Things started happening real fast.
First, to my amazement, Dean Mendelsohn got out of the helicopter, with luggage.
“I’ll stay and wind things up here, for you,” he said.
The Dean? Here? That sly old devil – still wanted to show he could do fieldwork, I guess. Or maybe this was so urgent that they didn’t have anyone else to come in for me.
But either way, this was happening fast, fast.
Because as he was stepping out of the chopper, they told me to pack up my gear, because I was flying out with them.
So within an hour of their arrival I found myself flying across country with two men from DARPA, heading for training for this mission.
Here’s the thing: I didn’t know anything about time travel. I still don’t, really, not the complexities of the math, or the real science behind it. I’d heard or read that we couldn’t change the past, but that we could learn from it. In other words, no matter what you or I did 12,000 years ago, wouldn’t matter – we’d end up exactly as we were. That always seemed a little weird to me, but I didn’t really think about it very much.
And when I did think about it, it was usually to envy someone like Carver, who had had the opportunity to actually go back in time and study the Pleistocene.
So as we flew, White tried to explain time travel to me.
“Let’s start with time travel itself, first, before we talk about the beacons, okay?”
I thought that sounded like a good plan.
“As you know (I hadn’t), the secret to time travel is quantum entanglement – spooky action at a distance. Turns out it works over time as well as space.”
“But it requires amazingly accurate pinpoint computation, to synchronize this ‘now’ with that ‘then.’ We’re talking about the kind of calculations that make supercomputers seem slow. It’s so slow and expensive that we’ve only got these three stations up and running, ASU, St. Louis, and Fairbanks.”
“Yes, but how does it actually work? What happens?”
“Why, from your standpoint, that of the time traveler, it’s easy and painless. The transmitter, say the one at Washington University, is a big box. They call it a tesseract – it’s a multi-dimensional cube. They build a smaller one inside it, and that is sent back to the time you’re aiming at. Then, you and your companions and your gear stand within the main tesseract, it does quantum scanning, and transmits you to the slightly smaller tesseract which has been prepositioned at the time you wish to visit.”
“Wait – it transmits me? How? Am I de-materialized? What?”
This started sounding a little scary.
“No, not at all. ‘Transmits’ is just the term we use for the process. What happens is that the quantum field set up within the tesseract substitutes the previously chosen time for the present. That is the variable that changes. You are within the field, and the three physical dimensions –- length, height, width, you know — remain the same, but the fourth dimension – time – is switched. That’s the math part that we’ve been talking about.”
“Yeah, right, spooky action at a distance. Got it. But it’s safe, you say?”
“Oh yes. You stand there, or sit, for that matter, while you’re scanned, and then the tesseract changes the one variable – the time in which you exist – substitutes the past for the present.
“And that’s it?”
“Yes, that’s it. You feel a flash or some people have described at as a twitch, or a tingle, and look around, and you’ll see that instead of being in the lab at Wash. U., you’re back sometime in the past – whatever time you’ve picked.”
And, he explained, you come back the same way – step into the tesseract that is back when and where you are, and it does its magic and the one variable that changes – time – flips, and instead of being back there ten thousand years ago, here you are, back in the present.
But as it turned out, time travel had some odd, or at least not-obvious limitations. Kramer said that this was party due to the fact that time travel was so new, and partly, I think, because they didn’t fully understand the math or physics that underlay it. They could make it work – they had made it work –but apparently no one completely understood how it worked. But he explained to me what they had learned.
Kramer: “First, we have established that one cannot use the past to change the present – one cannot go back in time and kill Hitler, for example, tempting though that might be.”
Yeah? Have they tried? I’d sure as hell try.
So I asked. “Did you guys try?”
Kramer glared at me. “Damn right we tried. Nailed him, too. Only it doesn’t matter.”
“What? Why not?” I asked. “Why doesn’t our present change, if you go back in time and change something in our past? I don’t get it.”
“Excellent question,” White said smoothly. “Why this is – that is not well understood. The prevailing theory, though, is that the present, our present, is immutable, because of a theory of multiverses. That is, we don’t travel back into our past per se, but rather back into a past that the time travel process itself calls into being, a past identical in all ways to our own, with the simple problem that whatever is done back there, has no change on the present we return to.”
“In other words,” he said, “you can go back in time, kill all the Hitlers you want, but when you come back to our time, our history includes Hitler; is unchanged.”
But wait a minute.
“Wait,” I said. “Is the past we go to the real past, or a fake past, called up out of the ether?”
“Excellent question,” he said again. Guy must have given this lecture, answered all these question hundreds of times before. He was unflappable.
“It’s both,” he said. “It’s the real past – we see the actual events that happened, observe historical events that we know happened – all the data matches. But at the same time, it’s parallel, dual, identical to our past, but not our past. It’s a past on a different track: equally real, equally viable, solid, real. It exists. But there’s a disconnect somewhere. Like I say, you can kill Hitler back there, but whatever you do, the present you return to – our present – includes the bloody history of Europe in the thirties, and World War II.”
“That’s why the program has evolved as it has. All time travel can do is let us learn from the past. We cannot change the past we know in our present. That we cannot do. But we can change our future, change our behavior in the future. If we learn, for example, why mammoths became extinct in North America about twelve thousand years ago, maybe we can prevent some other extinction events in our time.”
Kramer jumped back in. “And time travel has – so far, at least – strict, but poorly understood limits on retrieval.”
“Yes, bringing material forward, from the past.”
“It’s a phenomenon called “quantum identification.” Each time traveler, and all of his or her equipment must first be scanned at the quantum level, before transmission into the past. This scan provides the template, as it were for retrieval back to our present. “
“But only what is scanned can be retrieved. In practical terms, what this means, at least at present, is that only what is sent back in time can be retrieved, brought forward to the present. So, no mammoths, no cave men, not even tissue samples, as yet, can be brought back.”
Now that’s weird. Why not? Why can’t they bring anything back? Look I know I’m not a physicist, and I’m sure I could never understand the math, but it seemed so unfair. I mean, wouldn’t it be cool if you could go back in time, and bring back a baby mammoth or something? Can’t they figure that part of it out?
Matter is energy, I guess, and I know we’re not talking about travel to a place, but travel to a different time. Maybe a different kind of energy? I don’t know. And White and Kramer didn’t – or couldn’t – explain it in a way I could understand.
But I got the rule, though. That I understood. Nothing from back then comes back to here and now. But not clear, and not fair.
He was still talking.
“Now this rule can be bent, even if we can’t yet break it. So, for example, data stored electronically can be brought back – photos on digitized chips, digitally stored voice or video recordings. Drawings, notes, those are fine too.”
Well, that’s interesting. I’ll bring a sketch pad, to go with my cameras.
“But intriguingly, that is it, at least for now. Nothing more can be brought back. Even the dirt that one would expect to find on the shoes or clothing of returning time travelers does not return to the present. We haven’t found even a microbe, or bacteria.”
“So the problem of quantum identification is an intriguing, and perplexing one.”
Well, those, it seemed, were the rules of time travel. The math supporting all this was, I was given to understand, remarkably complex, incredibly sophisticated. I am not a mathematician, thankfully, so they didn’t even try to explain that all to me.
On to the time beacons.
The way it worked was that from any of the three centers, travelers would be shifted back in time, but not transported through space. They’d end up right where they had been – in Arizona, or Missouri, or Alaska, simply back in an earlier time. All well and good, but then your time traveler wants to actually, you know, travel. Walk around, see the country, do some research. So for the duration of that trip, the time traveler is wandering around, travelling, doing whatever.
So each traveler is given little beacons, about the size of a tea light, to send at the same time every day, sort of like checking in, saying all is well. It just triggers a flash on the tesseract sensors, letting the monitors know where you are (since the terrain then is the same geographically as the terrain now), and that you’re still alive, well enough to send the beacon. And every traveler was given an emergency beacon, saying, basically, “send help now!”
And, up until now, it had been safe. So long as a given station kept running, the time traveler could always just come home. Or if he or she needed help, a second team could be sent back to help out. Which they told me had never been necessary.
And Carver had gone back, successfully, since he’d sent two of the time beacons. But three days ago, Carver hadn’t sent the beacon. And none had come in since. And then, yesterday, the telemetry and chronometers and everything at ASU had gone offline. Everything had been debugged, power cables checked, tech guys called in – everything. But for some reason, stubbornly, obstinately, the station remained down. Never happened before. Shouldn’t have happened now. In fact, it was theoretically impossible.
The only problem was that it had happened. An “oh shit!” moment for the people at DARPA. Because they couldn’t tell what had happened to Carver, and because the station was down, they couldn’t just zap someone back to find out.
But DARPA had a protocol for situations like this. Even though, as I say, it was theoretically impossible, they had planned for it.
And now, I was part of that plan.