Course Spotlight: Philosophy & Time Travel

This is the inaugural post in a Course Spotlight series. In this post, Lucas Dunlap presents Philosophy & Time Travel.


The course is called “Philosophy & Time Travel”, and focuses on the philosophy of physics issues related to time travel (the various ways kinds of time travel are consistent with our best physical theories) and the metaphysical issues (metaphysics of time, personal identity, and the logical issues with time travel like the grandfather paradox). The course began its life as a 6-week online summer course, which was offered three times, but it has since been expanded into a full 15-week online course, and it is currently being run for the third time in that format.

So far, the course has only been offered at the University of Maryland as a 300-level (junior level) course. When it was offered as a summer course, I would get a blend of students with various backgrounds (including a large proportion of STEM majors). During the regular semester runs of the course, it has tended to be more humanities students (with a significant number of philosophy majors). The class size has varied from as few as 8 (during a summer term) to as many as 61, when I ran two sections during a regular semester.

The basic idea is to use the question about the possibility of time travel to get students thinking about what exactly “physical possibility” means. The main tension is between time travel to the future and time travel to the past. Time travel to the future is “possible” in the sense that all motion with respect to some other frame of reference physically necessitates time dilation (according to Einstein’s special theory of relativity), and therefore (minuscule) amounts of future-directed time travel. Time travel to the past, however, is possible in a very different sense—it is consistent with our current best theories of physics, but we don’t really have any reason to believe that the necessary kinds of structures that we would need to exploit to get to the past actually exist in our universe. In thinking through these issues, I try to guide the students to a better understanding of exactly what we are licensed to conclude about the structure of the universe based on our best current physics.


The course readings are primarily from two books:

 But we also read selections from John Norton’s excellent online book

and some classic papers in the area, like


This is an online-only class, which has led to some challenges. When I first expanded it to a full-semester course, I recorded video lectures, which was very time consuming. But that has freed me up in subsequent semesters to focus on other aspects of the implementation, since I use those same videos each time. Getting discussion and group work (two important components of the assessment) to work in an online-only environment can be difficult, but I’m reasonably happy with the model I’ve been using recently. Another important component of the class is that the students are assigned science fiction movies, TV show episodes, and short stories on “SciFi Fridays”. Figuring out how to make that streaming content available to them was a challenge, but I discovered that the UMD Library Media Services can install a module on our LMS (Canvas) where the videos can be uploaded directly from the library. That solved the problem for many of the titles I assign.

Lucas Dunlap

I’m currently a post-doc at the Rotman Institute of Philosophy at the University of Western Ontario. My research is in philosophy of physics, philosophy of science, and metaphysics. My current focus is on whether the information-theoretic approach to quantum theory can offer novel explanatory or interpretational resources that can help solve the puzzles associated with quantum mechanics.


Do you run an interesting philosophy class that you would like to share with your fellow philosophy teachers? Perhaps you have a non-standard topic for a class or unusual reading material. Perhaps you make novel use of class time or use unconventional assignments. This series will feature a range of classes from unique courses to twists on old standbys. We need philosophy instructors willing to share their course design. Those interested in participating should email

2 thoughts on “Course Spotlight: Philosophy & Time Travel

Comments are closed.