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Is Time Travel Possible?

Aired November 28, 2003 - 14:30:00   ET



UNIDENTIFIED MALE: It's possible sir,

UNIDENTIFIED MALE: Not in this world.

UNIDENTIFIED MALE: Can we go anywhere we want at any time?

UNIDENTIFIED MALE: You can do anything you want.

UNIDENTIFIED FEMALE: You are charged with violations of TPC (ph) code 40.8, time travel with intent to alter the future.

ZAIN VERJEE, CNN INTERNATIONAL ANCHOR (voice-over): It's been the mainstay of popular Hollywood film for years, the ability to move through time. No wonder time travel has fascinated humanity since, well, since time began. Now, some scientists say time travel is possible. On this edition of Q&A, we hear from them and you. Is time travel possible?


VERJEE: Welcome to Q&A. Today, a scientist who claims that time travel may not only be possible but imminent. An American physics professor says he is working on a device which might ultimately be able to transport anything from an atom to a person, from one time to another. That professor is Ronald Mallett from the University of Connecticut. Here is here with us from New York.

Also in our New York studios Charles Seife, a writer with "Science" magazine. We would love to hear from you as well, the viewer, on this one. We are opening up the phone lines for you. So please call us on 404-827- 1010 and weigh in on this show.

Welcome, gentlemen, both of you. Ronald Mallett to you first. Is time travel really possible?

RONALD MALLETT, PROFESSOR, UNIVERSITY OF CONNECTICUT: Yes, it is. And this is based on Einstein's theory of relatively. In fact, Einstein showed that time travel was possible -- in fact, his key point was that time is not absolute. It can be affected by matter, it can be affected by motion, it can be affected by energy. And it has been demonstrated.

VERJEE: Charles Seife, are you convinced? I mean, a theory is one thing but is it really feasible in practicality?

CHARLES SEIFE, WRITER, "SCIENCE" MAGAZINE: Well, I am convinced that time travel is mathematically possible. And that a lot of effects that are as strange as time travel have been demonstrated in the lab and in experiments. For example, if you take a clock and you put it on an airplane and have it zoom around the earth very fast, and compare it to an identical clock, which is sitting on the earth stationary, the two clocks will mismatch. And this is because the flow of time has changed as you move threw space. And so, what people like Dr. Mallett are you doing is trying to investigate to see whether, in fact, not only can you change the flow of time while moving or can you change the flow of time while pumping energy into a particular spot in space time. Can you actually move backwards in time? And ...

VERJEE: So you think it is possible then?

SEIFE: I think it is certainly a possibility. There are always loopholes in nature. Nature has a very, very interesting way of blocking things that seem not to make sense. Stephen Hawking, for example, posited the idea of what's called a chronological sensor, to prevent people from going back in time and causing paradoxes. Imagine if you could actually go back in time and affect the past. What would prevent me, for instance, from going back into the past, meeting my mother before she conceived me and killing her? Would I suddenly disappear because I wasn't conceived and wasn't born.

VERJEE: OK, you are taking that a step further into some of the ethical issues also involved in that. But if I could just get down -- Ronald Mallett -- to the specifics of how exactly you think I could be transported to the past or to the future in some sort of a machine. And I understand that you are building some kind of device.

MALLETT: Well, that's correct. I am interested in a way of doing it that, once again, is anchored in Einstein's theory of relatively, but makes use of the technology that we have presently available, in particular, lasers. And remember that I said that Einstein said that time could be affected by matter and energy. We know that, in fact, the gravitational field of matter can, in fact, cause a clock to slow down. But in turns out that if light doesn't have solid matter but light has energy, and it turns out that that energy can create a gravitational field and that can also affect time. The type of device that I am talking about is a very simple one. It is a device that is called a ring laser. And it sounds exotic but it is actually very simple.

And let me just simply draw a rapid diagram of what I am talking about as far as a ring laser is concerned. A ring laser is just simply a device that consists of a laser beam with four mirrors that are spaced in such a way that one of the mirrors - this is the laser - and this mirror is semi- transparent. It allows light to come through in this direction. These other mirrors are totally reflective. So the laser beam comes through it is reflected from this mirror. It hits this mirror. It is reflected off of this mirror and bounced back here. So this means that you can create a circulating beam of light. And that is what I mean by a circulating beam of light. It is just simply a device of ...

VERJEE: Well, what does that do?

MALLETT: All right, now what it does is that this circulating beam of light causes a twisting of empty space here. You have to remember that in Einstein's theory the energy, the circulating energy can cause empty space to twist. Now you might say what do I mean by twisting empty space. It is a very simple analogy that I can show you that represents what I am talking about. I have a cup of coca here. Think of this coca in the cup as being empty space. So this coca is just simply empty space. Think of this spoon as being the circulating laser beam. What happens when I take the laser -- take the spoon, OK. Notice what happens to the coca as I stir it around. It starts spinning around. That's what the laser beam is doing, empty space is moving around just the way in which this coca is moving around. So the spoon is the laser beam. And the coco is empty space.

VERJEE: And so what if you have a laser beam going fast enough creating or going into the empty space it creates something that will enable time travel?

MALLETT: It creates a loop in time. That's right. In fact, remember you can't see the stirring of empty space. But if I put something like this marshmallow in here you can see the marshmallow moving around. In that same way, if you put a particle in this empty space in here, the circulating laser beam will cause the empty space to twist around, and a little particle that is sitting in here will actually move around, OK, in empty space. But something really strange is happening to time. In Einstein's theory, time and space are connected to each other. You have to remember that.

And so what is happening to time is the following, let's just demonstrate by taking a simple strip of paper. And on this paper, what I am gong to do is to draw a line that will represent a time line. Ok, this represents time. Now, all of us live along this time line. At the bottom of the line, represents the past. At the middle of the line is the present. And at the top of the line is the future. Now, as I said, this is our unconscious timeline, all of us live our lives. This is whatever we were doing yesterday, having here n the United states Thanksgiving. In the middle of the line is today. And whatever we are doing over the weekend is the future, the top of the line.

Now, according to Einstein's theory, time is flexible, it is affected by matter and energy.. So, let's come back to the ring laser here. Not only is space being twisted in here, but time is being twisted as well. What that means is that this loop -- this timeline if it's put into this region of the laser beam, it will be twisted into a loop in that region, just like this. Now look at what this is implying. Since this is a loop, I can start out at the past, I can move along the presence to the future but then back to the past.

VERJEE: All right, all right, so we have a sense of how we view the mechanics of this actually working, before we go into some of it, Oz (ph) from Spain is on the line. Oz, your question?

CALLER FROM SPAIN: Yes, I would like to know if time travel is possible, how come nobody has visited us yet from the future?

VERJEE: Charles Seife. That's a very good objection.

SEIFE: And that is a very powerful argument to say that time travel isn't possible at least on a large scale. Particles are different than human beings. And while it may be mathematically possible to send a particle or a human being back in time, it may be harder to send a human being than a particle. But there are ways around that objection. For instance, one popular way of moving back in time in science fiction is by using a device called the worm hole, which is not that dissimilar to what Dr. Mallett was talking about.

It is also a distortion in the fabric of space and time. But the thing is you cannot travel further back in time than the worm home will allow you. And the furthest back in time you can move is to the first dates that this worm hole was created. So you can't have visitors from the past - sorry, visitors from the future coming beyond the point ...

VERJEE: But that's pretty convenient, though, isn't for your theory?

SEIFE: Well, it is a very nice way of censoring objections to the theory. There is now way to prove at this point that time travel is possible.

VERJEE: OK, Allo (ph) from England is on the line. Allo (ph), your question on Q&A.

CALLER FROM ENGLAND: Good evening . I just want to know if you really time travels, how can this affect our present environment?

VERJEE: Ronald Mallett?

MALLETT: Well, that, in fact, brings up the paradox that was alluded to by Charles a few months ago. In fact, the problem is that if you go back to the past and you affect the past then that affects the present. And how can that be, if someone had gone back to the particular time?. The problem is that we don't know that the past that we can affect is all really our past. One of the things that has been brought up - and I do think it is an important idea is the notion that there may be parallel universes as well as our own. And what this means is that if you go back into the past as soon as you reach the past, the universe branches, it splits.

Now this is consistent with quantum theory. Quantum theory is the basic theory of matter. Without quantum theory, we will not be able to understand something as simple as the atom. So quantum theory is a very real and important theory. And it leads to this possibility of parallel universes. So suppose you go back into the past, at that point, the universe could split. You could make a decision and that decision would influence one branch but it wouldn't influence the branch that you came from. So since you lived your life along one branch of this parallel universe, your life would appear to have been the same.

VERJEE: OK, you are talking parallel universes, time travel, a lot of people Ronald Mallet will be listening to this, or listening to you, your diagrams, your idea and say, with due respect, this guy is crazy. This is impossible.

MALLETT: Well, the thing is that I wouldn't believe it either if it wasn't based on Einstein's theory. That is very important. And because without that theory we wouldn't be able to understand something as simple as how we get the energy from the sun. More importantly, this is done in stages, in now way am I or my colleague, I have an experimental colleague Chandler Chowder (ph) who is working with me, he is in protonics, we are trying to send people back. We are not even trying to send sizable objects back. What we are saying is that space and time can influenced. What you can show is that space is being twisted first. And that is something that can be done straight in the laboratory.

VERJEE: OK, you already made that point. I want to bring in Abdullah (ph) from Lebanon to ask a question. Abdullah, go ahead.


VERJEE: Your question.

CALLER: Yes, I wonder, if time travel is possible how can we know that the present we are living in now was not altered by somebody in the past, somebody who travels to the past and alters our presence?

VERJEE: Charles Seife.

SEIFE: We don't know. We don't know because the theory isn't there yet. We don't have any evidence that anyone has traveled back in time. And there are ways of looking at time travel that are both consistent. You can think of if there is time travel then the time traveler can affect the past, or the time traveler can't affect the past, both are mathematically consistent. And we have no way of distinguishing the two. At the moment, the experimental basis such we don't seem like we can affect the past. There was a very interesting experiment done in 2000 by Weijun Wang (ph) at NEC in Princeton, where by setting up a chamber in a special way, he was able to send a pulse of light so that it emerged from the chamber before it arrived into the chamber.

This sounds utterly ridiculous but it actually happened. And last month in "Nature" magazine, a serious peer reviewed journal, there was an article discussing whether you can use this super luminal back in time signal to send information, to send a message back in time. And from what they see, no. It is not possible, even though it does look like you are sending a single back in time, that something emerges from a chamber before it enters, you cannot send a message.

VERJEE: OK, Charles Seife, a writer with "Science" magazine, Ronald Mallett, a professor of physics at the University of Connecticut. Thank you, gentlemen, both for talking to us on Q&A today.

MALLETT: Thank you.

SEIFE: Thank you very much.

VERJEE: We are out of time. I wish we could travel back and redo that perhaps, but that is it for this edition of Q&A. Before we go, we always want to hear from you, e-mail us Q&

We'll have more news in a moment. This is CNN.



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