Papers

We present a covariant modified gravity theory which reproduces all the galactic phenomenology usually attributed to dark matter in the low acceleration regime, including the flat rotation curves of massive tracers, and the deflection angles of photons as inferred through gravitational lensing. We first derive a fully covariant description of galactic space-times under a spherically symmetric and static approximation. This description accounts for flat rotation curves, observed gravitational lensing phenomenology and the Tully-Fisher mass scalings of the above. The resulting covariant description is then used to constrain the parameters of a minimally coupled gravitational action using power laws for both the Ricci scalar and the matter Lagrangian. The action presented hence leads to field equations whose trace, under the approximations taken, has as solutions metric coefficients which exactly reproduce flat rotation curves, gravitational lensing observations and observationally determined Tully-Fisher galactic mass scalings of any required index. This last allowing for an accurate fitting of observational dynamics up to galaxy cluster scales.

The answer is "Yes". As it has been shown in the Ref.[1] (22 Sep.2017, see also the comments), useing a new definite mathematical axiomatic-algebraic matrix approach, all the fundamental laws of nature could be derived uniquely (where the axiom of "no zero divisors" of the ring of integers has been generilzed and written in a new definite formulation, then basically assuming that all the physical quantities could only and only take the rational values). Based on this new mathematical approach along with the C, P and T symmetries of the derived field equations, it is concluded that the universe could be realized solely with the (2+1) and (3+1)-dimensional space-times. Moreover it is shown that the (3+1) dimensional cases of the directly determinated general covariant field equations (including two definite classes: a two indexes and a four indexes tensor fields), respectively, represent two new massive forms of the bispinor fields of spin-1and spin-2 particles; and the (2+1)-dimensional cases of the drived equations (including: a two indexes and a four indexes tensor fields), represent (asymptotically) two new massive forms of the bispinor fields of spin-3/2 and spin-1/2 particles, respectively. As a particular result, based on the formulation of the derived Electromagnetic Maxwell equations (representing by the bispinor fields of spin-1 particles, including new field equations - corresponding to the YangMills equations - compatible with two specified forms of the gauge symmetry groups), it has been concluded that magnetic monopoles could not exist in the nature to any extend. Furthermore, as the only elementary particles that could be existed in nature, along with the all discovered particles, eight new particles, including four charge-less right-handed spin-1/2 fermions (two leptons and two quarks), and a spin-3/2 fermion, and also three spin-1 massive bosons are also solely predicted.

In the standard $\Lambda$CDM cosmology, dark matter is assumed to be a pressureless cold fluid with $w_{\rm dm}=0$. However, the microscopic nature of dark matter remains unknown, and whether its equation-of-state parameter strictly vanishes deserves observational scrutiny. In this work, we introduce a free dark matter equation-of-state parameter $w_{\rm dm}$ within the Modified Emergent Dark Energy (MEDE) framework, constructing the MEDE+$w_{\rm dm}$ model. We systematically derive its background evolution and linear perturbation equations, and constrain the model parameters using Planck 2018 cosmic microwave background (CMB), DESI DR2 baryon acoustic oscillation (BAO), and three independent Type Ia supernova datasets: Pantheon+, Union3, and DES5YR. Using the CMB + BAO + DES5YR combination, we find a preference for a positive dark matter equation of state, $w_{\rm dm}=0.00128\pm0.00044$, together with a 3$\sigma$ level preference for quintessence-like dark energy evolution, $\alpha=-0.66\pm0.22$. When the local $H_0$ prior is included, the constraint on $w_{\rm dm}$ remains essentially unchanged, whereas $\alpha$ shifts toward the $\Lambda$CDM limit, yielding $\alpha=-0.18\pm0.18$. Bayesian model comparison favors $\Lambda$CDM over MEDE+$w_{\rm dm}$, although the preference is reduced to the weak level after including the local $H_0$ prior. Overall, current observations exhibit a $2.6\sigma$–$3\sigma$ preference for a nonzero $w_{\rm dm}$ at the parameter-posterior level, but this indication does not yet constitute a robust detection of non-cold dark matter.

I contend that physics should provide a coherent account of reality, in addition to be an efficient algorithm for the prediction of empirical results. This article offers pictures of reality derived from theories of modern physics. In particular it is shown that Bose quantum fields may be interpreted as pure wave fields via the Weyl-Wigner representation. The most relevant result being the existence of a stochastic vacuum field, corresponding to the quantum vacuum fluctuations of the standard, canonical, formulation of field theory. That field provides explanations for the particle (photons) behaviour of the electromagnetic field. Also a realistic interpretation is offered for the interference experiments with actual particles, like atoms. The interpretation of classical general relativity is standard but emphasis is made on the principle of equivalence. Problems like the spacetime singularities (black holes) and the empirical violation of Bell inequalities are touched but slightly. Asides from these problems the main incompleteness of the article is the absence of a realistic interpretation of Fermi fields.

We formulate new Barrow holographic dark energy (NBHDE) as a second-order expansion of the Barrow entropy correction near the standard holographic dark energy (HDE) limit, adopting the future event horizon as the infrared cutoff. Writing the Barrow factor in exponential form identifies $(\Delta/2)\ln S_{\rm BH}$, rather than $\Delta$ alone, as the expansion parameter. In a flat universe containing pressureless matter and NBHDE without a cosmological constant, we derive the background equations, establish consistency with the integral definition of the future event horizon, and recover HDE exactly at $\Delta=0$. We assess this approximation against the unexpanded Barrow holographic dark energy (BHDE) density, locally and through independently normalized background evolutions. Across $0.50\leq c\leq1.20$ and $0\leq\Delta\leq0.003$, the maximum fractional density difference remains below $1\%$ over $-0.99\leq z\leq5$, while the normalized Hubble rates differ by less than $0.074\%$ over $0\leq z\leq5$. Within this domain, the Barrow correction modestly changes the expansion rate and acceleration transition but more strongly affects the dark energy equation of state and phantom crossing. At $c=0.80$, $w_{d0}$ shifts from $-1.031$ in HDE to $-0.900$ at $\Delta=0.003$. We perform a conditional comparison with 36 spectroscopic cosmic chronometer (CC) measurements. At fixed $H_0=67.4\,{\rm km\,s^{-1}\,Mpc^{-1}}$ and $\Omega_{m0}=0.30$, the minimum lies on the HDE boundary at $\Delta=0$ and $c=0.8457$. Minimizing over $c$ at $\Delta=0.003$ gives $c_{\min}=0.6879$, with $\Delta\chi_{\rm CC}^2\simeq1.0\times10^{-3}$. NBHDE therefore provides a self-consistent, quantitatively controlled framework near the HDE limit, showing that Barrow corrections can alter dark energy behavior even when their effect on $H(z)$ is largely compensated by changing $c$.

We present a comprehensive observational analysis of modified Gauss–Bonnet, or $f(G)$, gravity by investigating both the background cosmological expansion and sub-horizon linear matter perturbations. We consider two viable functional forms: an arctangent parameterization (Model~I) and a generalized polynomial power-law model (Model~II). Using a Markov Chain Monte Carlo (MCMC) ensemble sampler, we constrain their parameter spaces through background and structure-growth observations. Our analysis employs cumulative combinations of Cosmic Chronometers (CC), the Pantheon+ Type Ia Supernovae compilation (PP), Redshift-Space Distortions (RSD), and the Year-1 Baryon Acoustic Oscillation measurements from the Dark Energy Spectroscopic Instrument (DESI BAO). The inclusion of DESI BAO data produces a noticeable downward shift in the preferred values of the Hubble constant, $H_0$, and present matter density parameter, $\Omega_{m0}$. For Model~II, the full analysis yields $H_0=64.02^{+4.13}*{-3.08},\mathrm{km,s^{-1},Mpc^{-1}}$ and $\Omega*{m0}=0.249^{+0.047}_{-0.038}$. We further assess the statistical performance of the models relative to $\Lambda$CDM using $\Delta\mathrm{AIC}_c$, $\Delta\mathrm{BIC}$, and $\Delta\mathrm{DIC}$. For Model~II, the full dataset gives $\Delta\mathrm{AIC}_c=4.233$ and $\Delta\mathrm{DIC}=5.971$, favoring the $\Lambda$CDM baseline. At the perturbation level, both models exhibit stable growth histories compatible with large-scale structure observations. The models predict transitions in the late-time expansion dynamics at $z\approx0.5005$ and $z\approx0.6086$ for Models~I and II, respectively, highlighting differences in their cosmological evolution.

Previous works [1,2,3] expose a synthetic, Riemannian geometrization of electromagnetism that emerges naturally from the experimental bases provided by the Lorentz force and the Maxwell equations. Since the components of the associated space-time metric tensor depend on the four-vector velocity, Riemannian geometry does not fully describe the space-time geometry. The present work aims to provide a suitable geometrical basis for the problem, applying a pseudo-Finsler geometry – a Finsler geometry with a non-homogeneous norm.

Moiré theory is a revolutionary alternative arising from solid-state physics that can be extended to gravity, forming a framework called Moiré gravity. The idea behind it is that Einsteinian gravity has a validity limit and must be extended to Moiré gravity, in which the Friedmann equation changes and a new scalar field emerges. In this vein, in this paper, we propose an analytic solution for the Moiré scalar field coupled with the modified Friedmann equation, studying the viability and constraining the value for the main parameter of the scalar field and cosmology in general, through the use of datasets that contain cosmic chronometers, type Ia supernovae, intermediate-luminosity quasars, and hydrogen II galaxies. Our results allow for an accelerated phase with two peaks, but also predict an extremely decelerated stage, with $q(z=0)=15.376^{+6.403}_{-4.692}$ when the characteristic parameter of the theory is $\jmath=0.677^{+0.001}_{-0.002}$, in contrast to other models that decelerate at $z=0$.

We present a joint observational analysis confronting viable $f(R)$ modified gravity theories, specifically the Hu & Sawicki and Starobinsky models, with background and large-scale structure (LSS) data. Utilizing Monte-Carlo Markov chain (MCMC) sampling across datasets including baryon acoustic oscillations (BAO), type Ia supernovae (SNeIa), cosmic microwave background (CMB) distance priors, and linear growth measurements ($f\sigma_8$, $f$, $\sigma_8$), we place tight constraints on the model parameters governing deviations from General Relativity. For the full dataset combination, we obtain $\log_{10} b_\mathrm{HS} = -6.325_{-1.138}^{+1.216}$ for the Hu & Sawicki model and $b_\mathrm{S} = (0.8\pm61.0)\times10^{-4}$ for the Starobinsky model. Model comparison based on the Akaike Information Criterion indicates that these $f(R)$ extensions are statistically favored over flat $\Lambda\text{CDM}$ ($|\Delta\text{AIC}| \ge 3.99$) for the combined data. However, when considering the Bayesian Information Criterion, the evidence for support is significantly reduced. Furthermore, we construct two-dimensional phase-space diagrams in the $(\mu, \gamma)$ and $(\mu, \Sigma)$ planes across several redshifts, establishing a novel diagnostic null-test allowing us to probe for deviations from $\Lambda\text{CDM}$, corresponding to the fixed point $(1,1)$ in both planes, using LSS observables. Should future weak-lensing and galaxy surveys provide data points with $\mu-1<0$ and $\gamma-1>1$ or $\Sigma-1 < 0 $, then the aforementioned models could be directly ruled out.

Bound states in the continuum (BICs) are ubiquitous wave phenomena, but have not yet been demonstrated for gravitational waves (GWs). Here, in-plane periodic perturbations, exponentially localized at the plane $z = 0$, are shown to lead to distributional surface energy tensors at this plane and to be regular vacuum solutions ($T_{\mu \nu} = 0$) of the linearized Einstein field equations outside of it. These are achieved by explicitly calculating the Ricci tensor components and the Ricci scalar from the metric perturbation tensor. To fulfill each vacuum solution ($R_{{\sigma \nu}_{(+, \times)}} = 0$ and $R_{{}_{(+, \times)}} = 0$), different surface polariton-like dispersions are required. These bound perturbations decay exponentially to a flat metric ($h_{{BIC}_{(+,\times)}} \propto e^{- k_z |z|}$), and each localized metric has a correspondence to a different planar GW polarization ($+,\times$). The Lorenz gauge-fulfilling solutions exist at the $\Gamma$ point in momentum space, dwelling within the continuum of wavevectors of propagating GWs. The strains in the unit cell of the periodic perturbations have opposite parities relative to the corresponding planar GWs under a $C_2$ in-plane rotation, making them incompatible by symmetry with their propagating counterpart, indicating localization via symmetry protection.

We present a quotient-space Bayesian formulation for DESI-era anomaly interpretation. Given a pattern-labeled catalog with map \(i\mapsto \Act(i)\), the induced posterior \(p(\Act\mid D)\), sector inclusion probabilities \(P_\alpha\), co-activation probabilities \(P_{\alpha\beta}\), and grouped Bayes factors \(B_\alpha(D)\) are exact summaries over predeclared physical activation events. Pairwise comparisons such as \(\lcdm\) versus \(\wacdm\) remain ordinary Bayes-factor tests between specified families; the quotient construction addresses the coarser question of which physical sector carries posterior support when different sectors are represented by unequal numbers of catalog elements. We derive a sector-resolved DESI-CMB-SN likelihood specification for late-time background, early-time ruler, supernova calibration, perturbation, and gravitational-wave propagation sectors. The construction includes an Alcock-Paczynski/isotropic-scale BAO decomposition, a pure-ruler projection, analytic marginalization of low-rank supernova calibration modes, Fisher-normalized sector priors, inactive-sector leakage tests, log-evidence uncertainty propagation, and prior/sector-partition diagnostics. The result is a quantitative procedure for reporting model-comparison support at the level of physically interpretable sectors.

We investigate the late-time accelerated expansion of the Universe in power-law $f(Q)$ gravity, $f(Q) = Q + 6\gamma H_0^2 \left(\frac{Q}{Q_0}\right)^n$, combined with two dynamical dark energy parametrizations, Barboza-Alcaniz (BA) and Jassal-Bagla-Padmanabhan (JBP), which allow a smooth evolution of the equation of state beyond the standard constant $\omega$ assumption. We derive analytical expressions for the Hubble parameter and the dark energy density, and constrain the model using Pantheon$^+$ Type Ia Supernovae, DESI DR2 Baryon Acoustic Oscillations, and Cosmic Chronometers. Going beyond purely geometrical probes, we incorporate Redshift Space Distortion (RSD) measurements to test the growth of cosmic structures and distinguish modified gravity from General Relativity through the effective Newton's constant. Both parametrizations reproduce the observed late-time acceleration and remain consistent with growth data, with only mild deviations from $\Lambda$CDM over low and intermediate redshifts. Notably, both configurations yield $G_{\rm eff} < G$, indicating suppressed growth of matter perturbations. These results establish power-law $f(Q)$ gravity with BA and JBP parametrizations as a viable and versatile alternative to $\Lambda$CDM across both background and perturbative regimes.

In this work, we introduced a positive viscosity coefficient into Newtonian dynamics to explore the rotational properties of disk galaxies. Our results show that the rotational behaviors of disk galaxies predicted by this modified Newtonian dynamics share notable similarities with those from the well-known MOND model. Specifically, the modified framework naturally recovers the deep-MOND limit postulated in MOND. Furthermore, we derived an explicit interpolation function relating centripetal acceleration to Newtonian acceleration-a relation that is purely empirical within the MOND model. We also identify key differences from MOND: the critical acceleration a0, regarded as a universal constant in MOND, actually varies with galactic mass and increases for more massive galaxies. Additionally, driven by the anti-dissipation effect of the viscosity coefficient, disk galaxies undergo extremely slow radial expansion over cosmic time, analogous to the expansion of the Universe. But regrettably, the fundamental physical origin of the viscosity coefficient introduced here remains unclear for us. But relevant hints can be found in existing literature, pointing to a promising direction for our future research.

We explore two scenarios of $f(Q,\mathcal{L}_m)$ gravity: linear and non-linear gravity models. The dynamical system analysis identifies two critical points for each of the proposed linear and nonlinear matter–geometry coupling models. These equilibrium points correspond to distinct phases of cosmic evolution. Depending on the model parameters, the resulting critical points successfully reproduce the observed sequence of cosmic evolution, from a decelerated matter-dominated Universe to the present epoch of accelerated expansion. The effective equation of state parameter ($\omega_{\text{eff}}$) and the deceleration parameter ($q$) exhibit smooth transitions from decelerated to accelerated expansion, with transition epochs around $N_{\text{tr}} \approx -0.27$ for linear Model and $N_{\text{tr}} \approx -0.32$ for non-linear Model, consistent with late-time cosmic acceleration. Statistical constraints derived from CC+BAO, DESI DR II, and Pantheon$^+$ datasets provide best-fit values for the model parameters ($\alpha, \beta, \gamma, H_0$), showing compatibility with current cosmological observations. The analysis employs Akaike (AIC) and Bayesian (BIC) information criteria to evaluate model performance. Our results demonstrate that $f(Q,\mathcal{L}_m)$ gravity provides a viable alternative framework for explaining late-time acceleration, with rich dynamical features that merit further exploration in view of upcoming high-precision surveys.

Dark Energy Survey has shown that the emission light curve widths $\Delta t_{\rm em}$ of supernovae increase to $\Delta t_{\rm obs}$, obeying $\Delta t_{\rm obs}/\Delta t_{\rm em}=(1+z)^b$ with $b=1.003\pm0.011$, excluding a nondilating redshift. We test hybrid models with $1+z=(1+z_p)(1+z_t)$ and the phenomenological stretch $(1+z_p)R(z)$, where $z_p$ is the redshift associated with the expanding parent universe cosmology, $z_t$ is a tired-light (TL) contribution, and $R$ is the hybrid-to-parent lookback-time ratio. At $z=1$, $R$ and $1+z_t$ differ by $1.3\%$ for CCC+TL and $0.5\%$ for $\Lambda$CDM+TL, and their 95% bands overlap the observed relation. This compatibility shows that the observations do not exclude the hybrid models, only fully nonexpanding ones.

The algebraic structure of the equation governing the propagation of an elastic SHwave through an isotropic inhomogeneous layer surrounded by two homogeneous half-spaces is revisited. It is shown that the problem under a quartic variation has a hidden sl(2) symmetry based on which quasi-exact solutions are available via a completely analytical approach. This is of particular interest as the approach proposed for the corresponding tri-confluent Heun equation can be generalized to some other classes of geometries as well and the complicated considerations in case of Heun equations are absent.

Machine learning capabilities are expanding into scientific domains at an accelerating pace. When applied to high-energy physics pattern discovery, they will generate candidates faster than traditional evaluation can absorb. ML finds patterns in past data it is inherently post hoc. Whether those patterns reflect structure or coincidence is unknowable at discovery time; this limitation applies equally to human and computational pattern-finding. What differs is scale: ML candidate generation is effectively unbounded, while human evaluation capacity remains fixed. When generation rate exceeds evaluation bandwidth, binary accept/reject degenerates to random sampling. Information-theoretically, the only response that preserves ranking under finite evaluation budget is stratification. By focusing on stratification rather than binary filtering, rule adjustments can be made retroactively, thresholds tuned as results accumulate, and evaluation bandwidth focused on top-ranked candidates. This paper attempts to codify those criteria, proposing seven computationally evaluable standards for stratifying ML-generated patterns. The goal is not to deliver verdicts but to prioritize which candidates merit pre-registration and longitudinal tracking. The framework preserves the essential paradigm: pattern plus theory equals potentially real physics. Patterns alone, however striking, remain candidates until theoretical understanding arrives. Making these criteria explicit enables prefiltering at scale while creating a collaborative resource rather than a competitive one. ML capabilities extend what physicists can search while preserving how physicists evaluate. We offer this provisional framework for community calibration, with the goal of developing validation infrastructure before the capability fully arrives.

In 1911 Einstein suggested that photons which pass close to the Sun are deflected by its effective mass which would apparently shift the positions of stars by up to one arcsecond, something that should be observable by astronomers during solar eclipses. Einstein`s ideas including the later doubling of the value due to relativistic space curvature met with enthusiastic responses from astronomers. The history of these efforts, their motivations and interactions with Einstein is presented here, beginning with the expedition that failed due to WWI of the young Erwin Freundlich in 1914 and ending with the unsuccessful Potsdam campaign to Öland (Sweden) in 1954. A newly found conference photograph from the first post-war meeting of the Astronomische Gesellschaft in 1921 shows Albert Einstein as a new member of the AG on the Telegraphenberg in Potsdam.

In this work, we build a general framework for constraining interacting scalar fields with cosmological observations, applicable to a broad family of scalar–field potentials and interaction kernels. As a representative example, we derive constraints on a model in which dark matter is described by a scalar field $\phi$ with a quadratic potential and dark energy by a scalar field $\psi$ with the Albrecht–Skordis potential, considering both the uncoupled case and a more general scenario in which the exchange of energy occurs through an interaction kernel proportional to the kinetic energies of the scalar fields $Q \propto \dot{\phi}^2 \dot{\psi}^2$. The scalar field parameters are constrained by using Planck 2018 CMB data, DESI BAO measurements, Ly-$\alpha$ forest constraints, and SNeIa observations, and we find that the scalar field parameters are driven toward their $\Lambda$CDM-like limits; the early dark energy fraction is largely suppressed, and the SFDM mass is bounded to values for which the field behaves close to cold dark matter. In the interacting case, the results show no significant preference for the transfer of energy between dark energy and dark matter at 95% C.L. In general, the model keeps $H_0$ close to the Planck-$\Lambda$CDM range and provides best-fit $\chi^2$ values comparable to those of the corresponding $\Lambda$CDM fits.

Diffusion functions in unimodular gravity induce a dynamical effective cosmological constant, providing an appealing framework in light of recent DESI observations. In this work, we investigate the observational viability of a general class of diffusion models using baryon acoustic oscillation measurements from DESI DR2, Type Ia supernova compilations (Pantheon+, DES-Dovekie, and DESY5), and Cosmic Chronometer data. We find that diffusion models systematically achieve lower best-fit $\chi^{2}$ values than $\Lambda$CDM across all dataset combinations considered, indicating a modest but persistent improvement in goodness of fit. Nevertheless, the reduction in $\chi^{2}$ is insufficient to offset the larger parameter space, leading standard information criteria to favor the simpler $\Lambda$CDM model. Despite this result, all dataset combinations consistently prefer a nonvanishing diffusion contribution corresponding to approximately $20\%$ of the present dark-energy budget, with a posterior probability $P(f_Q>0.05) =96.78\%$. From an observational perspective, diffusion models therefore remain a viable extension of the standard cosmological scenario and motivate the exploration of simpler diffusion parameterizations, particularly in light of upcoming high-precision cosmological surveys.

We investigate an interacting dark sector scenario in which a deviation from the standard dilution law of cold dark matter is parametrized by a perturbative correction $\epsilon$, thereby inducing a dynamical vacuum component. We extend this framework by allowing dark matter to behave as an imperfect fluid with bulk viscosity. Within the Eckart formalism, we consider a power-law dependence of the bulk viscous coefficient on the dark matter energy density which yields an effective density scaling for the viscous pressure. We obtain the parameter constraints using multi-nested sampling with Dynesty, employing DES 5YR Type Ia Supernovae, DESI Baryon Acoustic Oscillations, Cosmic Chronometers, the local $H_0$ measurement from H0DN, and Cosmic Microwave Background distance priors. Redshift Space Distortion measurements from SDSS-IV and the DES weak-lensing constraint on $S_8$ are included to probe structure formation. We also examine the thermodynamic consistency of the cosmological scenarios and find that they satisfy the Generalized Second Law of thermodynamics. We find that bulk viscous effects can modify the late-time interaction dynamics, while their contribution is suppressed once early-Universe information is included. These results provide observational and thermodynamic constraints on departures from the standard cold dark matter evolution and a constant vacuum energy.

In this study, we investigate the role of bulk viscosity in the evolution of a spatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) universe dominated by dust. We parameterize the bulk viscosity as p_tilde = -3[l + m(H'(t) + H^2) + nH^2]H, derive the modified Einstein field equations, and reformulate them in terms of redshift z. Using 46 Hubble parameter measurements and the Pantheon+ compilation of 1701 supernovae, we estimate the model parameters (H0, l, m, n) through chi2 minimization and refine them using Markov chain Monte Carlo (MCMC) simulations. The analysis gives a transition redshift z_t = 0.585 and a present deceleration parameter q0 = -0.705, consistent with Lambda CDM. The present age of the universe is estimated as t0 = 14.5734 Gyr. We obtain H0 = 68 km/s/Mpc from the Hubble datasets and approximately 73 km/s/Mpc from Pantheon+. These results illustrate the Hubble tension between late- and early-universe determinations of H0. We further investigate the evolution of the equation-of-state parameter omega(z), energy density rho(z), and pressure p(z). Statefinder diagnostics (r,s) demonstrate deviations from and convergence toward Lambda CDM at different epochs. The results highlight the potential role of bulk viscosity in describing the accelerated expansion of the universe and provide a useful framework for studying cosmological models.

Generalized trace dynamics (GTD) is a deterministic dynamics of aikyons (atoms of space-time-matter) whose near-equilibrium statistical mechanics yields quantum dynamics, while large anti-self-adjoint fluctuations drive spontaneous localisation and emergent classical spacetime. We separate two independent large limits: long-Connes-time coarse-graining of a finite system, which conditionally yields the quantum Ward identities, and the extensive many-aikyon/large-matrix limit required for a collective singularity. We turn the condensed-matter analogy of the E8 x omega E8 programme into a quantitative, falsifiable effective framework. Four coupled composite channels (bifermionic localisation, geometric soldering/Lorentz-Higgs, gauge-invariant electroweak, and matrix-valued flavour) define an exact susceptibility matrix and Legendre effective action, giving zero-mode and free-energy criteria for a common continuous or first-order transition. We pose the nonequilibrium problem in Schwinger-Keldysh form, define a projected fluctuation-dissipation defect and the martingale condition for Born probabilities, identify Newton's constant with the stiffness of the ordered geometric phase, and give conditions under which the Sakharov, constrained-BF, Jacobson, Padmanabhan and Verlinde descriptions of gravity are limits of one substrate. A regulated two-sector surrogate ensemble (a Myers-deformed geometric triple coupled to a matter matrix, with a Grassmann-regulated fermionic extension) shows that selected diagnostics are calculable: exact Adler-Millard charge conservation, a multi-channel first-order jump, a verified fluctuation-dissipation relation and its quench defect, and a fermionic spectral dimension d_s = 1.96 on the emergent two-sphere. The result is a calculational programme, not a completed derivation; the next step is the many-aikyon composite two-point matrix for GTD itself.

We develop a covariant Hamiltonian formalism in which evolution is measured along the proper-time flow of an observer congruence, replacing the external coordinate-time derivative with the Lie derivative. Our formalism keeps the Hamiltonian split between evolution and configuration variables and expresses it through spacetime tensors projected relative to the chosen congruence. After quantization, the resulting observer-congruent brackets lead to relativistic Heisenberg and Schrödinger equations whose evolution parameter is proper time. We then apply this framework to gravity by taking the projected spatial metric and its conjugate momentum as canonical variables, obtaining a complete model of canonical quantum gravity. Among the predictions of this theory we find a resolution to the singularity problems in cosmology, black holes and black hole thermodynamics.

The existence of three fermion generations remains one of the unexplained structural features of the Standard Model. This article reviews an algebraic framework in which an intrinsic $S_3$ family symmetry relates three gauge-equivalent fermion sectors. The framework is motivated by division- and Clifford-algebra constructions in which the complex octonions and $\mathbb{C}\ell(6)$ organise the colour and electromagnetic quantum numbers of one generation. Continuing the Cayley–Dickson sequence, the sedenions provide an intrinsic $S_3$ automorphism structure, while their complexified left-multiplication operators generate an associative algebra isomorphic to $\mathbb{C}\ell(8)$. In the $\mathbb{C}\ell(8)$ formulation, the order-three family action generates three linearly independent fermion sectors while leaving a single $\mathfrak{su}(3)_C\oplus\mathfrak{u}(1)_{\mathrm{em}}$ gauge algebra. Extension to $\mathbb{C}\ell(10)$ incorporates a single $\mathfrak{su}(3)_C\oplus\mathfrak{su}(2)_L\oplus\mathfrak{u}(1)_Y$ gauge algebra, with each generation including a right-handed neutrino sterile under the SM gauge interactions. We place the construction in context by comparing it with representative algebraic and family-symmetry approaches to three generations, including triality-based proposals, and clarify why the family symmetry used here is distinct from standard $\operatorname{Spin}(8)$ triality despite the common appearance of $\mathbb{C}\ell(8)$ and $S_3$. The framework remains algebraic and representation theoretic rather than a complete dynamical theory; family-symmetry breaking, realistic fermion masses and mixing, and a dynamical account of the gauge and matter sectors remain open problems.

The Big Bang singularity marks a fundamental breakdown of General Relativity, yet all proposed quantum gravitational remedies invoke microphysical assumptions beyond the observational reach. We show that a minimal, purely classical modification of the gravitational potential — preserving the inverse-square law where tested, but free to depart at unmeasured scales — is sufficient to produce a non-singular, cyclic universe. The resulting modified gravitational formulation leads to a cosmic evolution exhibiting a bounce at a finite minimum size, followed by a regime closely akin to the concordant $\Lambda$CDM model, and an eventual collapse to another bounce. Cosmic Chronometer, Supernovae type Ia, Baryon Acoustic Oscillation, Cosmic Microwave Background and Nucleosynthesis data constrain both the new length scales, implying a cycle period of $\simeq 89\,$Gyr, and this framework — subsuming a broad class of bounce scenarios within a single testable model — opens a direct route for distinguishing cyclic cosmologies from $\Lambda$CDM.

Quantum techniques matter to optical astronomy when they preserve information in the parameter-bearing measurement channel after realistic loss, calibration, covariance, and inference are propagated to the final astrophysical observable. We compare 7 approaches by the quantity they change: internal optical-path delay, sub-Rayleigh source separation, coronagraphic planet throughput & stellar leakage, coherent field quadratures, nonlocal complex visibility, null depth, active phase sensing. In an Earth-analog astrometry case, 6-dB squeezed internal metrology improves the measured phase quadrature by 1.58 and the complete readout by ~1.20, but fixed-time planet-mass precision by only 1.010 (95 % interval 1.005-1.045); mission duration, useful baseline, cadence, calibration have greater modeled leverage. For a close young binary, signed spatial-mode demultiplexing preserves sub-Rayleigh orbital information that is substantially degraded in the tested direct-imaging comparator. A representative matched-model calculation gives a dynamical-mass RMSE gain 1.77 1.47-2.15). For illustrative equal-prior pre-main-sequence predictions at 0.10 and \(0.12M_\odot\), mass precisions of 15%, 10%, 7% correspond to correct-selection probabilities of ~73%, 82%, 90%. The numerical gain remains provisional because the event-level continuous-image comparator, strict tail convergence, externally measured broadband transfer matrix, and finite-photon calibration are not yet closed. Modal coronagraphy and quantum-enhanced heterodyne reception define conditional receiver opportunities, while the nonlocal, nuller, and prepared-NOON cases identify physical bottlenecks that prevent an astrophysical advantage in the stated configurations. The common result is that quantum technology is most valuable when it changes an information-bearing observable and that channel remains consequential in the final science measurement.

The quantum harmonic oscillator (QHO) is normally built on a structure that contains a Hilbert space, ladder operators, and a Born rule. Here we derive it from counting. We adopt three information-theoretic postulates: information is carried by binary sequences of length $n$; only symbol counts, not the sequences themselves, are observable; and the transition measure must account for exactly the $2^n$-configuration capacity of the register. The first two postulates force the counting problem into the Hamming/Delsarte association scheme and endow it with an exact symmetry under relabeling of the two symbols. Given an exchange-symmetric bilinear transition measure we prove a rigidity theorem: relabeling symmetry and normalization together force the alternating sign $(-1)^t$ which drives interference. The variable that carries the sign, i.e. the overlap between input and output sequences, or equivalently their Hamming distance $d_{ab}$, is a hidden quantum number of the transition as a whole, defined only by the two endpoints jointly and unknowable from either alone. Interference thus enters as alternating-sign bookkeeping over a nonlocal, relational variable $d_{ab}$, rather than as a separate dynamical ingredient. This forced weighting makes the transition probability proportional to the square of a Krawtchouk polynomial, whose difference equation has an exactly equally spaced spectrum and which converges to the QHO as $n\to\infty$. At fixed excitation, deviations from the QHO are $\mathcal{O}(1/n)$, and are testable in laboratory realizations of the oscillator, since any real system has finite information capacity. In this framework, interference, quadratic (Born-rule-like) probabilities, and the particle-hole symmetric oscillator spectrum are consequences of counting; only the bilinear form of the measure is assumed (though well motivated) rather than derived.

Dark Energy Spectroscopic Instrument (DESI) Collaboration reported an evidence for dynamical dark energy model using baryon acoustic oscillation (BAO) measurements from DESI Data Release 2 (DR2), cosmic microwave background (CMB), and three Type Ia Supernovae (SNe) data (Pantheon+, Union3, and DES-SN5YR) recently. The significances are from $2.8\sim4.2\sigma$ depending on which SNe sample is used, and the highest significance is obtained based on the DES-SN5YR data. But more recently, Dark Energy Survey (DES) Collaboration recalibrated the DES-SN5YR data, and a significance of only $3.2\sigma$ is obtained based on the calibrated data, which is called DES-Dovekie. In this work, we perform a comprehensive analysis of five representative dynamical dark energy parametrization models, including Chevallier-Polarski-Linder (CPL), Barboza-Alcaniz (BA), exponential (EXP), logarithmic (LOG), and Jassal-Bagla-Padmanabhan (JBP), using DESI DR2 BAO, Planck CMB, ACT DR6, and SNe data from Pantheon+, Union3, and DES-Dovekie. Similarly, a significance of around $3\sigma$ is obtained based on the DES-Dovekie data. And the significances are $2.1\sim3.7\sigma$ for different SNe samples and different parametrization models, indicating an evolutionary dark energy dynamics. Furthermore, a phantom-like behavior in the past and has transitioned into quintessence-like behavior today for the dynamical dark energy is preferred.

We comment on the recent proposal (arXiv:2608.21211v1 (2026)) of a new transverse Hamiltonian for electromagnetic interacting charged particles that ignores both the classical and quantum-mechanical versions of the already known one. 1 Introduction