Physics terms starting with H

H-mode Confinement Plasma Physics s (Energy Confinement Time τ_E) High-confinement operating regime in tokamaks characterized by a steep edge pressure barrier (pedestal) and doubled energy confinement time. Energy Confinement Time τ_E(H-mode) ≈ 2 × τ_E(L-mode)

Hadrons Nuclear & Particle Physics Composite Particle Class Subatomic composite particles made of quarks and gluons held together by the strong nuclear force. Strongly interacting composite particles (Baryons & Mesons)

Half-Life Nuclear & Particle Physics Seconds, Hours, or Years The time required for half the radioactive nuclei in a given sample to undergo spontaneous radioactive decay. t_½ = ln(2) / λ ≈ 0.693 / λ, N(t) = N₀ (½)^(t / t_½)

Hall Effect Electromagnetism & Electronics V (Hall Voltage), m³/C (Hall Coefficient) The production of a transverse electric potential difference (Hall voltage) across a current-carrying conductor in an orthogonal magnetic field. V_H = (I B) / (n q t), R_H = 1 / (n q)

Hall Effect Thruster Plasma Physics N or mN (Thrust) & s (Specific Impulse ~1500–3000 s) A electric space propulsion plasma engine that accelerates ions across an electrostatic potential drop using trapped electrons in an annular magnetic field. F_thrust = ṁ v_exhaust, v_ex = √(2 e V_acc / m_ion)

Hamiltonian Formalism Mathematical & Computational Physics Joules (Energy) A formulation of classical mechanics describing system dynamics in 2N-dimensional phase space using position q_i and canonical momentum p_i. H(q, p, t) = ∑ p_i q̇_i - L, q̇_i = ∂H / ∂p_i, ṗ_i = -∂H / ∂q_i

Hardness Condensed Matter & Materials Physics MPa or GPa (Mohs scale 1 to 10) A material's resistance to localized plastic surface deformation induced by mechanical scratching, abrasion, or indentation. H = Load / Indentation Surface Area (Mohs, Vickers, Rockwell)

Harmonics Waves, Oscillations & Acoustics Hz Resonant frequencies of a system that are integer multiples of its fundamental frequency. f_n = n f1 (where n = 1, 2, 3, ...)

Hawking Radiation Astrophysics, Cosmology & Relativity Kelvin (Blackbody Temperature T_H) Thermal blackbody radiation predicted to be emitted by black holes due to quantum field fluctuations near the event horizon. T_H = ℏ c³ / (8 π G M k_B), P = ℏ c⁶ / (15360 π G² M²)

Heat Engine Thermodynamics & Statistical Physics W (J/s) A physical device that converts thermal energy absorbed from a high-temperature heat source into mechanical work, discharging waste heat to a cold sink. W = Q_hot - Q_cold, η = W / Q_hot

Heisenberg Uncertainty Principle Quantum & Atomic Physics J·s (Action Units) A fundamental quantum limit stating that canonical conjugate physical variables (such as position and momentum, or energy and time) cannot be simultaneously measured with arbitrary precision. Δx Δp ≥ ℏ / 2, ΔE Δt ≥ ℏ / 2

Helmholtz Free Energy Thermodynamics & Statistical Physics J A thermodynamic potential measuring maximum reversible work obtainable from a closed system at constant temperature and volume. F = U - T S, dF = -S dT - P dV

Hemodynamics Biophysics & Medical Physics L/min (Cardiac Output) & mmHg (Pressure) The physical study of blood flow dynamics, vascular resistance, and pressure relations within the circulatory system. Q = ΔP / R_v, R_v = (8 η L) / (π r⁴) (Poiseuille Flow)

Hermite Polynomials Mathematical & Computational Physics Dimensionless Orthogonal Polynomials A sequence of classical orthogonal polynomials satisfying Hermite's differential equation y'' - 2x y' + 2n y = 0. H_n(x) = (-1)^n e^(x²) (d^n / dx^n) (e^(-x²))

Hertzsprung-Russell (H-R) Diagram Astrophysics, Cosmology & Relativity Luminosity (L_☉) vs Surface Temp (K) A foundational scatter plot of stellar luminosity versus surface temperature (or spectral type) used to trace stellar evolution phases. L ∝ R² T^4 (Plot of Absolute Magnitude vs Spectral Type)

Hessian Matrix Mathematical & Computational Physics Second Derivative Matrix A square matrix of second-order partial derivatives of a scalar-valued function, describing local surface curvature and local extrema stability. H_ij = ∂²f / (∂x_i ∂x_j)

Higgs Boson Nuclear & Particle Physics GeV/c² (Mass Energy) An elementary scalar boson associated with the Higgs field that endows fundamental particles with rest mass via electroweak symmetry breaking. m_H ≈ 125.1 GeV/c², Spin = 0, Scalar Field φ

Hilbert Space Mathematical & Computational Physics Complete Inner Product Space A complete abstract vector space possessing an inner product that allows length and angle to be defined for infinite-dimensional function spaces. ⟨f, g⟩ = ∫ f*(x) g(x) dx, ||f|| = √(⟨f, f⟩)

Holography Optics N/A A technique for recording and reconstructing 3D wavefields by recording phase and amplitude interference patterns between object and reference laser beams. I(x,y) = |E_ref + E_obj|²

Hooke's Law Classical Mechanics N (k in N/m) A law of elasticity stating that restoring force exerted by a spring or elastic material is proportional to its extension or compression distance. F = -k x

Hubble's Law Astrophysics, Cosmology & Relativity km/s/Mpc (Hubble Constant) The cosmological observation that galaxies recede from Earth at velocities directly proportional to their proper distance. v = H₀ d, H₀ ≈ 70 (km/s) / Mpc

Hund's Rule of Maximum Multiplicity Quantum & Atomic Physics Dimensionless Rule A rule stating that when filling degenerate atomic orbitals, electrons occupy separate orbitals singly with parallel spins before pairing up. S_total = ∑ s_i (Maximized spin in degenerate orbitals)

Huygens-Fresnel Principle Waves, Oscillations & Acoustics N/A The wave propagation principle asserting that every point on a wavefront acts as a secondary source of spherical wavelets. New Wavefront = Envelope of Secondary Wavelets

Hydrogen Spectrum Quantum & Atomic Physics m⁻¹ (Wavenumber) The set of discrete electromagnetic emission and absorption lines produced when the electron in a hydrogen atom transitions between energy levels. 1 / λ = R_H (1 / n_f² - 1 / n_i²)

Terms starting with H