"Because whoever did this couldn't use a warning that was language based."
"Precisely. Only mathematical formulas are universal." He shook his head. "And to think of Flyte, and his talk of irrational numbers. He was more right than he knew. I think."
"Who?"
He gave a soft laugh. "Never mind."
Hui thought for a moment. "Why did they start with just one expression-and then begin broadcasting thousands?"
Crane shrugged. "Maybe they thought that division by zero was the simplest, most basic-that's why it was so pervasive. Maybe my touch triggered new behavior in the sentinel. Or maybe the fact that we hadn't stopped digging convinced the devices that we hadn't taken the hint-that we needed supplements."
He turned abruptly, took a step toward the door. All of a sudden, a sense of terrible urgency filled him: with every new minute, the digging brought them closer to an unthinkable oblivion.
"Where are you going?" Hui asked.
"You're looking at one guy who finally has taken the hint."
"What about me? Where should I go?"
"Stay here. It's as safe as anywhere-probably safer, because it's already been searched." He took her hand again, gave it a reassuring squeeze. "I'll be back for you-soon."
She took a deep breath. "Okay. Maybe I'll take another look at that initial transmission. The one Dr. Asher didn't translate."
"Excellent idea," Crane smiled. Then he stepped up to the lab door, paused to listen, and quickly slipped out into the corridor.
44
Admiral Spartan stood silently, looking at Crane. They were standing in a quiet corner of the observation chamber, and the only light came from the long window overlooking the Drilling Complex. The light was not sufficient to betray the expression on the admiral's face.
Crane glanced at the technicians and engineers, sitting at their monitoring stations. Then he looked down into the hangar. A crew of workers was prepping one of the remaining two Marbles for its descent. Even from this vantage point, there seemed to be a palpable excitement in the air: it seemed they were now just days, perhaps hours, from reaching the Moho, and any of the next few trips could be the breakthrough dive.
He returned his gaze to Spartan.
The admiral seemed to rouse himself from deep contemplation. He clasped his hands behind his back. "Let me get this straight. All the mysterious illnesses, the psychological problems, are the result of a signal?"
"It's the same digital signal the sentinels first transmitted via light waves. Except this other signal is transmitted in some way our technology can't pick up. And it triggers a highly abnormal spiking of theta waves in the brain. See, the brain works on electricity," Crane explained. "When that electricity misfires, it affects the autonomous nervous system. That in turn can cause nausea, visual field defects, arrhythmia-all the neurological deficits we've been seeing. It can also affect the frontal lobe of the brain. And that in turn accounts for the problems with memory and concentration, changes in character, even psychotic episodes."
"How can we counteract it? Negate its effects?"
"The signal? We can't even track it. The only solution is to avoid it. Stop the dig, get people to the surface, away from the source."
Spartan gave a dismissive shake of his head. "And this signal is transmitting a mathematical expression."
"Asher decoded several signals. All mathematical expressions, all impossible."
"You're saying they're a warning of some kind."
"The expressions are all forbidden by universal law. What better way to signal danger, when language isn't an option?"
"What better way, Doctor? Something more articulate. More direct."
Crane thought he heard skepticism in Spartan's tone. "Whoever planted these objects beneath the Moho-whoever created the sentinels-is clearly far, far more advanced than we are. Who's to say they aren't transmitting signals that are, as you say, more articulate-but we just aren't smart enough yet to intercept them?"
Spartan pursed his lips. "And we're the proud owners of an interstellar toxic dump. Or, perhaps, a cache of doomsday weapons from some distant arms race."
Crane didn't answer. The silence lengthened. Over his shoulder, he could hear the distant murmur of conversation, the clicking of keyboards.
At last, Spartan exhaled slowly. "I'm sorry, Doctor, but it all sounds very circumstantial to me. In fact, I have to wonder whether your own theta waves aren't beginning to spike. An alien civilization uses Earth as a waste repository, then sends out signals to warn us."
"No, not us. They couldn't care less about us-the violence of the original burial event proves that. We're insects to them. The civilization that did this probably comes from an environment of methane and sulfuric acid. Oxygen and nitrogen may even be toxic to them. They're not concerned about us; to them the Earth is a useless planet, and we're too primitive to deserve consideration. It's only a freakish chance we discovered their message in the first place. They're concerned about civilizations far more advanced. They're warning them to stay away from Earth."
Spartan did not reply.
After a moment, Crane sighed. "You're right. It is circumstantial. There's no way to conclusively prove what's down there without penetrating the Moho. But that's like saying a grenade is circumstantial until you pull the pin."
Still, Spartan did not respond.
"Look," Crane went on, hearing the urgency in his own voice. "I don't know what's down there exactly-I only know that it's unimaginably dangerous. Is it worth jeopardizing the Earth to find out what's down there? Because the stakes might be at least that high."
At last, Spartan roused himself. "And you're convinced of that?"
"I'd bet my life on it."
"And this deliberate erasing of Asher's hard drive-are you sure of that, as well?"
Crane nodded.
"Your talents seem to extend beyond the medical profession. Did you resurrect the data yourself?"
Crane hesitated. "I had assistance."
"I see." Admiral Spartan looked back at him, expression still unreadable. "Would you know where Hui Ping is?"
Crane kept his tone neutral. "No idea."
"Very well. Thank you, Doctor."
Crane blinked. "Excuse me?"
"You may go. I'm rather busy at the moment."
"But everything I've said-"
"I'll consider it."
Crane looked at Spartan in disbelief. "You'll consider it? Another dive, maybe two, and it'll be too late to consider anything." He paused. "Admiral, there's more at stake here than your mission, than what's down at the bottom of that shaft. There's also the lives of everyone on board this Facility. You have a duty, a responsibility, to them as well. Even if there's only a remote chance that I'm right, you owe it to them to examine my findings, the report I'm preparing. Because the risk is simply too great to do otherwise."
"You're dismissed, Dr. Crane."
"I've done my job-I've solved the mystery. Now you do yours! Stop this fool's task, save this Facility, or I'll-"
Dimly, Crane became aware that he was raising his voice, and heads were turning. He abruptly fell silent.
"Or you'll what?" Spartan asked.
Crane did not reply.
"I'm glad to hear you've done your job. Now I suggest you leave the Drilling Complex on your own accord, Doctor. Before I have an armed detail escort you out."
For a moment, Crane stood where he was, rooted in place by anger and disbelief. Then, without another word, he spun on his heel and exited the observation chamber.