Falsifiable anthropic model from the string landscape
Abstract
We combine the axiverse with a negative cosmological constant Λ, both originating from the string landscape, and apply an observation-time-weighted anthropic argument. Adopting a uniform prior on Λ and a typical string-motivated axion decay constant comparable to the reduced Planck scale, this framework predicts a ∼ 40% probability of observing 0.1 < Ωm < 0.9, thereby naturally resolving the long-standing fine-tuning and coincidence problems of dark energy. Unlike many scalar-field dark energy models, the anthropic Lambda-axion universe (ALAverse) statistically disfavors slow-roll dynamics, as slow-roll requires fine-tuning of the initial field displacement. Moreover, the negative cosmological constant renders fast-roll scenarios anthropically unfavorable, since they typically yield only a very brief observational window with positive dark energy density. Having ruled out both extremes, the ALAverse characteristically predicts a moderate-roll dynamics. We derive a two-parameter parametrization in terms of δΩ and |εs| that covers ALAverse solutions as well as a broad class of canonical and phantom field models. Current observational data yield δΩ= −0.0498 ± 0.0186, corresponding to a 2.7σ rejection of ΛCDM (δΩ= 0) and single-field thawing phantom models (δΩ> 0). The data also show a mild preference for the ALAverse over slow-roll quintessence, a trend that can be conclusively tested with future high-precision measurements of the Hubble diagram.
Versions
Related
- On the foundations of anthropic reasoning: Implications for life across the universe
- The decay rate of metastable cosmic strings beyond the thin-string approximation
- Axionic Quintessence in Heterotic String Theory
- Diamonds in the sky: the shape of gravitational waves from cosmic string cusps
- Evolution of Cosmic String Loops under Gravitational Backreaction
BibTeX
@misc{huang2026falsifiable,
title = {{Falsifiable anthropic model from the string landscape}},
author = {Zhiqi Huang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.24100},
eprint = {2607.24100},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.24100},
}
RIS
TY - UNPB
TI - Falsifiable anthropic model from the string landscape
AU - Zhiqi Huang
PY - 2026
DA - 2026/09/25
PB - arXiv
DO - 10.48550/arxiv.2607.24100
UR - https://arxiv.org/abs/2607.24100
AB - We combine the axiverse with a negative cosmological constant Λ, both originating from the string landscape, and apply an observation-time-weighted anthropic argument. Adopting a uniform prior on Λ and a typical string-motivated axion decay constant comparable to the reduced Planck scale, this framework predicts a ∼ 40% probability of observing 0.1 < Ω_m < 0.9, thereby naturally resolving the long-standing fine-tuning and coincidence problems of dark energy. Unlike many scalar-field dark energy models, the anthropic Lambda-axion universe (ALAverse) statistically disfavors slow-roll dynamics, as slow-roll requires fine-tuning of the initial field displacement. Moreover, the negative cosmological constant renders fast-roll scenarios anthropically unfavorable, since they typically yield only a very brief observational window with positive dark energy density. Having ruled out both extremes, the ALAverse characteristically predicts a moderate-roll dynamics. We derive a two-parameter parametrization in terms of δ_Ω and |ε_s| that covers ALAverse solutions as well as a broad class of canonical and phantom field models. Current observational data yield δ_Ω= −0.0498 ± 0.0186, corresponding to a 2.7σ rejection of ΛCDM (δ_Ω= 0) and single-field thawing phantom models (δ_Ω> 0). The data also show a mild preference for the ALAverse over slow-roll quintessence, a trend that can be conclusively tested with future high-precision measurements of the Hubble diagram.
ER -