If someone told you, “Hey man, I took a trip in a time machine and pet a dinosaur,” you’d probably think he or she should take a trip to the psychiatrist. Philosophers, though, are more apt to take this idea seriously.

NC State philosophy professor John Carroll has explored this subject alongside students since 2000 in his metaphysics course and honors time travel seminar, which began in the spring of 2002.

Together, they wrote A Time Travel Dialogue, a fictitious (though highly realistic) account of a physicist, a graduate assistant and a philosopher-turned computer scientist who debate whether their anomalous lab experiment proves the existence of time travel.

Carroll modeled the book after philosopher John Perry’s work A Dialogue on Personal Identity and Immortality, in which a conversation takes place between a dying philosopher (Gretchen Weirob), his chaplain and friend (Sam Miller) and Weirob’s former philosophy student (Dave Cohen) about the possibility of an afterlife among other musings.

“It was great, and I remember reading it as a student and, for a while, I really didn’t know whether it was real or not,” Carroll said. “I thought this might really have been a discussion, but in that one, in the end, it’s so wild. They start talking about brain transplants, and I said, ‘Oh, OK, this isn’t real …’”

When the University Honors Program came along and started looking for seminars, Carroll had the perfect idea for a time travel course in order to continue the book he had started with his metaphysics students.

“It just seemed like something fun to do with the students,” Carroll said. “I didn’t know it was going to amount to what it did amount to, but it just kept getting better and more fun.”

In Carroll’s book, the dialogue takes place during the course of five days at the Jefferson National Laboratory, with each day representing a new philosophical theme.

“There have been several proofs that time travel to the past is consistent with the general theory of relativity,” Carroll said.

One example of a proof involves wormholes, a “shortcut” from one point in space-time to another point in space-time that lies outside of our conception of normal space and time, according to Carroll.

“Now no one is sure that there are any wormholes — this is a theoretical posit — it’s just that the general theory of relativity allows them, but the physicists also know that the general theory of relativity is not the whole story,” Carroll said. “It’s an excellent theory of gravity especially on a large scale, you know the motion of planets and the universe as a whole, but it doesn’t mesh well with the theory of quantum mechanics, which is about the little tiny things and works very well at that level …”

Carroll said he wanted this scientific viewpoint to be clear because it shows that scientists are considering time travel just as much as philosophers are.

“One of the questions philosophers ask, though, is not really about whether time travel is consistent with the best science or the laws of nature of our universe,” Carroll said. “We’re also interested in the question, ‘Does it even make sense?’ It might be ruled out by logic instead of by science, so a lot of A Time Travel Dialogue is addressing that question.” 

To answer these philosophical questions, Carroll assigned groups of students to work on topics, such as paradoxes and multidimensional time, on a rotational basis. Carroll then took the best pieces of their work — a process that took about 14 years — and tied it all together for publishing last summer through Open Book Publishers. 

“This publisher is the British equivalent of a non-profit organization, and they’re completely dedicated to open access publishing, where they make versions available free to be read online,” Carroll said. “That’s really great because that’s what we always wanted, is wide readership…so this has just been a really great opportunity for us.” 

The publisher also provides low-cost eBooks and printed copies for purchase, according to Carroll.

Nathan Sasser, a 2002 graduate of philosophy and English, took Carroll’s metaphysics course in 2000 and witnessed the birth of the project.

“The book really embodies Dr. Carroll’s philosophical rigor and also his greatness as a teacher by bringing his students along to a high level and taking them seriously as philosophers and collaborators,” Sasser said.

The course also engaged students in a creative way by asking them to draw examples from popular time travel movies, such as Back to the Future, according to Sasser. 

“I was really clueless and probably didn’t have a faint idea of what metaphysics was and not a much better idea of philosophy, but Dr. Carroll’s class in that way in particular was really informative for me,” Sasser said. “He really taught me to think. Dr. Carroll is an excellent philosopher, and I’ve learned probably as much about doing philosophy from him than from anybody else.”

For most of the course, students look at philosophical arguments against time travel, though Carroll said most of those arguments fail.

Still, Sasser said the theory of time travel remains unconvincing to him.

To purchase A Time Travel Dialogue or read it free online, visitwww.openbookpublsihers.com. For more information about the philosophy of time travel, check out http://www.timetravelphilosophy.net/, a site designed by Carroll and his students.