“You’re a monster,” Alex said. “You could have used another rock instead of a living thing. You just wanted to see it blow apart, didn’t you?”
“Wasn’t it you I saw demonstrating this technology on people?” Ryan said.
“They were actors. It wasn’t real.”
“You work for Lockheed Martin,” he said, annoyed now. “What, you think the military is paying you billions so they can put on stage performances? This technology is meant to kill people—quickly, efficiently, and from a distance. It’s made to make our soldiers invincible. So don’t get all high and mighty on me.”
“The bird didn’t have to die.”
They kept arguing, but Sandra wasn’t looking at them. She was still staring at the empty space where the hawk used to be. No wonder the military was so interested. Ryan had basically just snapped his fingers and the bird had died. He could have done the same to her. For that matter, she now had the same power, to kill or destroy at a distance and then disappear from the scene. What would happen if this ability went public? If anyone could kill with a thought and then escape the consequences? It could tear the whole fabric of society apart. Never mind the varcolac—it was this technology they should fear.
“Shut up, both of you,” she said.
Alex and Ryan stopped arguing and looked at her. Sandra was surprised; she hadn’t expected that to work.
“Well?” Alex said. “What do you want?”
“Arguing won’t get us anywhere. We’re supposed to be talking about how to defeat the varcolac. Or at the least, discussing what we think it’s capable of.”
“Right,” Ryan said. “Time travel.”
“So you keep telling us,” Alex said. “Though I don’t know how we’re supposed to defeat it if it can just go back in time and change anything we do.”
“How does that even work?” Sandra said. “I thought time travel was impossible.”
“Einstein was the first to suggest that it might really be possible,” Ryan said. “We always say that Einstein’s theory of general relativity sets the speed of light as a limit for travel, but that’s not exactly true. His equations do allow for velocities faster than the speed of light, but only if you use negative values for time. Einstein himself recognized that, at least in theory, relativity meant time-travel was possible. But it wasn’t until more than a century later that M-theory was experimentally proven and gravity was successfully incorporated into quantum mechanics.”
Sandra sighed. “I knew this was how this conversation was going to go. What’s M-theory? Though really, I’m afraid to ask.”
“It stands for Membrane Theory,” Alex said. “Think membranes in multiple dimensions.”
Ryan frowned. “That’s not what it stands for.”
“What, then?”
“I don’t think it stands for anything. I know it doesn’t stand for membrane, though.”
“Matrix?” Alex said.
“Look, I don’t care,” Sandra said. “Just tell me what the Muffin Theory says, and why I should care.”
Ryan laughed. “Okay, here’s how it works. You normally live in four dimensions, right?”
“The fourth being time?”
“Yes. But space-time is actually composed of eleven dimensions. There’s the four you usually think about, and seven more that are all curled up where you can’t see them. The four dimensions we generally experience are what we call a ‘brane’—they’re roughly fixed in reference to each other, and they float around in the other dimensions, which we call the ‘bulk.’ Most particles, and thus most matter, are confined to the standard four dimensions, but there are some exceptions.”
“Like gravity,” Sandra said.
Ryan raised an eyebrow and whistled.
“I did grow up with a physicist as a father,” Sandra said. “I picked up a few things.”
“Well, you’re right.” Ryan threw a pebble over the edge of the ridge and watched it fall into the wooded valley below. “Gravity—meaning, of course, the gravitons that communicate the force of gravity—bleeds out into the other dimensions. It’s what makes gravity the weakest of all the standard forces.”
“And the varcolac lives out among those other dimensions,” Sandra said.
“That’s what we think,” Alex said.
“So, I’m losing the thread a little. What does this have to do with time travel?”
Ryan scooped up a handful of pebbles and started throwing them over the edge, one at a time. “It has to do with a very special particle called the Higgs singlet.”
“The God Particle,” Sandra said.
“Nope,” Alex said. “That’s the Higgs boson. This is a different one.”
“The Higgs singlet’s remarkable, special property is that it is affected only by gravity, and not by any of the other forces,” Ryan said.
Sandra wrinkled her forehead. “So… it can travel into those other dimensions?”
“Exactly. If there’s a sufficiently high velocity collision of protons in the super collider, then Higgs singlets will also be created that travel backward in time, through those other dimensions. That is, their decay paths appear in our universe before they’re created in the first place.”
Sandra sat down on a rock, enjoying the fresh breeze blowing her hair back. A large golden eagle caught a thermal and emerged over a ridge, dwarfing the smaller red-tailed hawks circling below it. “Why does going into other dimensions mean going back in time?”
Ryan stood on the edge of the cliff. “You see that eagle out there?”
“Don’t kill it,” Alex said.
“I’m not going to kill it.” He turned back to Sandra. “Why can’t the eagle instantaneously travel over here, to our ridge?”
“It can’t fly that fast.”
“What if it was a really good flier?”
Sandra rolled her eyes. “It couldn’t fly faster than the speed of light, so it still couldn’t do it instantaneously.”
“Exactly. Alex, I think your sister’s smarter than you.”
Alex stuck out her tongue.
“So, we could describe the places the eagle could theoretically fly with a sphere, expanding as time passes. In the first nanosecond, it could reach no more than about a foot in any direction, even flying at the speed of light. In two nanoseconds, two feet in any direction.”
“Okay, with you so far.”
“We call that a light cone, and I’d show you how we draw it if I had some paper.”
“Why doesn’t that bother you?” Alex said.
Ryan turned, confused. “What? Not having paper?”
“No. You’re afraid of taking the elevator, yet you crouch at the very edge of a cliff, and you don’t blink an eye.”
Ryan glared at her. “I’m not afraid of taking the elevator. I just don’t trust the people who built it. This cliff is a different matter. It’s solid stone. It’s not going anywhere.”
“If you say so.”
Ryan turned back to Sandra. “As I was saying, our expanding sphere image isn’t quite accurate.”
“Why not?” Sandra asked.
“The planet,” Alex said.
“Two points for the ugly sister,” Ryan said.
Alex rolled her eyes. “Nice.”
“The point is, the sphere will be slightly deformed toward the Earth,” Ryan said. “Our speed-of-light eagle can fly farther toward the Earth than it can away from it.”
“Because of gravity?” Sandra asked dubiously.
“That’s right. Earth’s gravity isn’t a pulling force, like a giant magnet attracting things toward itself. Gravity deforms space-time. Even a beam of light, which has no mass, will bend when it passes by a massive planet. So our speed-of-light eagle will actually travel farther if it flies toward the Earth than if it flies away from it, though by only the tiniest amount. Our sphere is deformed, but not noticeably. So, what would happen if we made the Earth more massive?”