English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Investigating the dynamics of gravitational systems, especially in the regimeof quantum gravity, poses a problem of measuring time during the evolution. Oneof the approaches to this issue is using one of the internal degrees of freedomas a time variable. The objective of our research was to check whether a scalarfield or any other dynamical quantity being a part of a coupled multi-componentmatter-geometry system can be treated as a `clock' during its evolution. Weinvestigated a collapse of a self-gravitating electrically charged scalar fieldin the Einstein and Brans-Dicke theories using the 2+2 formalism. Our findingsconcentrated on the spacetime region of high curvature existing in the vicinityof the emerging singularity, which is essential for the quantum gravityapplications. We investigated several values of the Brans-Dicke couplingconstant and the coupling between the Brans-Dicke and the electrically chargedscalar fields. It turned out that both evolving scalar fields and a functionwhich measures the amount of electric charge within a sphere of a given radiuscan be used to quantify time nearby the singularity in the dynamical spacetimepart, in which the apparent horizon surrounding the singularity is spacelike.Using them in this respect in the asymptotic spacetime region is possible onlywhen both fields are present in the system and, moreover, they are coupled toeach other. The only nonzero component of the Maxwell field four-potentialcannot be used to quantify time during the considered process in theneighborhood of the whole central singularity. None of the investigateddynamical quantities is a good candidate for measuring time nearby the Cauchyhorizon, which is also singular due to the mass inflation phenomenon.

Scalar field as an intrinsic time measure in coupled dynamical matter-geometry systems. II. Electrically charged gravitational collapse