Physics

Alternating current is electric current that periodically reverses direction, forming the basis of most electrical power distribution systems.

Anharmonicity is departure from harmonic oscillation, producing nonlinear restoring forces, amplitude-dependent frequencies, unequal quantum energy spacings, and interactions between vibrational modes.

Astronomy is the scientific study of celestial objects, cosmic phenomena, and the structure and evolution of the universe.

Brownian motion is the irregular thermal movement of particles suspended in a fluid and the continuous random process used to model such movement.

Condensation is the change of a substance from gas to liquid, releasing latent heat and occurring in atmospheric processes and industrial equipment.

Energy density measures energy per unit volume, or, in some engineering contexts, per unit mass, and is used to describe fields, fuels, and storage systems.

Evaporation is the conversion of a liquid into vapor at its surface, governed by energy supply, molecular interactions, and vapor transport.

Friction is resistance to relative motion between contacting surfaces or within materials, arising from interactions and deformation.

The greenhouse effect is atmospheric warming of a planetary surface through the absorption and emission of outgoing infrared radiation.

Interferometry uses wave interference to measure displacement, optical properties, celestial structure, and physical effects with high sensitivity.

Latent heat is energy absorbed or released during a phase transition, typically without a temperature change under equilibrium conditions.

Magnetic flux is the surface integral of the normal component of a magnetic field, governing electromagnetic induction and many electrical and superconducting devices.

Three foundational laws of classical mechanics describing inertia, the relationship between force and acceleration, and reciprocal forces between interacting bodies.

Optical coherence describes correlations in a light field across space and time, governing interference visibility and the statistical properties of photodetection.

Quantum decoherence is the suppression of observable quantum interference through interactions that distribute coherence into correlations with an environment.

A telescope collects radiation from distant objects to produce images or measurements, enabling observations beyond the sensitivity and resolving power of the unaided eye.

Torque measures the turning effect of a force about a point or axis and governs changes in angular momentum.