“Traversable Achronal Retrograde Domains In Spacetime”, written by physicists Ben Tippett and David Tsang (2013), suggests the TARDIS is scientifically possible.
“In order for a TARDIS to function, it needs to exist in a universe where the construction of closed timelike curves (CTCs) is possible. A closed timelike curve is defined by instances where the time dimension curves back on itself creating a closed loop. Hypothetically speaking, you could get in this loop (or build one around yourself) and travel forward and backwards in time at will.”
I can’t even pretend to understand that. Hoping the summmary straight from the authors (Cornell University Library, General Relativity and Quantum Cosmology) is better. Take it away, Benjamin K. Tippett, David Tsang (Cornell University Library):
“The purpose of this paper is to propose such a spacetime geometry which emulates 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.”
Hmmm…maybe the brighter Whovians can make sense of this.