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Nuclear & Particle Physics

Spontaneous Symmetry Breaking

A physics phenomenon where the underlying mathematical equations of a system possess symmetry, but the ground state (vacuum) drops into a…

Vacuum Expectation Value ⟨0|φ|0⟩ = v ≠ 0 Energy VEV (GeV) Nuclear & Particle Physics

Standard Model

The theoretical physics framework classifying all known elementary particles and describing three fundamental forces: electromagnetism…

SU(3)_C × SU(2)_L × U(1)_Y Gauge Symmetry Theoretical Framework Waves, Oscillations & Acoustics

Standing Waves

A stationary wave pattern formed by the superposition of two identical waves traveling in opposite directions along the same medium.

y(x,t) = [2 A sin(k x)] cos(ω t) m Quantum & Atomic Physics

Stark Effect

The shifting and splitting of atomic spectral lines caused by the presence of an external static electric field.

ΔE = -p · E_ext (First-order: ΔE ∝ E_ext) eV (Energy Shift) Classical Mechanics

Static Equilibrium

The state of a rigid body where both net external force and net external torque are zero, keeping the body completely at rest.

∑ F = 0, ∑ τ = 0 N, N·m Mathematical & Computational Physics

Statistics and Probability

The mathematical frameworks for analyzing random phenomena, quantifying measurement uncertainty, and modeling ensemble behavior in…

P(A|B) = P(B|A) P(A) / P(B), μ = E[X], σ² = Var(X) Probability (0 to 1) Thermodynamics & Statistical Physics

Stefan-Boltzmann Law

The physical law asserting that total radiant power emitted per unit surface area of a blackbody is proportional to the fourth power of its…

E = σ T⁴, σ = 5.670374 × 10⁻⁸ W/(m²·K⁴) W/m² Astrophysics, Cosmology & Relativity

Stellar Nucleosynthesis

The collective nuclear fusion reactions inside stars that synthesize heavier chemical elements from lighter primordial hydrogen and helium.

3 α → ¹²C (Triple-Alpha Process at T ~ 10⁸ K) Nuclear Energy & Abundances Plasma Physics

Stellarator

A magnetic confinement fusion device that produces a helical magnetic field using complex, 3D non-planar external electromagnetic coils…

Rotational Transform ι = 1 / q (Generated entirely by 3D external coils) Dimensionless Magnetic Transform Quantum & Atomic Physics

Stern-Gerlach Experiment

A landmark 1922 experiment that proved space quantization and the intrinsic angular momentum (spin) of subatomic particles.

F_z = μ_z (∂B_z / ∂z), S_z = ± ℏ / 2 N (Force), J/T (Magnetic Moment) Quantum & Atomic Physics

Stimulated Emission

The process in which an incoming photon stimulates an excited atom to drop to a lower state, emitting a second identical photon.

Rate = B₂₁ ρ(ν) N₂ s⁻¹ (Transition Rate) Biophysics & Medical Physics

Stochastic vs Deterministic Radiation Effects

The classification of biological radiation damage into probability-driven stochastic risks (cancer) and threshold-driven deterministic…

Stochastic Probability P ∝ Dose; Deterministic Severity ∝ Dose (Threshold D_th) Risk Factor / Dose Threshold (Gy) Classical Mechanics

Stokes' Law

A mathematical law expressing viscous drag force experienced by small spherical particles moving at low speeds through a viscous fluid.

Fd = 6 π η r v N Mathematical & Computational Physics

Stokes' Theorem

A fundamental vector calculus theorem relating the surface integral of the curl of a vector field over an open surface S to the line…

∮_(∂S) F · dr = ∬_S (∇ × F) · dA Vector Line/Surface Integral Equality Geophysics & Environmental Physics

Stratosphere

The second major layer of Earth's atmosphere, extending from the tropopause (~12 km) up to the stratopause (~50 km), containing the…

dT / dz > 0 (Temperature Inversion via O₃ Absorption) km (Altitude ~12 to 50 km) Nuclear & Particle Physics

Strong Nuclear Force

The powerful fundamental interaction that binds quarks together into hadrons and holds protons and neutrons together inside the atomic…

F_strong ≫ F_EM (Range r ≤ 1–3 fm) N (Newtons) Thermodynamics & Statistical Physics

Sublimation

The direct phase transition of a substance from solid to gas state without passing through an intermediate liquid phase.

ΔH_sub = ΔH_fus + ΔH_vap J/kg or J/mol Condensed Matter & Materials Physics

Superalloys

High-performance metallic alloys engineered to maintain exceptional mechanical strength, creep resistance, and oxidation resistance at high…

γ' Phase Precipitation: Ni₃(Al, Ti) High Temperature Strength (MPa at >800 °C) Condensed Matter & Materials Physics

Superconductivity

A macroscopic quantum state of matter where certain materials exhibit exactly zero electrical DC resistance and complete expulsion of…

R = 0 (for T < T_c), B = 0 (Meissner expulsion) K (Critical Temperature T_c) Condensed Matter & Materials Physics

Superfluidity

A macroscopic quantum state of matter where a fluid flows with exactly zero viscosity and zero kinetic entropy.

Viscosity η = 0 (Below Lambda point T_λ = 2.17 K) K (Lambda Transition Temperature) Astrophysics, Cosmology & Relativity

Supernova

A catastrophic stellar explosion marking the death of a star, briefly outshining an entire galaxy and dispersing heavy elements into space.

Type Ia: M = M_Ch; Type II: Core Collapse M > 8 M_☉ 10⁴⁴ Joules (Energy Output) Condensed Matter & Materials Physics

Surface Energy

The excess thermodynamic energy at the surface of a material relative to its interior bulk, caused by disrupted, incomplete atomic bonds.

γ = dW / dA J/m² or N/m Nuclear & Particle Physics

Synchrotron

A large ring-shaped particle accelerator in which guiding magnetic fields and accelerating RF electric fields increase synchronously as…

B(t) ∝ p(t), RF Frequency Synchronized to Beam Speed GeV or TeV (Beam Energy) Foundations of Physics

Systematic Error

A consistent, repeatable error in experimental measurements that skews data in the same direction from the true value.

Offset = Mean Measured - True Value Various