at ease. Laura reached out and touched the walls.
The thin ridges ran vertically and were finer than in the old version.
She rubbed her thumb against her fingertips. The full-body exoskeleton was made of the same material.
"The walls, floor, and ceiling," Filatov said from the hatch, "are rear-projection, high-definition television grills, as are the membranes of your exoskeleton. Where is your hood?"
"My what?" she asked, surprised to hear the faint quiver in her voice.
"Your hood?" Filatov disappeared, leaving Laura alone in the room. There was a faint odor — the smell of plastic. "You need to put this on," Filatov said as he leaned into the chamber. He held out a limp bag — like a large sock but with holes in it — that was the same dull gray as her suit. Laura had seen it in the changing room but didn't know what it was. "You need to put it on. Like this."
Filatov stretched the bottom of the sock open and lifted it to her head. She dodged out of the way and stepped back. "What's that?"
"It's a hood! It goes on over your head and face." His irritation grew, Laura sensed, with each minute wasted on this joyride of hers. "Since you didn't choose to use the razor, the sensory feedback will be dulled somewhat by your body hair. But you still need to put it on. If I'm going to spend the damn resources, then you're going to get the full treatment, now [garbled]."
Laura gathered her hair in back, and Filatov slipped the hood over her head. "Ow!" she said as it pulled her hair on its way down.
Filatov kept tugging at it, however. It briefly covered her eyes, and then her mouth, but when he was through it fit her face like a ski mask. Her eyes, nostrils, and mouth were clear, and there were small holes over her ears through which Filatov stuck his fingers to adjust the lie.
When he stood back satisfied, she looked up at him — every pore of her face, scalp, and neck pressed and pulled in an unnaturally confining fit. "Is this supposed to seem, like, normal?" she asked, the pressure on her lips distorting her speech. "Because I feel like a mummy."
"Trust me, you'll forget all about it in no time. Think of it as the space suit you have to wear in your new world." Laura's stomach turned cartwheels inside her.
"Okay," Filatov said, "these skeletons give you high-resolution feedback. The glove will, for example, give you even pressure and cool temperature to simulate immersion of your hand in water. They'll also lock up the joints at full inflation to create resistance like the version 3Hs. But the big difference between the old workstations and this one is that these floors, walls, and ceilings morph."
"They do what?"
"They reshape themselves. The surfaces are flexible, just like the grill of your suit, and elaborate servomotors change their shape. They bulge them out or suck them in to give their surfaces low resolution textures. To simulate a rock lying on the ground, the floor will morph into the general shape of the rock. But if you run your hand across it, the vibrations that feed back the rock's texture are produced in your glove. There's a crossover point between the walls' and floors' low-resolution feedback and the gloves' high-resolution tactile imaging."
Laura didn't understand half of what he said. "Shouldn't I read a manual or something?"
Filatov rolled his eyes. "The training course is five months long, with forty hours of classroom work for every hour in the workstation. My boss, however, said to put you in and turn it on, so that's what I'm doing. There is one thing, though, that you need to keep in mind for your safety. The morphing of the floor and walls and ceiling — it's real. If you're walking along and you see a pipe or something hanging low, duck! If you don't, you're going to come out of here with more bruises than you got last night when you fell off the roof. This isn't a toy, it's built for work. When these morphing units make something 'hard,' it's hard. Understood?"
She nodded, took a deep breath, and let it out slowly. "Okay, so what do I do?"
"Whatever you want. Just be careful, that's all. Don't run. Watch your step. No horseplay. And remember — if it looks hard, then it's hard. The morphing is a simulation and it's real."
Laura realized just how much the distinction between those two terms was being blurred. "Any questions?"
"How do I get out of here?"
"Oh, yeah. Just ask, that's all."
"You mean speak the words?"
"Yes. The 4C supports complete voice-recognition capabilities. It'll let you out if you ask."
"What if it doesn't? I mean, you're going to leave me in here."
"We'll come check on you. I promise."
"Every ten minutes."
"What?"
"I want you to check on me every ten minutes. That's what I want."
Filatov frowned, thinking only, she was sure, about the imposition on his schedule. He nodded. "Okay. Every ten minutes I or one of my people will check the monitors in the ready room."
"You — I want you, not one of your 'people.' And I want you to ask me how I'm doing. I want to know you've been there and checked. Is that a deal?"
Filatov nodded and shook her hand. She could feel almost nothing at all through her glove. The suit was powered up and active. Only the computer's simulation would feel real to her now.