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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We give a well-motivated explanation for the origin of dark energy, claimingthat it arises from a small residual negative scalar-curvature present even inempty spacetime. The vacuum has this residual curvature because spacetime isfundamentally discrete and there are more ways for a discrete geometry to havenegative curvature than positive. We explicitly compute this effect in thewell-known {\em dynamical triangulations} (DT) model for quantum gravity andthe predicted cosmological constant $\Lambda$ agrees with observation.  We begin by almost completely characterizing the DT-model's vacuum energiesin dimension three. Remarkably, the energy gap between states comes inincrements of [\Delta\mathcal{A} =\frac{\ell}{8\mathcal{V}}] in natural units,where $\ell$ is the "Planck length" in the model and $\mathcal{V}$ is thevolume of the universe. Then, using only vacua in the $N$ energy levels nearestzero, where $N$ is the universe's radius in units of $\ell$, we apply our modelto the current co-moving spatial volume to get $|\Lambda| \approx 10^{-123}$.  This result comes with a rigorous proof and does not depend on anyholographic principle or carefully tuned parameters. Our only unknown is therelative entropy of the low-energy states, which sets the sign of $\Lambda$.Numerical evidence strongly suggests that spacetime entropy in the DT-model isa decreasing function of scalar-curvature, so the model also predicts thecorrect sign for $\Lambda$.

A Reasonable Ab Initio Cosmological Constant Without Holography