Physics terms starting with M

Mach Number Waves, Oscillations & Acoustics Dimensionless A dimensionless speed ratio equal to the speed of an object or fluid divided by local speed of sound in the surrounding medium. M = v / v_sound

Machine Learning in Physics Mathematical & Computational Physics Computational AI Framework The application of artificial intelligence, neural networks, and statistical learning models to solve complex physical equations and discover empirical patterns in experimental data. Physics-Informed Neural Networks (PINN): Loss = L_data + λ L_physics

Macrostate Thermodynamics & Statistical Physics N/A The macroscopic state of a thermodynamic system defined by observable thermodynamic variables like pressure, volume, temperature, and total energy. Defined by (P, V, T, N, U)

Magnetic Confinement Plasma Physics Dimensionless Ratio (Plasma Beta β) The trapping of high-temperature fusion plasma using intense magnetic fields that exert Lorentz forces to prevent plasma particles from contacting container walls. β = p / (B² / (2 μ₀)) = 2 μ₀ n k_B T / B²

Magnetic Dipole Electromagnetism & Electronics A·m² (or J/T) The basic magnetic structure created by a closed circulating current loop or intrinsic particle spin, possessing North and South magnetic poles. μ = I A, τ = μ × B

Magnetic Dipole Moment Electromagnetism & Electronics A·m² (or J/T) A vector quantity determining the torque experienced by a magnetic dipole when placed in an external magnetic field. μ = I A, U = -μ · B

Magnetic Domains Condensed Matter & Materials Physics μm to mm (Domain Size) Microscopic regions within a ferromagnetic material where atomic magnetic moments are aligned parallel in a uniform direction. Domain Wall Energy E_total = E_exchange + E_anisotropy

Magnetic Field Electromagnetism & Electronics T (Tesla = N/(A·m)) A vector field generated by moving electric charges, electric currents, or intrinsic magnetic moments that exerts magnetic forces on other moving charges and dipoles. F_mag = q (v × B), B = μ₀ I / (2π r)

Magnetic Flux Electromagnetism & Electronics Wb (Webers = T·m²) The measure of the total magnetic field passing normally through a specified surface area. Φ_B = ∫ B · dA = |B| |A| cos θ

Magnetic Helicity & Taylor Relaxation Plasma Physics Wb² (Magnetic Helicity Units) A topological invariant measuring the linking, twisting, and tangling of magnetic flux lines in a closed plasma volume. K = ∭ A · B dV, ∇ × B = μ B (Taylor State)

Magnetic Hysteresis Electromagnetism & Electronics J/m³ (Joules per cubic meter) The lagging of magnetization behind the applied magnetizing field in ferromagnetic materials during cyclic magnetization. Hysteresis Loss Area = ∫ H dB

Magnetic Mirror Plasma Physics Dimensionless Mirror Ratio B_max / B_min A magnetic confinement configuration where converging magnetic field lines reflect charged particles back toward regions of weaker magnetic field. Sin²(θ_loss) = B_min / B_max (Loss Cone Angle)

Magnetic Permeability Electromagnetism & Electronics H/m (or T·m/A) A material property measuring the degree to which a medium supports and concentrates magnetic flux inside itself when subjected to a magnetic field. μ = B / H = μ_r μ₀, μ₀ = 4π × 10⁻⁷ T·m/A

Magnetic Reconnection Plasma Physics MW or Joules (Energy Conversion) A fundamental plasma process where opposing magnetic field lines break and explosively reconnect, releasing stored magnetic field energy into kinetic and thermal particle energy. E_reconnection ≈ M_A v_A B (Alfvénic Reconnection Rate)

Magnetic Resonance Imaging (MRI) Biophysics & Medical Physics Tesla B₀ (~1.5–3.0 T) & MHz A non-invasive medical imaging modality utilizing powerful magnetic fields, radiofrequency (RF) pulses, and nuclear magnetic resonance (NMR) of hydrogen protons to image soft tissue. Larmor Frequency ν₀ = (γ / 2π) B₀ (γ_proton ≈ 42.58 MHz/T)

Magnetic Susceptibility Electromagnetism & Electronics Dimensionless A dimensionless material property measuring the degree of magnetization induced in a material per unit applied magnetic field strength. M = χ_m H, μ_r = 1 + χ_m

Magnetized Target Fusion (MTF) Plasma Physics Hybrid Density & Time Scale A hybrid fusion approach that combines magnetic confinement thermal insulation with rapid mechanical or laser inertial compression. Hybrid MTF: Density n ~ 10²⁴ m⁻³, Confinement Time τ_E ~ 1 μs–1 ms

Magnetoencephalography (MEG) Biophysics & Medical Physics fT (Femtoteslas = 10⁻¹⁵ T) A non-invasive functional neuroimaging technique mapping brain activity by measuring weak magnetic fields produced by neuronal electric currents using SQUID sensors. Magnetic Field B ~ 10–100 fT (10⁻¹⁵ Tesla)

Magnetohydrodynamics Plasma Physics MHD Equations Framework The fluid framework describing the macroscopic dynamics and magnetic field interactions of electrically conducting fluids and magnetized plasmas. ∂B / ∂t = ∇ × (v × B) + η ∇²B, ρ (dv/dt) = -∇p + J × B + ρ g

Magnetosphere Geophysics & Environmental Physics Earth Radii (R_E ~ 10 R_E sunward) The region of space surrounding Earth dominated by Earth's geomagnetic field, shielding the planet from harmful solar wind plasma. Magnetopause Distance R_mp ≈ (B₀² / (2 μ₀ ρ v²))^(1/6)

Magnetron Sputtering Plasma Physics nm/s (Deposition Rate) A physical vapor deposition (PVD) technique utilizing magnetically confined glow discharge plasma to sputter target material onto substrates. E × B Electron Trapping drift path near cathode target

Magnification Optics Dimensionless The ratio of image height to object height, or ratio of image distance to object distance in an optical system. m = h_image / h_object = -v / u

Main Sequence Astrophysics, Cosmology & Relativity H-R Diagram Band The continuous evolutionary diagonal band on the Hertzsprung-Russell diagram containing stars fusing hydrogen into helium in their cores. L ∝ M^3.5 (Mass-Luminosity Relation)

Majority & Minority Carriers Condensed Matter & Materials Physics cm⁻³ (Carrier Density) The classification of charge carriers in a doped semiconductor based on their relative concentrations. N-Type: n_majority = N_D, p_minority = n_i² / N_D

Terms starting with M