Tuesday, December 11, 2007

The New Time Travelers

I can't change the past because the past has happened; I can’t kill my grandfather because I didn’t. But that in itself doesn't mean I can't travel to the past.

The dream of time travel has been shaped and sculpted by movies, science fiction, and our own imaginations; but in those hands it’s only a dream. But to a few capable scientists, time travel is a real possibility in our universe, and one that can be examined with theories of physics. The recently published book The New Time Travelers: A Journey to the Frontiers of Physics, is "a history of the serious study of time travel" by physicists, beginning in 1988. From what the author David Toomey told me about his book, the answers to many of your time travel questions may pleasantly surprise you.

Toomey is an avid science writer, but not a scientist himself, and he brings an outsider's perspective to these sometimes mind-boggling concepts. I’m very excited about this book and made my dad buy a copy. I knew he’d be excited by the time travel aspect and it’s written for a general audience so he can understand all of it. Plus, being the only physicist in my family, my parents tell me, "We're always looking for ways to understand what it is you do.”

David Toomey also happens to be a former professor of mine (a comparable honor). He and I joined a chance to catch up with a blog entry for me. My questions are in italics, and David's responses are in regular print.


First, tell me what the book is about.

The book is a history of the serious study of time travel that began with a 1988 paper by a group of theoretical physicists at the California Institute of Technology. The authors of that paper (Mike Morris, Kip Thorne and Ulvi Yurtsever) concluded that pastward time travel might well be possible in the universe we know. Their work inspired a serious and sustained study of the question and engaged more than thirty physicists working at universities and institutes around the world.


Did you write about anything from your own experience?

I talk briefly about when I was in Jr. High School and I read H.G. Wells’ The Time Machine. I was intrigued by the conversation in the beginning when the character known as The Time Traveler and his friend discuss the theory of the 4th dimension. I was disappointed that they’d got the theory, and later the machine, but the how is glossed over. Of course, it’s glossed over because Wells didn’t have a how. When I found that physicists were exploring the “how”, that was exciting. And it answers the question left unanswered by Wells.


Ideas about time travel are viewed by some scientists as far-fetched or not worth investigating. I've also heard that some scientists believe that talking to the general public about theories for time travel are almost misleading because any actual experiments in time travel are very, very far off. What do you think?

The physicists who have done this work understand that it is unlikely to lead to any actual experiments. These are *thought* experiments, and thought experiments are valuable in that they can lead to deeper insights into the nature of our universe. Specifically, work on the possibility of pastward time travel has offered physicists a way to approach quantum gravity, the 'theory of everything.'

It is true that the general public can be misled into believing that someone is building a time machine in a university laboratory (or a garage, or a basement or an attic!); my book makes a point early on of dispelling such notions.

The public is interested in time travel, quite naturally, because its problems – the grandfather paradox, the bootstrap paradox and so forth - are 'fun' in the highest, best sense of that word. So while the book admits that no time travel is likely to be in our (near) futures, I hope it also engages in the pleasure of that thinking about it.

(The physicists are having fun, too, although a somewhat more refined sort of fun. Many physicists, even those who read science fiction, are likely to say that the real world is far more interesting than any that has been imagined by writers - and it has the added virtue of reality.)


Can you think of something really unexpected that you came across in your search?

Yes. There's an idea for something called a "clever spacecraft." Igor Novikov and a physicist named Andrei Lossev were interested in the idea that a time machine could enable us to get something from nothing. For instance, an author might go to the future, find a printed book with her name on it as author, and return with the book to the present, thereby saving herself the trouble of writing it. One question prompted by this scenario is Exactly who wrote the book? The answer is: no one. It was generated, quite literally, from nothing. Novikov and Lossev called artifacts like the book “jinn,” a word meaning a spirit that arises from nothing.

Novikov and Lossev claimed that if we presume there is a natural or pre-existing time machine somewhere in the universe (this would be a wormhole time machine of the type imagined by Kip Thorne, Mike Morris, and Ulvi Yurtsever in their 1988 paper), we might take advantage of the situation described above both to find that time machine and to use it.

First, we assemble an unmanned spacecraft and a computer that can 1) store its own design and the location of the wormhole time machine, 2) run the design and 3) give instructions for the spacecraft’s construction to an automated plant. If we do all this and simply get out of the way, so say Novikov and Lossev, immediately a very old and battered, unmanned spacecraft lands, whereupon it feeds its own design and the location of the time machine into the computer. The computer downloads this information to the plant, which then constructs a new spacecraft. The spacecraft departs Earth in the direction of the wormhole time machine. When it arrives at the time machine, it enters the "present day" mouth, emerges from the "past" mouth. The past mouth may be 100 years earlier than the “present” mouth, or 1000, or 100,000. It doesn't matter. If the spacecraft can get to Earth before it left, it departs in that direction immediately. If it needs more travel time, it returns to the “present” mouth and travels further pastward before beginning its journey homeward. By using the time machine over and over, it can buy all the travel time it needs. In any case the spacecraft that eventually returns to Earth is the “very old and battered” spacecraft we met before.

Novikov and Lossev’s idea is something of a stunner, and it may be one of the areas in this inquiry not much discussed in the other books on the serious study of time travel. Matt Visser is a physicist at Victoria University of Wellington, New Zealand. He has done quite a bit of work on time machines, and he told me that at a 1992 workshop in Aspen the idea was discussed, and the whole thing was taken kind of lightheartedly. At the same time he also said that if pastward time travel is possible, in the view of many, it has to be self-consistent. Self-consistent pastward time travel is the kind you see in a lot of Hollywood movies. To take an oft-cited example, if I travel to the past and try to kill my grandfather, something will prohibit me. It might be a slip on the wet floor, a change of mind, or a particle in the barrel of the gun; but it will be something. I can't change the past because the past has happened; I can’t kill my grandfather because I didn’t. But that in itself doesn't mean I can't travel to the past. It only means that if I travel to the past I will have always traveled to the past.



Wow. I’m kind of trying to wrap my head around that.

What questions does your book leave open or unanswered?

That would be telling, wouldn't it? Just kidding. The book leaves open the big question - that is, "Is pastward time travel possible?” It leaves the question open because, so far as most of the researchers are concerned, it *is* open, and it will remain open until we have a theory of quantum gravity.


I've also heard that there are a lot of "crazy" ideas out there about time travel physics. In a subject like time travel, how do you distinguish between a "crazy" theory and a "legitimate" one?

Well I don’t. I leave it for the physicists. What I do is look for the articles that are the most cited. The ones that are a little too crazy are the ones that are not usually cited or never cited. There were a few ideas that have been published, in fairly well-respected journals, that I was curious about. So when I interviewed a physicist I put the question to them: “What do you think about this?” And in one case, I think the physicist said to me, “It’s just wrong.”


Do you know of anyone else who has made a collection of these ideas?

Not on this subject. There are other books on science that have done things like this, and almost all of those I think were written by physicists who had done work in it.


What inspired you to write a book like this? And how did you get the idea to go about it in this way?

I think that everyone is interested in time travel. That's why it's so widely treated in fiction and film.

I got the idea for the book when I learned that physicists were studying it seriously, and when I looked a little harder, I could see the shape of a story of their investigation - in fact, I could see a whole book as what in the publishing world is often called a 'scientific detective story.'


You don't have a scientific background: what challenges did you face writing the book? What advantages did it give you?

The challenges were, simply, an initial unfamiliarity with what journals count as important, with some specialized vocabulary, and so forth. I'm not sure my non-scientist status gave me any advantage at all, except that I could better anticipate places where my readers would be confused and need help.


After talking to so many of them, do you think physicists are weird?

Ha! I'm not sure I have enough of a data set to draw that conclusion. Seriously, the several I talked with at length seemed no weirder than academics in any field. But I will say that I now know that their chosen subjects – especially astrophysics and cosmology - can bring out weirdness in others. Since the book's publication, I've had my share of emails from well-meaning people who want to share their theories of ... well, everything.





David Toomey is a professor of English at the University of Massachusetts, Amherst where he teaches writing and technical writing courses. He holds a Ph.D. in English Literature from the University of Virginia (1998). He is the author of Stormchasers: the Hurricane Hunters and their Flight into Hurricane Janet; co-author of Amelia Earhart's Daughters: the Wild and Glorious Story of American Women Aviators from World War II to the Dawn of the Space Age; and second author of Scientific and Technical communication in Theory, Practice and Policy.

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