Sources and scope

What this edition is

This is a pedagogical starting collection for investigation, checked against selected literature on 12 September 2026. It contains 16 chapters, 80 new question prompts, a reading map, an investigation guide, a glossary, and a browser notebook. It does not claim to catalogue every important unsolved problem or certify that every suggested extension is novel.

The chapters distinguish observed phenomena, inference under a model, exact toy results, approximations, numerical evidence, and conjectural mechanisms. The “first investigation” in each chapter is an editorial recommendation about a useful entry calculation. It is not a claim that the calculation is unpublished, sufficient to solve the parent problem, or guaranteed to become a paper.

How sources were used

The links below were checked through primary publication or preprint records, collaboration pages, and official problem statements. Source inspection comprised records and abstracts, with selected technical passages and the current collaboration statement for the recent LZ result. This is not a line-by-line technical review of every cited paper. Author reviews are identified as such and used to enter a subject; they are not presented as original experiments.

The explicit elementary calculations in the chapters were developed as pedagogical derivations, and the supplied figures are generated from their stated models. A source link next to a status claim supports that particular claim; it does not imply that the source proves every proposed extension on the page. The numerical illustrations are not simulations of actual black holes, cuprate samples, or the universe.

Recent results that affect the wording

• Dark matter: the LZ collaboration's 1 September 2026 extended-recoil preprint reports an unusual event and $2.6$-standard-deviation global tension with its specified background model. It is treated as an anomaly requiring follow-up, not a confirmed detection. [12]
• Dark energy: DESI DR2's 2025 evolving-dark-energy preferences depend on the datasets and parametrization. A subsequent 2026 joint clustering-shape and distance analysis is included to keep the dependence on data combinations and statistical treatment visible. [8] [9]
• Neutrinos: KATRIN's 259-day bound, the 2025 T2K–NOvA joint analysis, and JUNO's first oscillation result are tied to their stated datasets. The text does not turn a parameter improvement into an established mass ordering or a CP discovery. [20] [21] [22]
• Mathematical problems: the current official Clay statements retain the unsolved status of four-dimensional Yang–Mills existence and mass gap and of the specified three-dimensional Navier–Stokes regularity problem. [28] [34]

Older experimental references, such as the BICEP/Keck tensor benchmark and neutron electric-dipole measurement, are explicitly dated. They explain the type of evidence and do not purport to be an exhaustive survey of the newest bounds. Likewise, a 2013 naturalness discussion is used for its conceptual argument, not current collider exclusions.

The supplied cuprate document

The file in reference/cuprate-problem-original.html is an unchanged copy of the supplied high-temperature-superconductivity project document. It is a precedent and an additional research input, not a newly validated chapter. Its strong mechanism claims, material comparisons, and proposed computations need their own artifact- and source-based assessment when pursued. No changes were made to the original project.

The new superconductivity chapter provides an independently scoped entry. In particular, an exchange energy, small-cluster pair binding, pairing-channel preference, stiffness bound, and thermodynamic superconducting state are treated as different statements.

Local use and the investigation record

Open index.html to begin. The new pages, equation renderer, styling, and figures are local; they do not need an internet connection. External literature links do. The unchanged reference copy retains its original external font and equation-renderer links, so its rendering can depend on internet access.

Notes entered in the question bank are stored in the current browser for this origin. Browser policies for local files differ, and moving or opening the folder through another address can create a separate notebook. Export the notebook before moving it or changing browsers. Import merges notes while preserving existing entries. No notes are sent to a server by this collection.

The Print / save PDF control prints the current chapter or companion page. Editable Markdown sources are in the content folder. Rebuilding the HTML replaces the generated pages but does not alter the original reference or a browser's saved notebook. The included README describes rebuilding and figure generation.

How the collection should grow

When a question is pursued, add its result and the evidence needed to reproduce it. Record corrected claims and failed routes rather than deleting their history. Expand a chapter when a strategic question requires deeper machinery, or create a new page when a distinct physical problem deserves an independent explanation. A useful expansion ends with a sharper question and a reason that answering it matters.

All linked sources

• [1] Donoghue (1994), General relativity as an effective field theoryRead for the separation of predictable long-distance quantum corrections from unknown short-distance coefficients.
• [2] Maldacena (1997/1998), The Large N Limit of Superconformal Field Theories and SupergravityRead for the proposed gauge/gravity duality and its specific boundary conditions and theories.
• [3] Bose et al. (2017), A Spin Entanglement Witness for Quantum GravityA proposed experiment. Identify the assumptions about mediation and the distinction between witnessing entanglement and identifying a complete theory.
• [4] Page (1993), Average Entropy of a SubsystemThe random-state benchmark; a kinematic calculation, not an evaporation dynamics.
• [5] Penington (2019/2020), Entanglement Wedge Reconstruction and the Information ParadoxRead for the entropy transition and the conditions on interior reconstruction in a holographic setting.
• [6] Almheiri et al. (2020/2021), The entropy of Hawking radiationAuthor review explaining generalized entropy and islands; use its derivations to enter the original research literature.
• [7] Martin (2012), Everything You Always Wanted To Know About The Cosmological Constant ProblemTechnical review of regularization and renormalization; particularly useful for correcting the naive cutoff story.
• [8] DESI Collaboration (2025), DR2 Results II: BAO measurements and cosmological constraintsOriginal collaboration inference. Keep the data combination and the two-parameter dark-energy model attached to every significance.
• [9] Cosmological constraints from a joint DESI DR1 Full-Shape and DR2 BAO (2026)A subsequent analysis combining clustering shape with BAO; illustrates dependence on the information included and statistical treatment.
• [10] Planck Collaboration (2018/2020), VI. Cosmological parametersThe baseline cosmological parameter inference. Read the model assumptions before using numerical constraints.
• [11] Clowe et al. (2006), A direct empirical proof of the existence of dark matterOriginal Bullet Cluster lensing analysis. Distinguish the measured spatial offset from stronger model-independent claims about all conceivable gravity theories.
• [12] LZ Collaboration (1 September 2026), Extended nuclear-recoil energy searchCollaboration preprint: one unusual high-energy event, global background-only tension of 2.6 standard deviations; not a discovery.
• [13] Hall et al. (2009/2010), Freeze-In Production of FIMP Dark MatterA concrete production mechanism for particles that never equilibrate; compare its coupling dependence with freeze-out.
• [14] Planck Collaboration (2018/2020), X. Constraints on inflationOriginal constraints on primordial perturbations; separate what is measured from the inflationary interpretation.
• [15] BICEP/Keck XIII (2021), Improved Constraints on Primordial Gravitational WavesA dated tensor benchmark, with foreground and cosmological assumptions; not labelled the latest limit in this collection.
• [16] Maldacena (2002/2003), Non-Gaussian features of primordial fluctuations in single field inflationary modelsThe three-point calculation and its squeezed-limit consistency relation under specified single-field assumptions.
• [17] Sakharov (1967), Violation of CP Invariance, C asymmetry, and baryon asymmetry of the universeOriginal conditions for dynamical asymmetry generation in the usual local, CPT-invariant setting.
• [18] Kajantie et al. (1996), Is There a Hot Electroweak Phase Transition at large Higgs mass?Nonperturbative evidence that the first-order transition ends before the observed Higgs-mass regime.
• [19] Buchmüller, Di Bari and Plümacher (2004/2005), Leptogenesis for PedestriansA worked kinetic treatment of production and washout. Bounds inherit the particular thermal leptogenesis assumptions.
• [20] KATRIN Collaboration (2024/2025), Direct neutrino-mass measurement based on 259 days of dataA laboratory bound on the effective electron-antineutrino mass, not on each mass separately.
• [21] T2K and NOvA (2025), Joint neutrino oscillation analysisCombined ordering and CP-phase inference; neither a universal ordering determination nor an unconditional CP discovery.
• [22] JUNO Collaboration (2025/2026), First measurement of reactor neutrino oscillationsFirst oscillation measurements with 59 days of data; precision on solar-sector parameters does not itself determine the mass ordering.
• [23] ATLAS Collaboration (2012), Observation of a new particle in the search for the Standard Model Higgs bosonDiscovery evidence anchoring the electroweak-scale question; not a source for current coupling precision.
• [24] Giudice (2013), Naturalness after LHC8Conceptual discussion of naturalness. Its experimental status is historical; no old exclusion is presented as current here.
• [25] Peccei and Quinn (1977), CP Conservation in the Presence of PseudoparticlesThe original dynamical symmetry mechanism behind the axion solution.
• [26] Abel et al. (2020), Measurement of the permanent electric dipole moment of the neutronA dated null measurement constraining strong CP violation; translating it to a theta bound requires hadronic input.
• [27] Wilson (1974), Confinement of quarksLattice gauge theory and its strong-coupling area law; the continuum-limit difficulty is part of the lesson.
• [28] Clay Mathematics Institute, Yang–Mills and the Mass GapOfficial statement and current unsolved status of the mathematical construction problem.
• [29] Borsányi et al. (2014/2015), Ab initio calculation of the neutron-proton mass differenceAn example of quantitative lattice success; computing observables and proving continuum existence are different achievements.
• [30] Schlosshauer (2003/2005), Decoherence, the measurement problem, and interpretations of quantum mechanicsRead for exactly which parts of the measurement problem decoherence addresses.
• [31] Bassi et al. (2012/2013), Models of Wave-function Collapse, Underlying Theories, and Experimental TestsExplicit modifications of quantum dynamics and observable consequences; distinguish models from interpretations.
• [32] Hensen et al. (2015), Loophole-free Bell inequality violation using electron spinsOriginal Bell-test evidence, with locality and measurement-setting assumptions; it does not select a measurement interpretation.
• [33] Rigol, Dunjko and Olshanii (2007/2008), Thermalization and its mechanism for generic isolated quantum systemsConcrete evidence for eigenstate thermalization in a model; not a theorem for every isolated quantum system.
• [34] Clay Mathematics Institute, Navier–Stokes EquationOfficial regularity problem. Keep it distinct from the physical problem of predicting turbulent statistics.
• [35] Eyink (2018), Review of the Onsager Ideal Turbulence TheoryEnergy transfer across scales and the role of velocity roughness; explains the conservation-law issue.
• [36] Patel, Guo, Esterlis and Sachdev (2022/2023), Universal theory of strange metals from spatially random interactionsA mechanism in a large-number-of-flavors, disorder-averaged model. Ask what survives outside those assumptions.
• [37] Xu et al. (2023/2024), Coexistence of superconductivity with partially filled stripes in the Hubbard modelControlled numerical comparisons and extrapolations in a specified model; not a complete material-specific theory.
• [38] Hazra, Verma and Randeria (2018/2019), Upper bounds on superfluid stiffness and superconducting transition temperatureA rigorous constraint with explicit dimensional and Hamiltonian scope. A ceiling need not be saturated.
• [39] Witten (2018), Notes on Some Entanglement Properties of Quantum Field TheoryAccessible mathematical account of local algebras, modular theory, and why a naive spatial tensor factorization fails.
• [40] Casini (2008), Relative entropy and the Bekenstein boundRelative entropy as a finite, operationally meaningful replacement for a bare entropy difference in the appropriate setting.