SAT – Domain – Boundaries

This section defines the outer limits of a scientific field: what kinds of phenomena it is meant to explain, and what falls outside its responsibility. A boundary is not a list of topics, but a precise description of where the field’s explanations apply and where they no longer work. By identifying both the included range and the excluded conditions, this section prevents overlap between disciplines, clarifies each field’s proper territory, and establishes a clear starting point for all deeper analysis in the Science Project.

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Science Analysis Template

Below are the results of cycles 1 & 2 of The Science Project

Across all disciplines, the boundaries reveal a single unifying outcome: every science is defined by the conditions under which its explanations hold and the point where those explanations fail and must yield to another field.

From the full set of entries, several clear structural patterns emerge:

1. Each field is carved out by its operative scale, mechanisms, and assumptions.
   Classical mechanics belongs to slow, macroscopic bodies; quantum mechanics to atomic behavior; evolutionary biology to population-level genetic change; syntax to structural sentence formation; macroeconomics to aggregated system dynamics. No field claims universality—each claims a domain demarcated by its characteristic explanatory logic.
2. All disciplines explicitly define their exclusion zones.
   The boundaries consistently specify the regimes where the field does not apply:
   classical excludes relativistic; microeconomics excludes macro outcomes; geology excludes biological processes unless physically driven; semantics excludes contextual interpretation; proof theory excludes semantic truth except as constraints. This pattern forces disciplines to remain non-overlapping and modular.
3. Transitions and handoffs form the architecture of the entire science map.
   As conditions shift—speed, scale, energy, complexity, interaction level—the explanatory authority passes cleanly from one field to the next. This builds a coherent, layered system where no field overreaches and no phenomenon floats unassigned.
4. Domains are distinguished by their fundamental unit of analysis.
   • Physics → particles, fields, continua
   • Chemistry → molecules, bonds, reactions
   • Earth sciences → rocks, plates, oceans, atmosphere
   • Biology → molecules → cells → tissues → organisms → populations → ecosystems
   • Formal sciences → proofs, models, sets, computable procedures
   • Social sciences → individuals, households, networks, institutions, communities
     Boundaries consistently anchor each field to its proper unit.
5. The aggregate result is a fully partitioned atlas of scientific responsibility.
   What the full list collectively establishes is a map in which every major scientific discipline has:
   • a defined problem space,
   • a defined failure space,
   • a defined neighbor,
   • and a defined mechanism by which explanations transition across domains.

			Element	1. Domain
			Scope Category	1.1 Scope of the Domain
			Sub-Item	Boundaries
Science Name Link	Branch Name Link	Field Name Link	Definition	The range of phenomena the science includes and excludes.
Natural Sciences	Physics	Classical Physics	Classical Mechanics	Classical Mechanics covers the motion of physical bodies under forces in regimes where speeds are far below the speed of light and quantum effects are negligible. It excludes relativistic, quantum, and strong-gravity conditions.
Natural Sciences	Physics	Classical Physics	Classical Electromagnetism	Classical Electromagnetism studies electric and magnetic fields, charges, currents, and electromagnetic waves as described by Maxwell’s equations. It does not cover quantum electrodynamics or strong-field/ultra-relativistic regimes where classical fields fail.
Natural Sciences	Physics	Classical Physics	Classical Thermodynamics	Classical Thermodynamics studies macroscopic systems and their energy, work, heat, and equilibrium properties without reference to microscopic structure. It excludes statistical mechanics, quantum thermodynamics, and non-equilibrium microscopic dynamics.
Natural Sciences	Physics	Classical Physics	Statistical Mechanics (Classical)	Classical Statistical Mechanics studies the behavior of macroscopic systems by modeling them as large ensembles of classical particles obeying Newtonian mechanics. It connects microscopic dynamics to macroscopic thermodynamic laws. It excludes quantum statistics (Fermi–Dirac, Bose–Einstein) and systems where classical trajectories break down.
Natural Sciences	Physics	Classical Physics	Optics (Classical Wave Theory)	Classical Optics (Wave Theory) studies the propagation, interference, diffraction, reflection, refraction, and polarization of light treated as a classical electromagnetic wave. It excludes quantum photon behavior and regimes where geometric optics or quantum electrodynamics must be applied.
Natural Sciences	Physics	Classical Physics	Acoustics	Classical Acoustics studies the generation, propagation, reflection, absorption, and perception of mechanical waves in physical media (gases, liquids, solids). It excludes electromagnetic waves, quantum phonon behavior, and relativistic or ultra-high-frequency phenomena where continuum mechanics breaks down.
Natural Sciences	Physics	Classical Physics	Continuum Mechanics	Continuum Mechanics studies how materials deform, flow, and transmit forces by treating matter as a continuous substance. It excludes microscopic, atomic, and quantum descriptions where discrete particles dominate, and excludes phenomena where continuum assumptions break down.
Natural Sciences	Physics	Classical Physics	Classical Field Theory	Classical Field Theory studies physical quantities that have values at every point in space and time and evolve according to deterministic field equations. It includes electromagnetic fields, gravitational fields (in classical form), elastic fields, and other continuous field distributions. It excludes quantum fields, discrete particle models, and regimes where quantization or relativistic corrections are essential.
Natural Sciences	Physics	Classical Physics	Pre-Relativistic Frameworks	Pre-relativistic frameworks describe physical systems using classical assumptions: absolute space, absolute time, instantaneous interactions, Euclidean geometry, and Galilean transformations. They exclude relativistic effects such as time dilation, length contraction, finite-speed causality, and spacetime curvature.
Natural Sciences	Physics	Modern & Fundamental Physics	Quantum Mechanics	Quantum Mechanics describes physical systems at atomic and subatomic scales where classical mechanics fails. It governs wavefunctions, probability amplitudes, quantized energies, spin, superposition, tunneling, atomic structure, molecular structure, and discrete measurement outcomes. It excludes classical deterministic trajectories and macroscopic behavior unless coarse-grained into classical limits.
Natural Sciences	Physics	Modern & Fundamental Physics	Relativistic Quantum Mechanics	Relativistic Quantum Mechanics describes quantum systems whose particles move at speeds comparable to the speed of light. It includes spin-half and spin-one particles described by wave equations consistent with special relativity. It excludes fully interacting quantum field theories and excludes low-energy regimes where non-relativistic quantum mechanics is sufficient.
Natural Sciences	Physics	Modern & Fundamental Physics	Special Relativity	Special Relativity describes the behavior of space, time, energy, and momentum in inertial reference frames where velocities may approach the speed of light. It excludes gravitational effects, accelerated frames requiring general relativity, and quantum-scale phenomena requiring quantum mechanics or quantum field theory.
Natural Sciences	Physics	Modern & Fundamental Physics	General Relativity	General Relativity describes gravity as the curvature of spacetime produced by mass, energy, and momentum. It includes black holes, gravitational waves, cosmological expansion, light bending, time dilation in gravitational fields, and motion in curved spacetime. It excludes quantum-scale gravity, extremely small-distance physics, and low-speed regimes where Newtonian gravity suffices.
Natural Sciences	Physics	Modern & Fundamental Physics	Quantum Field Theory (QFT)	Quantum Field Theory describes particles as excitations of underlying fields and governs interactions through quantized fields consistent with special relativity. It includes particle creation and annihilation, virtual processes, interactions mediated by gauge fields, and renormalizable forces. It excludes non-relativistic approximations, classical field interpretations, and gravity unless extended to quantum gravity frameworks.
Natural Sciences	Physics	Modern & Fundamental Physics	Particle Physics (High-Energy Physics)	Particle Physics studies elementary particles, their interactions, and the symmetry structure of the Standard Model. It includes quarks, leptons, bosons, neutrinos, and high-energy collision processes that probe femtometer scales. It excludes macroscopic classical behavior, low-energy quantum systems, and gravitational phenomena unless extended into unified frameworks.
Natural Sciences	Physics	Modern & Fundamental Physics	Nuclear Physics	Nuclear Physics studies the structure, properties, and interactions of atomic nuclei, including nuclear forces, decay modes, reaction chains, collective nuclear behavior, and links to nuclear astrophysics. It excludes electron-shell behavior (atomic physics), quark-level structure (particle physics), and gravitational effects.
Natural Sciences	Physics	Modern & Fundamental Physics	Quantum Statistical Physics	Quantum Statistical Physics studies quantum many-body systems and ensembles of indistinguishable particles. It includes quantum phases, emergent excitations, low-temperature phenomena, condensation, fermionic degeneracy, and collective behavior in macroscopic quantum systems. It excludes single-particle quantum mechanics and classical statistical systems unless used as limiting cases.
Natural Sciences	Physics	Modern & Fundamental Physics	Quantum Optics	Quantum Optics studies the quantum behavior of light and its interaction with atoms, molecules, and optical fields. It includes nonclassical states of light, photon control, cavity systems, atom–photon interactions, and coherent quantum technologies. It excludes classical wave optics unless used as limiting behavior and excludes high-energy photon interactions handled in particle physics.
Natural Sciences	Physics	Modern & Fundamental Physics	Quantum Information Science	Quantum Information Science studies how quantum systems store, process, communicate, and protect information. It includes quantum computation, quantum communication, quantum simulation, quantum sensing, manipulation of entanglement and coherence, and development of error-resilient quantum protocols. It excludes classical information systems unless used as limiting behavior or control infrastructure.
Natural Sciences	Physics	Theoretical & Mathematical Physics	Symmetry & Group Theory	Symmetry & Group Theory provides the mathematical description of symmetries that constrain physical laws. It includes continuous and discrete symmetries, Lie groups, Lie algebras, representation theory, classification of particles and fields, and symmetry-breaking structures. It excludes specific physical systems unless used as examples.
Natural Sciences	Physics	Theoretical & Mathematical Physics	Gauge Theory	Includes theories where interactions come from local gauge symmetry, such as Yang-Mills, QED, QCD, electroweak theory, and the Standard Model. Excludes global-symmetry-only systems, non-gauge classical theories, and non-field models.
Natural Sciences	Physics	Theoretical & Mathematical Physics	String Theory	Includes theoretical frameworks where the fundamental entities are one-dimensional strings or higher-dimensional extended objects. Includes superstrings, branes, dualities, and higher-dimensional compact spaces. Excludes point-particle-only models, classical field theories without extended objects, and low-energy physics when string effects decouple.
Natural Sciences	Physics	Theoretical & Mathematical Physics	Differential Geometry in Physics	Includes the use of geometric structures such as manifolds, curvature, and connections to describe physical systems. Essential for gravity, gauge theories, classical field theories, and topological phases. Excludes physical models that do not rely on geometric interpretation or do not require smooth structure.
Natural Sciences	Physics	Theoretical & Mathematical Physics	Statistical Field Theory	Includes field-based descriptions of systems with many degrees of freedom, including critical phenomena, phase transitions, stochastic dynamics, and continuous limits of lattice models. Excludes systems with few degrees of freedom where field descriptions are unnecessary and purely microscopic models without coarse-grained interpretation.
Natural Sciences	Physics	Condensed Matter & Materials Physics	Mathematical Foundations of Quantum Mechanics	Includes the rigorous mathematical structures used to define quantum mechanics: operators, Hilbert spaces, linear transformations, probability rules, functional analysis, and axiomatic reconstructions. Excludes heuristic or purely operational quantum models lacking formal mathematical grounding.
Natural Sciences	Physics	Condensed Matter & Materials Physics	General Mathematical Physics	Includes the development and application of advanced mathematical tools used to analyze, construct, and unify physical theories. Covers areas not tied to a single physical system, such as differential equations, variational principles, algebraic structures, integrable systems, and topological methods. Excludes purely empirical physics without deep mathematical formulation.
Natural Sciences	Physics	Condensed Matter & Materials Physics	Solid-State Physics	Includes the physical properties of crystalline and amorphous solids, electronic structure, lattice behavior, vibrations, transport phenomena, and collective excitations. Excludes isolated atoms or molecules, fluids, gases, and systems without long-range structural organization.
Natural Sciences	Physics	Condensed Matter & Materials Physics	Semiconductor Physics	Includes electronic and optical behavior of materials with engineered band gaps, charge transport in doped materials, excitonic effects, recombination processes, junction behavior, and carrier dynamics. Excludes metals with fully filled or empty bands, insulators with extremely large gaps, and systems lacking controllable carrier populations.
Natural Sciences	Physics	Condensed Matter & Materials Physics	Magnetism & Spin Physics	Includes magnetic ordering, spin interactions, magnetic materials, spin dynamics, magnetic excitations, spin transport, and nanoscale magnetic phenomena. Excludes purely electric phenomena, non-spin-based conduction processes, and systems where magnetic interactions are negligible.
Natural Sciences	Physics	Condensed Matter & Materials Physics	Superconductivity	Includes materials that exhibit zero electrical resistance and the expulsion of magnetic fields below a critical temperature; includes type I and type II superconductors, Cooper pairing, quantum coherence, and flux quantization. Excludes normal conductive states, non-coherent low-temperature phases, and materials that never achieve superconductivity under any known condition.
Natural Sciences	Physics	Condensed Matter & Materials Physics	Soft Matter Physics	Includes materials that deform easily under small forces, such as polymers, colloids, gels, foams, liquid crystals, emulsions, and biological soft materials. Excludes crystalline solids with rigid structure, ideal gases, and systems dominated by purely quantum or purely electronic effects.
Natural Sciences	Physics	Condensed Matter & Materials Physics	Nanomaterials & Nanostructures	Includes materials and structures with features at the nanometer scale, such as nanoparticles, nanotubes, nanowires, quantum dots, thin films, and nanoengineered surfaces. Excludes bulk materials without nanoscale features and atomic-scale systems not exhibiting collective nanoscale behavior.
Natural Sciences	Physics	Condensed Matter & Materials Physics	Strongly Correlated Electron Systems	Includes materials where electron electron interactions dominate behavior, such as Mott insulators, heavy fermion systems, unconventional superconductors, quantum spin liquids, and charge ordered states. Excludes weakly interacting electron systems that can be described by simple band theory or independent electron models.
Natural Sciences	Physics	Condensed Matter & Materials Physics	Topological Matter	Includes phases of matter defined by topological properties rather than symmetry breaking, such as topological insulators, topological superconductors, quantum Hall states, Weyl and Dirac materials, and systems with protected boundary modes. Excludes ordinary phases described only by local order parameters or conventional symmetry breaking without topological character.
Natural Sciences	Physics	Condensed Matter & Materials Physics	Materials Science (Physical Perspective)	Includes study of the physical structure, properties, and behavior of materials across scales, including metals, ceramics, polymers, composites, semiconductors, and functional materials. Focuses on structure property relationships, phase behavior, mechanical and thermal response, electronic structure, and processing effects. Excludes purely chemical synthesis design without physical characterization, and excludes purely biological materials unless treated through physical principles.
Natural Sciences	Physics	Astrophysics & Cosmology	Stellar Astrophysics	Includes the structure, evolution, and life cycles of stars; nuclear fusion processes; stellar interiors; atmospheres; winds; variability; compact remnants; and stellar populations. Excludes galactic scale dynamics, planetary atmospheres, cosmological evolution, and non-stellar compact objects not formed from stellar collapse.
Natural Sciences	Physics	Astrophysics & Cosmology	Galactic Astrophysics	Includes the structure, dynamics, composition, and evolution of galaxies; star formation processes; interstellar medium behavior; molecular clouds; stellar populations; dark matter distribution within galaxies; and internal galactic interactions. Excludes extragalactic environments beyond the galaxy as a whole, large scale cosmological evolution, and stellar scale nuclear or atmospheric processes.
Natural Sciences	Physics	Astrophysics & Cosmology	Extragalactic Astrophysics	Includes the study of galaxies beyond the Milky Way, their formation, evolution, interactions, active galactic nuclei, large scale structure, galaxy clusters, and intergalactic medium behavior. Excludes stellar scale processes inside single galaxies and excludes primordial cosmology beyond the galactic formation context.
Natural Sciences	Physics	Astrophysics & Cosmology	Cosmology	Includes the origin, structure, content, and evolution of the universe as a whole: expansion history, cosmic microwave background, large scale structure, dark matter, dark energy, primordial nucleosynthesis, and cosmic inflation. Excludes local astrophysical processes within single stars or galaxies except where they contribute to cosmic-scale inference.
Natural Sciences	Physics	Astrophysics & Cosmology	High-Energy Astrophysics	Includes astrophysical phenomena dominated by extreme energies, such as supernovae, gamma ray bursts, accretion onto compact objects, relativistic jets, pulsars, magnetars, cosmic rays, high energy radiation, and particle acceleration in astrophysical environments. Excludes low energy stellar evolution, galactic scale structure not driven by high energy processes, and cosmology except where directly linked to high energy events.
Natural Sciences	Physics	Astrophysics & Cosmology	Gravitational Astrophysics	Includes the formation, structure, composition, atmospheres, surfaces, climates, and evolution of planets and moons inside and outside the solar system; includes detection and characterization of exoplanets, planetary interiors, orbital dynamics, and habitability studies. Excludes stellar physics, galactic scale processes, and cosmological evolution except where they affect planetary formation.
Natural Sciences	Physics	Astrophysics & Cosmology	Planetary Science & Exoplanets	Includes the study of planets, moons, rings, atmospheres, surfaces, interiors, orbital dynamics, climates, formation pathways, and exoplanet detection and characterization. Excludes stellar physics, galaxy scale dynamics, and cosmology except where they influence planetary formation or environment.
Natural Sciences	Physics	Astrophysics & Cosmology	Astrochemistry & Interstellar Medium Physics	Includes the chemistry, composition, physical processes, and evolution of gas and dust in interstellar and circumstellar environments; formation and destruction of molecules; ionization processes; grain surface chemistry; phase structure of the interstellar medium; and transitions between cold, warm, and hot gas regimes. Excludes stellar interiors, planetary atmospheres, and galaxy scale structure except where ISM conditions influence them.
Natural Sciences	Physics	Astrophysics & Cosmology	Astrobiology	Includes the study of the origin, evolution, distribution, and potential detection of life in the universe; examines habitability conditions, biosignatures, extremophiles, prebiotic chemistry, planetary environments, and life’s relationship to astrophysical and geochemical processes. Excludes metaphysical definitions of life, purely terrestrial ecological dynamics unrelated to universal principles, and stellar or cosmological processes except where they influence habitability.
Natural Sciences	Physics	Plasma & Fluid Physics	Fluid Dynamics	Includes the motion, stability, and behavior of liquids and gases across all scales; covers laminar and turbulent flow, boundary layers, shocks, vorticity, transport processes, and continuum mechanical behavior governed by conservation laws. Excludes molecular-scale kinetic descriptions unless used to justify continuum approximations, and excludes solid mechanics except where fluids interact with solid boundaries.
Natural Sciences	Physics	Plasma & Fluid Physics	Hydrodynamics (Ideal Fluids)	Includes the behavior of electrically conducting fluids in magnetic fields, coupling of fluid motion and electromagnetic forces, plasma stability, magnetic reconnection, dynamos, Alfvén waves, and large scale plasma dynamics. Excludes nonconducting fluids, purely kinetic plasma behavior outside fluid approximations, and electromagnetic systems lacking fluid motion.
Natural Sciences	Physics	Plasma & Fluid Physics	Magnetohydrodynamics (MHD)	Includes the physics of electrically conducting fluids under magnetic and electric fields, covering plasmas, liquid metals, astrophysical flows, magnetic confinement, dynamos, magnetic reconnection, and MHD waves. Excludes nonconducting fluids, collisionless plasma phenomena not representable in fluid form, and electromagnetic systems without fluid motion.
Natural Sciences	Physics	Plasma & Fluid Physics	Plasma Physics (General)	Includes the study of ionized gases in which collective electromagnetic behavior dominates; covers plasma waves, instabilities, turbulence, transport, collisions, magnetized and unmagnetized plasmas, fusion plasmas, space plasmas, and plasma interactions with fields or materials. Excludes neutral fluid dynamics except as a limiting case, solid state plasma analogs not governed by collective EM behavior, and purely relativistic particle physics except where it affects plasma phenomena.
Natural Sciences	Physics	Plasma & Fluid Physics	Space & Astrophysical Plasmas	Includes plasmas in astrophysical and space environments such as solar wind, magnetospheres, ionospheres, stellar atmospheres, accretion disks, jets, interstellar plasmas, and galactic or intergalactic plasma structures. Covers waves, shocks, turbulence, reconnection, heating, transport, and large scale magnetic field evolution. Excludes neutral gas dynamics and purely laboratory plasmas except when used as analogs.
Natural Sciences	Physics	Plasma & Fluid Physics	Fusion Plasma Physics	Includes the physics of high-temperature ionized plasmas confined for nuclear fusion; covers confinement systems, heating methods, plasma stability, transport, turbulence, fusion reactions, radiation, and plasma-wall interactions. Excludes non-ionized fluids, low-temperature discharges, astrophysical plasmas except as analogs, and nuclear reactor engineering outside plasma behavior itself.
Natural Sciences	Physics	Plasma & Fluid Physics	Computational Fluid & Plasma Physics	Includes numerical simulation of fluid and plasma systems using discretized forms of governing equations; covers fluid dynamics, MHD, kinetic plasma models, turbulence modeling, multi scale coupling, wave propagation, reconnection, shocks, transport, and stability. Excludes purely analytical theory, experiments without computational components, and solid-state or materials simulations unless directly related to fluid or plasma behavior.
Natural Sciences	Physics	Plasma & Fluid Physics	Non-Newtonian & Complex Fluids	Includes fluids whose stress–strain relationship is nonlinear or history-dependent, including shear-thinning, shear-thickening, viscoelastic, thixotropic, yield-stress, polymeric, colloidal, granular, suspension, and biological fluids. Excludes ideal Newtonian fluids and purely solid mechanics unless treated as continuum analogs.
Natural Sciences	Physics	Plasma & Fluid Physics	High-Energy-Density Physics (HEDP)	Includes matter under extreme pressures, temperatures, or radiation fields where energy density exceeds about 1 megajoule per cubic meter; covers warm dense matter, laser-driven compression, shock physics, inertial confinement fusion, astrophysical interior analogs, radiation hydrodynamics, and ionized matter at extreme states. Excludes low-energy plasma physics, conventional fluid mechanics, and solid-state physics except when serving as starting states prior to compression.
Natural Sciences	Physics	Interdisciplinary & Applied Physics	Biophysics	Includes the application of physical principles to biological structures, dynamics, and functions across all scales; covers molecular motors, protein folding, membranes, ion channels, neural signaling, biomechanics, cellular mechanics, electrophysiology, population-level dynamics, and biological energy transfer. Excludes purely chemical biology, ecological macro-systems not grounded in physical laws, and medical physics unless tied directly to biological function.
Natural Sciences	Physics	Interdisciplinary & Applied Physics	Medical Physics	Includes the application of physical principles to medical imaging, radiation therapy, radiation safety, treatment planning, diagnostic measurements, dosimetry, and device calibration. Covers interactions of ionizing and non ionizing radiation with biological tissues, image formation physics, therapeutic dose delivery, and technological optimization of diagnostic and therapeutic systems. Excludes purely biological interpretation of disease, clinical decision making, and non physical medical sciences.
Natural Sciences	Physics	Interdisciplinary & Applied Physics	Geophysics	Includes the physical processes governing Earth’s interior, crust, oceans, atmosphere, magnetic field, gravity field, and dynamic evolution. Covers seismology, volcanism, tectonics, geodynamics, geomagnetism, geodesy, hydrology, cryosphere physics, and interactions across Earth systems. Excludes purely chemical geology, biological ecology, or meteorology unless directly grounded in physical processes.
Natural Sciences	Physics	Interdisciplinary & Applied Physics	Optics & Photonics	Includes the generation, propagation, detection, manipulation, and interaction of light and electromagnetic radiation across classical and quantum regimes. Covers geometric optics, wave optics, laser physics, nonlinear optics, quantum optics, fiber optics, imaging, interferometry, photonic materials, and optical communications. Excludes non EM wave systems unless analogized, and excludes electronics not directly tied to photonic processes.
Natural Sciences	Physics	Interdisciplinary & Applied Physics	Computational Physics	Includes the numerical simulation of physical systems using discretized or algorithmic representations of governing laws; covers classical mechanics, electromagnetism, quantum mechanics, statistical physics, fluid dynamics, plasma physics, materials physics, astrophysics, and multiscale modeling. Excludes purely analytical theory, experiments without computational components, and numerical work that does not involve physical systems.
Natural Sciences	Physics	Interdisciplinary & Applied Physics	Engineering Physics	Includes the application of foundational physical principles to the design, analysis, and optimization of engineered systems. Covers mechanics, materials, thermodynamics, electromagnetism, photonics, acoustics, control theory, micro/nanoscale devices, energy systems, sensors, and applied computational modeling. Excludes purely theoretical physics and engineering fields that do not rely on explicit physical modeling (e.g., organizational systems).
Natural Sciences	Physics	Interdisciplinary & Applied Physics	Chemical Physics	Includes the physical principles governing chemical structure, bonding, reaction dynamics, spectroscopy, molecular interactions, transport processes, and thermochemical behavior. Covers quantum chemistry, molecular collisions, reaction rate theory, statistical mechanics of molecules, intermolecular forces, and condensed-phase behavior using physical models. Excludes purely empirical chemistry without physical modeling and macroscopic engineering systems not grounded in molecular physics.
Natural Sciences	Physics	Interdisciplinary & Applied Physics	Environmental & Climate Physics	Includes the physical processes governing Earth’s atmosphere, oceans, cryosphere, land–atmosphere interactions, radiation balance, climate dynamics, and anthropogenic forcing. Covers energy transport, fluid dynamics, thermodynamics of climate systems, radiative forcing, greenhouse gas physics, aerosol interactions, and large-scale circulations. Excludes biological ecology, political climate policy, and purely chemical modeling unless tied to physical climate processes.
Natural Sciences	Physics	Interdisciplinary & Applied Physics	Applied Materials Physics	Includes the physical principles underlying material structure, properties, processing, fabrication, and performance in engineered applications. Covers electronic materials, structural materials, magnetic materials, optical materials, energy materials, nanomaterials, and functional composites. Excludes purely chemical synthetic methods unless tied to physical properties, purely biological materials unless modeled through physical rules, and macro-engineering topics not grounded in material physics.
Natural Sciences	Chemistry	Physical Chemistry	Quantum Chemistry	Studies atoms, molecules, ions, and electrons using quantum mechanics; excludes classical models unable to represent wavefunctions or quantization.
Natural Sciences	Chemistry	Physical Chemistry	Statistical Mechanics	Studies macroscopic behavior arising from ensembles of microscopic states; excludes single-particle or purely deterministic, non-probabilistic descriptions.
Natural Sciences	Chemistry	Physical Chemistry	Thermodynamics	Studies macroscopic energy, work, heat, and state variables; excludes microscopic mechanisms except as summarized in bulk relations.
Natural Sciences	Chemistry	Physical Chemistry	Kinetics & Reaction Dynamics	Studies the rates, pathways, and mechanisms of chemical reactions; excludes purely thermodynamic descriptions of equilibrium without regard to rate or pathway.
Natural Sciences	Chemistry	Physical Chemistry	Spectroscopy	Studies the interaction of electromagnetic radiation with matter to extract structural, energetic, or dynamic information; excludes processes unrelated to light–matter coupling.
Natural Sciences	Chemistry	Physical Chemistry	Electrochemistry	Studies systems where chemical and electrical processes are coupled; excludes purely chemical reactions without charge transfer and purely electronic systems without chemistry.
Natural Sciences	Chemistry	Physical Chemistry	Surface & Interface Science	Studies physical and chemical phenomena occurring at surfaces and interfaces; excludes bulk-only behavior not influenced by interfacial structure or surface interactions.
Natural Sciences	Chemistry	Physical Chemistry	Colloid & Solution Chemistry	Studies systems where dispersed particles, ions, or molecules interact within a continuous medium; excludes purely bulk phases without interparticle or interfacial effects.
Natural Sciences	Chemistry	Physical Chemistry	Chemical Physics	Studies the physical principles underlying chemical phenomena: molecular structure, energy flow, reaction dynamics, spectroscopy, and force interactions; excludes purely empirical chemistry.
Natural Sciences	Chemistry	Organic Chemistry	Structural & Mechanistic Organic Chemistry	Studies the structure of organic molecules, movement of electrons, and mechanistic pathways of reactions; excludes bulk thermodynamics without mechanistic interpretation.
Natural Sciences	Chemistry	Organic Chemistry	Stereochemistry & Conformational Analysis	Studies the three-dimensional arrangement of atoms in molecules and how spatial orientation influences reactivity, stability, and physical properties; excludes purely 2D structural descriptions that ignore spatial effects.
Natural Sciences	Chemistry	Organic Chemistry	Synthetic Organic Chemistry	Studies the design, construction, and transformation of organic molecules through controlled chemical reactions; excludes purely analytical, structural, or non-transformative chemistry.
Natural Sciences	Chemistry	Organic Chemistry	Physical Organic Chemistry	Studies how structure influences reactivity through quantitative and mechanistic principles; excludes purely empirical synthetic outcomes lacking mechanistic or energetic interpretation.
Natural Sciences	Chemistry	Organic Chemistry	Organometallic Organic Chemistry	Studies molecules containing metal–carbon bonds and the reactivity of these species in catalysis and stoichiometric transformations; excludes purely inorganic complexes without organic ligands.
Natural Sciences	Chemistry	Organic Chemistry	Polymer Chemistry (Carbon-based)	Studies carbon-based macromolecules, their synthesis, structure, properties, and reactions; excludes inorganic polymers and small-molecule chemistry lacking chain-based behavior.
Natural Sciences	Chemistry	Organic Chemistry	Bioorganic Chemistry	Studies organic chemistry within biological contexts: biomolecule structure, reactivity, mechanistic behavior, and synthetic mimicry; excludes purely inorganic biochemistry or non-organic catalysis.
Natural Sciences	Chemistry	Organic Chemistry	Natural Products Chemistry	Studies chemical compounds produced by living organisms, including their structures, biosynthesis, reactivity, and isolation; excludes synthetic analogs unless derived from natural scaffolds.
Natural Sciences	Chemistry	Organic Chemistry	Medicinal Chemistry	Studies the design, synthesis, optimization, and biological evaluation of molecules intended to modulate biological systems for therapeutic use; excludes purely biological pharmacology without chemical intervention.
Natural Sciences	Chemistry	Inorganic Chemistry	Main-Group Chemistry	Studies the chemistry of s- and p-block elements (groups 1–2 and 13–18), including bonding, structure, reactivity, and compounds; excludes d- and f-block behavior except where mixed bonding occurs.
Natural Sciences	Chemistry	Inorganic Chemistry	Transition-Metal Chemistry	Studies chemistry of d-block metals: their oxidation states, bonding, coordination behavior, magnetism, catalysis, and reactivity; excludes s/p-block chemistry except where mixed bonding occurs.
Natural Sciences	Chemistry	Inorganic Chemistry	f-Block Chemistry	Studies the lanthanides and actinides, their bonding, electronic structure, coordination chemistry, redox behavior, spectroscopy, magnetism, and reactivity; excludes d-block–only chemistry except in mixed systems.
Natural Sciences	Chemistry	Inorganic Chemistry	Coordination Chemistry	Studies metal–ligand complex formation, structure, bonding, stability, reactivity, and properties; includes d-, f-, p-block metal complexes; excludes pure organometallic M–C bond–centered chemistry unless in a coordination context.
Natural Sciences	Chemistry	Inorganic Chemistry	Solid-State Chemistry	Studies the synthesis, structure, bonding, electronic properties, and reactivity of solid materials; excludes gas- and solution-phase chemistry except where they affect solid formation or behavior.
Natural Sciences	Chemistry	Analytical Chemistry	Qualitative Analysis	Identifies what substances or species are present in a sample; establishes identity but not quantity. Excludes quantitative measurement, calibration, or statistical concentration determination.
Natural Sciences	Chemistry	Analytical Chemistry	Quantitative Analysis	Determines the amount or concentration of substances with statistical rigor; excludes qualitative identification without quantification or non-numerical presence/absence testing.
Natural Sciences	Chemistry	Analytical Chemistry	Separation Science	Studies the physical and chemical processes used to separate components of mixtures based on their differing properties; excludes identity-only analysis (qualitative) or pure quantification without separation.
Natural Sciences	Chemistry	Analytical Chemistry	Instrumental Analysis	Studies analytical methods that rely on scientific instruments for detection, identification, and quantification of chemical species; excludes purely classical wet-chemistry tests or non-instrumented qualitative analysis.
Natural Sciences	Chemistry	Biochemistry	Structural Biochemistry	Studies the three-dimensional structure, architecture, folding, assembly, and physical organization of biological macromolecules; excludes purely sequence-level biology without structural context or purely metabolic/kinetic analysis.
Natural Sciences	Chemistry	Biochemistry	Enzymology	Studies how enzymes catalyze biochemical reactions: mechanisms, kinetics, specificity, regulation, and structure–function relationships; excludes purely structural biology without catalytic context or metabolic pathway mapping without mechanistic focus.
Natural Sciences	Chemistry	Biochemistry	Metabolism & Bioenergetics	Studies biochemical pathways, energy conversion, thermodynamics of life, metabolic flux, nutrient processing, ATP generation/consumption; excludes purely structural biochemistry or purely regulatory biology without metabolic context.
Natural Sciences	Chemistry	Biochemistry	Molecular Biology & Gene Expression	Studies how genetic information is stored, replicated, transcribed, processed, translated, and regulated; excludes pure evolutionary biology without molecular mechanisms, and structural biochemistry without gene-expression context.
Natural Sciences	Chemistry	Biochemistry	Cellular Biochemistry	Studies biochemical processes as they occur inside living cells: molecular interactions, pathways, compartmentalization, signal handling, and emergent biochemical behavior; excludes isolated in-vitro biochemical processes lacking cellular context.
Natural Sciences	Chemistry	Biochemistry	Membrane Biochemistry	Studies the biochemical composition, structure, dynamics, and functions of biological membranes, including lipid organization, membrane proteins, transport, signaling, trafficking; excludes purely structural biology without membrane context or intracellular biochemistry unrelated to membrane interfaces.
Natural Sciences	Chemistry	Biochemistry	Protein Chemistry	Studies the chemical properties, reactions, folding, stability, interactions, and modifications of proteins; excludes gene-expression processes unless directly tied to protein structure/function, and excludes purely metabolic pathways without protein-chemistry focus.
Natural Sciences	Chemistry	Biochemistry	Biochemical Genetics	Studies how genetic variation influences biochemical pathways, enzyme function, metabolic phenotypes, molecular defects, inheritance patterns, and disease mechanisms; excludes purely structural genetics or purely metabolic biochemistry not tied to genotype–phenotype relationships.
Natural Sciences	Earth & Space Sciences	Geology	Mineralogy & Crystallography	Studies the composition, structure, properties, and formation of minerals; includes crystalline structure, symmetry, lattice behavior, defects, and phase transformations. Excludes large-scale geological processes unless directly tied to mineral structural behavior.
Natural Sciences	Earth & Space Sciences	Geology	Petrology	Studies the origin, composition, formation, transformation, and classification of rocks and the processes that create them (igneous, metamorphic, and sedimentary); excludes large-scale tectonics unless directly tied to rock-forming processes, and excludes pure mineral chemistry unless applied to bulk rock evolution.
Natural Sciences	Earth & Space Sciences	Geology	Structural Geology & Tectonics	Studies the deformation of Earth’s crust and mantle, including faults, folds, fabrics, strain patterns, tectonic forces, plate interactions, and stress fields; excludes petrology unless tied to deformation, and excludes pure geophysics unless linked to structural processes.
Natural Sciences	Earth & Space Sciences	Geology	Sedimentology & Stratigraphy	Studies the transport, deposition, diagenesis, and lithification of sediments and the interpretation of layered sedimentary successions; includes facies analysis, depositional environments, basin evolution, and temporal stratigraphic relationships. Excludes igneous/metamorphic processes unless influencing sedimentation.
Natural Sciences	Earth & Space Sciences	Geology	Geomorphology	Studies the formation, evolution, and dynamics of Earth’s surface landforms and the processes that shape them (erosion, transport, deposition, weathering); includes rivers, coasts, glaciers, hillslopes, aeolian systems. Excludes deep-crustal tectonics unless expressed at the surface, and excludes pure sedimentology unless linked to landscape processes.
Natural Sciences	Earth & Space Sciences	Geology	Geophysics	Studies the physical properties, structure, and dynamic processes of the Earth (and other planetary bodies) using physics-based observations and models; includes seismology, gravity, magnetism, heat flow, electrical properties, geodynamics, and imaging of the subsurface. Excludes purely chemical, biological, or surface-only processes unless linked to physical fields.
Natural Sciences	Earth & Space Sciences	Geology	Geochemistry	Studies the chemical composition, reactions, distributions, and cycles of elements and isotopes within the Earth and other planetary bodies. Includes mineral–fluid interactions, rock chemistry, aqueous geochemistry, isotope geochemistry, redox systems, and global geochemical cycles. Excludes purely physical processes unless tied to chemical behavior.
Natural Sciences	Earth & Space Sciences	Geology	Paleontology	Studies the history of life on Earth through fossils, including organisms, their environments, evolution, extinction, and biological interactions as preserved in the rock record. Includes body fossils, trace fossils, microfossils, paleoecology, taphonomy, and biostratigraphy. Excludes living organisms except as analogs, and excludes purely geologic processes unless related to fossil preservation or interpretation.
Natural Sciences	Earth & Space Sciences	Geology	Hydrogeology	Studies the occurrence, movement, storage, and quality of groundwater in soils and rocks; includes aquifers, recharge/discharge, groundwater–surface water interactions, contaminant transport, and hydrogeologic properties. Excludes surface hydrology unless linked to groundwater, and excludes pure geochemistry unless tied to subsurface water processes.
Natural Sciences	Earth & Space Sciences	Geology	Economic & Applied Geology	Studies the formation, distribution, exploration, evaluation, and extraction of Earth materials with economic value (metals, industrial minerals, hydrocarbons, groundwater, construction materials). Includes ore-deposit science, mineral exploration, petroleum geology, geothermal systems, engineering geology, and resource assessment. Excludes purely academic geology unless it directly informs resource discovery or extraction.
Natural Sciences	Earth & Space Sciences	Meteorology	Dynamic Meteorology	The study of atmospheric motion and the physical laws governing winds, circulation, waves, turbulence, and large-scale fluid behavior; excludes atmospheric chemistry, microphysics, and surface processes except where they directly affect dynamics.
Natural Sciences	Earth & Space Sciences	Meteorology	Thermodynamic Meteorology	Concerns the transformation, transfer, and distribution of heat, moisture, and energy within the atmosphere—including phase changes, stability, convection, lapse rates, and vertical thermodynamic structure. Excludes purely dynamical motion except where driven by thermodynamic processes.
Natural Sciences	Earth & Space Sciences	Meteorology	Cloud Physics & Microphysics	Focuses on the formation, growth, interaction, and phase transitions of cloud particles—droplets, ice crystals, aerosols—and the microphysical processes governing precipitation. Excludes large-scale dynamics except where they influence microphysical environments.
Natural Sciences	Earth & Space Sciences	Meteorology	Synoptic & Mesoscale Meteorology	Examines atmospheric phenomena from mesoscale (1–500 km) to synoptic scale (500–3,000+ km), including fronts, jets, cyclones, thunderstorms, squall lines, mesoscale convective systems, and surface–boundary interactions. Excludes global circulation except as background forcing, and excludes purely microphysical processes except where coupled to mesoscale organization.
Natural Sciences	Earth & Space Sciences	Meteorology	Atmospheric Physics & Chemistry	Atmospheric Physics examines the radiative, thermodynamic, optical, and dynamical behavior of the atmosphere; Atmospheric Chemistry studies atmospheric composition, chemical reactions, aerosol formation, and trace-gas transformations. Excludes large-scale circulation except as a forcing environment and excludes purely microphysical or biological processes unless chemically relevant.
Natural Sciences	Earth & Space Sciences	Meteorology	Climatology & Climate Dynamics	Climatology studies long-term atmospheric patterns, variability, and statistics; Climate Dynamics examines the physical mechanisms driving climate variability and change across the atmosphere, ocean, land, and cryosphere. Excludes weather-scale prediction except as it contributes to climate statistics or feedbacks.
Natural Sciences	Earth & Space Sciences	Oceanography	Physical Oceanography	Studies the physical properties, motion, and dynamics of seawater, including currents, waves, tides, mixing, stratification, heat and salt transport, and ocean–atmosphere interactions. Excludes chemical, biological, and geological processes unless they interact with physical dynamics.
Natural Sciences	Earth & Space Sciences	Oceanography	Chemical Oceanography	Studies the chemical composition, reactions, distributions, sources, and sinks of dissolved and particulate substances in the ocean; includes nutrients, gases, trace metals, carbon system chemistry, redox processes, and element cycling. Excludes purely physical or biological processes unless they influence chemical behavior.
Natural Sciences	Earth & Space Sciences	Oceanography	Biological Oceanography	Studies the distribution, abundance, physiology, interactions, and ecological roles of marine organisms, and how physical, chemical, and geological processes structure ocean life. Includes plankton ecology, food webs, biogeochemical cycles, primary production, microbial processes, and ecosystem dynamics. Excludes purely physical, chemical, or geological processes except where they influence biology.
Natural Sciences	Earth & Space Sciences	Oceanography	Geological Oceanography	Studies the geology of the ocean floor and the processes that shape it, including sediments, sedimentation, plate tectonics, seafloor spreading, volcanism, hydrothermal activity, submarine geomorphology, and past ocean conditions recorded in sediments. Excludes purely biological or chemical processes unless tied to geological structure or sediment formation.
Natural Sciences	Biology	Molecular Biology	Nucleic Acid Biology	Nucleic Acid Biology studies the structure, chemistry, and functional behavior of DNA and RNA, including replication, repair, transcription, nucleotide modification, and nucleic acid conformations. It excludes protein-level mechanisms and organism-level genetics except where nucleic acids directly mediate them.
Natural Sciences	Biology	Molecular Biology	Gene Regulation & Epigenetics	Focuses on the mechanisms controlling gene expression, chromatin state, transcriptional activation/repression, epigenetic marks, and heritable regulatory patterns. Excludes protein-level functional outcomes, broad metabolic pathways, and organism-level physiology except where they directly depend on regulatory control.
Natural Sciences	Biology	Molecular Biology	Protein Biology	Protein Biology examines the structure, folding, dynamics, interactions, functions, and regulatory roles of proteins. It includes primary-to-quaternary structure, post-translational modifications, enzyme kinetics, and protein–protein/protein–ligand interactions. It excludes DNA/RNA-level information and cellular/organism-level processes except when directly mediated by proteins.
Natural Sciences	Biology	Molecular Biology	Molecular Complexes & Information Flow	The field examines multi-molecular assemblies—protein complexes, nucleoprotein machines, membrane-bound assemblies, ribonucleoproteins, and signaling complexes—and the ways they transmit, transform, and integrate biochemical information. Excludes isolated single-molecule behavior except when acting as part of a larger information-processing system.
Natural Sciences	Biology	Molecular Biology	Molecular Methods & Technologies	Focuses on experimental methods and technological platforms used to manipulate, measure, detect, visualize, sequence, modify, engineer, or isolate molecular components. Includes sequencing technologies, imaging systems, molecular manipulation tools, purification techniques, analytical platforms, and genome-editing systems. Excludes large-scale physiology, ecology, and organism-level processes except when directly dependent on molecular techniques.
Natural Sciences	Biology	Cell Biology	Cell Structure & Organelles	Studies the architecture, composition, and function of intracellular compartments and structural systems. Includes membranes, organelles, cytoskeleton, and organelle biogenesis. Excludes tissue-level physiology and whole-cell behavior not tied directly to structural organization.
Natural Sciences	Biology	Cell Biology	Cellular Dynamics & Trafficking	Focuses on the movement, sorting, and exchange of molecules, vesicles, and organelles within cells. Includes motor-driven transport, diffusion, vesicle trafficking, membrane turnover, secretion, endocytosis, and autophagy. Excludes tissue-scale transport, circulatory-system movement, or organism-level distribution except where directly tied to intracellular dynamics.
Natural Sciences	Biology	Cell Biology	Cell Signaling & Communication	Focuses on how cells detect, transmit, amplify, integrate, and respond to information via chemical, electrical, and mechanical signals. Includes receptor activation, signal transduction cascades, second messengers, phosphorylation networks, ligand–receptor interactions, and cell–cell communication. Excludes organism-level neural circuitry or hormonal physiology except where rooted in intracellular signaling principles.
Natural Sciences	Biology	Cell Biology	Cell Cycle, Fate & Death	Focuses on how cells grow, replicate DNA, divide, differentiate, arrest, senesce, or undergo programmed or unprogrammed death. Includes cell-cycle regulation, checkpoint control, mitosis/meiosis, stem-cell fate decisions, lineage restriction, apoptosis, necroptosis, autophagy-dependent death, and senescence. Excludes organism-level aging, whole-tissue development, or immune-mediated cell elimination unless directly tied to intrinsic cellular decision mechanisms.
Natural Sciences	Biology	Cell Biology	Cell Interactions & Microenvironment	Focuses on how cells interact with surrounding cells, extracellular matrix (ECM), soluble factors, mechanical forces, gradients, niches, and microenvironmental conditions. Includes adhesion, mechanotransduction, ECM remodeling, paracrine signaling, cell–cell junctions, matrix stiffness, and niche-governed behaviors. Excludes whole-organ architecture, organ-wide physiology, and organism-level environment except where directly tied to immediate cellular surroundings.
Natural Sciences	Biology	Cell Biology	Cell Morphology & Motility	Focuses on how cells generate, maintain, and remodel their shape, and how they move through space using cytoskeletal systems, adhesion structures, force generation, and polarity. Includes actin/microtubule dynamics, protrusion formation, contraction, migration modes, shape transitions, and mechanical–biochemical coupling. Excludes organism-level locomotion, tissue-scale movement, or whole-organ shape changes except where rooted in single-cell behaviors.
Natural Sciences	Biology	Genetics & Evolution	Classical & Transmission Genetics	Focuses on the transmission of heritable traits from parents to offspring through discrete genetic units (genes/alleles). Includes segregation, independent assortment, dominance relationships, recombination, linkage, and pedigree patterns. Excludes molecular gene regulation, genome architecture, or evolutionary processes not directly tied to inheritance.
Natural Sciences	Biology	Genetics & Evolution	Population Genetics	Focuses on how allele frequencies and genotype distributions change in populations over time under mutation, selection, drift, migration, and mating systems. Includes Hardy–Weinberg equilibrium, gene-flow and structure, effective population size, inbreeding, and polymorphism dynamics. Excludes individual-level Mendelian inheritance and molecular mechanisms except where they affect population-level change.
Natural Sciences	Biology	Genetics & Evolution	Quantitative Genetics	Focuses on traits influenced by many genes of small effect plus environmental variation. Includes quantitative trait variation, resemblance among relatives, heritability, genetic variance components, breeder’s equation, genomic prediction, and selection response. Excludes single-gene Mendelian inheritance and molecular mechanisms unless they contribute to variance decomposition.
Natural Sciences	Biology	Genetics & Evolution	Genomic Evolution & Comparative Genomics	Focuses on how genomes change over evolutionary time and how genome architecture, content, and organization differ across species. Includes mutation, substitution, genome rearrangements, duplications, deletions, transposons, synteny, orthology/paralogy, phylogenomics, and comparative sequence/structure analysis. Excludes individual-level inheritance (Mendelian genetics) and functional regulation unless directly tied to evolutionary or comparative interpretation.
Natural Sciences	Biology	Genetics & Evolution	Phylogenetics & Systematics	Focuses on reconstructing evolutionary relationships among organisms and classifying biodiversity based on shared ancestry. Includes phylogenetic tree inference, clade identification, character evolution, species delimitation, taxonomic hierarchy, and comparative trait mapping. Excludes ecological interactions or evolutionary mechanisms unless they inform ancestral relationships.
Natural Sciences	Biology	Genetics & Evolution	Macroevolution & Speciation Theory	Focuses on evolutionary processes operating above the population level: speciation, extinction, diversification, macroevolutionary trends, adaptive radiations, long-term morphological change, and lineage-splitting dynamics. Includes mechanisms of species formation, tempo and mode of evolution, and large-scale biodiversity patterns. Excludes short-term microevolutionary allele-frequency shifts unless they scale up to macroevolutionary consequences.
Natural Sciences	Biology	Physiology	Cellular & Tissue Physiology	Focuses on functional behavior of cells, tissues, and multicellular structures above the cellular scale. Includes membrane transport, epithelial and connective tissue functions, muscle contraction, signaling integration, and mechanical/biophysical tissue properties. Excludes organ-level physiology and whole-system regulation except where directly determined by cellular/tissue mechanisms.
Natural Sciences	Biology	Physiology	Neurophysiology	Focuses on electrical and chemical signaling in the nervous system and its control of organismal function. Includes membrane excitability, synaptic transmission, neurotransmitter dynamics, sensory encoding, motor control, and network integration. Excludes whole-organism behavioral ecology, psychiatric-level cognition, and molecular genetics except when directly shaping neuronal signaling.
Natural Sciences	Biology	Physiology	Endocrine & Regulatory Physiology	Examines hormone synthesis, secretion, circulation, receptor signaling, feedback loops, and organism-wide regulatory control. Includes endocrine glands, hormone–target interactions, metabolic regulation, stress responses, growth/reproductive control, and homeostatic adjustment. Excludes detailed molecular genetics and whole-organism behavior except where directly driven by hormonal regulation.
Natural Sciences	Biology	Physiology	Cardiovascular & Respiratory Physiology	Examines the functional behavior of the heart, vasculature, lungs, airways, and blood—focusing on flow, pressure, gas exchange, transport, and regulatory control. Includes cardiac electrophysiology and mechanics, vascular resistance, ventilation, diffusion, perfusion matching, and autonomic/endocrine regulation. Excludes cellular-level biochemistry and whole-organism metabolism except where determined by CV–respiratory processes.
Natural Sciences	Biology	Physiology	Metabolic & Energetic Physiology	Examines how organisms acquire, transform, store, and expend energy. Includes nutrient metabolism, ATP production, thermogenesis, substrate utilization, redox balance, metabolic signaling networks, and integrative energy homeostasis. Excludes molecular-level enzymology and whole-organism behavior except when directly driven by metabolic demand.
Natural Sciences	Biology	Physiology	Renal, Fluid & Homeostatic Physiology	Examines kidney function, fluid and electrolyte balance, acid–base regulation, filtration–reabsorption–secretion processes, osmotic control, blood-volume maintenance, and systemic homeostasis. Includes nephron transport physiology, hormonal regulation (RAAS, ADH, ANP), and whole-body fluid distribution. Excludes cellular-level transporter biochemistry and cardiovascular/respiratory homeostasis except when they directly mediate renal–fluid control.
Natural Sciences	Biology	Developmental Biology	Cell Fate & Lineage Specification	Focuses on how cells acquire stable identities and diverge into distinct lineages during development. Includes potency transitions, germ-layer specification, differentiation hierarchies, lineage segregation, asymmetric division, and regulatory determinants of cell identity. Excludes post-developmental plasticity, mature-cell physiology, and evolutionary comparisons unless directly tied to developmental lineage specification.
Natural Sciences	Biology	Developmental Biology	Pattern Formation & Embryonic Axes	Focuses on how spatial information, positional cues, and morphogen gradients establish structured body plans and embryonic axes (anterior–posterior, dorsal–ventral, left–right). Includes gradient formation, positional information decoding, axis polarization, boundary formation, segmentation, and Hox-patterning logic. Excludes later tissue morphogenesis unless directly governed by axis or pattern instructions.
Natural Sciences	Biology	Developmental Biology	Morphogenesis & Tissue-Level Mechanics	Focuses on how tissues change shape, generate forces, and undergo coordinated mechanical and geometric transformations to build organs and body structures. Includes epithelial folding, invagination, convergent extension, cell intercalation, tissue flows, mechanical feedback, and multi-cellular force integration. Excludes molecular-level developmental signaling unless it directly drives mechanical processes, and excludes adult wound healing unless used as a model for morphogenetic mechanics.
Natural Sciences	Biology	Developmental Biology	Organogenesis & Multi-Tissue Assembly	Focuses on how multiple tissues coordinate to form organs with defined architecture, function, and spatial organization. Includes tissue–tissue signaling, mechanical integration, branching morphogenesis, lumen formation, compartmentalization, pattern refinement, and organ-specific assembly rules. Excludes single-tissue morphogenesis unless it directly contributes to higher-order organ structure, and excludes mature organ physiology unless relevant to formation logic.
Natural Sciences	Biology	Developmental Biology	Growth, Timing, Regeneration & Life-Cycle Transitions	Focuses on how organisms grow in size and complexity, how developmental timing is regulated, how tissues regenerate after injury, and how organisms transition between major life-cycle stages (embryo → juvenile → adult → reproductive → senescent). Includes growth-rate control, hormonal and molecular timing pathways, regeneration programs, metamorphosis, molting, and developmental checkpoints. Excludes normal adult physiology unless it relates to growth or timing, and excludes ecological life-history strategy unless tied to developmental mechanisms.
Natural Sciences	Biology	Developmental Biology	Evolutionary Development (Evo–Devo)	Focuses on how changes in developmental processes drive evolutionary variation in form, body plans, morphology, and life cycles. Includes regulatory-network evolution, heterochrony, heterotopy, modularity, constraint, developmental plasticity, deep homology, and comparative embryology. Excludes purely ecological or genetic-population dynamics unless linked to developmental mechanisms, and excludes functional physiology not tied to developmental patterning.
Natural Sciences	Biology	Ecology	Organismal Ecology	Examines how individual organisms interact with their physical environments through behavioral, physiological, and morphological strategies. Includes habitat selection, thermoregulation, foraging, migration, water/energy balance, and stress tolerance. Excludes full population dynamics, species interactions, and ecosystem-level processes except when directly affecting individual organisms.
Natural Sciences	Biology	Ecology	Population Ecology	Examines the dynamics of populations: growth, regulation, age structure, density dependence, dispersal, survivorship, reproduction, and demographic patterns. Excludes individual-level physiological mechanisms and community-level interactions except when they directly influence population processes.
Natural Sciences	Biology	Ecology	Community Ecology	Focuses on the structure, composition, diversity, and interactions of multiple co-occurring species within a shared environment. Includes competition, predation, mutualism, commensalism, trophic structure, diversity patterns, and community assembly. Excludes single-species population dynamics except as components of multi-species interactions.
Natural Sciences	Biology	Ecology	Ecosystem Ecology	Focuses on the flows of energy, matter, and nutrients through biological communities and their physical environment. Includes productivity, decomposition, trophic energy transfer, nutrient cycling, carbon/water fluxes, and biogeochemical processes. Excludes individual behavior, species-level interactions, and fine-scale physiology except when directly influencing ecosystem-scale fluxes.
Natural Sciences	Biology	Ecology	Landscape & Spatial Ecology	Examines how ecological processes vary across space, how spatial patterns influence ecological dynamics, and how landscapes shape movement, dispersal, interactions, and ecosystem function. Includes fragmentation effects, connectivity, spatial heterogeneity, patch structure, corridors, barriers, and spatial scaling. Excludes fine-scale individual behavior or community interactions except when mediated by spatial structure.
Natural Sciences	Biology	Ecology	Global Ecology & Earth-System Interactions	Examines ecological processes operating at planetary scale and their coupling with Earth’s physical, chemical, and climatic systems. Includes global biogeochemical cycles, climate–biosphere feedbacks, planetary productivity patterns, global species distributions, large-scale ecosystem shifts, and Earth-system feedback loops. Excludes local ecological interactions except as components of global-scale dynamics.
Formal Sciences	Logic	Proof Theory	Proof Calculi	Studies formal systems for derivations and inference; includes syntactic proof structures, rule applications, derivability; excludes semantic truth conditions except as constraints on proof correctness.
Formal Sciences	Logic	Proof Theory	Structural Proof Theory	Studies the structural features of proofs and derivations independent of specific logical connectives; includes sequent structure, structural rules, cut-elimination, normalization; excludes purely semantic truth definitions or model-theoretic validity except where needed to justify structural results.
Formal Sciences	Logic	Proof Theory	Proof Theory of Non-Classical Logics	Studies proof systems for logics that deviate from classical principles (e.g., intuitionistic, modal, linear, relevant, paraconsistent, many-valued). Includes sequent calculi, natural deduction, tableaux, deep inference, and structural variants tailored to each logic. Excludes model-theoretic semantics except where required to validate or motivate proof rules.
Formal Sciences	Logic	Proof Theory	Ordinal & Strength Analysis	Studies the proof-theoretic strength of formal systems by assigning ordinals or comparable measures of transfinite complexity. Includes ordinal assignments, well-ordering principles, reflection principles, consistency strength comparisons, and calibration of theories via transfinite induction. Excludes semantic model-theoretic strength measures except as tools for ordinal characterization.
Formal Sciences	Logic	Proof Theory	Proof Complexity	Studies the resources required to produce proofs in various formal systems. Includes proof length, size, width, space, depth, and time; comparisons of propositional proof systems; complexity lower bounds; automatizability; and relationships between proof systems and classical complexity classes (e.g., NP, coNP, PSPACE). Excludes semantic validity except when used to relate proof systems to complexity-theoretic classes.
Formal Sciences	Logic	Proof Theory	Automated & Interactive Reasoning	Studies algorithmic and human–machine systems for deriving proofs, solving logical problems, and constructing formal reasoning artifacts. Includes automated theorem proving, SAT/SMT solving, proof assistants, interactive proof construction, program verification, and reasoning engines. Excludes purely philosophical epistemic reasoning except when formalized.
Formal Sciences	Logic	Model Theory	Structures, Languages & Interpretations	Concerned with formal languages, structures, signatures, and interpretations; includes domains, functions, relations, and symbol assignments. Excludes semantic content not expressible in first-order definability.
Formal Sciences	Logic	Model Theory	Satisfaction & Definability Theory	Concerned with the satisfaction relation (⊨), truth in structures, definability of sets/functions, and expressibility of formulas; excludes semantics not reducible to first-order or the governing logic.
Formal Sciences	Logic	Model Theory	Quantifier Theory & Model Completeness	Studies the behavior, expressive power, and elimination of quantifiers; includes quantifier-rank analysis, prenex forms, definability via quantifier patterns, and the theory of model completeness (every embedding is elementary). Excludes higher-order quantifiers not interpreted in first-order semantics.
Formal Sciences	Logic	Model Theory	Classification Theory	Studies dividing lines among first-order theories (stable, superstable, simple, NIP, NSOP, o-minimal, etc.); includes ranks, independence relations, and behavior of types. Excludes empirical classification or semantic categories outside model-theoretic structure.
Formal Sciences	Logic	Model Theory	Tame / O-Minimal Model Theory	Studies structures whose definable sets in one variable are finite unions of points and intervals; includes o-minimality, tame geometry, definable functions, cell decomposition. Excludes pathological or wild definability such as arbitrary subsets of ℝ.
Formal Sciences	Logic	Set Theory	Axiomatic Foundations & Cumulative Hierarchy	Studies the ZFC axiom system, transfinite recursion, ordinal-indexed stages of the von Neumann hierarchy, rank functions, and the formation of all sets through iterative cumulative stages; excludes non-well-founded set theories unless explicitly adopted.
Formal Sciences	Logic	Set Theory	Constructibility & Inner Models	Studies canonical internal universes such as Gödel’s (L), fine-structure models, Jensen hierarchies, sharps, core models; includes definability-based constructions and minimal models satisfying ZFC. Excludes arbitrary non-definable sets and general forcing extensions unless used externally for comparison.
Formal Sciences	Logic	Set Theory	Large Cardinal Theory	Studies strong axioms of infinity such as inaccessible, Mahlo, weakly compact, measurable, supercompact, huge, and stronger cardinals; includes embeddings, ultrafilters, extender sequences, and consistency strength. Excludes forcing extensions unless used to analyze relative consistency.
Formal Sciences	Logic	Set Theory	Forcing & Independence Theory	Studies forcing extensions, independence proofs, Boolean-valued models, generic filters, preservation theorems, combinatorial independence, and relative consistency results. Excludes absolute results provable within ZFC unless used as contrast; does not cover constructive forcing unless explicitly adopted.
Formal Sciences	Logic	Set Theory	Descriptive Set Theory	Studies definable sets of reals in Polish spaces; includes Borel sets, analytic/coanalytic sets, projective hierarchies, regularity properties (measurability, Baire property), classification by definability and complexity. Excludes arbitrary subsets of reals unless considered relative to axioms extending ZFC (e.g., determinacy).
Formal Sciences	Logic	Computability Theory	Models of Computation & Recursive Function Theory	Studies the formal definitions of computability across equivalent models (Turing machines, μ-recursive functions, λ-calculus, register machines, Post machines). Includes the Church–Turing thesis, partial computable functions, effective procedures, and mechanistic characterizations of algorithms. Excludes informal or intuitive notions of “effective method” unless formalized.
Formal Sciences	Logic	Computability Theory	Recursively Enumerable (r.e.) Sets & Degrees	Studies semi-decidable sets and the classification of their algorithmic difficulty. Includes r.e. sets, partial computable enumerations, Turing reductions, degrees of unsolvability, complete r.e. sets, Post’s problem, and priority constructions. Excludes sets requiring full decidability, higher-type recursion frameworks, or non-effective enumerations not representable by partial computable functions.
Formal Sciences	Logic	Computability Theory	Reducibility & Degrees of Unsolvability	Studies formal relationships of relative computability among sets/problems via reducibilities (Turing, many-one, truth-table, weak tt, bounded-Turing). Includes degree structures, completeness, jumps, and incomparable degrees. Excludes informal heuristic comparisons of difficulty not captured by effective reductions.
Formal Sciences	Logic	Computability Theory	Arithmetical & Analytical Hierarchies	Studies the classification of definable sets and problems by logical complexity. Includes the arithmetical hierarchy (Σₙ⁰, Πₙ⁰, Δₙ⁰), the analytical hierarchy (Σₙ¹, Πₙ¹, Δₙ¹), quantifier alternation, definability over ℕ and ℕ^ℕ, completeness under many-one or Turing reducibility, and normal forms. Excludes semantic classifications not tied to formal logical quantifier structure.
Formal Sciences	Mathematics	Algebra	Group Theory	Studies sets equipped with a single associative binary operation with identity and inverses. Includes abstract groups, symmetry groups, permutation groups, matrix groups, quotient groups, group actions, and homomorphisms. Excludes non-associative algebraic systems unless viewed via group-like abstractions.
Formal Sciences	Mathematics	Algebra	Ring Theory	Studies algebraic structures with two operations—addition and multiplication—satisfying distributivity, additive associativity/commutativity, and the existence of additive identity/inverses. Includes commutative rings, noncommutative rings, integral domains, ideals, factorization, homomorphisms, modules, polynomial rings, and matrix rings. Excludes algebraic systems lacking stable two-operation structure (e.g., quasigroups, semigroups without addition).
Formal Sciences	Mathematics	Algebra	Field Theory	Studies algebraic structures where addition, subtraction, multiplication, and division (except by 0) are always possible and satisfy the field axioms. Includes extensions of fields, algebraic and transcendental elements, splitting fields, Galois groups, valuations, and topological/ordered field structures. Excludes rings without multiplicative inverses (except as substructures) and non-associative algebraic systems.
Formal Sciences	Mathematics	Algebra	Module Theory	Studies algebraic structures where a ring acts linearly on an Abelian group. Includes left/right modules, submodules, quotient modules, free and projective modules, module homomorphisms, tensor products, exact sequences, and decomposition theorems. Excludes structures lacking bilinear ring action (e.g., raw Abelian groups without scalar action, vector spaces that require fields unless viewed as modules).
Formal Sciences	Mathematics	Algebra	Linear Algebra	Studies vector spaces and linear transformations over fields or rings. Includes matrices, determinants, eigenvalues/eigenvectors, inner products, orthogonality, linear systems, bases, dimension, diagonalization, spectral theory, and canonical forms. Excludes nonlinear transformations except when linearized; excludes general module theory except when specializing to vector spaces.
Formal Sciences	Mathematics	Algebra	Representation Theory	Studies how algebraic structures—groups, algebras, Lie algebras—act linearly on vector spaces. Includes group representations, modules over algebras, characters, irreducible decompositions, tensor products, induced representations, and geometric representation frameworks. Excludes nonlinear actions and structure theories unrelated to linearization.
Formal Sciences	Mathematics	Algebra	Universal Algebra	Studies algebraic structures in complete generality, defined by sets equipped with operations of specified arities. Includes groups, rings, lattices, modules, Boolean algebras, semigroups, algebras over fields, and all structures definable by operations and identities. Excludes analytic, topological, and measure-theoretic structure unless encoded algebraically; excludes systems defined by partial operations unless explicitly extended.
Formal Sciences	Mathematics	Algebra	Algebraic Combinatorics	Studies discrete structures using algebraic methods and studies algebraic structures using combinatorial methods. Includes symmetric functions, Young tableaux, posets, Coxeter groups, association schemes, polynomial invariants, representation theory of symmetric and related groups, generating functions, and algebraic graph theory. Excludes continuous analysis unless discretized or encoded combinatorially; excludes combinatorics without meaningful algebraic structure.
Formal Sciences	Mathematics	Mathematical Analysis	Real Analysis	Studies rigorous properties of real numbers, limits, continuity, differentiation, integration, sequences, series, and convergence in real-valued settings. Includes metric spaces, measure theory, Lebesgue integration, function spaces, approximation theory, compactness, completeness, and real-variable techniques. Excludes complex-specific holomorphic phenomena and algebraic structures not expressible through limits or measure.
Formal Sciences	Mathematics	Mathematical Analysis	Complex Analysis	Studies analytic (holomorphic) functions of one or several complex variables, emphasizing differentiability in the complex sense, contour integration, residues, conformality, harmonic relationships, analytic continuation, and the structure of singularities. Excludes real-only differentiability, non-analytic complex functions, and general PDEs unless tied to holomorphic or harmonic structure.
Formal Sciences	Mathematics	Mathematical Analysis	Functional Analysis	Studies infinite-dimensional vector spaces (normed, Banach, Hilbert spaces) and the linear operators acting on them. Includes norms, inner products, bounded and unbounded operators, dual spaces, weak/weak-* topologies, spectral theory, compactness, operator algebras, distributions, and functional-analytic foundations of PDEs. Excludes purely finite-dimensional linear algebra except as special cases; excludes nonlinear analysis except where structurally tied to linear operators or functional spaces.
Formal Sciences	Mathematics	Mathematical Analysis	Harmonic Analysis	Studies the decomposition of functions, signals, or distributions into basic wave-like components (often via Fourier analysis). Includes Fourier series, Fourier transforms, convolution, singular integrals, maximal functions, Littlewood–Paley theory, representation-theoretic harmonic analysis on groups, and analysis on manifolds. Excludes purely algebraic signal manipulations with no analytic structure and excludes PDEs except where spectral or transform methods apply.
Formal Sciences	Mathematics	Mathematical Analysis	Differential Equations (ODE/PDE)	Studies equations involving derivatives of unknown functions, including ordinary differential equations (ODEs), partial differential equations (PDEs), systems of differential equations, and boundary/initial value problems. Includes existence/uniqueness theory, stability, qualitative analysis, spectral methods, variational principles, distributional solutions, and numerical approximations. Excludes algebraic equations, discrete dynamical systems (except as approximations), and stochastic processes unless incorporated within deterministic DE frameworks.
Formal Sciences	Mathematics	Geometry & Topology	Differential Geometry	Studies smooth manifolds and smooth geometric structures defined using calculus: smooth maps, curvature, connections, geodesics, differential forms, and tensor fields. Excludes non-smooth or purely topological settings unless smooth structures are imposed.
Formal Sciences	Mathematics	Geometry & Topology	Algebraic Geometry	Studies geometric spaces defined by polynomial equations over fields, rings, or schemes; includes varieties, schemes, morphisms, divisors, cohomology, moduli, and birational geometry. Excludes arbitrary topological spaces or analytic manifolds unless endowed with algebraic structure.
Formal Sciences	Mathematics	Geometry & Topology	Metric Geometry	Studies geometric structures where distance is the primary invariant: metric spaces, geodesic spaces, length spaces, CAT(0)/CAT(k) spaces, Gromov–Hausdorff limits, curvature bounds via comparison geometry. Excludes smoothness assumptions unless additional structure (Riemannian, Finsler) is imposed.
Formal Sciences	Mathematics	Geometry & Topology	Point-Set Topology	Studies topological spaces defined by open sets, continuity, convergence, compactness, connectedness, separation axioms, and product constructions. Excludes algebraic or geometric structures unless explicitly imposed.
Formal Sciences	Mathematics	Geometry & Topology	Homotopy Theory	Studies spaces up to continuous deformation (homotopy); includes homotopy classes of maps, fundamental group, higher homotopy groups, fibrations, cofibrations, homotopy equivalences, CW-complexes, spectra, stable homotopy theory. Excludes point-set topology not relevant to homotopy invariants and geometric structures requiring rigid metrics or smoothness.
Formal Sciences	Mathematics	Geometry & Topology	Knot Theory	Studies embeddings of circles (S^1) (and higher-dimensional analogues) into 3-dimensional space, up to ambient isotopy; includes link theory, knot invariants, diagrams, Reidemeister moves, polynomial invariants, and 3-manifold connections. Excludes geometric/analytic structures unless added, and excludes physical knots unless abstracted into embeddings.
Formal Sciences	Mathematics	Number Theory	Elementary Number Theory	Studies integers using classical arithmetic methods: primes, divisibility, modular arithmetic, congruences, arithmetic functions, Diophantine equations. Excludes analytic, algebraic, or geometric number theory unless tools reduce to elementary methods.
Formal Sciences	Mathematics	Number Theory	Algebraic Number Theory	Studies number fields, rings of integers, valuations, ideals, units, class groups, Galois extensions, and local–global principles. Excludes transcendental structures unless algebraic approximations apply, and excludes analytic methods except where they reduce to algebraic forms.
Formal Sciences	Mathematics	Number Theory	Analytic Number Theory	Studies integers through analytic methods, especially limits, sums, integrals, complex analysis, asymptotics, and estimates. Includes distribution of primes, L-functions, zeta functions, character sums, exponential sums, and analytic techniques for arithmetic functions. Excludes purely algebraic or geometric number theory unless analysis is explicitly applied.
Formal Sciences	Mathematics	Number Theory	Arithmetic Geometry	Studies solutions to polynomial equations using both algebraic geometry and number theory; includes rational points, integral points, Diophantine sets, reduction modulo primes, heights, arithmetic schemes, and global fields. Excludes analytic approaches unless used in service of algebraic–arithmetic structure; excludes purely geometric varieties with no arithmetic structure.
Formal Sciences	Mathematics	Number Theory	Modular and Automorphic Forms	Studies complex analytic or algebraic functions invariant under actions of arithmetic groups (e.g., SL₂(ℤ)), as well as their generalizations on adele groups and higher-rank Lie groups. Includes modular forms, cusp forms, automorphic representations, Hecke operators, L-functions, eigenforms, and Fourier expansions. Excludes non-arithmetic or arbitrary analytic functions unless they satisfy automorphy conditions.
Formal Sciences	Mathematics	Number Theory	Transcendental Number Theory	Studies numbers that are not algebraic over ℚ, focusing on proving transcendence or algebraic independence of specific constants (e, π, log α, ζ-values, exponential values). Includes linear/analytic independence results, transcendence criteria, Diophantine approximation, and auxiliary polynomial methods. Excludes algebraic numbers and analytic number theory except where used to establish transcendence.
Social Sciences	Anthropology		Human Evolutionary Anthropology	Studies human origins, hominin evolution, primate comparison, and biological variation shaped by ecological and cultural pressures. Includes fossil lineages, skeletal morphology, paleoenvironments, primate behavior, human variation, adaptation, and evolutionary genetics. Excludes purely cultural explanations unless integrated with biocultural models; excludes modern human social behavior unless relevant to evolutionary inference.
Social Sciences	Anthropology		Kinship, Descent & Domestic Organization	Studies how human societies structure relationships of descent, marriage, alliance, inheritance, household formation, and domestic labor. Includes kin groups, lineage systems, residence rules, marriage systems, household economies, caregiving patterns, relatedness, and genealogical representation. Excludes large-scale political organization unless rooted in kinship; excludes purely genetic ancestry unless linked to social kinship structures.
Social Sciences	Anthropology		Ritual, Cultural Practice & Symbolic Systems	Studies how human groups create, transmit, perform, and interpret ritual action, symbolic meaning, cultural practices, expressive systems, and cosmological frameworks. Includes ceremonies, rites of passage, collective performances, belief systems, symbolism, myth, cultural codes, embodied practices, material symbols, art, speech genres, and sacred/secular ritual domains. Excludes purely biological explanations unless integrated bioculturally; excludes institutional politics unless ritualized.
Social Sciences	Anthropology		Subsistence Systems, Environment & Human Adaptation	Studies how human populations obtain food, water, materials, and energy from their environments, and how ecological and cultural factors shape adaptive strategies. Includes foraging, horticulture, pastoralism, agriculture, fishing, mixed economies, mobility patterns, niche construction, ecological knowledge, and long-term human–environment interaction. Excludes purely economic markets unrelated to ecological subsistence; excludes biological evolution unless it directly intersects with adaptive behavior.
Social Sciences	Anthropology		Material Culture, Technology & Archaeological Interpretation	Studies how human societies create, use, modify, and discard material objects and technologies, and how archaeologists reconstruct behavior, social organization, and cultural meaning from material remains. Includes artifacts, manufacturing processes, technological systems, site formation, depositional practices, spatial patterning, taphonomy, chaîne opératoire, experimental replication, and interpretive frameworks. Excludes purely symbolic systems unless materially expressed; excludes environmental processes unless interacting with material deposition.
Social Sciences	Anthropology		Ethnographic Method & Comparative Analysis	Focuses on the systematic study, documentation, and interpretation of lived human experience through participant observation, interviewing, immersion, and cross-cultural comparison. Includes fieldwork methods, cultural description, interpretive analysis, comparative datasets, intercultural patterning, and ethnographic theory. Excludes laboratory-based behavioral testing unless incorporated into field contexts; excludes statistical generalization unless linked to cross-cultural datasets.
Social Sciences	Economics		Choice (Microeconomic Foundations)	Studies how individuals and firms make decisions under constraints. Includes preferences, utility, optimization, tradeoffs, risk, time, information, and choice under uncertainty. Excludes macroeconomic aggregates unless derived from micro behavior; excludes strategic interactions (game theory) unless modeling individual optimization in response to expectations.
Social Sciences	Economics		Interaction (Markets, Strategy & Mechanisms)	Studies how multiple agents interact, coordinate, compete, or strategize through markets, prices, institutions, contracts, and mechanism design. Includes supply–demand, price formation, market power, Nash equilibrium, incentives, auctions, matching markets, externalities, public goods, bargaining, contracts, information asymmetry, and general equilibrium. Excludes individual decision-making in isolation (pure micro choice) and excludes aggregate macro behavior unless emerging from interaction structure.
Social Sciences	Economics		Aggregation & Dynamics (Macroeconomic Systems)	Studies the evolution of entire economic systems arising from the interaction and aggregation of many micro-level agents. Includes growth, business cycles, inflation, unemployment, fiscal/monetary dynamics, aggregate production, consumption dynamics, expectations, capital accumulation, technological change, and propagation of shocks. Excludes purely individual decision-making (micro) unless aggregated; excludes general equilibrium without dynamics; excludes market-by-market strategic behavior except where it generates macro patterns.
Social Sciences	Geography (Human)		Spatial Patterns & Spatial Analysis	Studies how human activities, populations, infrastructures, and built environments are arranged across the Earth’s surface and how spatial structures form, persist, or change. Includes spatial distribution, clustering, dispersion, gradients, location theory, spatial interaction, regional differentiation, GIS-based pattern detection, and urban morphology. Excludes purely temporal analyses without spatial components; excludes non-human spatial ecology unless integrated into human systems.
Social Sciences	Geography (Human)		Mobility, Flows & Connectivity	Studies the movement of people, goods, information, capital, and resources across space, and the networks, infrastructures, and spatial relationships that structure these flows. Includes migration systems, commuting patterns, transportation networks, digital connectivity, supply chains, diffusion processes, accessibility and reachability, and temporal–spatial compression. Excludes processes without spatial displacement; excludes static spatial patterns unless tied to flows.
Social Sciences	Geography (Human)		Human–Environment Interaction & Landscape Modification	Studies how human societies perceive, use, transform, engineer, degrade, restore, and adapt to environmental systems, and how landscapes evolve in response to cultural, economic, and technological activities. Includes land-use change, resource extraction, agriculture, urbanization, deforestation, terracing, hydrological modification, hazard mitigation, ecosystem engineering, and long-term socioecological dynamics. Excludes purely natural environmental processes without human involvement; excludes human behavior unrelated to landscape outcomes.
Social Sciences	Geography (Human)		Place, Territory & Spatial Experience	Studies how humans perceive, construct, inhabit, claim, and emotionally or symbolically attach meaning to places and territories. Includes experiential and phenomenological dimensions of space, cultural constructions of landscape, territoriality, boundary-making, sense of place, emplacement, lived experience, identity-space relations, and contested spatial meanings. Excludes purely geometric or quantitative spatial analysis unless tied to human interpretation; excludes non-human territorial behavior except for analogy.
Social Sciences	Linguistics		Phonetics & Phonology	Examines the physical, cognitive, and linguistic systems governing the production, perception, and patterned organization of speech sounds. Includes articulatory/ acoustic phonetics, prosody, syllable structure, phonological features, tone, stress, phonotactics, assimilation, lenition/fortition, phonological alternations. Excludes morphological or syntactic structure except where phonological processes interface with them.
Social Sciences	Linguistics		Morphology	Examines the internal structure of words and the rules by which meaningful units (morphemes) combine to form complex words. Includes inflection, derivation, compounding, reduplication, morphological parsing, agreement, case marking, and allomorphy. Excludes phonological alternations unless morphologically conditioned; excludes syntactic structure except where morphology interfaces with syntax.
Social Sciences	Linguistics		Syntax	Examines the structural organization of phrases, clauses, and sentences, and the rules, constraints, or computations determining how words combine into hierarchical structures. Includes constituent structure, dependency relations, grammatical functions, movement, agreement, case marking, word order, binding, and syntactic features. Excludes lexical semantics, discourse structure, or phonology except where they interface with syntax.
Social Sciences	Linguistics		Semantics	Examines how linguistic expressions encode and convey meaning, including lexical semantics, compositional semantics, truth conditions, reference, quantification, scope, entailment, presupposition, aspect, modality, and semantic features. Excludes pragmatic inference, discourse structure, or world knowledge except where required to compute literal meaning.
Social Sciences	Linguistics		Pragmatics	Examines how meaning is shaped by context, speaker intentions, shared knowledge, discourse structure, social norms, and inferential reasoning. Includes implicature, presupposition projection, deixis, speech acts, politeness, discourse coherence, relevance, and contextual enrichment. Excludes purely truth-conditional meaning (semantics) and purely structural form (syntax), except when interacting with pragmatic interpretation.
Social Sciences	Political Science		Political Institutions & Formal Political Order	Studies the rules, structures, and decision procedures that allocate authority, constrain actors, and define how power is exercised within a political system. Includes constitutions, electoral systems, party systems, legislatures, executives, courts, federalism, bureaucratic systems, veto players, agenda control, institutional stability, authoritarian vs democratic rule. Excludes informal norms unless formally institutionalized; excludes individual political behavior (covered in political mobilization) except as it interacts with institutional rules.
Social Sciences	Political Science		Political Behavior, Mobilization & Collective Action	Studies how individuals and groups engage in political life: voting, participation, identity formation, mobilization, protest, activism, cooperation, conflict, political persuasion, social movements, and collective-action dynamics. Includes turnout, political psychology, mass opinion, identity politics, revolution and rebellion dynamics, and group coordination problems. Excludes institutional rules themselves (covered under political institutions) except as constraints on behavior; excludes macro outcomes unless emergent from collective action.
Social Sciences	Political Science		Governance, Policy Formation & State Capacity	Studies how states and governments formulate, implement, and enforce public policy, and how institutional capacity enables or constrains governance. Includes policymaking processes, bureaucratic capability, regulatory quality, corruption control, state reach, taxation and extraction, service delivery, administrative professionalism, crisis governance, and long-term institutional performance. Excludes political behavior, electoral competition, and formal constitutional structure unless directly shaping policy processes or capacity.
Social Sciences	Political Science		International Relations & Global Order	Studies how states, international organizations, non-state actors, and transnational networks interact in a global system. Includes war and peace, diplomacy, alliances, deterrence, international law, trade, globalization, cooperation problems, security dilemmas, balance-of-power dynamics, multilateral governance, and systemic change. Excludes purely domestic politics unless it shapes foreign behavior; excludes individual psychology except as embedded in leadership or bargaining models.
Social Sciences	Psychology		Cognitive Processes & Mental Architecture	Examines internal mechanisms by which the mind perceives, encodes, stores, retrieves, transforms, and manipulates information. Includes perception, memory systems, attention, reasoning, language comprehension, decision-making, problem-solving, mental imagery, and representational structures. Excludes social, emotional, or developmental phenomena unless emergent from cognitive operations.
Social Sciences	Psychology		Learning, Conditioning & Behavioral Mechanisms	Examines how behavior is acquired, modified, strengthened, or extinguished through experience, reinforcement, punishment, contingencies, cues, and environmental shaping. Includes classical conditioning, operant conditioning, reinforcement schedules, habit formation, extinction, stimulus generalization, shaping, and behavioral modeling. Excludes cognitive processes unless mediated through observable learning mechanisms.
Social Sciences	Psychology		Emotion, Motivation & Affect Regulation	Examines the processes by which emotions arise, are experienced, expressed, shaped, regulated, and used to motivate behavior. Includes affective appraisal, emotional expression, motivational drives, reward systems, regulatory strategies, stress responses, and adaptive behavioral functions. Excludes purely cognitive processing unless shaped by affective states, and excludes social emotions unless mediated through internal affective mechanisms.
Social Sciences	Psychology		Development, Individual Differences & Psychometrics	Examines developmental trajectories, stable and situationally expressed individual differences, and the measurement and modeling of psychological traits and abilities. Includes lifespan development, temperament, personality traits, cognitive abilities, psychometric test theory, factor structures, reliability/validity frameworks, and growth modeling. Excludes purely clinical symptomatology unless tied to trait or developmental variance.
Social Sciences	Sociology		Social Interaction Mechanisms	Examines micro-level processes through which meanings, norms, expectations, roles, identities, emotions, and patterned behaviors emerge from interpersonal interaction. Excludes macro-structural systems unless mediated through direct interactional processes.
Social Sciences	Sociology		Social Structure Mechanisms	Examines patterned arrangements of social positions, roles, institutions, group boundaries, and stratification systems that distribute resources, opportunities, power, and status. Excludes micro-interactional episodes unless linked to underlying structural patterns, and excludes purely psychological explanations.
Social Sciences	Sociology		Social Network & Relational Dynamics	Examines how social ties, relational structures, patterns of connection, and flows of information, influence, support, and resources shape individual and collective behavior. Excludes strictly psychological dyadic processes unless embedded in network relations, and excludes macro-structures not reducible to relational patterns.