arXiv subjects

V. Memari

Publications and source records attributed to V. Memari.

3 recordsLinked to original sources

arXiv2024

Extremal Black Holes in Cosmology from Colliding Light Beams

From the duality between the interaction region of colliding waves and black holes (BHs) it is known that certain BH solutions can be obtained from colliding gravity coupled electromagnetic (em) waves. In the limit of vanishing gravity waves, we show that extremal Reissner-Nordstrom (RN) BH can form. We show also that direct collision of pure em waves creates the near horizon geometry (NHG) of the same BH, supporting our point. Due to the quantum restrictions such BHs can have horizon radii in the range $R>10^{8}m$. If such BHs from pure light do exist this may open a new frontier in our understanding of cosmological BHs at large. The generation of impulsive gravitational waves in the process may be instrumental in the detection of a BH created from pure light.

gr-qc↗

arXiv2024

Charged particle geodesics and closed timelike curves in an electromagnetic universe

The spinning electromagnetic universe, known also as the Rotating Bertotti-Robinson(RBR) spacetime is considered as a model to represent our cosmos. The model derives from different physical considerations, such as colliding waves, throat region, and near horizon geometry of the Kerr-Newman black hole. Our interest is whether such a singularity-free spinning cosmology gives rise to a natural direction of flow, a 'chirality' for charged particles. Homochiral structures are known to be crucial for biology to start. Our concern here is cosmology rather than biology, but as in biology, the stable structures in cosmology may also rely on homochiral elements. We show the occurrence of closed timelike curves a 'la' G{\"o}del. Such curves, however, seem possible only at localized cell structures, not at large scales, but according to our prescription of near horizon geometry, they arise in the vicinity of any charged, spinning black hole.

gr-qc↗

arXiv2023

Generating spacetimes from colliding sources

Certain well-known spacetimes of general relativity (GR) are generated from the collision of suitable null-sources coupled with gravitational waves. This is a classical process underlying the full nonlinearity of GR that may be considered alternative to the quantum creativity at a large scale. Schwarzschild, de Sitter, anti de Sitter and the $\gamma $-metrics are given as examples.

gr-qc↗