They looked at him.
Then Alexa smiled. “Gravity.”
Grady nodded. “The gravity mirror.” He approached the holographic 3D image of the building. “Cotton, your examination for weaknesses probably made a significant assumption.”
“What’s that?”
Grady swept his hand to turn the building’s image upside down. “That the direction for ‘down’ would never change. Reexamine the plans. Try to find something significant at the outer perimeter wall that might suffer a malfunction if the world were to suddenly turn upside down.”
Cotton studied the altered view of the BTC headquarters building. A grin crossed his face. “I must say, Mr. Grady, you have a decidedly devious mind…”
CHAPTER 27
Learning to Fall
Jon Grady adopted a wrestler’s stance in a forty-foot section of the workshop that they’d cleared of all shelving and equipment. He wore a stripped-down version of the gravity-mirror harness that Cotton had cannibalized from Morrison’s damaged armor. Grady also wore Morrison’s armored boots and gauntlets. The boots were roomier than he’d like, but he’d padded them with foam inserts. Besides he didn’t think he’d be doing too much walking with them.
Grady studied the microscopic circuitry of the harness, glittering in the workshop’s light. “This is the gravity mirror all right, but God, it’s shrunk down a thousand times in size. How in the hell do they get enough energy to it?”
Cotton tapped an assembly elsewhere on the harness. “Sixty megawatt fusion reactor.”
“That little thing?”
“Well, it’s got armor around it, so the reactor is smaller than that.”
“Good lord. I’m walking around with enough power to light a small city.”
Alexa pushed between them. “Let’s get on with this.”
Several nylon safety straps ran from Grady’s harness to metal beams ahead, behind, left, and right, as well as iron rings on the ground and a strap looped over a rafter. Whatever direction he might fall, he wouldn’t fall far.
Alexa checked his equipment, loosening the harness a bit. “You don’t need the gravis so tight. Remember it’s not like a rappelling harness—you’re not hanging from this; it’s changing the direction of down, and you’ll be falling along with it.”
He grimaced. “Gravis—who came up with that name?”
“I don’t know. Somebody on the BTC’s mirror project team.”
“I invented the damn thing. I should have had a chance to name it.”
Cotton stood nearby. “That was your first mistake, Mr. Grady. A thing can’t exist in people’s minds until it has a name. But with a name, it can exist in people’s minds without existing at all. You should always come up with a name before you set out to create anything.”
Grady frowned. “What does gravis mean, anyway?”
Alexa was inspecting his boots. “Latin for ‘weighty.’ ‘Heavy.’”
He jumped slightly to test the weight. “Well, maybe the name fits after all. This must weigh forty pounds.”
“It won’t once you activate it. And that’s a military gravis—armored. Mine is much lighter. The suit this was part of had electroactive polymer musculature to carry around the weight.”
Cotton murmured, “We might be seeing some of those later, if things go amiss.”
“Ignore him.” She was kneeling at his boot. “You feel the control interfaces at your toes?”
The padded lining of his overlarge boots made them fit better, and Grady depressed two small nodules with this toes. “Yeah. Got ’em.”
Alexa gestured to his other boot. “And here?”
He nodded as he did the same on the left.
“All right. Default control setup works like this: You control yaw by—”
“Yaw? What’s yaw?”
“Aeronautical term—it’s the horizontal direction you’re heading.” She pirouetted gracefully and came back to her start. “You control yaw direction for descent by angling your foot like this.”
“Direction of descent—I thought you said it was a horizontal direction?”
She gave him a look.
“Oh. Right. We’re choosing the direction of down.”
Cotton snickered. “You invented the technology, Mr. Grady. Try to keep up.”
Alexa lifted her right foot and flexed it first rightward, then leftward again.
Grady lifted his own right foot and did likewise.
“Good. And you control pitch—that is, vertical direction—with your left foot.” She tapped his leg.
He picked up his left foot.
She demonstrated. “Flex your foot downward or upward—you go where your toes point.”
“Got it. Seems simple enough. And the controls inside the shoe?”
“Each shoe has a button and a slide controller. Ignore the buttons for now—they’re locks, so you can maintain whatever setting you’re on without effort. But indoors, that could be dangerous for a novice. So only work with the slide controller for now. Do you feel them?”
Grady felt with his toes and nodded. “Yeah.”
“The right controller sets the diameter of the gravity mirror—you can make it just big enough to cover you, or a bit bigger than that to accommodate extra material. And the left controller sets the focus—nudge it forward with your toes and the gravity is focused one hundred percent in that direction; pull back on it and the gravity gets dispersed.”
“So half gravity, quarter gravity—like that?”
“A percentage, but yes.”
Grady frowned. “Wait. Even in microgravity, I’d keep accelerating until I achieved relative terminal velocity.”
“Normally true, but software in the gravis curtails acceleration.”
“How’s it do that?”
“It flips the mirror for microseconds in order to maintain constant velocity relative to the ambient gravitational field.”
Grady considered this. “Huh. I probably would have thought of that eventually…”
“Pay attention, Jon.” She motioned to her boot. “Pull the slide controller all the way back, and you diffuse gravity into an equilibrium.”
“Meaning I float at a full stop.”
“Well, as you know, equilibrium won’t cancel out momentum you already have. To slow down you need to reverse direction of descent momentarily.” She looked him up and down. “You ready to give it a try?”
He tugged at the nylon harnesses holding him in place. They seemed secure. “Sure. How much trouble can I get in?”
Cotton chuckled. “Famous last words.”
“Start out by pulling the right controller all the way back. I want your gravity field to be as narrow as possible. That’ll make it just above your height.”
Grady used his toes to pull the controller back. “So a roughly six-foot sphere around me will be subjected to my gravity field.”
“Right. In fact, do press the button to lock that setting. We don’t want you accidentally expanding the sphere and bringing a wall down on us.”
He clicked the button and tried nudging the slider. It was locked down fast. “Okay. I got it. It’s locked.”
“Now pull back on the left controller to set it to equilibrium. That way you won’t fly off anywhere.”
He did so and nodded.
“Okay. Let’s power it up.”
Grady hesitated a moment before studying his gauntlets for the control interface. The boots and gauntlets apparently had power sources of their own and were paired via a q-link to the harness—and presumably to the rest of the assault armor, had it been present. In a moment Grady remembered how to make a pop-up holographic control panel appear above his arm.