On October 17, 2012, Professor Ronald L. Mallett joined Jack Hitt onstage at the Institute Library in New Haven, Connecticut, as part of the ongoing series “Amateur Hour,” in which various tinkerers, zealots, and collectors discuss their obsessions. Mallett is Research Professor of Physics at the University of Connecticut, where he has been developing a theory for time travel. He is the author of Time Traveler: A Scientist’s Personal Mission to Make Time Travel a Reality. The conversation that follows was recorded live and has been edited for brevity and meaning.
Jack Hitt: There are two essential ways one can be an amateur: One is to be kept outside of a fortress of expertise, usually by an elitism masked as credentials, and the other is to wander past the boundary of acceptable knowledge, where there are no credentialed anybodies. At best, one is a pioneer. And I think that you qualify in the latter category.
In preparation for this, Ron, I started digging up movies that involve time travel. Midnight in Paris, Austin Powers, GalaxyQuest, Star Trek, especially part four; It’s a Wonderful Life, Bill & Ted, Dr. Who, Harry Potter, the Terminator movies, Groundhog Day, and so many others.
My favorite is The Time Machine, the 1960 version, which was the closest to the way H. G. Wells wrote the book. They actually try to explain the notion of a fourth dimension. A lot of people may not realize it, but Wells wrote the book ten years before Albert Einstein’s special theory of relativity. In fact, Wells was the first one to mention time as a fourth dimension, which is the foundation of the scientific notion of time.
So is The Time Machine the best or your favorite?
It’s the best and my favorite. A really close second for me is Time Cop—a really underrated movie, but it’s superb. Jean-Claude Van Damme! People thought it would be just a fight movie, but it plays with the notion of time travel in a very clever way. It involves an agency that has the job of enforcing the time continuum—that is to say, these are police that actually find out if something is going to go wrong, and they go out and try to correct it.
Is there some aspect in particular that makes it a favorite?
The ethics of time travel. If you can go back in time, there’s an ethical issue. It can be used for good or bad. Once time travel into the past actually becomes a reality—and it will become reality—we’ll have the responsibility of making sure that it’s used in the right way. And just as we have other regulatory agencies, we will eventually have a regulatory agency that addresses the question of how this technology is used. But first we have to realize that we cannot not use the technology.
It seems like time travel involves a lot of discussion about how we manage it, or how we run it. I can’t think of any other potential invention that got this kind of prediscovery ethical treatment. After the atomic bomb, or the internet, the reaction was, “It’s done. We can’t get it back in the bottle.” Why do you think time travel gets this treatment?
I think it’s because of the nature of time travel, what it means to us. The whole notion is in some way a primordial issue. If we go back through history, people at one time or another have asked: What if I could do something to change the past? What if I could’ve taken another path? What if I could see that loved one again? This is an ancient feeling that touches something deep in us about the longing for things past and the quest to try and understand the things to come. So even before technology was able to engage the notion of time travel, we already had an emotional connection with the possibility.
Incidentally, another thing about H. G. Wells is that he was the first one to talk about this in terms of a mechanism. The notion of time travel in stories is older than Wells—Mark Twain’s A Connecticut Yankee in King Arthur’s Court, for example. But that happens because a guy gets kicked in the head. It’s uncontrolled. What Wells posited was a mechanism, like a clock. It’s something that we actually do, and he was doing it at the beginning of the twentieth century, when we were inventing airplanes and x-rays, the beginning of a control over nature, which we had never experienced before.
You told me that there was one movie that got the science pretty much right-on.
The one that got it precisely right was Charlton Heston’s Planet of the Apes. The astronauts arrive in the future because their rocket has traveled close to the speed of light, which caused a dilation of time, and that suggests that time can be manipulated and slowed the faster an object moves. So if you move an object close to the speed of light, you can actually arrive in the future younger than everyone else. This is real.
What are some real-world examples where this plays out?
Well, there was an experiment that was done at the Naval Observatory in 1971 with atomic clocks, the most precise timekeeping mechanism we have. One clock was put on an ordinary passenger jet and another was kept stationary at the observatory. They flew the passenger jet around the world at the speed of sound and found that the clock on the passenger jet had actually slowed down, had actually lost time, in exactly the way that Einstein had predicted. This means that the scientists on board were actually younger. You might ask why this wasn’t on the front page of the New York Times. It’s because the effect was very, very small. Even though they were traveling at the speed of sound, that’s only about 700 miles per hour. Compared to the speed of light, that’s slow. Just to give you an example: As you know, sound is measured in Mach numbers—Mach 1 is one times the speed of sound, 2 is two times, and so on. We have passenger jets that can do about Mach 1. We have jet fighters that can do Mach 2. We even have stealth fighters that can do Mach 3. Light travels at almost Mach 1 million.
So we have a little ways to go.
Right. Compared to light, sound is practically standing still. And according to Einstein, the effect occurs at almost any speed, even when you’re in a car. But it only happens noticeably when you get close to the speed of light. Now it turns out that NASA is trying to develop rockets that can go close to the speed of light—some of them have exotic names like “ion engines.” Eventually we will have rockets that can go close to the speed of light. But even if you were in one, you wouldn’t notice it, just like when you’re in a car going sixty-five miles per hour, you don’t know that you’re doing sixty-five miles per hour. According to Einstein, any rhythmic information will slow down the faster you move. But it slows down for people who are watching you move, not you.
Suppose an astronaut has a family, and she volunteers to take the flight. It could happen that when she comes back, only a few years have passed for her. But time will have marched on in the normal way here on Earth, so that when she returns she can actually come back and find out that she’s younger than her children.
So we might need some time-cop therapists.
Well, yeah, it could lead to a sociological problem. The thing is, we’ve already seen the baby steps of this in the experiment at the observatory. And the hallmark of science is repeatability.
What about the near-term stuff? Granted, the speed of light and the ion engine and stuff like that might be a while. But say we could go Mach 50. Would it be enough to be obvious?
We’re actually traveling close to that. Space capsules travel at about 25,000 miles per hour, and the effect is much more noticeable but still not enough. You’d actually have to be at about half the speed of light, or three quarters of the speed of light, to see it in a dramatic way.
So what would you see? You’d leave the planet, you’d zip around a distant star, and come back. And you’d have spent a week in space, and you’d come back and …
From your standpoint, you’d have been away for a week. But when you come back to Earth, ten years would have passed. That’s what happened in Planet of the Apes. What they didn’t realize, of course, was which future they were going into.
Is it a different thing, going into the future and going into the past?
Absolutely. In my work we’re doing both. But there are actually two quite different theories that allow you to go into the future and the past. What we’ve been talking about so far is Einstein’s special theory of relativity, and no matter how fast you go, you can’t go back into the past. Einstein developed a second theory, the general theory of relativity, and that has to do with how gravity affects time: The stronger gravity is, the more time will slow down.
How have we seen this particular effect? A GPS system, for one. A GPS works like this: Right now, about 12,000 miles above us, there are twenty-four satellites in geosynchronous orbit, at least three of which are covering any particular region of the Earth. When they originally set up this system, it wasn’t working correctly. It was giving them the wrong locations. At first, the engineers were perplexed, but then they realized that they had forgotten to take into account Einstein’s theory of gravity. What’s happening is that your unit, which is close to the surface of the Earth, where gravity is stronger, is actually running slower than the unit onboard the satellites, which are farther away from the surface of the Earth. The time on those units is actually running faster than the time in your unit. So they’re out of sync. So they had to calibrate the system to keep it adjusted. This is a real effect that gravity has on time. That’s the basis for my work—using gravity to manipulate time.
Okay, let’s go right to the garage of your idea. How do we get our 2≈4s and our nails and put together a time machine?
Well, first I need to explain the difference between a theoretical physicist and an experimental physicist. In all the other sciences—chemistry, biology, et cetera—there isn’t a dichotomy between the theoretical and experimental. In physics, there is a dichotomy. Theoretical physicists use mathematics. When a theoretical physicist says that he has a theory, he doesn’t mean it in the colloquial way, he means he has a mathematical model, which tells you exactly how a portion of the world is working. Einstein was a theoretical physicist. When he came up with E=mc, he didn’t build reactors and the atomic bomb. That was done by engineers and experimental physicists. So I’m a theoretical physicist. What I did was take Einstein’s theory and develop a theory based on that.
What’s the theory?
Everyone’s familiar with the fact that matter creates gravity. The Earth pulls you down due to gravity. Part of Einstein’s theory is that not only does matter create gravity, but light itself can create gravity. My breakthrough was to realize that if gravity can control time, and light can create gravity, then light can control time. That was it—to realize that you can use light, in particular laser light, to manipulate time. What I found was that if you use circulating light—there’s a device called a “ring laser,” and it’s essentially a series of mirrors that bounce light around to create a circulating beam of light—the beam does two things. First, it causes a twisting of empty space itself. This room, for instance—if I had a circulating beam of light going on, it would actually drag empty space around.
Imagine that I have a cup of coffee in front of me. Think of the coffee in the cup as being a portion of space. Think of my spoon as being like the circulating light beam. What happens to the coffee when I start moving the spoon in the coffee? It starts swirling around, right? It creates a vortex. That’s what the circulating light beam is doing to empty space. Now, it’s empty space, so how do I see it? Let’s come back to the coffee. Suppose that I throw in a sugar cube or a coffee bean. As I stir the coffee around with the spoon, the coffee is going to drag the bean around, which allows me to see the effect of the spoon. The thing that plays the role of the coffee bean in the work that I’m doing is the neutron, which, as you know, is a part of every atom. If I put a neutron into empty space, and turned on the circulating light beam, if space is being dragged around it will drag the neutron around. So even though I can’t see the empty space being dragged around I’ll be able to see the neutron being dragged around, and I’ll know that space is being twisted.
Now, in Einstein’s theory, whatever you do to space also happens to time. Space and time are linked to each other. Time we normally think of as a straight line that goes from the past to the present to the future. All of us live along that line. For instance, at the bottom of that line is what you were doing yesterday. At the middle of the line is what you were doing today. At the top of the line is the future. So all of us go from the past to the present to the future. The second half of my theory is that if you increase the intensity of the circulating beam of light, you can go from the future to the past. By twisting space strongly enough, I can eventually twist time into a loop and along that loop go back into the past.
So make me see this. What would it look like? Would it be a box that we would step into?
It would be something like that. It would actually be a cylinder, and that cylinder would cause this twisting of space and time. When you go into this cylinder of light, you would feel yourself getting dragged around in space, but if you were to move in a certain direction you would be able to go back into the past. The device would allow you to go into the future as well. I’ve developed the basic mathematical equation for this. I have a colleague named Chandra Roychoudhuri, who’s an expert in lasers and is attempting to prove this mathematical theory.
Would you stay whole, as a person, in the cylinder machine?
Well, when you fall you’re in a gravitational field, right? Pieces of you don’t fall, you fall as a unit. And that’s the thing—this is a gravitational field that’s being created, so it’s affecting you as a whole. I should mention that what we’re doing is not trying to send people back into the past. We’re trying to send information back. If you think about it, sending information back is even more important than going back. People have asked me, What’s the good of this time machine? What would you use it for? For me, one of its most important applications is as an early-warning device. Imagine if we had a way of sending information back to the past to warn ourselves about Hurricane Katrina or the tsunami that devastated Japan, the thousands of lives that we could save. An early-warning system would allow us to have command of things that we haven’t even been able to dream of.
Okay, we’ll go back to the practical stuff in a second, but say you did send a message back to September 10, 2001, to be on your guard for planes taking off on September 11. You do get into some paradoxes, right?
Absolutely. The grandfather paradox—and by the way, there is no paradox if you’re traveling to the future. But if you travel to the past, there’s an obvious paradox, and the most famous of them is what’s known as the grandfather paradox. The milder form of it, the one that I like, is going back into the past and preventing your grandparents from meeting each other. The other form of it is you go back and kill your grandparents. That one’s not my favorite. But let’s suppose you go back to the past and prevent your grandparents from meeting each other. Then they don’t have your parents and your parents don’t have you. So how could you go back and prevent them from meeting each other? That’s the grandfather paradox, a classic paradox.
It turns out that physics is actually ambiguous in terms of dealing with this because there’s more than one possibility. One of the possibilities comes from a discipline called quantum physics, which is very bizarre in the way it operates. QP deals with probabilities, it doesn’t deal with exact predictions. For instance, when I throw a ball at you, if I know exactly the position and speed at which I’m throwing it, I can predict exactly where it’s going to land. In the world of quantum physics, you can only predict probabilities. A physicist back in 1957 named Hugh Everett decided to see what would happen if you apply QP not just to systems, like atoms, but to the universe as a whole. He found that it leads to the following bizarre result—the notion that whatever alternative can occur will occur, but in different universes. Let me put that into a precise context. Suppose today you were trying to decide between a tuna sandwich or a cheeseburger. At the instant that you decide and order the cheeseburger, there’s a split of the universe, a new universe in which you actually have the tuna sandwich. In other words, these are two separate real universes. One is parallel to the other, and neither of you know about the other. This theory was originally called the many-worlds theory, but it’s now more popularly called parallel-world interpretation, and this happens in every single decision that you make, and it doesn’t have simply to do with humans. For example, if an electron has the possibility of going on this path, or this path, in QP it will take both paths—but in different universes. I like to think that this leads to an interesting philosophy of life, because I can know that whatever decision I make, in some universe I got it right.
I’m still looking for that universe.
The thing is, there’s a physicist named David Deutsch at Oxford University, and he applied Everett’s parallel-world notion to time travel. What he found was that when you work out the calculation and go back into the past, you arrive in the past of a parallel universe. In that universe, you could do something like preventing your grandparents from meeting each other, and you would find yourself in a weird universe, you were never born in that universe. However, remember what I said—as you arrive in the parallel universe, the original universe that you were in was split off, and in that original universe your grandparents meet each other and get married and so on. What it means is that you can go back and change the past, but the past you change is not the past you came from.
And there’s also a split world where you didn’t go to the past, right?
That’s right. And from the point of view of the people in the other world, you didn’t go into the past. You just disappeared one day and were never heard from again. So that’s quantum physics, and that’s one possibility. The other possibility, and this is even weirder, is that you actually do change reality. The problem is that we think, moment by moment, that everything that has happened to us has a history. It doesn’t occur to us that if somebody actually changes the past that everything from that moment would be part of our history, we don’t think—we will never know—that it has actually been altered, because we will always think that that is the way that things always were.
And that solves the other paradox, which is that, if there could be time travel, we’d already know it, because people already would have come back and interfered with us, or visited us right now.
Well, only if they acknowledge that they were time travelers.
We’ve arrived at our Dr. Who portion of the show now.
If they acknowledged that they were time travelers, that would be a different issue, a sociological question. There’s actually a story about how people who visit the past have a restriction that they can’t do anything that could possibly alter the future. One of the famous stories about what happens if that’s violated is by Ray Bradbury, called “A Sound of Thunder.” There’s another possibility of limitation: You can only go back to the point at which the time machine was first turned on.
But otherwise this column of light will somehow create an alternate universe that goes back to the time you want?
Well, it could. We don’t know. That’s the thing. Part of it is when it comes to time travel into the past, we don’t know what’s going to happen until we do the experiment. The stage we’re at now has to do with funding.
So you’re now actually actively raising money for the feasibility study. How much do you need?
Quarter of a million bucks.
What would you do with it?
We’d actually computer-model it, to figure out which types of energies are needed, what would be the best configuration for the system. Then we’d test a small array of lasers to see what we could do with that information. We’d try to cause that small twisting of space. And that’s fundamental, it’s a brand new prediction.
Was there a time in your life when you realized that this was what you wanted to do? Were you seized by an obsession with time travel?
Oh yes, absolutely. The obsession—it actually has to do with a tragic story from my own life. I was the oldest of four children, grew up in the Bronx. My father was a television repairman, and for me, the sun rose and set on him. He really was the center of my universe. He looked like a very healthy, robust man, but we didn’t realize that he had a very weak heart. And he died of a massive heart attack. He was only thirty-three. I was ten. To say I was devastated just understates it. My world just fell completely apart. Mentally, I just couldn’t handle it. I went from being a rather happy kid to being a really depressed child. I was inconsolable.
The thing is, he left me with many gifts, and one of them was curiosity and love of reading. And I loved reading science fiction. About a year after he died, I came across H. G. Wells’s The Time Machine. And that turned everything around for me. When I read it, I said: This is it. This is the solution to my dilemma. If I can go back into the past, I can see him again and maybe save his life. That became my goal, my mission. I have to say that even at eleven I was astute enough to know that people were already worried about me, so I had better not tell them. So I kept it as a secret to myself.
When did you come out?
Actually, I didn’t come out until my breakthrough, back in 2000, when I realized that circulating light could be used to twist space and time. It would’ve been professional suicide.
But as a kid I loved reading popular-science books, and when I was twelve, I came across a book called The Universe and Dr. Einstein. The cover shows Einstein next to an hourglass. I knew who Einstein was, and what I realized was that the cover was indicating that Einstein might have something to do with time. So I got the book. I should mention that after my father died, my family plunged into poverty. It was disastrous. So when I say that I got the book, I got it at the Salvation Army, with a little bit of money, which my mother would give us for lunch. I was getting sick, because I was spending all my money on books. I developed anemia. But in any case, I got this book, and I made out that Einstein was saying that time was not fixed. According to Newton, time could not be altered by anything; but according to Einstein, time could actually be altered, and I knew that if I could figure out what Einstein was saying, how time could be altered, then this might lead to the real possibility of a time machine. So first it was H. G. Wells, then it was Einstein, who became my second passion. Of course, the Einstein passion was one I was able to tell people about.
How old were you when you put all this together and realized, maybe I can invent a time machine and get back to my dad?
Well, there are two pieces to that. When I was twelve, after I realized that Einstein might be able to lead the way, it was no longer just fantasy or science fiction. But figuring out how to do that took me the rest of my life. I had to learn Einstein’s general theory of relativity, which took him nearly ten years to develop because of the sophisticated mathematics, which is something called tensor calculus. As a physicist, I knew I would have to learn all of that, and that it would take many, many years. Incidentally, the way I was able to afford to go to college was to go into the Air Force after high school and use the GI Bill to go to Penn State. But I didn’t tell anyone what I was doing. It was a very lonely existence. Even while I was in the Air Force, I didn’t want anyone to know what I was doing. I was a computer technician, but I was trying to read everything I could about Einstein. I had zip social life. Even when I went to college, I knew I couldn’t tell anyone, so I chose an area of physics in Einstein’s theory that would allow me to study time, and that happened to be black holes—which were considered to be a crazy idea but, as opposed to time travel, legitimate. I realized that if I studied black holes, and how black holes affect time, I could make a career out of it, and on the sly I could try to understand how time might be controlled.
There’s legitimate crazy and illegitimate crazy.
And you think that time travel has moved from illegitimate to legitimate?
Yes. As far as time travel into the past, other people are looking at this possibility besides me. There’s the notion of using wormholes.
You’ve been obsessed with this most of your life. Has that obsession cost you?
It’s cost me a couple of marriages. You pay a price when you are that obsessed with something. It happens in any field. The thing is, I would become very depressed when I thought I wasn’t figuring out what to do. It also made me feel alone even among my colleagues, because I was living this double life, of doing legitimate work in cosmology and black holes but with my real interest in time travel. I think it also affected me physically—heart problems, which is ironic. So yeah, it was costing me a lot.
But it was worth it. The passion of what was driving me: Even though I had personal problems, it kept me on the straight and narrow. I always felt that I wanted to do something that was going to make my father proud. Stephen King has this great series of stories called the Gunslinger series—Dark Tower stories—and the phrase that I like in it is, “He has not forgotten the face of his father,” which means that the person is an honest person. I tried to be a teacher and, as much as I could, a good husband until things fell apart. But this obsession was always there, and it’s still there. But what I feel satisfied with is that I now know how to do it.
So when you’re not thinking about circular light and gravity and time, do you fantasize about what you would say to your dad?
Oh, yeah. I think about that a lot. One of the unfortunate habits my father had was that he was a smoker. And when I say smoker I mean two packs a day. In those days, they didn’t know the correlation, but it definitely affected his health. So, if I was to go back to that time, I’d say two things. You know, as an adult, you get to say goodbye to people, or tell them that you love them. I don’t remember consciously having done that with my father. And so the two things that I would say to him would be, “Dad, I love you.” And the other thing I would say to him would be, “Stop smoking.” And hopefully that would help him change his destiny.