Wikipedia:Vital articles/Level/5/Physical sciences/Physics

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Vital articles is a list of subjects for which Wikipedia should have corresponding high-quality articles. It serves as a centralized watchlist to track the status of Wikipedia's most essential articles. This is one of the sub-lists of the fifty thousand article Vital articles/Level 5 and is currently under construction.

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Total articles: 1,038/1,200

Physics basics (62 articles)

General (50 articles)

1. Physics (Level 2)
2. Outline of physics
3. Physical property
4. Physical quantity
5. Energy (Level 2)
   1. Conservation of energy (Level 4)
   2. Energy density
6. Matter (Level 3)
   1. Exotic matter
7. Vacuum (Level 3)
8. Fundamental interaction
   1. Gravity (Level 3)
   2. Electromagnetism (Level 3)
   3. Strong interaction (Level 3)
   4. Weak interaction (Level 3)
   5. Fifth force
9. Spacetime (Level 4)
   1. Space (Level 3)
   2. Time (Level 2)
      1. Time in physics
10. Mass–energy equivalence (Level 4)
11. Conservation law
12. Hysteresis
13. Transport phenomena
14. Radiation (Level 4)
    1. Ionizing radiation (Level 4)
    2. Background radiation
15. Scalar
16. Field (Level 4)
    1. Flux (Level 4)
17. Gauge theory (Level 4)
    1. Introduction to gauge theory
18. Symmetry (Level 4)
19. Instability
    1. Metastability
20. Classical physics
    1. Classical field theory
21. Theoretical physics (Level 4)
22. Experimental physics
23. Computational physics
24. Statistical physics
25. Atmospheric physics
26. Biophysics
27. Chemical physics
28. Polymer physics
29. Mathematical physics
30. List of unsolved problems in physics
31. Scale invariance
32. Classical limit
33. Macroscopic scale

Physical constants (12 articles)

1. Physical constant
2. Bohr magneton
3. Bohr radius
4. Boltzmann constant
5. Electron magnetic moment
6. Elementary charge
7. Fine-structure constant
8. Gravitational constant
9. Planck constant
10. Speed of light (Level 3)
11. Vacuum permeability
12. Vacuum permittivity

Atomic, molecular and optical physics (92 articles)

Atomic physics (44 articles)

1. Atom (Level 2)
2. Atomic physics (Level 4)
3. Atomic theory (Level 4)
4. Atomic nucleus (Level 4)
   1. Hypernucleus
   2. Isotope (Level 4)
   3. Nucleon
   4. Nuclide (Level 4)
5. Atomic orbital (Level 4)
6. Binding energy (Level 4)
7. Plum pudding model
8. Rutherford model
9. Bohr model (Level 4)
10. Electron configuration (Level 4)
11. Electron shell (Level 4)
12. Exotic atom
    1. Onium
       1. Positronium
13. Ion (Level 4)
    1. Oxonium ion
14. Energy level (Level 4)
    1. Fine structure
    2. Hyperfine structure
    3. Spin–orbit interaction
    4. Degenerate energy levels
15. Geiger–Marsden experiments (Level 4)
16. Principal quantum number
17. Azimuthal quantum number
18. Magnetic quantum number
19. Spin quantum number
20. Spectral line
    1. Stark effect
    2. Zeeman effect
    3. Stimulated emission
    4. Spontaneous emission
    5. Hydrogen spectral series
       1. Rydberg formula
       2. H-alpha
    6. Hydrogen line
    7. Einstein coefficients
    8. Optical pumping
21. Spherical harmonics
22. Density functional theory
23. Rutherford scattering

Molecular physics (9 articles)

1. Molecular physics
2. Molecular orbital (Level 4)
   1. Molecular orbital theory (Level 4)
3. Rigid rotor
4. Molecular dynamics
5. Cross section
6. Emission spectrum
7. Rotational–vibrational spectroscopy
   1. Rotational spectroscopy

Optics (39 articles)

1. Optics (Level 3)
2. Geometrical optics
3. Physical optics
4. Focus (Level 4)
5. Focal length (Level 4)
6. Photonics
7. Ray
8. Polarization (Level 4)
   1. Circular polarization
   2. Linear polarization
   3. Stokes parameters
9. Reflection (Level 4)
   1. Reflection coefficient
   2. Transmission coefficient
   3. Total internal reflection
10. Refraction (Level 4)
    1. Refractive index (Level 4)
    2. Snell's law
11. Transparency and translucency (Level 4)
12. Opacity
13. Optical depth
14. Optical power
15. Fresnel equations
16. Nonlinear optics
17. Birefringence
18. Intensity
19. Rayleigh scattering
20. Aperture
21. Angle of incidence
22. Virtual image
23. Dispersion
24. Optical coating
25. Shadow
26. Beer–Lambert law
27. Fourier optics
28. Photometry
    1. Illuminance
    2. Luminous flux
    3. Luminous intensity

Color (99 articles)

Basics (29 articles)

1. Color (Level 3)
2. Blacklight
3. CIE 1931 color space
4. CIELAB color space
5. CIELUV
6. CMYK color model (Level 4)
7. Color theory (Level 4)
   1. Primary color (Level 4)
   2. Secondary color
   3. Tertiary color
8. Gloss (Level 4)
9. ISCC–NBS system
10. Munsell color system
11. RGB color model (Level 4)
    1. RGB color spaces
       1. Adobe RGB color space
       2. DCI-P3
       3. HSL and HSV
       4. ProPhoto RGB color space
       5. scRGB
       6. sRGB
       7. Wide-gamut RGB color space
12. RYB color model
13. Impossible color
14. Chromaticity
    1. Line of purples
15. Hue
16. Tint, shade and tone
17. Web colors

Colors (70 articles)

1. Amber
2. Azure
3. Beige
4. Black (Level 4)
   1. Shades of black
5. Blue (Level 4)
   1. Navy blue
   2. Shades of blue
   3. Sky blue
   4. Ultramarine
6. Brown (Level 4)
   1. Shades of brown
7. Burgundy
8. Celadon
9. Cerulean
10. Chartreuse
11. Copper
    1. Bronze
12. Coral
13. Cream
14. Crimson
15. Cyan
    1. Capri
    2. Shades of cyan
16. Fuchsia
17. Gold
18. Green (Level 4)
    1. Lime
    2. Shades of green
19. Grey (Level 4)
    1. Shades of gray
    2. Slate gray
20. Indigo
21. Lavender
22. Lilac
23. Magenta
    1. Shades of magenta
24. Maroon
25. Mauve
26. Olive
27. Orange (Level 4)
    1. Shades of orange
28. Peach
29. Pink (Level 4)
    1. Shades of pink
30. Purple (Level 4)
    1. Tyrian purple
    2. Shades of purple
31. Red (Level 4)
    1. Scarlet
    2. Shades of red
32. Rose
33. Ruby
34. Saffron
35. Sapphire
36. Silver
37. Spring green
38. Tan
39. Teal
40. Turquoise
41. Vermilion
42. Violet
    1. Shades of violet
43. Viridian
44. White (Level 4)
    1. Ivory
    2. Shades of white
45. Yellow (Level 4)
    1. Lemon
    2. Shades of yellow

Condensed matter physics (78 articles)

Basics (12 articles)

1. Condensed matter physics (Level 4)
2. Solid-state physics (Level 4)
3. Mesoscopic physics
4. Einstein solid
5. Electronic band structure
   1. Band gap
   2. Valence and conduction bands
6. Free electron model
7. Soft matter
8. Bonding in solids
9. Rock magnetism
10. Bloch's theorem

Crystallography (28 articles)

1. Crystallography (Level 4)
2. Crystal (Level 4)
3. Crystallization (Level 4)
   1. Crystal growth
   2. Grain growth
4. Crystal structure
   1. Crystal system
      1. Triclinic crystal system
      2. Monoclinic crystal system
      3. Orthorhombic crystal system
      4. Tetragonal crystal system
      5. Hexagonal crystal family
      6. Cubic crystal system
   2. Bravais lattice
5. Crystal optics
6. Crystallographic defect
   1. Grain boundary
   2. Dislocation
   3. Misorientation
   4. Vacancy defect
7. Crystal twinning
8. Miller index
9. Atomic packing factor
10. Coordination number
11. Polymorphism (materials science)
12. X-ray crystallography
13. Crystal engineering
14. Unit cell

States of matter (17 articles)

1. State of matter (Level 3)
2. Solid (Level 4)
   1. Amorphous solid (Level 4)
3. Liquid (Level 4)
4. Gas (Level 4)
   1. Vapor (Level 4)
5. Plasma (Level 4)
6. Degenerate matter (Level 4)
   1. Bose gas
   2. Fermi gas
7. Bose–Einstein condensate (Level 4)
8. Superfluidity
9. Supercritical fluid
10. Supersolid
11. Liquid crystal
12. Quasiparticle
    1. Electron hole

Phase transitions (21 articles)

1. Phase transition (Level 4)
2. Phase (Level 4)
3. Phase diagram (Level 4)
4. Boiling (Level 4)
   1. Boiling point
5. Melting (Level 4)
   1. Melting point
6. Freezing (Level 4)
7. Evaporation (Level 4)
8. Condensation (Level 4)
9. Vaporization
10. Ionization (Level 4)
11. Plasma recombination
12. Sublimation (Level 4)
13. Deposition
14. Critical point (Level 4)
15. Triple point (Level 4)
16. Miscibility
17. Metallic hydrogen
18. Curie temperature
19. Phase rule

Electromagnetism (120 articles)

Basics (14 articles)

1. Classical electromagnetism
2. Electricity (Level 2)
3. Magnetism (Level 3)
   1. Magnet (Level 4)
      1. Electromagnet (Level 4)
4. Dipole (Level 4)
5. Metamaterial (Level 4)
   1. Negative-index metamaterial
   2. Photonic metamaterial
   3. Tunable metamaterial
   4. Nonlinear metamaterial
6. Oil drop experiment (Level 4)
7. Photoelectric effect (Level 4)
8. Bubble chamber

Electrostatics (16 articles)

1. Electrostatics (Level 4)
   1. Static electricity
2. Coulomb's law (Level 4)
3. Electric charge (Level 4)
   1. Charge density
4. Electric field (Level 4)
   1. Electric displacement field
5. Electric potential (Level 4)
   1. Voltage
6. Electric potential energy
7. Electric flux
8. Electric dipole moment
9. Polarization density
10. Dielectric (Level 4)
11. Electric susceptibility
12. Permittivity

Magnetostatics (18 articles)

1. Magnetostatics (Level 4)
2. Magnetic field (Level 4)
3. Magnetic flux
4. Biot–Savart law
5. Magnetic dipole
6. Magnetic moment
7. Magnetization
   1. Antiferromagnetism
   2. Diamagnetism
   3. Ferrimagnetism
   4. Ferromagnetism (Level 4)
   5. Paramagnetism
   6. Spontaneous magnetization
8. Magnetic susceptibility
9. Permeability
10. Magnetic monopole
11. Magnetohydrodynamics
12. Ampère's force law

Electrodynamics (23 articles)

1. Maxwell's equations (Level 4)
   1. Gauss's law
   2. Gauss's law for magnetism
   3. Ampère's circuital law
   4. Faraday's law of induction
2. Lorentz force (Level 4)
3. Electromagnetic field (Level 4)
4. Electromagnetic four-potential
   1. Lorenz gauge condition
5. Electric current (Level 4)
   1. Alternating current (Level 4)
   2. Direct current (Level 4)
   3. Current density
6. Displacement current
7. Electric power
   1. AC power
8. Electromagnetic induction (Level 4)
9. Electromotive force (Level 4)
10. Eddy current (Level 4)
11. Hall effect
12. Electrical resistivity and conductivity
13. Retarded time
14. Lenz's law

Electromagnetic radiation (33 articles)

1. Electromagnetic radiation (Level 3)
   1. Electromagnetic wave equation
2. Electromagnetic spectrum (Level 4)
   1. Radio wave (Level 4)
   2. Microwave (Level 4)
   3. Terahertz radiation
   4. Infrared (Level 4)
   5. Visible spectrum (Level 4)
      1. Light (Level 3)
   6. Ultraviolet (Level 4)
   7. X-ray (Level 4)
   8. Gamma ray (Level 4)
3. Poynting vector
4. Evanescent field
5. Transverse mode
6. Waveguide
7. Larmor formula
8. Bremsstrahlung (Level 4)
9. Cyclotron radiation
10. Synchrotron radiation
11. Compton scattering
12. Radiative transfer
13. Fluorescence (Level 4)
14. Faraday effect
15. Absorption
    1. Absorption band
16. Near and far field
17. Radiant flux
18. Irradiance
19. Point source
20. Radiance
21. Radiometry
22. Spectral density

Electrical circuits (16 articles)

1. Electrical network (Level 4)
2. Electrical impedance (Level 4)
3. Electrical reactance
4. Electrical resistance and conductance (Level 4)
5. Electrical conductor
6. Insulator
7. Semiconductor (Level 4)
8. Superconductivity (Level 4)
   1. Cooper pair
   2. High-temperature superconductivity
9. Capacitance (Level 4)
   1. Ohm's law (Level 4)
10. Gain (Level 4)
11. Ground
12. Inductance (Level 4)
13. Kirchhoff's circuit laws (Level 4)

Mechanics (278 articles)

Basics (25 articles)

1. Mechanics (Level 4)
   1. Ballistics (Level 4)
   2. Continuum mechanics (Level 4)
   3. Dynamics (Level 4)
      1. Analytical dynamics
   4. Flight (Level 4)
   5. Kinematics (Level 4)
   6. Mechanical advantage
   7. Relativistic mechanics (Level 4)
   8. Statics (Level 4)
2. Oscillation (Level 4)
   1. Harmonic oscillator (Level 4)
      1. Simple harmonic motion (Level 4)
   2. Normal mode
3. Collision
   1. Elastic collision
   2. Inelastic collision
4. Degrees of freedom
5. Free particle
6. Point particle
7. Virial theorem
8. Shock
9. Mechanical equilibrium
10. Displacement
11. Test particle

Quantum mechanics (74 articles)

1. Quantum mechanics (Level 3)
   1. Introduction to quantum mechanics
   2. Quantum
2. AdS/CFT correspondence
3. Born rule
4. Bra–ket notation
5. Correspondence principle
   1. Ehrenfest theorem
6. Dirac equation
7. Expectation value
8. Gyromagnetic ratio
   1. g-factor
9. Interpretations of quantum mechanics
   1. Copenhagen interpretation
   2. De Broglie–Bohm theory
      1. Quantum potential
   3. Many-worlds interpretation
10. Mathematical formulation of quantum mechanics
11. Measurement in quantum mechanics
    1. Measurement problem
12. Observable
    1. Schrödinger's cat
13. Operator
    1. Angular momentum operator
    2. Hamiltonian
    3. Momentum operator
    4. Position operator
14. Parity
15. Particle in a box
    1. Finite potential well
       1. Delta potential
16. Path integral formulation
17. Pauli exclusion principle (Level 4)
18. Perturbation theory
19. Planck postulate
20. Position and momentum spaces
21. Probability amplitude
22. Quantization
23. Quantum chromodynamics (Level 4)
24. Quantum electrodynamics (Level 4)
25. Quantum entanglement (Level 4)
    1. Problem of time
26. Quantum field theory (Level 4)
    1. Casimir effect
    2. Conformal field theory
27. Quantum fluctuation
    1. Quantum foam
28. Quantum gravity (Level 4)
    1. Loop quantum gravity
29. Quantum harmonic oscillator
30. Quantum indeterminacy
31. Quantum number
32. Quantum state
    1. Bound state
    2. Excited state
    3. Ground state
    4. Stationary state
33. Quantum superposition
34. Quantum tunnelling (Level 4)
35. Relativistic quantum mechanics
36. Schrödinger equation (Level 4)
37. Stern–Gerlach experiment
38. Symmetry in quantum mechanics
39. Uncertainty principle (Level 4)
40. Wave function (Level 4)
    1. Wave function collapse
41. Wave–particle duality (Level 4)
    1. Compton wavelength
    2. Davisson–Germer experiment
    3. Electron diffraction
       1. Double-slit experiment
    4. Matter wave
42. WKB approximation
43. Zero-point energy

Classical mechanics (89 articles)

1. Classical mechanics (Level 3)
   1. Hamiltonian mechanics (Level 4)
   2. Lagrangian mechanics (Level 4)
      1. Euler–Lagrange equation
      2. Generalized coordinate
      3. Stationary-action principle
2. Mass (Level 3)
   1. Reduced mass
   2. Density (Level 4)
   3. Center of mass
   4. Conservation of mass (Level 4)
3. Momentum (Level 3)
4. Force (Level 3)
5. Motion (Level 3)
   1. Newton's laws of motion (Level 3)
      1. Newtonian dynamics
   2. Position
   3. Speed (Level 4)
   4. Velocity (Level 4)
   5. Acceleration (Level 4)
   6. Jerk
   7. Equations of motion (Level 4)
   8. Linear motion
   9. Circular motion
   10. Projectile motion
   11. Trajectory
   12. Bouncing ball
   13. Equations for a falling body
   14. Free fall
   15. Steady state
6. Kinetic energy (Level 4)
7. Potential energy (Level 4)
   1. Potential well
8. Scalar potential
   1. Equipotential
9. Vector potential
10. Moment
11. Inertia (Level 4)
12. Moment of inertia (Level 4)
13. Friction (Level 4)
    1. Rolling resistance
14. Impulse (Level 4)
15. Power (Level 4)
16. Work (Level 4)
17. Action
18. Angular displacement
19. Angular frequency
20. Angular velocity
21. Angular acceleration
    1. Angular momentum (Level 4)
    2. Centripetal force (Level 4)
22. Rotation (Level 4)
23. Rolling
24. Torque (Level 4)
25. Weight (Level 4)
    1. Weighing scale (Level 4)
26. Frame of reference (Level 4)
    1. Inertial frame of reference
    2. Non-inertial reference frame
27. Newton's law of universal gravitation (Level 4)
    1. Cavendish experiment
28. Fictitious force
    1. Centrifugal force
    2. Coriolis force (Level 4)
29. Free body diagram
30. Central force
31. Restoring force
32. n-body problem
    1. Two-body problem
       1. Kepler problem
33. Radiation pressure
34. Gravitational field
35. Gravitational potential
36. Tidal force
37. Impact
38. Precession
39. Vibration
    1. Mechanical resonance
40. Damping
41. Conservative force
42. Force field
43. Normal force
44. Canonical coordinates
45. Resultant force
46. Perpetual motion
47. Galilean transformation
48. Galilean invariance
49. Projectile
50. Reaction

Fluid mechanics (37 articles)

1. Fluid mechanics (Level 4)
2. Computational fluid dynamics
3. Rheology
4. Bernoulli's principle (Level 4)
5. Buoyancy (Level 4)
   1. Archimedes' principle
6. Convection (Level 4)
7. Drag (Level 4)
8. Diffusion (Level 4)
   1. Diffusion equation
9. Fluid dynamics (Level 4)
   1. Aerodynamics (Level 4)
10. Lift (Level 4)
11. Navier–Stokes equations (Level 4)
12. Osmosis (Level 4)
13. Reynolds number (Level 4)
14. Surface tension (Level 4)
15. Turbulence (Level 4)
16. Viscosity (Level 4)
17. Flow measurement
    1. Mass flow rate
    2. Volumetric flow rate
18. Flow velocity
19. Fluid
    1. Newtonian fluid
    2. Non-Newtonian fluid
20. Mass flow
21. Vorticity
22. Laminar flow
23. Compressible flow
24. Incompressible flow
25. Hydrostatic equilibrium
26. Deformation
27. Boundary layer
28. Euler equations
29. Circulation
30. Pipe flow

Solid mechanics (30 articles)

1. Solid mechanics (Level 4)
2. Deformation (Level 4)
   1. Poisson's ratio
3. Elastic modulus (Level 4)
4. Elasticity (Level 4)
5. Fatigue (Level 4)
6. Hooke's law (Level 4)
7. Plasticity (Level 4)
   1. Brittleness
   2. Ductility
8. Rigid body
   1. Rigid body dynamics
9. Stiffness (Level 4)
10. Strength of materials (Level 4)
11. Stress (Level 4)
    1. Cauchy stress tensor
    2. Compression
    3. Tension
    4. Torsion
    5. Shear stress
12. Shearing
13. Bulk modulus
14. Finite strain theory
15. Shear modulus
16. Young's modulus
17. Contact mechanics
18. Piezoelectricity
19. Toughness
20. Fracture toughness
21. Crystallite

Soil mechanics (3 articles)

1. Soil mechanics
2. Angle of repose
3. Granular convection

Statistical mechanics (20 articles)

1. Statistical mechanics (Level 4)
2. Microstate
3. Boltzmann distribution
4. Partition function
5. Distribution function
   1. Maxwell–Boltzmann distribution
6. Density of states
7. Identical particles
8. Particle statistics
   1. Maxwell–Boltzmann statistics
   2. Bose–Einstein statistics
   3. Fermi–Dirac statistics
      1. Fermi energy
9. Entropy
10. Canonical ensemble
    1. Grand canonical ensemble
    2. Microcanonical ensemble
11. Maxwell's demon
12. Work
13. Molecular diffusion

Nuclear physics (25 articles)

1. Nuclear physics (Level 4)
2. Radioactive decay (Level 3)
   1. Alpha decay
      1. Alpha particle (Level 4)
   2. Beta decay
      1. Beta particle (Level 4)
   3. Neutron radiation
   4. Decay product
   5. Half-life
   6. Decay energy
   7. Radioactive source
3. Nuclear binding energy
4. Nuclear fission (Level 4)
5. Nuclear fusion (Level 4)
   1. Cold fusion
6. Nuclear reaction
7. Nuclear isomer
8. High-energy nuclear physics
9. Nuclear force
10. Nuclear structure
11. Nucleosynthesis (Level 4)
12. Semi-empirical mass formula
13. Nuclear magnetic resonance
    1. Nuclear magnetic resonance spectroscopy
14. Island of stability

Particle physics (113 articles)

General (44 articles)

1. Particle physics (Level 3)
2. Standard Model (Level 3)
   1. Yang–Mills theory
   2. Higgs mechanism
3. Physics beyond the Standard Model (Level 4)
   1. Axion
   2. Grand Unified Theory
   3. Neutrino oscillation
   4. String theory (Level 4)
      1. Brane
      2. M-theory
      3. String
      4. Superstring theory
   5. Supergravity
   6. Supersymmetry (Level 4)
      1. Minimal Supersymmetric Standard Model
   7. Theory of everything
   8. Unified field theory
4. Particle (Level 4)
5. Scattering (Level 4)
   1. Elastic scattering
   2. Inelastic scattering
   3. Thomson scattering
6. Annihilation
7. CP violation
8. CPT symmetry
9. Electroweak interaction
10. Hierarchy problem
11. Feynman diagram
12. Generation
13. Pair production
14. Particle decay
    1. Proton decay
    2. Free neutron decay
15. Discovery of the neutron
16. Charge conservation
17. QCD matter
18. Quark model
19. Scalar field theory
20. Symmetry breaking
    1. Spontaneous symmetry breaking
21. Noether's theorem
22. Baryon asymmetry
23. Vacuum energy

Quantum numbers (11 articles)

1. Spin (Level 4)
2. Baryon number
3. Lepton number
4. Color charge
5. Flavour
6. Strangeness
7. Isospin
8. Weak isospin
9. Hypercharge
10. Weak hypercharge
11. Chirality

Devices (10 articles)

1. Particle accelerator (Level 4)
   1. Collider
   2. Linear particle accelerator
   3. Large Hadron Collider (Level 4)
   4. Tevatron (Level 4)
   5. Relativistic Heavy Ion Collider
2. Particle detector (Level 4)
   1. Semiconductor detector
   2. Cloud chamber (Level 4)
   3. Calorimeter

Subatomic particles (42 articles)

General (8 articles)

1. Subatomic particle (Level 3)
2. Elementary particle
3. Force carrier
4. List of particles
5. Hadron (Level 4)
6. Massless particle
7. Virtual particle
8. Tachyon

Fermions (21 articles)

1. Fermion (Level 4)
2. Lepton (Level 4)
   1. Electron (Level 3)
   2. Muon (Level 4)
   3. Tau (Level 4)
   4. Neutrino (Level 4)
      1. Electron neutrino
      2. Muon neutrino
      3. Tau neutrino
3. Quark (Level 4)
   1. Up quark
   2. Down quark
   3. Strange quark
   4. Charm quark
   5. Bottom quark
   6. Top quark
4. Baryon (Level 4)
   1. Neutron (Level 3)
   2. Proton (Level 3)
   3. Hyperon
5. Pentaquark

Bosons (13 articles)

1. Boson (Level 4)
2. Gauge boson (Level 4)
   1. Photon (Level 3)
      1. Biophoton
   2. Gluon (Level 4)
   3. W and Z bosons (Level 4)
   4. Graviton
3. Higgs boson (Level 4)
4. Meson (Level 4)
   1. Pion
   2. Kaon
   3. J/psi meson
5. Tetraquark

Antimatter (6 articles)

1. Antimatter (Level 4)
   1. Antihydrogen
2. Antiparticle (Level 4)
   1. Positron (Level 4)
   2. Antiproton
   3. Antineutron

Theory of relativity (35 articles)

1. Theory of relativity (Level 3)
2. General relativity (Level 4)
   1. Introduction to general relativity
   2. Mathematics of general relativity
   3. Einstein field equations
      1. Kerr–Newman metric
   4. Tests of general relativity
   5. White hole
3. Special relativity (Level 4)
4. Principle of relativity (Level 4)
5. Equivalence principle (Level 4)
6. Gravitational wave (Level 4)
   1. First observation of gravitational waves
7. Lorentz transformation (Level 4)
8. Michelson–Morley experiment (Level 4)
9. Four-vector
   1. Four-momentum
10. Relativity of simultaneity
11. Time dilation
    1. Gravitational time dilation
    2. Twin paradox
12. Length contraction
    1. Ladder paradox
13. Causality (Level 4)
14. Proper time
15. Lorentz factor
16. Cherenkov radiation
17. Energy–momentum relation
18. Minkowski space
19. Luminiferous aether
20. Gravitational singularity
21. Hawking radiation
22. Spacetime diagram
23. Stress–energy tensor
24. No-hair theorem

Thermodynamics (89 articles)

1. Thermodynamics (Level 3)
2. Heat (Level 3)
3. Temperature (Level 3)
   1. Thermodynamic temperature
   2. Absolute zero (Level 4)
4. Pressure (Level 4)
   1. Internal pressure
   2. Partial pressure
   3. Pressure–volume diagram
5. Particle number
6. Laws of thermodynamics (Level 4)
   1. Zeroth law of thermodynamics
   2. First law of thermodynamics
   3. Second law of thermodynamics
   4. Third law of thermodynamics
7. Fundamental thermodynamic relation
8. Heat capacity (Level 4)
   1. Heat capacity ratio
9. Latent heat
10. Heat transfer (Level 4)
    1. Heat equation
    2. Thermal conduction
    3. Convection (heat transfer)
    4. Thermal radiation
    5. Newton's law of cooling
11. Entropy (Level 4)
    1. Introduction to entropy
    2. Entropy (classical thermodynamics)
    3. Boltzmann's entropy formula
12. Internal energy (Level 4)
13. Thermodynamic cycle (Level 4)
    1. Brayton cycle
    2. Carnot cycle
    3. Diesel cycle
    4. Ericsson cycle
    5. Heat pump and refrigeration cycle
    6. Otto cycle
    7. Rankine cycle
    8. Stirling cycle
14. Thermodynamic free energy (Level 4)
15. Ideal gas
    1. Ideal gas law (Level 4)
16. Heat engine
    1. Carnot heat engine
    2. Stirling engine
17. Energy conversion efficiency
18. Kinetic theory of gases
19. Thermodynamic state
    1. Equation of state
       1. Van der Waals equation
       2. Redlich–Kwong equation of state
       3. Virial expansion
20. Thermal conductivity
21. Thermodynamic equilibrium
    1. Equilibrium thermodynamics
22. Thermodynamic potential
    1. Enthalpy (Level 4)
       1. Enthalpy of vaporization
    2. Helmholtz free energy
    3. Gibbs free energy
23. Black body
    1. Black-body radiation (Level 4)
       1. Planck's law
       2. Stefan–Boltzmann law
       3. Wien's displacement law
24. Equipartition theorem
25. Thermodynamic process
    1. Adiabatic process
    2. Isothermal process
    3. Endothermic process
    4. Exothermic process
    5. Quasistatic process
    6. Reversible process
    7. Irreversible process
26. Chemical potential
27. Intensive and extensive properties
28. Thermodynamic system
    1. Closed system
29. Brownian motion
30. Photon gas
31. Entropy of mixing
32. Fluctuation theorem
33. Thermal energy
34. Thermal equilibrium
35. Thermodynamic equations
36. Boltzmann equation
37. Maxwell relations
38. Thermal expansion
39. Thermal fluctuations

Waves (47 articles)

1. Wave (Level 3)
   1. Transverse wave
   2. Longitudinal wave
2. Mechanical wave
3. Acoustics (Level 4)
   1. Sound (Level 3)
      1. Speed of sound (Level 4)
      2. Sonic boom
      3. Sound pressure
   2. Ultrasound (Level 4)
   3. Beat
   4. Echo
   5. Acoustic resonance
4. Amplitude (Level 4)
5. Phase
6. Frequency (Level 4)
7. Wavelength (Level 4)
8. Wavenumber
9. Wave vector
10. Diffraction (Level 4)
    1. Diffraction-limited system
    2. Fraunhofer diffraction
    3. Huygens–Fresnel principle
       1. Fermat's principle
    4. Bragg's law
11. Doppler effect (Level 4)
    1. Relativistic Doppler effect
12. Wave interference (Level 4)
13. Noise (Level 4)
14. Resonance (Level 4)
15. Superposition principle (Level 4)
16. Wave equation (Level 4)
17. Node
18. Radio frequency
19. Wavefront
20. Harmonic
21. Pulse
22. Wave propagation
23. Group velocity
24. Phase velocity
25. Shock wave
26. Waveform
27. Coherence
28. Standing wave
29. Wave packet
30. Dispersion
31. Plane wave