# Tags

A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.

 Type to find tags:
 commutator× 206 study the effect of applying two operators in succession. rotational-kinematics× 205 A tag for questions about rotational motion, including angular velocity and angular acceleration. biophysics× 202 dirac-equation× 202 A fully relativistic (Lorentz covariant) description, first put forward by Paul Dirac in 1928, of the first quantized, spin one half fermion with nonzero mass. Physical notions to do with this equatio… particles× 202 galaxies× 198 Massive systems held together by gravitational attraction, consisting of stellar associations, star systems, star clusters and types of interstellar clouds, stellar remnants, gasses, cosmic dust and a… noethers-theorem× 197 A theorem that relates continuous symmetries (continuous transformations that don't affect the value of the lagrangian) to quantities conserved in time. dimensional-analysis× 197 Dimensional analysis means to obtain results by analyzing the units in question, etc. DO NOT USE THIS TAG if your question is about degrees of freedom or spatial dimensions. wave-particle-duality× 196 tensor-calculus× 195 higgs× 194 This higgs field breaks electroweak symmetry and provides mass to particles though a process called the higgs mechanism. The excitation of the higgs field is called a higgs boson. cosmological-inflation× 189 Cosmological inflation refers to an era of expansion that lasted for approximately $10^{-34}$ seconds, during which the universe expanded by a factor of approximately $10^26$ in every direction. This … topology× 186 rocket-science× 185 Colloquially referred to as one of the hardest professions, rocket science is actually a common name for spacecraft/space-systems engineering. However, one can also generalize this to include all form… linear-algebra× 185 To be used for linear algebra, and closely related disciplines such as tensor algebras and maybe clifford algebras. ads-cft× 181 a special case of the holographic principle. It states that a quantum gravitating theory in Anti-de-Sitter (AdS) space is exactly equivalent to the gauge theory/Conformal Field Theory (CFT… spinors× 181 software× 180 boundary-conditions× 180 action× 179 the integral of the Lagrangian over time, or the integral of the Lagrangian Density over both time and space. perturbation-theory× 178 Perturbation theory refers to methods for understanding physical systems by treating them as small modifications to exactly solvable systems. induction× 177 differentiation× 175 density× 174 defined as the mass per unit volume of a substance. oscillators× 174 popular-science× 173 must be answered in a manner that can be understood by a general audience with at most a basic understanding of physics, mathematics and related sciences. Apply it to questions w… stress-energy-tensor× 173 A rank-2 tensor in relativity, which expresses the flux of energy-momentum along timelike and spacelike axes. Also known as the energy-momentum tensor. In the Einstein field equations, it is the sourc… plasma-physics× 172 Theory, experiments and calculations related the physics of plasmas, i.e., matter constituted by ionized atoms. radioactivity× 172 The property of some materials by which individual atoms decay, emitting energy or particles often transforming into different elements in the process. observers× 169 crystals× 169 causality× 168 centripetal-force× 167 any force responsible for maintaining an object on a curved path around a fixed center. In introductory coursework this is usually "uniform circular motion" and yields several simple and useful relati… surface-tension× 167 Surface tension occurs due to the tendency of liquid molecules to favor their own kind. Surface tension is important in fluid multiphase systems typically at small length and velocity statics× 166 Analysis of a system of bodies where all forces are in balance and there is no motion relative to a chosen reference frame. time-dilation× 164