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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2508.04395 |
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| _version_ | 1866913977648283648 |
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| author | Perivolaropoulos, Leandros Ruchika |
| author_facet | Perivolaropoulos, Leandros Ruchika |
| contents | We critically examine recent claims challenging the viability of the G-step model (GSM) as a solution to the Hubble tension. The GSM proposes a $\sim$4 % increase in the effective gravitational constant $G_{\text{eff}}$ beyond $z \approx 0.01$ to reconcile local and early-universe measurements of the Hubble constant. Through detailed quantitative analysis, we demonstrate that many proposed constraints on the model require careful reconsideration. Key findings include: (1) Modern stellar modeling indicates a weaker $L \propto G^4$ scaling rather than the traditional $G^7$, significantly reducing tension with stellar evolution constraints; (2) The fluid-like behavior of Earth 150 Myr ago preserves the day/year ratio across any $G$ transition; (3) Paleoclimate data showing $\sim$20°C cooling over relevant timescales appears consistent with, rather than challenging, the GSM; (4) Distance indicator comparisons allow for $ΔG/G$ variations up to $\sim$20 % at 2$σ$ when systematic uncertainties are properly included; (5) The discrete nature of the proposed $G$ transition preserves relative stellar population ages used in cosmic chronometry. When accounting for proper uncertainty levels in both observations and theoretical modeling, we find the GSM remains a viable candidate for resolving the Hubble tension. We identify specific observational tests with next-generation facilities that could definitively confirm or rule out the model. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_04395 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Hubble Tension and the G-step Model: Re-examination of Recent Constraints on Modified Local Physics Perivolaropoulos, Leandros Ruchika Cosmology and Nongalactic Astrophysics We critically examine recent claims challenging the viability of the G-step model (GSM) as a solution to the Hubble tension. The GSM proposes a $\sim$4 % increase in the effective gravitational constant $G_{\text{eff}}$ beyond $z \approx 0.01$ to reconcile local and early-universe measurements of the Hubble constant. Through detailed quantitative analysis, we demonstrate that many proposed constraints on the model require careful reconsideration. Key findings include: (1) Modern stellar modeling indicates a weaker $L \propto G^4$ scaling rather than the traditional $G^7$, significantly reducing tension with stellar evolution constraints; (2) The fluid-like behavior of Earth 150 Myr ago preserves the day/year ratio across any $G$ transition; (3) Paleoclimate data showing $\sim$20°C cooling over relevant timescales appears consistent with, rather than challenging, the GSM; (4) Distance indicator comparisons allow for $ΔG/G$ variations up to $\sim$20 % at 2$σ$ when systematic uncertainties are properly included; (5) The discrete nature of the proposed $G$ transition preserves relative stellar population ages used in cosmic chronometry. When accounting for proper uncertainty levels in both observations and theoretical modeling, we find the GSM remains a viable candidate for resolving the Hubble tension. We identify specific observational tests with next-generation facilities that could definitively confirm or rule out the model. |
| title | Hubble Tension and the G-step Model: Re-examination of Recent Constraints on Modified Local Physics |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2508.04395 |