The title of the paper? "Traversable Achronal Retrograde Domains In Spacetime." Yes, it is real science, and yes, the paper's figures are excellent.

*Top image: Joe Roberts via **Deviant Art*

Co-authored by physicists Ben Tippett* and David Tsang (non-fictional physicists at the fictional Gallifrey Polytechnic Institute and Gallifrey Institute of Technology, respectively), the paper – which you can access free of charge over on arXiv – presents a spacetime geometry that would make retrograde time travel possible. Such a spacetime geometry, write the researchers, would emulate "what a layperson would describe as a *time machine*":

In our geometry, a bubble of curvature travels along a closed trajectory. The inside of the bubble is Rindler spacetime, and the exterior is Minkowski spacetime. Accelerating observers inside of the bubble travel along closed timelike curves. The walls of the bubble are generated with matter which violates the classical energy conditions. We refer to such a bubble as a Traversable Achronal Retrograde Domain In Spacetime.

Sound confusing? Don't worry. Tippett and Tsang have also authored "The Blue Box White Paper," which they've "written for laypeople who are interested in time travel, but have no technical knowledge of Einstein's Theory of General Relativity." The white paper introduces key ideas from relativity and describes the Traversable Achronal Retrograde Domain in Spacetime (TARDIS) time machine outlined in the first paper. Naturally, Tippett and Tsang accomplish this with an ample helping of *DW*-themed figures. For instance:

Read "Traversable Achronal Retrograde Domains In Spacetime" here and the white paper here. Even more Whovian goodness over on Tippett's tumblr.

*As Platypus Man points out in the comments, Tippett is the same physicist responsible for The Grand Unified Theory of Superman's Powers.

ht Toby!

## DISCUSSION

So, from a non-linear, non-subjective viewpoint, it really IS more like a big ball of wibbly-wobbly timey-wimey stuff?