10.17863/CAM.11517
Papallo, Giuseppe
0000-0002-3990-6761
Reall, Harvey
0000-0003-1363-6369
Graviton time delay and a speed limit for small black holes in Einstein-Gauss-Bonnet theory
Apollo - University of Cambridge Repository (staging)
2015
Apollo - University of Cambridge Repository (staging)
Apollo - University of Cambridge Repository (staging)
2015-11-17
Article
1126-6708
1029-8479
Camanho, Edelstein, Maldacena and Zhiboedov have shown that gravitons can experience a negative Shapiro time delay, i.e. a time advance, in Einstein-Gauss-Bonnet theory. They studied gravitons propagating in singular “shock-wave” geometries. We study this effect for gravitons propagating in smooth black hole spacetimes. For a small enough black hole, we find that gravitons of appropriate polarisation, and small impact parameter, can experience time advance. Such gravitons can also exhibit a deflection angle less than π, characteristic of a repulsive short-distance gravitational interaction. We discuss problems with the suggestion that the time advance can be used to build a “time machine”. In particular, we argue that a small black hole cannot be boosted to a speed arbitrarily close to the speed of light, as would be required in such a construction.
This work was supported by ERC grant No. ERC-2011-StG 279363-HiDGR and by an STFC studentship
This is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/JHEP11(2015)109