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

A semi-classical analysis of vacuum energy in the expanding spacetimesuggests that the cosmological term decays with time, with a concomitant matterproduction. For early times we find, in Planck units, $\Lambda \approx H^4$,where H is the Hubble parameter. The corresponding cosmological solution has noinitial singularity, existing since an infinite past. During an infinitely longperiod we have a quasi-de Sitter, inflationary universe, with $H \approx 1$.However, at a given time, the expansion undertakes a phase transition, with Hand $\Lambda$ decreasing to nearly zero in a few Planck times, producing a hugeamount of radiation. On the other hand, the late-time scenario is similar tothe standard model, with the radiation phase followed by a dust era, whichtends asymptotically to a de Sitter universe, with vacuum dominating again.Comment: This essay received an "honorable mention" in the 2006 Essay  Competition of the Gravity Research Foundatio

FROM DE SITTER TO DE SITTER: A NON-SINGULAR INFLATIONARY UNIVERSE DRIVEN BY VACUUM