Constant Measurements Research Articles

Mirror dark sector solution of the Hubble tension with time-varying fine-structure constant

We explore a model introduced by Cyr-Racine, Ge, and Knox (arXiv:2107.13000(2)) that resolves the Hubble tension by invoking a ``mirror world" dark sector with energy density a fixed fraction of the ``ordinary" sector of Lambda-CDM. Although it reconciles cosmic microwave background and large-scale structure observations with local measurements of the Hubble constant, the model requires a value of the primordial Helium mass fraction that is discrepant with observations and with the predictions of Big Bang Nucleosynthesis (BBN). We consider a variant of the model with standard Helium mass fraction but with the value of the electromagnetic fine-structure constant slightly different during photon decoupling from its present value. If $\alpha$ at that epoch is lower than its current value by $\Delta \alpha \simeq -2\times 10^{-5}$, then we can achieve the same Hubble tension resolution as in Cyr-Racine, et al. but with consistent Helium abundance. As an example of such time-evolution, we consider a toy model of an ultra-light scalar field, with mass $m <4\times 10^{-29}$ eV, coupled to electromagnetism, which evolves after photon decoupling and that appears to be consistent with late-time constraints on $\alpha$ variation and the weak equivalence principle.

A new facility for the measurement of the Sieverts’-constant for PbLi with tritium

The Sieverts’ constant of tritium in eutectic lithium-lead (PbLi) is of high importance for future fusion applications, where PbLi is one option for the breeding of tritium in the breeding blanket. Currently, literature reports Sieverts’ constant measurements with a spread of more than two orders of magnitude for eutectic PbLi. Additionally, there is only little data available for measurements actually using tritium, but mostly extrapolations from hydrogen or deuterium. With the setup presented in this publication, we try to address the lack of available tritium data for the Sieverts’ constant of eutectic PbLi as well as aiming for a robust and reliable measurement of all necessary parameters, including a cleaning procedure. This is paramount for the selection of promising breeding blanket technologies.

In situ simultaneous measurement of magnetic coil constants and nonorthogonal angles using atomic magnetometers

An in situ simultaneous measurement of magnetic coil constants and nonorthogonal angles method is proposed using the atomic magnetometer. Based on the transient response of the atomic spin polarization under the different magnetic fields, we establish the corresponding measurement model of magnetic coil constants and nonorthogonal angles through the relationship between the Larmor precession frequency and the external magnetic field. By this model, we experimentally obtained the coil constants of x , y, and z axes are, respectively, 9.04 ± 0.10, 8.94 ± 0.07, and 4.34 ± 0.02 nT / V in our system. The nonorthogonal angles are 89.04 deg between x axis and y axis, 88.60 deg between y axis and z axis, and 91.15 deg between z axis and x axis. This method can be used to simultaneously measure magnetic coil constants and nonorthogonal angles without relying on external instruments, which provides a basic guarantee for the accurate calculation sensitivity of spin-exchange-relaxation-free atomic magnetometers, especially for miniaturized atomic magnetometers.

Picosecond Ultrasonics for Studying Elastic Modulus of Polycrystalline Chromium Nanofilms: Thickness Dependence and Stiffness Enhancement

Accurate measurement of elastic constants in thin films is still an important issue to understand the scale behavior of nanosized materials. In the present study, we introduced an advanced non-destructive method, picosecond ultrasonics (PU), for measuring the out-of-plane elastic modulus of thin chromium (Cr) films. The femtosecond light pulse is focused on the Cr film to excite the longitudinal acoustic phonons (LAP), which propagate along the thickness direction and repeat reflections inside the Cr film. Then, the propagation/distribution of LAP is detected by the time-delayed probe light pulse through the photoelastic effect. Therefore, we can determine the out-of-plane modulus by measuring the periodic pulse echoes or the breathing mode vibrations within the Cr film. For most Cr films, the determined modulus is smaller than the corresponding bulk value and decreases with the decreasing thickness, while for some Cr films, it closes and may exceed the bulk value. This work describes the thickness-dependent elasticity of thin Cr films and provides evidence of the stiffness enhancement in Cr films on the Si substrate. In addition, since LAP with central frequency up to 310 GHz is excited in Cr films on the SiO2 substrate, we also demonstrate the potential of Cr films as high-frequency photoacoustic transducers.

Nonlinear acoustic characterization of heterogeneous plasticity in bent aluminium samples

Knowledge of the state of plastic deformation in metallic structures is vital to prevent failure. This is why non-destructive acoustic tests based on the measurement of first order elastic constants have been developed and intensively used. However, plastic deformations, which are usually heterogeneous in space, may be invisible to these methods if the variation of the elastic constants is too small. In recent years, digital image correlation techniques, based on measurements carried out at the surface of a sample, have been successfully used in conjunction with finite element modeling to gain information about plastic deformation in the sample interior. Acoustic waves can penetrate deep into a sample and offer the possibility of probing into the bulk of a plastically deformed material. Previously, we have demonstrated that nonlinear acoustic methods are far more sensitive to changes in dislocation density than linear ones. Here, we show that the nonlinear Second Harmonic Generation method (SHG) is sensitive enough to detect different zones of von Mises stress as well as effective plastic strain in centimeter-size aluminium pieces. This is achieved by way of ultrasonic measurements on a sample that has undergone a three-point bending test. Because of the relatively low stress and small deformations, the sample undergoes plastic deformation by dislocation proliferation. Thus, we conclude that the nonlinear parameter measured by SHG is also sensitive to dislocation density. Our experimental results agree with numerical results obtained by Finite Element Method (FEM) modeling. We also support the acoustic results by X-ray Diffraction measurements (XRD). Although intrusive and less accurate, they also agree with the acoustic measurements and plastic deformations in finite element simulations.

Dependence of Cosmological Constraints on Gray Photometric Zero-point Uncertainties of Supernova Surveys

Type Ia supernova (SN) measurements of the Hubble constant, H 0; cosmic mass density, Ω M ; and dark energy equation-of-state parameter, w, rely on heterogeneous SN surveys across three decades of observation. These distinct surveys may have undiagnosed, relative photometric zero-point errors. We determine the sensitivities of the SH0ES+Pantheon+ cosmological constraints to unknown gray systematics in the photometric zero-point calibration between the 19 surveys that comprise the Pantheon+ SN compendium. Varying the surveys’ gray zero-points simultaneously with cosmological parameters, we determine that the SH0ES+Pantheon+ measurement of H 0 is robust against gray intersurvey photometric miscalibration. Specifically, uncalibrated intersurvey systematics could represent a source of uncertainty no larger than 0.39 km s−1 Mpc−1 for H 0. This modest increase in H 0 uncertainty could not account for the 7 km s−1 Mpc−1 “Hubble tension” between the SH0ES measurement of H 0 and the Planck ΛCDM-based inference of H 0. However, the SH0ES+Pantheon+ best-fit values of Ω M and w are not robust against gray zero-point error, slipping by up to 0.16 and −0.63. Because measurements of Ω M and w depend on intrasurvey cross-band calibration, the hypothetical gray miscalibration underestimates the sensitivity of these measurements to zero-point miscalibration. Because the Pantheon+ compendium contains many surveys that share low-z Hubble flow (HF) and Cepheid-paired SNe, intersurvey photometric calibration errors do not significantly impede the joint use of SH0ES and Pantheon+ to measure H 0 to 1% accuracy. However, H 0 constraints that rely on one HF survey but numerous galactic distance calibration surveys are susceptible to intersurvey photometric miscalibration.

Muon and electron (g-2) anomalies with non-holomorphic interactions in MSSM

The recent Fermilab muon g-2 result and the same for electron due to fine-structure constant measurement through {}^{133}textrm{Cs} matter-wave interferometry are probed in relation to MSSM with non-holomorphic (NH) trilinear soft SUSY breaking terms, referred to as NHSSM. Supersymmetric contributions to charged lepton (g-2)_l can be enhanced via the new trilinear terms involving a wrong Higgs coupling with left and right-handed scalars. Bino-slepton loop is used to enhance the SUSY contribution to g-2 where wino mass stays at 1.5 TeV and the left and right slepton mass parameters for the first two generations are considered to be the same. Unlike many MSSM-based analyses completed before, the model does not require a light electroweakino, or light sleptons, or unequal left and right slepton masses, or a very large higgsino mass parameter. In absence of popular UV complete models, we treat the NH terms at par with MSSM soft terms, in a model independent framework of Minimal Effective Supersymmetry. The first part of the analysis involves the study of (g-2)_mu constraint along with the limits from Higgs mass, B-physics, collider data, direct detection of dark matter (DM), while focusing on a higgsino DM which is underabundant in nature. We then impose the constraint from electron g-2 where a large Yukawa threshold correction (an outcome of NHSSM) and opposite signs of trilinear NH coefficients associated with mu and e fields are used to satisfy the dual limits of Delta {a_mu } and Delta {a_e} (where the latter comes with negative sign). Varying Yukawa threshold corrections further provide the necessary flavor-dependent enhancement of Delta {a_e}/m_e^2 compared to that of Delta {a_mu }/m_mu ^2. A larger Yukawa threshold correction through A^prime _e for y_e also takes away the direct proportionality of a_e with respect to tan beta . With a finite intercept, a_e becomes only an increasing function of tan beta . We identified the available parameter space in the two cases while also satisfying the ATLAS data from slepton pair production searches in the plane of slepton mass parameter and the mass of the lightest neutralino.

Importance of accurately measuring LDOS maps using scanning tunneling spectroscopy in materials presenting atom-dependent charge order: The case of the correlated Pb/Si(111) single atomic layer

We address here general issues and show how to properly extract the local charge order in two-dimensional systems from scanning tunneling microscopy/spectroscopy (STM/STS) measurements. When the charge order presents spatial variations at the atomic scale inside the unit cell and is energy dependent, particular care should be taken. We show that the widely used lock-in technique performed while acquiring an STM topography in a closed feedback loop cannot be used to extract this local charge order from STS $dI/dV$ differential conductance maps. In such situations, the use of the lock-in technique leads to systematically incorrect $dI/dV$ measurements, giving a false local charge order. We show that a correct method is either to perform a constant height measurement or to perform a full grid of $dI/dV(V)$ spectroscopies, using a set point for the bias voltage outside the bandwidth of the correlated material where the local density of states (LDOS) is expected to be spatially homogeneous. We take as a paradigmatic example of two-dimensional material the 1/3 single-layer Pb/Si(111) phase. As large areas of this phase cannot be grown, charge ordering in this system is not accessible to angular resolved photoemission or grazing x-ray diffraction. Two previous investigations by STM/STS supplemented by ab initio density functional theory (DFT) calculations concluded that this material undergoes a phase transition to a low-temperature $3\ifmmode\times\else\texttimes\fi{}3$ reconstruction where one Pb atom moves up, the two remaining Pb atoms shifting down. A third STM/STS study by Adler et al. [F. Adler, S. Rachel, M. Laubach, J. Maklar, A. Fleszar, J. Sch\"afer, and R. Claessen, Phys. Rev. Lett. 123, 086401 (2019)] came to the opposite conclusion, i.e., that two Pb atoms move up, while one Pb atom shifts down. We show that this latter erroneous conclusion comes from an artifact induced by the lock-in technique. In contrast, using a full grid of $dI/dV$($V$) spectroscopy measurements, our results show that the energy-dependent LDOS maps agree very well with state-of-the-art DFT calculations, confirming the one-up two-down charge ordering. We show that this structural and charge reordering inside the $3\ifmmode\times\else\texttimes\fi{}3$ unit cell is equally driven by electron-electron interactions and the coupling to the substrate.

Measurement of the hyperfine coupling constants and absolute energies of the 8p P1/22 and 8p P3/22 levels in atomic cesium

We report measurements of the hyperfine coupling constant for the $8p \ ^2P_{1/2}$ level of atomic cesium, $^{133}$Cs, with a relative uncertainty of $\sim$0.019\%. Our result is $A = 42.933 \: (8)$ MHz, in good agreement with recent theoretical results. We also examine the hyperfine structure of the $8p \ ^2P_{3/2}$ state, and derive new values for the state energies of the $8p \ ^2P_{1/2}$ and $8p \ ^2P_{3/2}$ states of cesium.

Measurement of Henry's law and liquid-phase loss rate constants of peroxypropionic nitric anhydride (PPN) in deionized water and in n-octanol

Abstract. The Henry's law solubility (HS) and liquid-phase loss rate constants (kl) of the tropospheric trace gas constituents peroxyacetic nitric anhydride (PAN; CH3C(O)O2NO2, commonly known as peroxyacetyl nitrate) and peroxypropionic nitric anhydride (PPN; C2H5C(O)O2NO2, also known as peroxypropionyl nitrate) in deionized (DI) water and of PPN in n-octanol were measured using a flow bubble apparatus at temperatures between 5.0 and 25.0 ∘C. For PAN in DI water, the observed values for HS,aq are consistent with the literature, whereas the solubility of PPN in DI water is slightly lower than literature values, ranging from HScp(PPN)aq = (1.49 ± 0.05) M atm−1 at 25.0 ∘C to HScp(PPN)aq = (7.01 ± 0.25) M atm−1 at 5.0 ∘C (stated uncertainties are at the 1σ level). The data are best described by ln⁡(HScp(PAN)aq/[Matm-1]) = -(17.8±0.3) + (5620±85)/T and ln⁡(HScp(PPN)aq/[Matm-1]) = -(19.5±1.7) + (5955±480)/T, where T is in kelvin. For n-octanol, the PPN solubility ranges from HScp(PPN)oct = (88±5)Matm-1 at 25.0 ∘C to HScpoct = (204±16)Matm-1 at 5.0 ∘C and is best described by ln⁡(HScp(PPN)oct/[Matm-1]) = -(6.92±0.75) + (3390±320)/T. n-Octanol–water partition coefficients (KOW) for PPN were determined for the first time, ranging from 59 ± 4 at 25.0 ∘C to 29 ± 3 at 5.0 ∘C. Observed loss rate constants in DI water are consistent with recent literature and larger than the thermal dissociation rates for both PAN and PPN, consistent with a hydrolysis mechanism, whereas kl values in n-octanol are significantly smaller than gas-phase dissociation rate constants, likely owing to a “cage effect” in the organic liquid. The results imply that uptake of either PAN or PPN on cloud water and organic aerosol is negligible but that uptake of PPN may constitute an overlooked source of peroxy radicals in organic aerosol.

Nondestructive measurement of anisotropic elastic constants of selective laser melted 316L based on a tri-mode ultrasonic method

Selective laser melting (SLM) technology can rapidly form metal parts with complex geometry, but the internal microstructure and material properties are significantly different from those of traditionally manufactured parts, such as obvious anisotropy and inhomogeneity. This paper proposed a tri-mode ultrasonic system to nondestructively measure the anisotropic elastic constants of 316L stainless steel prepared by SLM. Firstly, the quantitative relationship between ultrasonic wave velocities and anisotropic elastic constants was derived for elliptical anisotropic materials. The anisotropic elastic constants and Thomsen anisotropic parameters can be determined by measuring four ultrasonic wave velocities , , , and . Therefore, a tri-mode ultrasonic transducer was designed and fabricated to build the elastic constant ultrasonic measurement system. Then, the elastic constants and Thomsen anisotropic parameters of SLM samples were measured, and the key process parameters’ influence was discussed. The standard static tensile test validated the result of the ultrasonic test, and the maximum relative error was 6.94%. This study will provide a novel nondestructive measurement method and system of anisotropic elastic constants to ensure internal quality and improve the additive manufacturing process.

SonicPy: a suite of programs for ultrasound pulse-echo data acquisition and analysis

ABSTRACT Sound speed and elastic constants measurements in solids and liquids are commonly performed using the ultrasound pulse-echo technique. Recent advances have expanded the use of this technique at numerous high pressure synchrotron beamlines and offline laboratories. However, the increased experimental throughput has revealed many limitations in existing software for handling the rapid measurement and the subsequent data-reduction. We report the development of a collection of computer programs for sound speed measurements using the ultrasound pulse-echo technique, compatible with stepped multi-frequency, as well as broadband-pulse, couplant-corrected methods. The programs provide a highly interactive graphical interface, enable efficient measurement, exploration and near real-time analysis of the ultrasound data, and contain features useful for working with samples under high pressure and/or high temperature. The included analysis programs can alleviate the time required for data reduction from hours to less than a minute, allowing users to make timely and informed decisions regarding the appropriate experimental parameters.

Dynamics and Control for Transverse Formation by a Distributed Drag Sail

The constant effective vertical measurement baseline provided by the transverse formation satellites in low orbit has a critical application prospect for ground and high-orbit target detection. However, traditional formation satellites decay owing to atmospheric perturbation, and their effective baseline is periodically time-varying. A distributed drag sail (DDS) with several louvered subsails is promoted based on the free molecular flow theory, which allows for high maneuverability in satellite-tether-sail (STS) transverse formation flying. Moreover, the fuzzy PD control is introduced into the attitude-orbit model, which attains the time-dependent PD coefficients based on the geometrical configuration, to handle coupled attitude-orbit of the DDS. The aerodynamic force vectors are distributed geometrically in a bounded two-dimensional area with a pentagonal shape, through different twist combinations of subsails. The size of the distributed area depends on the number of subsails, the length and width of DDS. Finally, it is achieved that the steering engines of DDS can work effectively in appropriate frequencies during the stable formation configuration. Binocular detection with a constant vertical measurement baseline can be provided by DDS to gain situational awareness of space targets in practical scenarios such as remote sensing applications.

Unleashing the Power of Information Theory: Enhancing Accuracy in Modeling Physical Phenomena

When building a model of a physical phenomenon or process, scientists face an inevitable compromise between the simplicity of the model (qualitative-quantitative set of variables) and its accuracy. For hundreds of years, the visual simplicity of a law testified to the genius and depth of the physical thinking of the scientist who proposed it. Currently, the desire for a deeper physical understanding of the surrounding world and newly discovered physical phenomena motivates researchers to increase the number of variables considered in a model. This direction leads to an increased probability of choosing an inaccurate or even erroneous model. This study describes a method for estimating the limit of measurement accuracy, taking into account the stage of model building in terms of storage, transmission, processing and use of information by the observer. This limit, due to the finite amount of information stored in the model, allows you to select the optimal number of variables for the best reproduction of the observed object and calculate the exact values of the threshold discrepancy between the model and the phenomenon under study in measurement theory. We consider two examples: measurement of the speed of sound and measurement of physical constants.

Multi-parametric sensing by multi-channel molecular fluorescent probes based on excited state intramolecular proton transfer and charge transfer processes

Considering the applications of fluorescent probes and the information they provide, their brightness of fluorescence and photostability are of paramount importance. However, in the case of steady-state fluorescence spectroscopy and fluorescence microscopy, the amount of information can be increased by the application of multi-channel probes, via a multi-band fluorophore introduced in the probe molecule. In most cases, the use of such a multi-band (or multi-channel) fluorophore can also be combined with the concomitant introduction of one or several analyte receptors. Most often, the design of ratiometric probes with multi-band fluorescence emission are based on phenomena such as photoinduced intramolecular charge transfer (ICT) or excited state intramolecular proton transfer (ESIPT). Although ICT probes were up to recently the most popular, ESIPT probes and among them 3-hydroxyflavone derivatives, were shown to be the most productive. Several general problems were resolved by this family of probes, as for example the measurement of local dielectric constant, local H-bond accepting ability, water local concentration and ATP concentration in small volumes.Incorporation of such multi-channel probes into lipid membranes allowed to measure the different membrane potentials and to detect cell apoptosis. Also, it enabled to recognize and characterize the rafts formation in different lipid bilayers and peculiar features of the charged membrane interface. Such probes are also able to provide a concentration-dependent fluorescence signals upon binding of H+, Mg2+and Ba2+ions, and thus to recognize these different cations.The multi-channel probes are effective tools in the study of interactions of macromolecules such as peptides, proteins and nucleic acids. The most useful feature is that they inform simultaneously about several physical parameters, in this way giving a better insight in the investigated system. Thus, by comparing the reviewed probes with other modern fluorescent approaches, it can be concluded they are more informative and accurate tools.

Fast measurement of the lattice constant of smartphones with a laser pen

Fast measurement of the lattice constant of smartphones with a laser pen

Supplementary comparison of national standard instruments in the field of magnetic flux density and magnetic flux measurements by sensing coils

Main textThe COOMET.EM-S26 (1715) supplementary comparison of national standard instruments in the field of magnetic flux density and magnetic flux measurements by sensing coils has been organized within the CCEM framework to test the abilities of the metrology institutes to measure magnetic flux density and magnetic flux.Five NMIs participated in the supplementary comparison COOMET.EM-S26 (1715). Ural Research Institute for Metrology (UNIIM) (since 2020 it has been called Affiliated Branch of D.I. Mendeleev Institute for Metrology (VNIIM-UNIIM)), Russian Federation, acted as the coordinating laboratory of the comparison.The comparison on DC magnetic flux density and magnetic flux was carried out through the measurement of the coil constant of transfer standard coils. In general, very good agreement of the results has been observed.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Conformational flexibility of the disaccharide β-L-Fucp-(1→4)-α-D-Glcp-OMe as deduced from NMR spectroscopy experiments and computer simulations.

Carbohydrates in biological systems are referred to as glycans and modification of their structures is a hallmark indicator of disease. Analysis of the three-dimensional structure forms the basis for further insight into how they function and comparison of crystal structure with solution-state conformation(s) is particularly relevant, which has been performed for the disaccharide β-L-Fucp-(1→4)-α-D-Glcp-OMe. In water solution the conformational space at the glycosidic linkage between the two sugar residues is identified from molecular dynamics (MD) simulations as having a low-energy exo-syn conformation, deviating somewhat from the solid-state conformation, and two anti-conformational states, i.e., anti-ϕ and anti-ψ, indicating flexibility at the glycosidic linkage. NMR data were obtained from 1D 1H,1H-NOESY and STEP-NOESY experiments, measurement of transglycosidic 3JCH coupling constants and NMR spin-simulation. The free energy profile of the ω torsion angle computed from MD simulation was in excellent agreement with the rotamer distribution from NMR experiment being for gt:gg:tg 38 : 53 : 9, respectively, with a proposed inter-residue O5'⋯HO6 hydrogen bond being predominant in the gg rotamer. Quantum mechanics methodology was used to calculate transglycosidic NMR 3JCH coupling constants, averaged over a conformational ensemble of structures representing various rotamers of exocyclic groups, in good to excellent agreement with Karplus-type relationships previously developed. Furthermore, 1H and 13C NMR chemical shifts were calculated using the same methodology and were found to be in excellent agreement with experimental data.

Real-Time Complex Dielectric Constant Measurement of Liquids Using Epsilon-Near-Zero Supercoupling Channels

This article proposes a device for real-time measurement of the complex dielectric constant of liquids at X-band. The device consists of a narrow waveguide channel operating at the cut-off frequency to achieve a large field enhancement based on Epsilon-Near-Zero (ENZ) supercoupling theory. A micro-3D-printed sample holder is placed inside the channel and connected to feeding tubes that are designed to prevent energy leakage from the channel. The field enhancement and confinement inside the channel creates a strong interaction with the liquids under test, thereby providing very sensitive measurements over a wide range of permittivities (approx. 1-65). Two variations of the device are fabricated. One that provides a higher accuracy and another that provides a higher sensitivity. A full-wave simulation based forward model is developed and optimized using a constrained Nelder-Mead simplex. An inversion is performed based on the optimized forward model to find the complex permittivity from the measured scattering parameters. Two sets of experiments are performed, one of static liquid mixtures and another of time-varying liquid mixtures. The static measurements are done with binary mixtures of ethanol-water and methanol-water. The time-varying measurements are done with ethanol-water-sugar mixtures and ethanol-water mixtures. The measured results are consistent between the two devices and are in very good agreement with the published literature over the entire range of dielectric constants tested.

Hubble-constant crisis

The Hubble constant quantitatively characterizes the expansion rate of the current Universe, and its precise measurement has become a crucial scientific problem. In recent years, there has been an increasingly serious discrepancy between the local direct measurements of the Hubble constant and the global fitting results, where the local direct measurements come from the local distance ladder measurements of the late universe, and the global fitting results come from fitting the standard model of cosmology to the microwave background radiation from the early universe. If this discrepancy is not caused by the observation error and systematic error of any of the observation methods, it probably means that there is a new physics beyond the existing standard model of cosmology. This article briefly reviews the Hubble constant problem from two aspects with observational and theoretical points of view, and finally provide a perspective view from both observational and theoretical aspects by combining the author’s research on this problem in recent years. The observational review includes cosmological observations from both early Universe (either depending or independent of the CMB measurements) and late Universe (either depending or independent of the distant-ladder measurements), and the theoretical review includes model buildings from modifying both early Universe (either recombination history or expansion history) and late Universe (either homogeneous modifications or inhomogeneous modifications). The final observational perspective includes both local and non-local cosmic variances with their Hubble residual correlated to the matter density contrasts of observer and sample, respectively, and the final theoretical perspective concludes the interacting dark energy model as the most promising candidate for both Hubble tension and &lt;i&gt;S&lt;/i&gt;&lt;sub&gt;8&lt;/sub&gt; tension, which can be specifically realized in a chameleon dark energy model, pointing to a scale-dependent effective cosmological constant.