A Time Travel Dialogue
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Colophon: Half-Title, Title, Copyright


Any question of philosophy, […] which is so obscure and uncertain, that human reason can reach no fixed determination with regard to it—if it should be treated at all—seems to lead us naturally into the style of dialogue and conversation.

—Pamphilus to Hermippus, from David Hume’s,
Dialogues Concerning Natural Religion

Theoretical physicists take seriously the idea of time travel; some, including J. Richard Gott and Paul Davies, have published monographs, accessible to the layperson, describing the extraordinary work that has been done. Experimental physicists have on occasion even come face to face with the possibility that time travel to the past is real. This book is built on conversations set in 2010 at the Jefferson National Laboratory where unanticipated data led distinguished physicist Dr. Carlene Rufus to investigate a hypothesis of backwards time travel.

The conversations are of philosophical interest. In addition to Dr. Rufus, the other participants in the conversations are Tad Logan, a graduate student research assistant, and William Esquire, a philosophically inclined computer scientist. Their careful, and often humorous, thoughts wander from the experimental data, to science fiction cinema, and even to thoroughly abstract and metaphysical paradoxes about the permanence of the past, the privilege of the present, the nature of causation, and what one can or cannot do. The question of the possibility of time travel is a truly abstract and multifaceted one. So, it should be no surprise that philosophy, with its diverse subject matter, speculative powers, and its reverence for logic, so grounded as it is in the tension between the familiar and the unfamiliar, should here rear its head. Indeed, it is Willie’s philosophical input that shapes both the planning and analysis of Dr. Rufus’s experiments.

At the beginning of Hume’s Dialogues Concerning Natural Religion, Pamphilus reports to Hermippus of having had the occasion to observe the insightful conversations of Cleanthes, Demea, and Philo. It is with similar good fortune that the conversations of Dr. Rufus, Tad, and Willie can now be made public. Thanks to detailed notes and well organized data, one week of our researchers’ scientific work and philosophical discussions is readily presentable, with tolerable accuracy, in the dialogue format long upheld by Plato, Berkeley, Hume and so many others. Enjoy!