Adeline thought for a moment. “You take an object—it would have to be a small mass, because the amount of power required to send something via Absolom is exponentially proportional to the mass of the object.”
“Good so far.”
“You’d want an object that contained some isotope that decayed over time so that you could measure how far back it went via radiometric dating—that would be your accuracy check. You target a time, then you find it and determine how old it is.”
“Very good.”
“But finding it would be difficult. Because, again, it’s small, and the world is large. But I guess you guys have figured that out, to a certain degree. You map the movements of the continents over time, and you know if you deposit something in a certain area in the past where it would be today.”
“That’s right.”
“But that could be anywhere in an area of, say, a few hundred miles or even a thousand-mile radius. You’d need a specific way to locate it. Like a radio isotope. Something harmless but strong enough for you to detect, even if it was buried below the surface.”
Elliott smiled and nodded. “Very good.”
“So you fashion one of these… test strips—”
“We call them tuning bars,” Elliott said.
“Tuning bars, which can be dated, and which give off a locating isotope, and you send it back, and then you go out to Death Valley, and you dig it up and see how close the location and time was to your predicted arrival?”
“Almost right.”
Adeline cocked her head. “Almost right?”
“Almost.”
“No. It is right. What I described is what you’re doing.”
“True. But the order is wrong.”
“It can’t be. You send it back, and then you go look for it.”
“It doesn’t work like that.” Elliott stepped closer to her. “Think about it in terms of causality.”
Adeline’s eyes went wide. “No way.”
“Do you see it?”
Adeline spoke carefully, her mind still trying to grasp what she was saying. “First, you make a plan.”
Elliott nodded. “Correct. We discuss the experiment in the lab. We make a pact between ourselves—Daniele, Constance, Hiro, and myself—that we will carry out the experiment no matter what happens.”
“And you acquire the tuning bar,” Adeline said.
“Yes.”
“But you don’t send it back.”
“No. We don’t. We lock it in a box in the lab, one only the four of us can access.”
Adeline nodded, still amazed. “Then you go out to Death Valley, and you try to find it.”
“That’s right.”
“And if you do, you send it.”
“Correct. Because if we don’t find it, then we never sent it.”
Adeline buried her face in her hands. “This is breaking my brain.”
Elliott’s voice was reflective. “What Hiro and I showed the group the night Nora died was one of our first successful experiments. We had been working on the updates to Absolom for quite some time and were finally sure we could target our universe consistently. So we planned the experiment. We went out to Death Valley and found the bar. We put it in a box. Then we procured the bar and put it in the machine and sent it back. I opened the box on the table and showed the group the aged version we had found. Proof positive that it was feasible to target our own universe. That set everything in motion. For that, I feel guilty.”
“Well, there’s one way to make it right,” Adeline said. “We get Dad back. Can we use Absolom Two to transport him to our timeline?”
“No. It doesn’t work that way.”
“Why?”
“Power. And machine mass. We can’t effectively transmit what he needs to the past.”
“But you’re changing that.”
“No. We can’t. That’s pretty much unsolvable.”
“I see. But you can send something to Dad?”
“We can,” Elliott said slowly. “Something smaller. But there are two issues.”
“I don’t like the sound of that.”
“The first is power.”
Adeline shook her head. “What are you talking about? You have a virtually limitless power source from the solar field in the sea of glass.”
“Accessing the power isn’t the problem. It’s using it without anyone knowing.”
Adeline shrugged. “Why?”