- We discuss the possibility to build and operate a time machine1, a device that produces closed timelike curves (CTCs).
- We specify the spacetime structure needed to implement a time machine2 and assess attempted no-go results against time machines3 in classical general relativity, semi-classical quantum gravity, quantum field theory on curved spacetime, and in Euclidean quantum gravity.
- Such no-go theorems for time machines4 would show that, under physically reasonable conditions, CTCs cannot develop in spacetimes initially free of these pathologies.
- Our review indicates that an investigation of the prospects of achieving no-go results has not been entirely successful in establishing such generality.
- At the same time, the pursuit of chronology protection results has proved to be a fruitful way to probe the foundations of classical GTR and the interface between general relativity and quantum field theory.
- Review of time travel5
- Operating a time machine6
- No-go results for time machines7 in classical GTR
- No-go results using semi-classical quantum gravity
- No-go results from quantum field theory on curved spacetime
- No-go results from Euclidean quantum gravity
Text Colour Conventions (see disclaimer)
- Blue: Text by me; © Theo Todman, 2019
- Mauve: Text by correspondent(s) or other author(s); © the author(s)