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Open research questions in Cosmology and Gravitation Theories

76 unresolved questions extracted from the limitations and future-work sections of 816 Cosmology and Gravitation Theories papers in our library. Each links back to the study that raised it.

What the literature leaves open

  • In this work, we have developed a systematic construction of spherically symmetric and static traversable wormholes sustained by exotic matter distributions inspired by dark matter halos. Adopting the polytropic n = 1 energy density profile as a physically motivated input, we derived the associated shape function b(r) and obtained explicit expressions for the radial and tangential pressures. The geometric requirements at the throat, in particular the flare-out condition and the absence of event horizons, were implemented consistently, leading to well-defined constraints on the free parameters of the model. A central result of our analysis is that zero-tidal force configurations can be realized through suitably chosen inhomogeneous equations of state. In this setting, the redshift function remains finite throughout the spacetime, ensuring the traversability of the wormhole geometry. Moreover, by extracting candidate redshift profiles directly from the structure of the third Einstein field equation, we demonstrated how analytic ansatze for (cid:3)(r) can be systematically tested against physically meaningful boundary conditions. This procedure makes explicit the delicate interplay between geometry and matter content, showing that seemingly admissible redshift functions may fail once the full set of constraints is enforced. Particular attention was devoted to the implementation of boundary conditions at a finite radius r = R, interpreted as the edge of the dark matter halo. Requiring the energy density and pressures to vanish smoothly at this boundary not only ensures physical consistency, but also provides a natural infrared cutoff for otherwise unbounded analytic redshift profiles. The asymptotic expansions of the pressures and metric functions near r = R further clarified the behavior of the matter sector in the transition region between the exotic interior and the exterior vacuum spacetime. An important conceptual outcome of this work is the reformulation of the Einstein field equations entirely in terms of the energy density, radial and tangential pressures, and their derivatives. This matter-driven perspective partially decouples the analysis from the explicit metric functions and yields a flexible framework for exploring a broad class of exotic sources. In particular, it allows one to start from physically motivated density profiles and reconstruct the corresponding geometry in a controlled and systematic way. The framework developed here naturally suggests several avenues for further investigation. A first extension concerns dynamical wormhole configurations, where time–dependent dark matter profiles could be incorporated to analyze stability, formation mechanisms, and possible evolutionary scenarios. Such a generalization would provide insight into whether these geometries can arise dynamically in realistic Fig. 4 ω for Proposal III ((cid:3)(cid:2) ∝ sin(x + D)/x) with x0 = 0.1, P = 0.5.

    Traversable wormholes induced by polytropic $$n=1$$ energy density · 2026 · DOI

  • And NGC 1277 — with a hyperdense bulge but compact radius — constitutes the critical exception that validates the model: a very high DUT Factor does not guarantee a high fDM if the galactic radius is insufficient to create a gradient.

    Decreasing Universe Theory: Dark Matter X Gravitational Gradient · 2026 · DOI

  • This remains a working diagnostic, not a confirmed result; the full high-ell CMB likelihood, Monte Carlo boundary calibration, and a proper MCMC (now planned with DESY5/Pantheon+/Union3 as co-equal supernova sets) remain to be done.

    Anatomy of the DESY5 preference for a single-mass thawing scalar: calibrated significance, cross-calibration degeneracy, and growth consistency · 2026 · DOI

  • Potential expansions include: ▪ Mathematical modelling of vacuum-wave interference ▪ Diagrammatic representations of mixed-phase domains ▪ Exploration of flavour-stress curvature ▪ A companion paper on vacuum-wave effects on black and white holes This framework opens a new frontier for speculative cosmology and theoretical development.

    Vacuum Wave Cosmology: A Multi‑State Framework for Dynamic Universal Structure · 2026 · DOI

  • Future work should focus on confronting the models with observational datasets (Planck 2018, BAO, Pantheon+), exploring alternative cutoffs or entropy generalizations to alleviate instability, and employing dynamical system analyses to rigorously assess their viability as cosmological scenarios.

    The Cosmological Dynamics of Tsallis Holographic Dark Energy in Saez-Ballester Gravity · 2026 · DOI

  • The entropy-inspired metric presented here is intended only as a first approximation. Several important questions remain open. 1. Derive the coherence functional directly from first principles. 2. Determine the correct relationship between entropy and informational coherence. 3. Replace the present observational proxy with a physically derived order functional. 4. Investigate whether coherence should be measured using finite-resolution integration governed by the informational coupling scale rather than infinitesimal calculus. 5. Extend the comparison against additional fixed dark matter halo models and independent observational catalogs. Ultimately, the objective is to derive a universal coherence functional whose form follows directly from statistical mechanics and informational geometry rather than empirical approximation.

    Toward a First-Principles Measure of Galactic Coherence · 2026 · DOI

  • Despite decades of intense experimen- tal effort, direct detection of dark matter particles (such as WIMPs or axions) remains elusive, and the theoretical justification for the observed magnitude of the cosmological constant suffers from a discrepancy of over 120 orders of magnitude compared to quantum field theory predictions.

    5D Holographic Cosmology · 2026 · DOI

  • Paper 62BD formulates the effective field-equation bridge. It does not derive G, close the action principle, solve all nonlinear correction dynamics, or complete all-order GR, Kerr, black-hole thermodynamics, numerical relativity, or gravitational-wave phenomenology. 8.10 Falsifier recap The falsifier structure is direct. The paper fails if the effective geometry cannot be defined: geff µν or Geff µν undefined. It fails if the support-source tensor cannot be defined: T support µν undefined.

    Paper 62BD: Effective Field Equations of Holosphere Gravity From the Conventional Einstein Tensor and Bianchi Target to a Support-Source Tensor, Correction Ledger, and Readability-Gated GR-Limit Field Equation · 2026 · DOI

  • In summary, even with reasonably accurate pa- rameter reconstruction, the limited knowledge of fNL can substantially weaken LISA’s ability to measure fPBH.

    The impact of non-Gaussianity when searching for Primordial Black Holes with LISA · 2026 · DOI

  • The origin of cosmological distance tensions remains a central open question in precision cosmology, complicated by the fact that most consistency tests between datasets cannot isolate which physical assumption is responsible for an observed discrepancy.

    The cosmic tetrarchy: four estimators breaking the assumption degeneracy in cosmological distance tensions · 2026

  • By extending the <ns0:monospace>pyGenISW</ns0:monospace> package, previously limited to the Lambda cold dark matter (ΛCDM) model, we aim to generate full-sky ISW maps for a suite of 791 wCDM cosmologies using the Gower Street N-body simulations, enabling ISW analyses across a broader dark-energy parameter space.

    Integrated Sachs–Wolfe maps from the Gower Street · 2026 · DOI

  • In the scale-breaking case g ̸= 0, it remains unclear if the cancellation persists, we therefore choose to assume a sufficiently large mass to ensure IR convergence.

    Every wrinkle carries a memory: an integro-differential bootstrap for features in cosmological correlators · 2026 · DOI

  • In this work, we extended the model of spontaneous baryogenesis considering two different scenarios. Firstly, we introduced a non-minimal coupling term between gravity and the inflaton. We showed that this term significantly enhances baryogen- esis, and accordingly the model can reproduce the experimental value of the baryon asymmetry. Then, we considered a complex scalar spectator field non-minimally coupled to gravity and through a biquadratic interaction to the inflaton. Also in this case, we obtained a remarkable improvement in terms of baryon asymmetry, but not sufficient to reproduce cosmological observations. Future works comprehend further extensions of the spontaneous baryogenesis framework, such as including the electromagnetic sector through a coupling with the inflaton. Another intriguing possibility is the introduction of a disformal non- minimal coupling between inflaton and gravity, as a generalization of the conformal one studied in this work. It would also be worthwhile to replace the complex scalar spectator field with a fermion, to evaluate its impact on baryogenesis. Lastly, a more realistic treatment of spontaneous baryogenesis would incorporate quantum chromodynamics, possibly unveiling new mechanisms of asymmetry generation.

    Impact of spectator fields and non-minimal couplings in spontaneous baryogenesis · 2026 · DOI

  • A full continuum-limit analysis, covariant 4-tensor relaxation of all βµν components, and direct cosmological evolution within FRW backgrounds remain to be implemented.

    Emergent Elastic Screening and First-Principles Matching Coefficients in an Elastic Vacuum Theory · 2026 · DOI

  • We have constructed a minimal effective scalar-field theory for a coherent spacetime substrate and shown that its linear-response weak-field limit reproduces Newtonian gravity. The construction rests on three ingredients: a canonical kinetic term and self-interaction potential for the substrate density field, written with respect to an auxiliary hydrodynamic reference metric; an effective metric with conformal and disformal sectors through which standard matter couples universally to the substrate; and an infrared matching condition by which the leading long-wavelength dynamics of the emergent metric reduces to the Einstein–Hilbert form. The principal technical result is the Newtonian calibration condition 𝛤(cid:2868) 𝜆(cid:3040) = 4𝜋𝐺. This relation expresses Newton’s constant as the macroscopic product of two distinct substrate-response coefficients: 𝜆(cid:3040) measures how efficiently baryonic matter sources the substrate density perturbation, and 𝛤(cid:2868) measures how efficiently substrate gradients accelerate matter. Section 4.5 has shown that this decomposition is not a free phenomenological splitting of 𝐺: a benchmark constitutive closure relating the conformal coupling 𝐴(𝜌) to the substrate free-energy density ℱ(𝜌) of the companion thermodynamic foundation maps both response coefficients to microscopic parameters of the substrate (𝜖(cid:3002) and 𝐾), with the calibration condition fixing one combination of these parameters. The principal conceptual result is the identification of the substrate-level Newtonian potential −𝛤(cid:2868) 𝛿𝜌 with the infrared metric Newtonian potential 𝛷(cid:2915)(cid:2916)(cid:2916). The matched framework therefore does not produce a doubled Newtonian response, but a single one expressed in two equivalent descriptions — under the matching prescription of Eq. (58), which we have characterized explicitly as a prescription rather than as a derived theorem. The logical status of the assumptions, derivations, matching prescriptions, and deferred components has been summarised in Table II (Section 7.5). The framework is honest about what it has not established. It has not derived general relativity from the microscopic substrate. The Einstein–Hilbert sector is introduced as an infrared matching condition, not as a derivation, and its coefficient is fixed by Newtonian calibration rather than computed from substrate microphysics. The conformal coupling 𝐴(𝜌), the disformal coupling 𝐵(𝜌), the dynamical effective potential 𝑈(𝜌), and the kinetic stiffness 𝐾 are constitutive functions whose explicit forms must ultimately be supplied by the microscopic statistics of the substrate.

    Spacetime Densification Theory and the Newtonian limit · 2026 · DOI

  • Higgs-Elastic Cosmology provides a unified mechanism for: • cosmic cycles • entropy reset • black-hole thermodynamics • time dilation • matter distribution • the finite volume of the universe It resolves several open problems in standard cosmology, including the low-entropy Big Bang, the role of black holes in cosmic evolution, and the nature of singularities.

    Higgs-Elastic Cosmology · 2026 · DOI

  • Two open problems remain (Tkemaladze, 2026f): 1. Derivation of the metric combination rule outside the limit p₁ → 0, p_j = 0.5 — a full Ze field theory. 2. First‑principles calculation of δZ_e ∼ 6×10^{−7} from a Ze electroweak model. If these succeed, Ze cosmology will move from a phenomenological alternative to a candidate fundamental theory.

    Beyond the Big Bang · 2026 · DOI

  • 1. The reconstruction is diagnostic and numerical; it is not a first-principles derivation. 2. The relation depends on the empirical slopes 4 and 3. 3. The assignment of the normalization channel to exponent 2 is framework-motivated but not independently derived here. 4. The expression fb = 2 mological dynamics. √ e/21 matches observation but is not derived from standard cos- 5. The condensation ladder mixes weak-field galaxy quantities and strong-field black-hole landmarks; this is useful diagnostically but not automatically dynamical. 6. The note does not perform a new fit to the baryonic mass–halo mass data. 7. The physical substrate of the residual channel remains open.

    The Gravitational Condensation Ladder: Geometric Origin of the Baryonic Mass–Halo Mass Turnover Scale · 2026 · DOI

  • Several tests and extensions follow naturally. 1. Refit the baryonic mass–halo mass relation using the normalized residual variable bM = 1 − Mb/M200 fb.

    The Gravitational Condensation Ladder: Geometric Origin of the Baryonic Mass–Halo Mass Turnover Scale · 2026 · DOI

  • Determination of E0 and Smin. The universal particle field energy E0 and the minimum sustainable field value Smin are new constants of nature in est. Their values must be determined from experiment or from a deeper theory connecting est to the Standard Model. 2. Strong-field regime. The nonlinear field equation (8) must be solved numerically for compact objects (neutron stars, black holes) to produce testable predictions for X-ray binaries, pulsar timing, and gravitational-wave waveforms. 3. Binary pulsar orbital decay. The rate of energy loss by gravitational radiation in est must be computed and compared with the Hulse–Taylor pulsar observations [Taylor & Weisberg, 1982], which match gr to 0.2%. 4. Light deflection in strong fields. The photon equation of motion (25) must be solved exactly (not in the weak-field limit) for the Schwarzschild analogue in est. 17 5. Shapiro time delay. The delay of radar signals passing through a strong spatial field should be computed and compared with Viking lander measurements. 6. Quantum structure of spatial particles. The connection between the fundamental spatial particles of est and the quarks and gauge bosons of the Standard Model requires development. 7. Cosmological implications. The expansion of the universe, the cosmic microwave background, and structure formation must be re-examined within est’s framework, which rules out both dark matter and dark energy. 8. Black hole mass measurements. est predicts M MilkyWay ≈ 2.2 × 1011M⊙, far exceeding current estimates. New observational constraints on the mass distribution of galactic nuclei are needed.

    Energetic Space Theory (EST) A Scalar Field Framework for Gravitational Interaction, Relativistic Phenomena, and Galaxy Dynamics Without Dark Matter · 2026 · DOI

  • 1. The framework re-expresses known equations; it does not replace their physical derivation. 2. The equation-of-state parameters wi are supplied by cosmological physics, not by the par- tition geometry. 3. The factor 3 comes from spatial volume scaling, not from the Thales partition identity. 4. Padmanabhan degree counts and Friedmann density fractions are different partitions and should not be merged into one simplex without additional physical justification. 5. The replicator form is mathematical. It does not imply biological selection or agency.

    Cosmological Density Evolution as Replicator Dynamics: Pairwise Coupling Flows on the Friedmann Simplex · 2026 · DOI

  • The framework is scalar and diagnostic, not tensorial and dynamical. 2. It does not derive the Einstein field equation. 3. It does not prove thermodynamic gravity. 4. It does not identify Rpart with physical entropy. 5. It does not claim C = 1/2 is a horizon or stability boundary. 6. Cosmic-web results are pilot diagnostics and require further statistical validation. 7. Connections to Padmanabhan, Jacobson, and Verlinde remain interpretive unless tied to explicit physical degrees of freedom.

    Compactness, Coupling Density, and Entropy-Like Organization on the Thales Partition Manifold: A Conservative Scalar Diagnostic for Equipartition, Horizon Response, and Cosmic-Web Local Modes · 2026 · DOI

  • The paper should explicitly exclude the following: • superluminal travel claims, • warp-drive language, • zero-inertia claims, • any dimensionally inconsistent energy formula, • engineering-frequency tables, • phase-locking analogies, • statements that an observational residual would confirm substrate manipulability. These ideas may exist in a separate speculative notebook, but they weaken the professional paper. The present manuscript is a phenomenological gravity paper, not an engineering proposal.

    Effective Torsion Phenomenology from an Informational-Substrate Interpretation · 2026 · DOI

  • 2 What Remains to Be Done The honest accounting of what remains to be done is as important as the accounting of what has been accomplished. The relationship between the field accumulation mechanism and the Higgs mechanism is an open question that this paper does not resolve — except to suggest, in Section 10.

    A Field-Based Machian Mechanism for Variable Mass, Inertia, and Cosmological Evolution · 2026 · DOI

  • تسبنب کیزیر کیسلا: ننادنز ناسون بلص (Rigid Oscillation Limit) کیزیف ۱۶۱ نویساآ ار کی نادیم یاهدخن (Scalar Field) ار مخج تراث $m$ دنیبیم ها قبا هلداعم نیلا- نودروگ ناسون دنکیم: $$\left[ \square - m^2 \right] \phi = 0 \implies \text{Conclusion: Classic models are limited by a fixed } m \text{ that cannot adapt to local galactic entropy.

    James Webb (JWST) Numerical Data in 100 Scenarios of This Article Showed That Current Physics Equations Are Only an Incomplete Approximation In Low Dimensions(4D). Hamzah Equation, By Integrating Field, Metric, and Stress Core, Matches Its Outputs With 99.28 % Accuracy and 0.72% Error to Cosmic Reality. With 1155-Dimensional Tensor Mechanics, Hamzah Equation · 2026 · DOI

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76 open questions have been extracted from the limitations and future-work passages of 816 Cosmology and Gravitation Theories papers in our library. Each one below links back to the study that raised it, so you can read the original claim in context.

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