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

On the way towards quantum gravity and the unification of interaction,several ideas have been rejected and avenues avoided because they wereperceived as physically unviable. But in the literature there are works inwhich it was found the contrary, namely that those rejected topics make senseafter all. Such topics, reviewed in this article, are negative energiesoccurring in higher derivative theories and ultrahyperbolic spaces, orderingambiguity of operators in curved spaces, the vast landscape of possiblecompactifications of extra dimensions in string theory, and quantization of a3-brane in braneworld scenarios.

On Negative Energies, Strings, Branes, and Braneworlds: A Review of Novel Approaches