arXiv subjects

Ahmed Farag Ali

Publications and source records attributed to Ahmed Farag Ali.

At least 19 recordsLinked to original sources

arXiv2026

Rainbow McVittie Horizons in an Expanding Universe

We derive the Friedmann dynamics and apparent-horizon thermodynamics of a spatially flat McVittie spacetime in Gravity's Rainbow and construct a consistent non-accreting perfect-fluid sector with an effective rainbow Hubble rate. The Einstein equations, trapping horizon, surface gravity, Misner--Sharp energy, unified first law, and Clausius relation form a closed thermodynamic system reproducing the Friedmann dynamics. We then introduce a low-energy rainbow deformation and constrain it using 32 cosmic-chronometer measurements and 1580 Pantheon+ light curves with the full covariance matrix. Combined with the Planck matter-density prior, the fit gives $H_0=68.75\pm2.63~\mathrm{km\,s^{-1}\,Mpc^{-1}}$, $Ω_m=0.3157\pm0.0070$, and $ε=0.0106^{+0.0234}_{-0.0231}$. The resulting constraints establish the observational viability of small late-time rainbow corrections and place the general-relativistic limit within the preferred parameter region.

gr-qc↗

arXiv2026

Spectral Admissibility of Real Observers in Euclidean de Sitter Gravity

The Euclidean de Sitter path integral contains the familiar phase associated with conformal negative modes. Maldacena's construction shows that a suitably included real observer can reorganize the refined state-counting problem. This paper does not rederive that cancellation. It addresses the prior semiclassical admissibility question: which observer sectors couple to the de Sitter saddle as genuine metric observers without becoming spectators or producing infrared-singular backreaction? On $S^D$, after gauge fixing and zero-mode projection, the observer's quadratic influence is governed by a Schur complement. We formulate a form-domain criterion: if the observer kernel is positive and the mixed metric-observer source is bounded after applying $Δ_{ΦΦ}^{-1/2}$, the induced metric correction is a bounded quadratic-form perturbation on the chosen channel. In the gapped case, $Δ_{ΦΦ}\geq m_*^2\mathbf{1}$ gives $\|K^\dagger Δ_{ΦΦ}^{-1} K\|_{\rm op} \leq \|K\|_{\rm op}^2/m_*^2$; metric-coupled soft modes produce corrections growing as $1/\varepsilon$. We prove a sufficiency theorem: on any stable channel with coercive form $Q_{gg}^P \geq δ_P \|h\|^2$, the Gaussian saddle remains controlled whenever $\|Δ_{ΦΦ}^{-1/2} \mathfrak{j}_P\|_{\rm op}^2 < δ_P$. We construct a localized gapped clock-detector with internal oscillators on a smeared worldline that satisfies the criterion with a computable bound and gives explicit $S^4$ benchmark versus the round-sphere TT scale. The conformal channel is treated only as an indefinite or contour-defined sector; boundedness does not imply positivity. The criterion identifies the semiclassically admissible observer class. Phase cancellation follows only when this class overlaps the relevant conformal or negative-mode sector and is combined with an independent contour or state-counting prescription.

hep-th↗

arXiv2026

When do real observers resolve de Sitter's imaginary problem?

The universal phase $\rev{\ii}^{D+2}$ of the Euclidean de Sitter path integral obstructs a straightforward state-counting interpretation of the Gibbons--Hawking entropy. Building on Maldacena's proposal that specific black-hole observers can reorganize this phase, we derive a general constraint on when such ``real observers'' can succeed. By distinguishing \emph{gravitational observers} from \emph{topological spectators}, we show at quadratic semiclassical order that any sector whose \emph{infrared effective} action is metric independent at the de Sitter saddle factorizes in the path integral, $\Ztot = \Zgrav^{(\text{obs})}\Ztop$, so the imaginary phase persists regardless of the sector's information-processing capabilities. Using confining $\SU(3)$ gauge theory and topological orders as examples, we demonstrate that an information-bearing clock is necessary but insufficient: only observers whose fluctuations share the negative modes of the conformal factor belong to the special class that can remove the de Sitter phase.

hep-th↗

arXiv2026

Mass Without Mass from a Berry--Shifted SU(3) Holonomy Rotor

We identify a local, gauge-invariant mechanism that generates a finite spectral scale in pure SU(3) Yang--Mills theory on a punctured three-ball. Fixing a $\mathbb{Z}_3$ center sector isolates a single gauge-invariant holonomy angle whose Berry shift produces a quantum rotor with strictly nonzero level spacing. Gauss law is enforced by a covariant Dirichlet Helmholtz projector built from the Dirichlet inverse of the covariant scalar Laplacian with relative boundary conditions. The slow holonomy mode is chosen variationally as the minimizer of transverse electric energy under the holonomy constraint, yielding an inertia \emph{independent of the gauge representative} with linear domain-size scaling and a controlled commutator-dominated regime. We prove projector stability and derive an adiabatic variational upper bound on the first positive Yang--Mills eigenvalue, with error controlled by the transverse vector gap of the covariant Laplacian on divergence-free one-forms. A femtometer-scale benchmark at realistic coupling gives an upper bound at a hadronic ($\sim 1\,$GeV) scale. In Wilczek's sense this realizes ``mass without mass'': no explicit mass term or Higgs field is introduced, and the nonzero level spacing is fixed by gauge invariance, topology, and the chosen center sector. The present results are derived on a finite domain; interpreting the length $R$ in Minkowski space requires an additional physical input (e.g.\ as a local confinement length), which we make explicit.

hep-th↗

arXiv2026

Relational de Sitter State Counting with an SU(3) Clock

Motivated by Maldacena's observer-centric formulation of de~Sitter physics \cite{Maldacena:2024spf}, we develop an observer-dependent state-counting framework in Euclidean de~Sitter space by modeling the observer as a massive equatorial worldline carrying an SU(3) clock. Starting from the gauge-fixed graviton path integral on $S^D$, we trace the one-loop phase $\ii^{D+2}$ to a finite set of scalar and conformal Killing modes and show that, once the worldline is included, the $(D-1)$ transverse negative modes cancel the corresponding $(D-1)$ conformal Killing directions mode by mode. The residual fixed-$β$ phase from the global conformal factor and reparametrizations is removed by imposing the Hamiltonian constraint $H_{\text{patch}} - H_{\text{clock}} - ν= 0$ via a Bromwich inverse Laplace transform, which under explicit complete-monotonicity assumptions yields a real and positive microcanonical density. We stress that this positivity statement is conditional on Assumptions (A1)--(A3) and is established at one loop about the round $S^D$ saddle in the probe regime $G E_{\rm clock}/R\ll 1$; a self-consistent backreacting or higher-loop extension is a natural next step. In earlier work \cite{Ali:2025wld,Ali:2024rnw} we argued that unbroken SU(3) confinement at $T\to 0$ can account for the observed value of the cosmological constant and for the origin of the fundamental constants $(\hbar,G,c)$ as effective couplings fixed by the SU(3) vacuum structure; this makes SU(3) the natural candidate for the internal clock of de~Sitter, whose radius and temperature are themselves set by the same cosmological constant. This idea is implemented with three explicit SU(3) realizations (qutrit, Cartan weight-lattice, and $U(1)^2$ rotor), for which the observer-inclusive density of states factorizes into a universal gravity factor, a universal worldline residue, and a clock-dependent SU(3) weight.

hep-th↗

arXiv2025

Quantum Spacetime Imprints: The 24-Cell, Standard Model Symmetry and Its Flavor Mixing

In our previous work \cite{FaragAli:2024jpo} we outlined an exploratory framework in which the 24-cell acts both as the quantum of spacetime and as a geometric representation of elementary particles. In this paper we provide comprehensive mathematical and phenomenological evidence that deepens and refines this primary model. The symmetry of the 24-cell yields a unified hypercharge functional that reproduces Standard Model hypercharge assignments while ensuring anomaly cancellation. By projecting the vertices of the 24-cell onto a three-dimensional flavor subspace using a Minimal Distortion Principle, an emergent tetrahedral structure appears that gives rise to an effective $A_4$ symmetry in the neutrino sector. Extending this discrete symmetry to its binary double cover $T^\prime$ provides the spinorial representations and intrinsic complex phases needed to generate realistic quark Yukawa textures. Guided by the tenet that spacetime and matter are inextricably linked, our analysis suggests that the intricate flavor mixing of the Standard Model may be a residual imprint of the underlying quantum-geometric nature of spacetime.

hep-ph↗

arXiv2025

GUP/BEB correspondence

We develop a fully expectation--value formulation of the GUP/Bekenstein--bound (BEB) correspondence, building on \cite{Ali:2024tbd,Ali:2022ckm,Ali:2022ulp}. Using Dirac's commutator--Poisson equivalence, the BEB supplies an information backreaction on the GUP--deformed bracket; at saturation the residual uncertainty in a sector cancels, enabling \emph{operational} simultaneity of conjugate expectations and resolving the EPR tension without hidden variables. A single self-consistency then fixes intrinsic confinement scales: the full (linear$+$quadratic) GUP reproduces the hydrogen Bohr radius (electron) and the proton charge radius (hydrogen nucleus). The same correspondence predicts an information--controlled crossover from a short--distance complex (evanescent) regime to an emergent real (Lorentzian) regime, with a symmetry flow from complex $SU(4)$ frames to $SO(1,3)$; under scale transmutation the short--distance $SU(4)$ is repurposed as the Pati--Salam $SU(4)_c$. Incorporating exterior--field entropy at horizons defines an effective Planck constant consistent with generalized--entropy extremality, tying entropy--area physics directly to the GUP at the expectation level.

gr-qc↗

arXiv2025

Deriving the Cosmological Constant and Nature's Constants from SU(3) Confinement Volume

We explore the interplay between three well-established physical principles: QCD confinement, the Third Law of Thermodynamics, and holography, and examine how their combined implications may shed light on several open problems in fundamental physics. As the Universe cools toward absolute zero, color confinement fragments the vacuum into proton-scale domains. The Third Law, which renders $T = 0$ unattainable and prohibits complete entropy elimination, implies that these domains must persist. This leads to a natural count $N \simeq (R_u / R_p)^3 \sim 10^{123}$, where $R_u$ is the radius of the cosmic horizon and $R_p$ is the proton radius. Assuming holographic saturation, each domain corresponds to a Planck-area patch on the cosmic horizon, allowing the Planck length, and hence $\hbar$, $G$, and $c$, to emerge as geometric quantities. The same tiling dilutes the bare Planck-scale vacuum energy by a factor of $N$, reproducing the observed value of $ρ_Λ$ without requiring fine-tuned counterterms.

gr-qc↗

arXiv2025

At the Edge of Uncertainty: Decoding the Cosmological Constant value with Bose-Einstein Distribution

We propose that the observed value of the cosmological constant may be explained by a fundamental uncertainty in the spacetime metric, which arises when combining the principle that mass and energy curve spacetime with the quantum uncertainty associated with particle localization. Since the position of a quantum particle cannot be sharply defined, the gravitational influence of such particles leads to intrinsic ambiguity in the formation of spacetime geometry. Recent experimental studies suggest that gravitational effects persist down to length scales of approximately $10^{-5}$ m, while quantum coherence and macroscopic quantum phenomena such as Bose-Einstein condensation and superfluidity also manifest at similar scales. Motivated by these findings, we identify a length scale of spacetime uncertainty, $L_Z \sim 2.2 \times 10^{-5}$ m, which corresponds to the geometric mean of the Planck length and the radius of the observable universe. We argue that this intermediate scale may act as an effective cutoff in vacuum energy calculations. Furthermore, we explore the interpretation of dark energy as a Bose-Einstein distribution with a characteristic reduced wavelength matching this uncertainty scale. This approach provides a potential bridge between cosmological and quantum regimes and offers a phenomenologically motivated perspective on the cosmological constant problem.

gr-qc↗

arXiv2024

Generalized Uncertainty Principle from the Regularized Self-Energy

We use the Schrödinger--Newton equation to calculate the regularized self-energy of the particle using a regular self-gravitational and electrostatic potential derived in the string T-duality. The particle mass $M$ is no longer concentrated into a point but it is diluted and described by a quantum-corrected smeared energy density resulting in corrections to the energy of the particle which is interpreted as a regularized self-energy. We extend our results and find corrections to the relativistic particles using the Klein-Gordon, Proca, and Dirac equations. An important finding is that we extract a form of generalized uncertainty principle (GUP) from the corrected energy. The form of GUP is shown to depend on the nature of particles; namely, for bosons (spin $0$ and spin $1$) we obtain a quadratic form of GUP, while for fermions (spin $1/2$) we obtain a linear form of GUP. The correlation we found between spin and GUP may offer insights into investigating quantum gravity.

hep-th↗

arXiv2024

Graviton mass due to dark energy as a superconducting medium: theoretical and phenomenological aspects

It is well known that the cosmological constant term in the Einstein field equations can be interpreted as a stress tensor for dark energy. This stress tensor is formally analogous to an elastic constitutive equation in continuum mechanics. As a result, the cosmological constant leads to a "shear modulus" and "bulk modulus" affecting all gravitational fields in the universe. The form of the constitutive equation is also analogous to the London constitutive equation for a superconductor. Treating dark energy as a type of superconducting medium for gravitational waves leads to a Yukawa-like gravitational potential and a massive graviton within standard General Relativity. We discuss a number of resulting phenomenological aspects such as a screening length scale that can also be used to describe the effects generally attributed to dark matter. In addition, we find a gravitational wave plasma frequency, index of refraction, and impedance. The expansion of the universe is interpreted as a Meissner-like effect as dark energy causes an outward "expulsion" of space-time similar to a superconductor expelling a magnetic field. The fundamental cause of these effects is interpreted as a type of spontaneous symmetry breaking of a scalar field. There is an associated chemical potential, critical temperature, and an Unruh-Hawking effect associated with the formulation.

gr-qc↗

arXiv2024

Modified gravity/entropic gravity correspondence due to graviton mass

Some time ago, it has been suggested that gravitons can acquire mass in the process of spontaneous symmetry breaking of diffeomorphisms through the condensation of scalar fields [Chamseddine and Mukhanov, JHEP, 2010]. Taking this possibility into account, in the present paper, first we show how the graviton mass intricately reshapes the gravitational potential akin to a Yukawa-like potential at large distances. Notably, this long-range force modifies the Newton's law in large distances and might explain the phenomena of dark matter. The most important finding in the present paper is the derivation of a modified Newtons law of gravity by modifying the Verlindes entropic force relation due to the graviton contribution. The graviton contribution to the entropy basically measures the correlation of graviton and matter fields which then reproduces the Bekenstein-Hawking entropy at the horizon. This result shows the dual description of gravity: in the language of quantum information and entropy the gravity can be viewed as an entropic force, however in terms of particles and fields, it can be viewed as a longe range force. Further we have recovered the corrected Einstein field equations as well as the $Λ$CDM where dark matter emerges as an apparent effect.

gr-qc↗

arXiv2024

Theoretical and Observational Implications of Planck's Constant as a Running Fine Structure Constant

This letter explores how a reinterpretation of the generalized uncertainty principle as an effective variation of Planck's constant provides a physical explanation for a number of fundamental quantities and couplings. In this context, a running fine structure constant is naturally emergent and the cosmological constant problem is solved, yielding a novel connection between gravitation and quantum field theories. The model could potentially clarify the recent experimental observations by the DESI Collaboration that could imply a fading of dark energy over time. When applied to quantum systems and their characteristic length scales, a simple geometric relationship between energy and entropy is disclosed. Lastly, a mass-radius relation for both quantum and classical systems reveals a phase transition-like behaviour similar to thermodynamical systems, which we speculate to be a consequence of topological defects in the universe.

physics.gen-ph↗

arXiv2024

A covariant tapestry of linear GUP, metric-affine gravity, their Poincaré algebra and entropy bound

Motivated by the potential connection between metric-affine gravity and linear Generalized Uncertainty Principle (GUP) in the phase space, we develop a covariant form of linear GUP and an associated modified Poincaré algebra, which exhibits distinctive behavior, nearing nullity at the minimal length scale proposed by linear GUP. We use 3-torus geometry to visually represent linear GUP within a covariant framework. The 3-torus area provides an exact geometric representation of Bekenstein's universal bound. We depart from Bousso's approach, which adapts Bekenstein's bound by substituting the Schwarzschild radius ($r_s$) with the radius ($R$) of the smallest sphere enclosing the physical system, thereby basing the covariant entropy bound on the sphere's area. Instead, our revised covariant entropy bound is described by the area of a 3-torus, determined by both the inner radius $r_s$ and outer radius $R$ where $r_s\leq R $ due to gravitational stability. This approach results in a more precise geometric representation of Bekenstein's bound, notably for larger systems where Bousso's bound is typically much larger than Bekensetin's universal bound. Furthermore, we derive an equation that turns the standard uncertainty inequality into an equation when considering the contribution of the 3-torus covariant entropy bound, suggesting a new avenue of quantum gravity.

gr-qc↗

arXiv2024

The Mass Gap of the Space-time and its Shape

Snyder's quantum space-time which is Lorentz invariant is investigated. It is found that the quanta of space-time have a positive mass that is interpreted as a positive real mass gap of space-time. This mass gap is related to the minimal length of measurement which is provided by Snyder's algebra. Several reasons to consider the space-time quanta as a 24-cell are discussed. Geometric reasons include its self-duality property and its 24 vertices that may represent the standard model of elementary particles. The 24-cell symmetry group is the Weyl/Coxeter group of the $F_4$ group which was found recently to generate the gauge group of the standard model. It is found that 24-cell may provide a geometric interpretation of the mass generation, Avogadro number, color confinement, and the flatness of the observable universe. The phenomenology and consistency with measurements is discussed.

hep-th↗

arXiv2024

Could GUP Act as a Model for the ER=EPR Conjecture?

Einstein, Podolsky, and Rosen (EPR) proposed, via a thought experiment, that the uncertainty principle might not provide a complete description of reality. We propose that the linear generalized uncertainty principle (GUP) may resolve the EPR paradox by demonstrating vanishing uncertainty at the minimal measurable length. This may shed light on the completeness of quantum mechanics which leads us to propose an equivalency between the linear GUP and the Bekenstein bound, a bound that prescribes the maximum amount of information needed to completely describe a physical system up to quantum level. This equivalency is verified through explaining the Hydrogen's atom/nuclei radii as well as the value of the cosmological constant. In a recent published study, we verified that the Einstein-Rosen (ER) bridge originates from the minimal length or GUP. Considering these findings together, we propose that linear GUP could function as a model for the ER=EPR conjecture.

quant-ph↗

arXiv2024

Gravitational Observations and LQGUP

Motivated by recent works, we employ the bounds on the dimensionless quantum-gravity parameter obtained from six gravitational tests in order to obtain bounds on the dimensionless parameter of the generalized uncertainty principle with linear and quadratic terms in momentum. The bounds obtained here are much tighter than those obtained, from the same six gravitational tests, for the dimensionless parameter of the uncertainty principle with only quadratic terms in momentum.

gr-qc↗

arXiv2023

Unraveling the mystery of the cosmological constant: Does spacetime uncertainty hold the key?

In addressing the cosmological constant problem, we propose that the discrepancy between the theoretical and observed values can be ascribed to the inherent uncertainty in the spacetime metric. Mach's principle, which posits that mass shapes spacetime, intersects with quantum mechanics' description of a particle as a quantum cloud, rendering the precise location of a particle's mass unknowable. Consequently, understanding spacetime structure at the quantum level becomes elusive. This connection between quantum and spacetime uncertainty could hold the key to resolving the cosmological constant problem. Intriguingly, the length scale of spacetime uncertainty, aligns with the macroscopic quantum weirdness observed in recent experiments. The spacetime uncertainty can be quantified by the scale factor in the Friedmann-Lemaitre-Robertson-Walker (FLRW) universe.

gr-qc↗