They dropped into seats, already feeling the aircraft begin to move on the runway. Moments later, the engines roared, and Marek looked out the window to see the French countryside fall away beneath them.
It could be worse, Gordon thought, sitting at the back of the plane and looking at the group. True, they were academics. They were a little befuddled. And there was no coordination, no team feeling among them.
But on the other hand, they all seemed to be in decent physical condition, particularly the foreign guy, Marek. He looked strong. And the woman wasn't bad, either. Good muscle tone in the arms, calluses on her hands. Competent manner. So she might hold up under pressure, he thought.
But the good-looking kid would be useless. Gordon sighed as Chris Hughes looked out the window, caught his own reflection in the glass, and brushed back his hair with his hand.
And Gordon couldn't decide about the fourth kid, the nerdy one. He'd obviously spent time outdoors; his clothes were faded and his glasses scratched. But Gordon recognized him as a tech guy. Knew everything about equipment and circuits, nothing about the world. It was hard to say how he'd react if things got tough.
The big man, Marek, said, "Are you going to tell us what's going on?"
"I think you already know, Mr. Marek," Gordon said. "Don't you?"
"I have a piece of six-hundred-year-old parchment with the Professor's writing on it. In six-hundred-year-old ink."
"Yes. You do."
Marek shook his head. "But I have trouble believing it."
"At this point," Gordon said, "it's simply a technological reality. It's real. It can be done." He got out of his seat and moved to sit with the group.
"You mean time travel," Marek said.
"No," Gordon said. "I don't mean time travel at all. Time travel is impossible. Everyone knows that."
"The very concept of time travel makes no sense, since time doesn't flow. The fact that we think time passes is just an accident of our nervous systems - of the way things look to us. In reality, time doesn't pass; we pass. Time itself is invariant. It just is. Therefore, past and future aren't separate locations, the way New York and Paris are separate locations. And since the past isn't a location, you can't travel to it."
They were silent. They just stared at him.
"It is important to be clear about this," Gordon said. "The ITC technology has nothing to do with time travel, at least not directly. What we have developed is a form of space travel. To be precise, we use quantum technology to manipulate an orthogonal multiverse coordinate change."
They looked at him blankly.
"It means," Gordon said, "that we travel to another place in the multiverse."
"And what's the multiverse?" Kate said.
"The multiverse is the world defined by quantum mechanics. It means that-"
"Quantum mechanics?" Chris said. "What's quantum mechanics?"
Gordon paused. "That's fairly difficult. But since you're historians," he said, "let me try to explain it historically."
"A hundred years ago," Gordon said, "physicists understood that energy - like light or magnetism or electricity - took the form of continuously flowing waves. We still refer to `radio waves' and `light waves.' In fact, the recognition that all forms of energy shared this wavelike nature was one of the great achievements of nineteenth-century physics.
"But there was a small problem," he said. It turned out that if you shined light on a metal plate, you got an electric current. The physicist Max Planck studied the relationship between the amount of light shining on the plate and the amount of electricity produced, and he concluded that energy wasn't a continuous wave. Instead, energy seemed to be composed of individual units, which he called quanta. "The discovery that energy came in quanta was the start of quantum physics," Gordon said.
"A few years later, Einstein showed that you could explain the photoelectric effect by assuming that light was composed of particles, which he called photons. These photons of light struck the metal plate and knocked off electrons, producing electricity. Mathematically, the equations worked. They fit the view that light consisted of particles. Okay so far?"
"Yes"
"And pretty soon, physicists began to realize that not only light, but all energy was composed of particles. In fact, all matter in the universe took the form of particles. Atoms were composed of heavy particles in the nucleus, light electrons buzzing around on the outside. So, according to the new thinking, everything is particles. Okay?"
"Okay"
"The particles are discrete units, or quanta. And the theory that describes how these particles behave is quantum theory. A major discovery of twentieth-century physics."
They were all nodding.
"Physicists continue to study these particles, and begin to realize they're very strange entities. You can't be sure where they are, you can't measure them exactly, and you can't predict what they will do. Sometimes they behave like particles, sometimes like waves. Sometimes two particles will interact with each other even though they're a million miles apart, with no connection between them. And so on. The theory is starting to seem extremely weird.
"Now, two things happen to quantum theory. The first is that it gets confirmed, over and over. It's the most proven theory in the history of science. Supermarket scanners, lasers and computer chips all rely on quantum mechanics. So there is absolutely no doubt that quantum theory is the correct mathematical description of the universe.
"But the problem is, it's only a mathematical description. It's just a set of equations. And physicists couldn't visualize the world that was implied by those equations - it was too weird, too contradictory. Einstein, for one, didn't like that. He felt it meant the theory was flawed. But the theory kept getting confirmed, and the situation got worse and worse. Eventually, even scientists who won the Nobel Prize for contributions to quantum theory had to admit they didn't understand it.
"So, this made a very odd situation. For most of the twentieth century, there's a theory of the universe that everyone uses, and everyone agrees is correct - but nobody can tell you what it is saying about the world."
"What does all this have to do with multiple universes?" Marek said.
"I'm getting there," Gordon said.
Many physicists tried to explain the equations, Gordon said. Each explanation failed for one reason or another. Then in 1957, a physicist named Hugh Everett proposed a daring new explanation. Everett claimed that our universe - the universe we see, the universe of rocks and trees and people and galaxies out in space - was just one of an infinite number of universes, existing side by side.
Each of these universes was constantly splitting, so there was a universe where Hitler lost the war, and another where he won; a universe where Kennedy died, and another where he lived. And also a world where you brushed your teeth in the morning, and one where you didn't. And so forth, on and on and on. An infinity of worlds.
Everett called this the "many worlds" interpretation of quantum mechanics. His explanation was consistent with the quantum equations, but physicists found it very hard to accept. They didn't like the idea of all these worlds constantly splitting all the time. They found it unbelievable that reality could take this form.
"Most physicists still refuse to accept it," Gordon said. "Even though no one has ever shown it is wrong."
Everett himself had no patience with his colleagues' objections. He insisted the theory was true, whether you liked it or not. If you disbelieved his theory, you were just being stodgy and old-fashioned, exactly like the scientists who disbelieved the Copernican theory that placed the sun at the center of the solar system - and which had also seemed unbelievable at the time. "Because Everett claimed the many worlds concept was actually true. There really were multiple universes. And they were running right alongside our own. All these multiple universes were eventually referred to as a `multiverse.' "