1. The analogous construction using a space-like geodesic and Lorentz boost is sometimes referred to as a tachyon, but it is equally appropriate to interpret it as the singularity inside a black hole, at least in spacetimes where such black holes exist
2. Here the radial coordinate q is defined to that the circumference of a circle q = const. is 2πq. These coordinates are related to another common form of the AdS metric, ds 2 = − cosh2 r dt 2 + dr 2 + sinh2 r dΩ2 by the substitution q = sinh r
3. See S Holst, Gen. Relativ. Gravit. 28, 387 (1996), where these coordinates are called ‘Poincaré coordinates’
4. Sören Holst, Horizons and time machines, Thesis in Theoretical Physics, Chapter 4, Department of Physics, Stockholm, 2000, ISBN 91-7265-054-0
5. Bañados, Teitelboim and Zanelli, Phys. Rev. Lett. 69, 1849 (1992) Bañados, Henneaux, Teitelboim and Zanelli, Phys. Rev. D48, 1506 (1993)