Wait a second. Sianna had been a bit slouched down in her seat. Now she sat straight up. Wait a second. On-off, pos-neg, yes-no, zero-one, dot-dash. The most basic signaling system. Signaling… Yes!
“Wally,” she said, “Wally!”
Wally looked up from his datapack, and turned to look at Sianna. He was clearly surprised to see her, but that was no surprise.
“Huh? What? What… what is it?” he asked.
Eyeball looked up from her own work. Sianna hurried on with her question before Eyeball could shush her.
“What would happen to an inert wormhole aperture with the same default settings as this one when this one opens up and something goes through? Like, say, the Earthpoint Singularity back in the Solar System. What would happen?”
Wally frowned and looked off into space for a second. “Well, if current theory is anywhere near right, in some dimensional domains, Earthpoint and Moonpoint are contiguous. Well, more than contiguous. They aren’t just two adjacent planes in space, but two sides of the same plane, coplanar. Anything that affected one would have to affect the other. And of course the other side of the Moonpoint Wormhole is coplanar with whatever it’s linking up with.”
“Huh?” Eyeball asked. Straight or Purple, that seemed to be the standard response to one of Wally’s explanations.
Wally looked around and found two sheets of scratch paper. “C’m‘ere,” he said. “I’ll show you.” The two women got up and stood over him at the console. He put one sheet of paper down on the counter top, then put a second sheet on top of it. “The sheets of paper are the wormholes, and the space between them is the plane of normal space that divides them.” He lifted a corner of the top piece of paper and pointed to the one below. “Here’s the bottom sheet, the first wormhole. The bottom side of it exits out to wherever the SCOREs are going. Top side opens up here in the Multisystem, in the middle of the Moonpoint Ring.” He dropped the corner of the upper sheet back down on top of the first. “Top sheet. The bottom side of it also opens here in the Multisystem, but the top comes out from the Earthpoint Singularity back in the Solar System.”
“Yeah, I got it,” Sianna said. This much she knew.
“Almost,” Eyeball said. “Go on.”
“Well, you could think of it in generations. Call the point we’re heading for Point X. Point X is the grandfather singularity, and it produced the Moonpoint Singularity. Moonpoint is the father to the Earthpoint Singularity back in the Solar System. Earthpoint would have to have similar resonance characteristics to its father and grand father, Moonpoint and Point X. Sort of like genetics. Characteristics would be passed down, with some variance—though not much. There’s probably no more than a fourth-power variance between them at best, enough to differentiate the Moonpoint from Earth-point and Point X.”
“Great, good to know,” Sianna said. “But it doesn’t answer my question.”
“It doesn’t?” Wally asked. Clearly he felt that the next stage in the reasoning was utterly self-evident.
Sianna looked to Eyeball and shrugged. “Does it?”
“Not so I suss, nohow. Come on, Walls—what would be popping at Earthpoint ifwhen Charos drop SCOREs down Moonpoint tube?”
Wally had not ever shown the slightest trouble understanding Purpspeak. “Earthpoint ought to ring like a bell, resonate in all sorts of gravitic frequencies. Sympathetic vibration. We’ve always assumed that a lot of the hardware on a Ring-and-Hole pair was to damp out that sort of vibration.”
“That’s what I thought,” Sianna said. “Okay. Would the people back in the Solar System be able to detect that? If they were running any sort of gravitic detection gear hooked to the Lunar Wheel or the Ring of Charon?”
“They’d be lucky if it didn’t blow every circuit breaker on the detector grid. Absolutely. In fact, I doubt they’d need detectors. The Lunar Wheel itself would react. No way they could miss it.”
“Charon Ring?” Eyeball asked.
Wally thought for a second. “Maybe. If they were running in the right sort of detection mode, they might pick it up. If the folks on the Moon warned them, they could certainly recalibrate and listen for the next one. Of course, we don’t know for sure anyone is still running the Ring, or if anyone is observing the Lunar Wheel.”
“Okay,” Sianna said. “Good. Great. There have been lots of openings and closings, lots of SCOREs headed through. Something like a hundred so far, and maybe another dozen to go.”
“And they’d have been watching them,” Wally said, getting I he idea. “And they know reverb theory as well as we do. They’ll know it means something is up with us.”
“Holdit holdit holdit,” Eyeball said. “We’re going through, right? We’re gonna send a command set to pop the hatch on that thing and dive in. That command set. Has to go through to your Point X so’s the other end of the hole knows to open. Right?”
“Sure, right. We’ll send the signal the same way the Charonians do. Earth will send a radio beam to the Ghoul Modules. The Ghouls will respond by sending out command modulations on a gravitic carrier beam,” Wally said.
Eyeball leaned back, stared at the ceiling, and thought for a moment. “Now how ’bout folks back home in Solar, at Charon? They be able to detect commands, maybe read ’em and reap?”
Wally shrugged. “Read them, sure, but I don’t know what they’ll get out of them. All the signals are virtually identical. Without some sort of code key, like we got off the Lone World, it’ll just be the same burst of noise over and over.”
“No,” Sianna said. “They have a code key, sort of. They knew enough Charonian visual symbol language to close the wormhole five years ago. They’ll know it’s a wormhole transit signal, and they’ll have enough of the syntax to be able to get something out of it. Besides, the signals aren’t precisely identical. There are timing variables and mass variables.”
“Okay, they’ll be able to parse the signal, work out the grammar. Maybe even mimic the signal. But there won’t be anything in the signal they’ll be able to read and understand.”
Sianna stood up straight rather suddenly and put her hand over her mouth. “Wait a second. Wally, stick around. I get my best ideas around you. There will be nothing they can read in the signal—unless we put it there.”
“Say what?”
“There’s a null sequence in the command set,” Sianna said. “Like a comment line. It’s preceded by a symbol telling the Ghoul Modules’ processors to disregard the following sequences. Probably it’s a place to put in the Charonian equivalent of a manifest name, or an explanatory note. We could use it.”
“Could we put something in there?” Wally asked, in a tone of voice that made it clear that he was not concerned with the technical challenge, but whether they would be allowed to do so, as if the grown-ups wouldn’t let them fool around with the equipment that way.
Sianna nodded enthusiastically. “I don’t see why not. Wally, pull up that diagram of the signal syntax. I want to see how much room we have.”
Wally got out his notepack and worked the controls. He shook his head. “Not much. About thirty characters, tops. Can’t say much in that.”
“But enough to tell them it’s us,” Sianna said. “Enough to say it’s Earth, it’s people going through.”
“What good would that do?” Wally asked.
“At least it would tell them we’re still alive,” Sianna said. “We’ve been out of contact for five years. They have no idea whether or not we’re still here.”