Data gaps in Physics

Representative open questions

Showing 30 of 39 — one per source paper, highest-quality first.

• Works for 4/24/2026 - Nicolas of Cusa (2026) · doi

  The structural non-equivalence test uses only five independent runs with identical initial condition classes (constant baseline plus two sinusoidal modes plus Gaussian perturbation plus small noise). Robustness of tau ordering under broader parametric variation in initial conditions, boundary perturbations, and functional form of D(x) and D(t) has not been systematically characterized.

• Entanglement entropy as a probe of topological phase transitions (2026) · doi

  While excellent agreement was achieved between ΔSA and analytical phase boundaries for binary disorder (P=1/2 and P=1/3), the behavior under continuous disorder distributions and correlated disorder patterns (e.g., power-law or exponential correlations in hopping terms) has not been explored.

• QUEST: Quasar unsupervised encoder and synthesis tool. A machine-learning framework for generating quasar spectra (2026) · doi

  The limited wavelength coverage (rest-frame UV to optical) in the VAE training prevents the model from capturing physical correlations between rest-frame UV and optical properties across redshift bins; inclusion of NIR data from Euclid (1.21–1.89 µm, R ∼ 450) could address this spectral baseline gap.

• Multimessenger flare in the quasar PKS 0446+11 (2026) · doi

  The multimessenger flare observations of PKS 0446+11 lack simultaneous high-cadence monitoring across radio, optical, X-ray, and neutrino channels during the entire flaring episode. Future coordinated campaigns should establish continuous coverage protocols for blazar jets to constrain the temporal correlation between gamma-ray emission and neutrino detection in quasars.

• Quantum skyrmions and high dimensional entanglement mediated by nanophotonics (2026) · doi

  The quantum state tomography (QST) for high-dimensional entanglement mediated by the nanophotonic platform requires projection onto two different polarization components using waveplates, but the complete characterization of all degrees of freedom (DoF) in the quantum skyrmion states—including both SAM and OAM contributions—and their mutual coherence properties remain incompletely specified.

• Quantum ground-state cooling of two librational modes of a nanorotor (2026) · doi

  The optomechanical coupling strength is determined from cavity-detuning scans and optical spring effect measurements for both 1D and 2D cooling scenarios, but the paper does not specify how these methods perform under different particle volume regimes or with varying susceptibility tensor anisotropy ratios that might affect the coupling constants kα and kβ.

• The elusive cyclotron line in 4U 1901+03: Hidden, yet present (2026) · doi

  The limited statistics above 40 keV prevented testing whether the cyclotron line energy (Ecyc) exhibits luminosity-dependent variation as observed in other accreting neutron star systems. High-energy spectroscopy with improved sensitivity above 40 keV is needed to determine if 4U 1901+03 follows the luminosity-dependent CRSF behavior pattern reported for sources like V 0332+53 and A 0535+262.

• Applications of materials with high cleavage power and quantum efficiency for water treatment (2026) · doi

  The paper reports that excessive catalyst concentrations cause aggregation and limit light availability, reducing photocatalytic effectiveness, but provides no quantitative analysis of the aggregation phenomenon, particle size distribution changes, or light absorption spectra as catalyst dose increases beyond the optimal 3 mg threshold.

• Neodymium Doped Copper Ferrite Nanocomposites as an Effective Magnetic Catalyst for the Organic Dyes Decomposition (2026) · doi

  The photocatalytic degradation was evaluated only under H2O2-assisted conditions with a single light source intensity. Systematic investigation of reaction kinetics under varying H2O2 concentrations, pH values, initial dye concentrations, and light wavelengths (UV vs. visible spectrum) would establish the operational parameter space and generalizability of the Langmuir–Hinshelwood pseudo-first-order kinetic model across different treatment conditions.

• Dark photon dark matter constraints at the Taiwan Axion Search Experiment with Haloscope (2026) · doi

  The conversion factor calculation assumes isotropic sampling of dark photon polarization directions (θX, ϕX) averaged over discrete scan intervals, but the sensitivity to dark photon polarization states that occur during time gaps between scans (particularly those exceeding 40 minutes) is not quantitatively assessed. Investigation of temporal sampling bias in polarization-dependent detection efficiency would clarify systematic uncertainties.

• Light-induced bimerons in a chiral magnet (2026) · doi

  While the paper demonstrates tuning of laser-induced bimeron density through applied magnetic fields, the quantitative relationship between applied field strength, bimeron nucleation rate, and topological charge distribution during femtosecond laser excitation is not systematically characterized.

• Evidence for odd-parity superconductivity underpinned by antiferromagnetism in heavy-fermion metal YbRh2Si2 (2026) · doi

  Microstructuring of YbRh2Si2 (ref. 52) and strain tuning via tension/compression (ref. 53) have been developed as tools to manipulate superconductivity, but their combined effects on the spatially modulated magnetic state and odd-parity pairing have not been investigated. Systematic studies coupling device engineering with control of the antiferromagnetic and hyperfine-driven quantum critical point are needed.

• The LOFAR sub-arcsecond view of the high-redshift radio relic in PSZ2 G091.83+26.11 (2026) · doi

  The radio relic power-cluster mass correlation for high-redshift systems (z > 0.6) is currently constrained by only three known clusters; establishing the correlation robustly requires significantly expanding the sample of high-redshift radio relics detected in galaxy clusters to mitigate observational biases including Malmquist bias and projection effects.

• "G-D's Physics" New Twenty-First Century's Paradigm's Resolution of "GRTQM's Theoretical Inconsistency", "Gravitational Enigma" & "Hubble's-Tension"! (2026) · doi

  The paper predicts specific mass increases (1 gram Uranium → 1.000968 km s⁻¹ Mpc grams by Sep. 13, 2026) tied to JRH cycles, but does not specify whether this MAI applies uniformly to all matter types and isotopes, how isotopic composition affects the predicted increase, or whether the formula requires adjustment for different chemical elements or molecular structures.

• Fine and hyperfine interactions with multi-level spin relaxation of the purified Giese-salt in veterinary medicine: Prussian blue compound ammonium-ferric-hexacyano-ferrate (2026) · doi

  The discrepancy between macroscopic particle sizes observed in light and electron microscopy (micrometer magnitude) and the XRD-estimated crystal size of D ≈ 19.1 nm ± 2.3 nm in AFCF has been attributed to agglomeration via weak interactions, but the bonding mechanisms and structural organization of these nano-clusters remain uncharacterized; detailed small-angle X-ray scattering (SAXS) analysis combined with magnetic force microscopy is needed to map the hierarchical structure of these agglomerates.

• Physics at the Bulgarian Academy of Sciences (1946–1988) (2023) · doi

  Research on electrical, optical and magnetic properties of crystals grown via the three different techniques is mentioned as one of four research groups, but specific experimental protocols, measurement conditions, or comparative property datasets for crystals produced under varying raw material conditions in hydrothermal growth apparatus are not detailed.

• Terrestrial matter effects on reactor antineutrino oscillations: constant vs. fluctuated density profiles (2026) · doi

  The study assumes matter density can be described by piecewise-constant profiles with moderate segmented fluctuations (±10%), which may not capture all complex geological structures along the JUNO baselines.

• Relativistic 56Ni decay lines in GRB 221009A (2026) · doi

  Current MeV neutrino detectors such as Super-Kamiokande and JUNO have sensitivities of roughly 10^-5–10^-4 erg cm^-2 s^-1 for short-duration bursts, which are insufficient to detect the predicted neutrino flux from GRB 221009A.

• Hyper-dimensional computing for enhanced label-free particle analysis in a flow-based optical detection system (2026) · doi

  The study employed only four types of polystyrene microparticles with distinct diameters (9, 12, 16, and 20 µm); evaluation on a broader range of particle sizes and material compositions is needed.

• Size and Magnetization Control of Magnetite NPs via Ethylene Glycol and Temperature for Ferrofluid and Magnetotargeting: Model Experiments (2026) · doi

  The study only tested magnetic field inductions ranging from 0.03 to 0.4 T; investigation of stronger magnetic fields or field gradients is not covered.

• Ultrathin Quarter-Waveplates Based on Two-Dimensional Anisotropic NbOCl2 (2026) · doi

  Long-term environmental stability and degradation mechanisms of NbOCl2 waveplates under exposure to moisture, oxygen, and UV radiation need to be characterized.

• The Plasma Observatory Synergies and Additional Science Working Group (2026) · doi

  Multipoint observations of ULF, EMIC, chorus, and whistler-mode waves will enable direct in-situ identification of acceleration, transport, and loss processes of energetic particles.

• Recent progress in low energy neutrino scattering physics and its implications for the standard and beyond the standard model physics (2024) · doi

  Inelastic CC and NC neutrino-nucleus scattering processes lack precise cross section knowledge, and the uncertainty on inelastic neutrino-argon cross sections will limit DUNE's capabilities for supernova neutrino detection.

• On the Temporal Tweezing of Cavity Solitons (2024) · doi

  The current analysis is limited to specific parameter ranges (0 < β < 20 with τf ≲ 4); behavior outside these ranges and for other system parameters requires investigation.

• Precision physics with the proton spectrometer and diffractive physics measurements from CMS (2024) · doi

  No signal was found in the Z + X and γ + X production searches, and this model-independent analysis will clearly benefit from higher luminosity at the LHC.

• Standardized extraction of optical band gap and urbach energy in zno and al-doped zno thin films from uv–vis spectra: an in-silico workflow (2026) · doi

  Results are based on synthetic spectra and simplified optical assumptions; absolute values should be interpreted as method-demonstration outputs rather than definitive material constants.

• Eco-sustainable magnetoresistive sensors towards disposable magnetoelectronics (2026) · doi

  The residence time of particles in water during recycling was kept below 1 hour; the effect of longer water exposure times on particle degradation and sensor performance is not systematically investigated.

• Evolution of topological charge in a triangular interference lattice (2026) · doi

  Data underlying the results are not publicly available at this time but may be obtained from authors upon request, limiting reproducibility and open science practices.

• Phase-selective sol–gel auto-combustion synthesis of γ-Fe2O3 and Fe3O4 nanoparticles (2026) · doi

  The lattice parameter expansion observed in nanoparticles compared to bulk values is attributed to structural defects, but the specific nature, concentration, and distribution of these defects are not directly characterized or quantified.

• Collective excited states at small amplitude in neutron elastic scattering at low-energies (2026) · doi

  This work aims to build a new generation of optical potential which can unify nuclear structure and nuclear reactions to study the exotic nuclei region, where experimental data are limited.