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

We explore how the stability of metric perturbations in higher derivativetheories of gravity depends on the energy scale of initial seeds of suchperturbations and on a typical energy scale of the gravitational vacuumbackground. It is shown that, at least in the cases of specific cosmologicalbackgrounds, that the unphysical massive ghost which is present in the spectrumof such theories is not growing up as a physical excitation and remains in thevacuum state, until the initial frequency of the perturbation is close to thePlanck order of magnitude. In this situation the existing versions ofrenormalizable and superrenormalizable theories can be seen as verysatisfactory effective theories of Quantum Gravity below the Planck scale.

Do we have unitary and (super)renormalizable Quantum Gravity below Planck scale?