PT Journal
AU Olmo, GJ
   Rubiera-Garcia, D
TI The quantum, the geon and the crystal
SO International Journal of Modern Physics D
JI Int. J. Mod. Phys. D
PY 2015
BP 1542013
EP 15pp
VL 24
IS 9
DI 10.1142/S0218271815420134
LA English
DE Effective geometries; crystalline structures; modified gravity; metric-affine approach; geons
AB Effective geometries arising from a hypothetical discrete structure of spacetime can play an important role in the understanding of the gravitational physics beyond General Relativity (GR). To discuss this question, we make use of lessons from crystalline systems within solid state physics, where the presence of defects in the discrete microstructure of the crystal determine the kind of effective geometry needed to properly describe the system in the macroscopic continuum limit. In this work, we study metric-affine theories with nonmetricity and torsion, which are the gravitational analog of crystalline structures with point defects and dislocations. We consider a crystal-motivated gravitational action and show the presence of topologically nontrivial structures (wormholes) supported by an electromagnetic field. Their existence has important implications for the quantum foam picture and the effective gravitational geometries. We discuss how the dialogue between solid state physics systems and modified gravitational theories can provide useful insights on both sides.
ER