Improving Physical Cosmology: An Empiricist's Assessment

Peebles, Patrick

doi:10.48550/arxiv.2106.02672

Cited by 15 publications

(17 citation statements)

References 109 publications

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“…Overall, our findings are fully consistent with the fundamental assumption of null variance of fundamental physical constants, therefore helping to underpin the foundations of the standard cosmological model [111].…”

Section: Discussionsupporting

confidence: 80%

A model-independent test of speed of light variability with cosmological observations

Rodrigues,

Bengaly

2021

Preprint

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A powerful test of fundamental physics consists on probing the variability of fundamental constants in Nature. Although they have been measured on Earth laboratories and in our Solar neighbourhood with extremely high precision, it is crucial to carry out these tests at the distant Universe, as any significant variation of these quantities would immediately hint at new physics. We perform a cosmological measurement of the speed of light using the latest Type Ia Supernova and cosmic chronometer observations at the redshift range 0 < z < 2.Our method relies on the numerical reconstruction of the data in order to circumvent a priori assumptions of the underlying cosmology. We confirm the constancy of the speed of light at such redshift range, reporting a ∼ 5% precision measurement of c = (3.22 ± 0.16) km s −1 in z 1.60 at a 1σ confidence level *

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Section: Discussionsupporting

confidence: 80%

A model-independent test of speed of light variability with cosmological observations

Rodrigues,

Bengaly

2021

Preprint

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“…However, even though it is successful at different scales and explains very diverse data sets, there exist some specific observational discrepancies and even theoretical shortcomings that open up the possibility for extensions of GR. As few examples, we mention the recent observation that the Universe is expanding faster than expected [1], the cosmic curvature problem [2], small-scale problems [3] and the statistically significant tension between the predictions for the Hubble constant value by early-time probes assuming the ΛCDM model and the corresponding determinations of H 0 by a number of late-time model-independent fits from local measurements; this incongruity is the so called Hubble tension [4,5]. For an interesting recent review on the ΛCDM model problems, we refer the reader to Ref.…”

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confidence: 99%

Observational constraints on varying fundamental constants in a minimal CPC model

Cuzinatto¹,

Holanda²,

Pereira³

2022

Preprint

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A minimal model based on the Covariant Physical Couplings (CPC) framework for gravity is proposed. The CPC framework is based on the assumptions of a metric-compatible four-dimensional Riemannian manifold where a covariantly conserved stress-energy tensor acts as source of the field equations which are formally the same as Einstein field equations, but where the couplings {G, c, Λ} are allowed to vary simultaneously. The minimal CPC model takes Λ as a genuine constant while c and G vary in an entangled way that is consistent with Bianchi identity and the aforementioned assumptions. The model is constrained using the most recent galaxy cluster gas mass fraction observational data. Our result indicates that the functions c(z) and G (z) = G 0 (c/c 0 ) 4 are compatible with constant couplings for the two different parameterizations of c = c(z) adopted here.

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“…While the LCDM (the Cosmological Constant Lambda + Cold Dark Matter) model has passed many observational tests (e.g. [1] for review), it is disturbing that we still don't know the nature of its two dark components, dark matter and dark energy.…”

Section: The Current Cosmological Modelmentioning

confidence: 99%

Knowing when to stop

Lahav

Silk

2021

Nat Astron

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When do we stop an ongoing science project to make room for something new? Decision-making is a complex process, ranging from budgetary considerations and tension between ongoing projects, to progress assessment and allowance for novel science developments.We make numerous decisions in everyday life on when to conclude or stop a process. Some are easier than others. When to cross the road? How to choose a spouse? How many candidates to short list for a job? And the focus of this Comment: when do we terminate costly science projects, notably in cosmology to open windows to new research directions?

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Improving Physical Cosmology: An Empiricist's Assessment

Abstract: The world is so full of a number of things, I'm sure we should all be as happy as kings.

Cited by 15 publications

References 109 publications

A model-independent test of speed of light variability with cosmological observations

A model-independent test of speed of light variability with cosmological observations

Observational constraints on varying fundamental constants in a minimal CPC model

Knowing when to stop

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