# 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.

1117 questions
For questions about materials which allow the flow of an electric charge (electrical conductors) or the transfer of heat (thermal conductors) through them.
1117 questions
Any of the various explanations of gravity as a quantum theory, including string theory and loop quantum gravity.
1107 questions
How is physics taught and learned. Teaching strategies, class examples and demonstrations; learning resources, career advice, etc. For explicit problems, use the 'homework' tag instead.
1104 questions
An event horizon is a type of boundary such that any information past this boundary is inaccessible to the observer it is defined for. Common examples are the Schwarzschild radius of a black hole (whi…
1102 questions
1101 questions
Vector-fields are vector valued functions which define a vector at each point in space. Examples of the vector field include the electric field and the velocity of a fluid.
1100 questions
A gas that behaves as randomly moving, non-interacting molecules. This allows a simplified equation of state.
1097 questions
The study of the composition or dynamics of the gaseous layers around planets, often applied to questions on Earth's atmosphere but can be applicable to all planets & moons in the solar system.
1089 questions
The union of special (SR) and general (GR) relativity. Use this tag if both SR and GR apply.
1081 questions
For questions about the propagation of waves carried by space-time, for instance as described by general relativity. Not to be confused with gravity waves, such as ocean surface waves.
1073 questions
Units are standards of measurement used for different types of quantities.
1052 questions
Polarization characterizes the oscillations in time the electromagnetic field is doing in the plane perpendicular to the propagation direction of a wave
1051 questions
for non-relativistic material strings, such as, e.g., a guitar string. PLEASE DO NOT USE THIS TAG for relativistic strings and string theory.
1042 questions
A research field within general optical physics concerned with light and its material interaction: where light is modelled by full quantum mechanical description.
1041 questions
Perturbation theory refers to methods for understanding physical systems by treating them as small modifications to exactly solvable systems.
1027 questions
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.
1025 questions
Earth is the planet on which we live, the 3rd planet from the Sun. Questions using this tag should be about Earth the planet and not Earth-like planets nor earth, as in dirt or soil.
1023 questions
The force on a body resulting from it's motion through a fluid (gas or liquid). This force is directly opposed to the direction of travel.
1012 questions
just because your question involves math! If your question is on simplification of a mathematical expression, please ask it at math.stackexchange.com The mathematics tag covers non…
1010 questions
A rough calculation or an approximation of the value, number, quantity, or extent of something so that it is usable for some purpose even if the input data may be incomplete or uncertain.
1006 questions
According to the current cosmological theories, it's the model that explains the early life of the universe, starting from a rapid expansion of hot and dense matter.
1004 questions
Diffraction is defined as the bending or flaring of light around the corners of an obstacle or aperture into the region of geometrical shadow of the obstacle. This flaring is consistent with the sprea…
992 questions
A mechanical or electronic system or device that works on the principles of oscillation, that is a periodic fluctuation between two things based on changes in energy. These range from abstract models …
990 questions
for questions regarding to the boundary conditions (b.c.) which expresses the behaviour of a function on the boundary (border) of its area of definition. The choice of the b.c. is fundamen…
973 questions
A vector space $\mathfrak{g}$ over some field $F$ and kitted with a bilinear, antisymmetric and Jacobi-identity-fulfilling product ("Lie Bracket" or "commutator"). In physics, most often arises as the…
969 questions
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…
969 questions
Quantum-ChromoDynamics (QCD) is the quantum field theory believed to describe the strong nuclear force.
965 questions
Any of several principles that find the physical trajectory of a system by minimizing or maximizing some value computed over the proposed path (for instance geometric optics can be reproduced by insis…
962 questions
Circular motion about a central point or axis
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Classical electrodynamics is the discipline that studies electromagnetic phenomena – such as electric and magnetic fields, radiation, and the dynamics of charged bodies – in classical terms.
958 questions
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…
954 questions
the practice of separating a signal by frequency (or sometimes energy or momentum) and analyzing the resulting spectrum.
948 questions
922 questions
History questions are welcome on this site whenever they have any bearing on our modern understanding of physics. However, if a question has only minimal or null bearing on our current understanding, …
919 questions
for questions relating to what, if anything, the quantum mechanical formalism and experimental results say about the way the world works.
907 questions