An examination of how time travel machines could potentially occur in the method seen in Doctor Who
Taylor Fry, Contributor Ω
Fans of the science fiction TV series Doctor Who were treated to a special guest lecture on the physics of time travel within the show on March 6. Benjamin Tippett, a sessional instructor from UBC Okanagan, spoke to students and faculty with a lecture filled with allusions to the popular show.
The lecture was based on his research in retrograde time travel as a theoretical framework for the type of time travel shown in Doctor Who.
Tippett’s lectured about the science of how time machines could potentially occur. His time travel proposal is called the T.A.R.D.I.S. (Traversable Acausal Retrograde Domain in Spacetime), in allusion to Doctor Who’s time traveling machine, and it deals with travelling in a closed loop through time and circumventing the physical limitations of that particular method of time travel.
Tippett, dressed similar to the show’s titular character, opened the lecture by explaining that in Einstein’s Theory of Relativity, the three dimensions of space are not separate from the dimension of time. This results in four-dimensional surfaces on which all matter exists.
Einstein’s theory also states that nothing in the universe can travel fast than the speed of light and the diagram of a light cone, i.e. light originating from a single point, can be used to show where anything with mass can travel as the edges of the cone expand at the speed of light and act as a boundary. This is the primary argument against the idea of time travel, as looping back to the focal point would require moving faster than the speed of light.
According to Tippett, the curvature of spacetime can cause light cones to “tip,” altering the space in which objects can travel. The angular momentum of spacetime allows for an object to spin, which cause light cones to tip in the direction of the objects trajectory. This is the basis behind the Tipler Cylinder, which is the idea that an infinitely long spinning cylinder could cause light cones to tip all the way over forming a loop and allowing for backwards time travel.
Tippett’s T.A.R.D.I.S. is expressing the idea of time travel without the need for the Tipler cylinder or other complications. His T.A.R.D.I.S. is self-described as a hollow bubble that allows subjects inside to travel along closed circular paths in time and space.
Tippett explained that his T.A.R.D.I.S. would require a type of matter that moves faster than light and gravitationally repels it, which violates the classical energy conditions in the universe.
When asked why he has done so much research into a science fiction-based idea, Tippett said it’s because he enjoys the work and he hopes to widen the appeal of less popular areas of physics. The idea behind this paper came from a desire to build a mathematical time machine that was similar to the ones seen in popular fiction.
Tippett has been the author of many papers on fiction science, and is the mind behind the Titanium Physicist podcast, which aims to explain ideas and various areas of physics to non-physicists.