# 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.

Geometric object with magnitude (length) and direction.
2232 questions
Questions asking "What is a good book about X?" or more generally, "What should I read to learn about X?", typically where there is not a single authoritative reference. Please READ THE GUIDANCE IN ME…
2197 questions
A specific reference frame that describes its coordinates in a manner that does not depend on time and is isotropic.
2182 questions
just because your question involves math! If your question is on simplification of a mathematical expression, please ask it at math.stackexchange.com. Mathematical physics is the m…
2177 questions
The term "harmonic oscillator" is used to describe any system with a "linear" restoring force that tends to return the system to an equilibrium state. There is both a classical harmonic oscillator and…
2143 questions
Time is defined operationally to be that which is measured by clocks. The SI unit of time is the second, which is defined to be
2050 questions
A model of the basic particles and forces featuring six quarks, three charged leptons, three massless neutral leptons and four fundamental force carrying bosons. The twelve fermions are arranged into …
2046 questions
Use this for questions relating to the proper use of physics terminology or nomenclature.
2046 questions
The time rate of change of the position of an object
2027 questions
Concerns the application of the laws of physics to analyze common situations encountered in everyday life.
2019 questions
A gauge theory has internal degrees of freedom that do not affect the foretold physical outcomes of the theory. The theory has a Lie group of *continuous symmetries* of these internal degrees of freed…
2007 questions
Quantum electrodynamics (QED) is the quantum field theory believed to describe electromagnetic interaction. It is the simplest example of a quantum gauge theory, where the gauge group is abelian, U(1)…
1948 questions
Group theory is a branch of abstract algebra. A group is a set of objects, together with a binary operation, that satisfies four axioms. The set must be closed under the operation and contain an ident…
1939 questions
Voltage is the unit of measurement for electronic potential, from one point location to another.
1889 questions
The science dealing with objects and phenomena located beyond Earth. In particular, this applies to observations and data. At its core, astronomy is the physically informed cataloging and classifying …
1807 questions
used in situations where the question is either about how some term or concept is defined or where the validity of an answer depends on a subtle definition of some term or concep…
1797 questions
Quantum entanglement is the mechanism by which quantum correlations between two sub-systems survive even after being physically separated from an interaction region. The correlations could in principl…
1744 questions
Two Hydrogen atoms covalently bonded to one Oxygen atom. One of the more common compounds on the surface of the earth.
1744 questions
Space expansion is a cosmological phenomenon wherein the proper distance between two spatial points for a given inertial reference frame increases from one moment of time to another. That is, space it…
1739 questions
The ability of an object to store electric charge.
1730 questions
for questions relating to collision which is the interaction between two or more bodies that results in physical contact and an exchange of momentum between the bodies involved. When it ha…
1708 questions
The Hamiltonian formalism is a formalism in Classical Mechanics. Besides Lagrangian Mechanics, it is an effective way of reformulating classical mechanics in a simple way. Very useful in Quantum Mecha…
1702 questions
Semiconductor physics is the branch of solid state physics that focuses on specific properties of semiconductors. It studies dynamics of different perturbations (mainly electrons and holes) in the sem…
1634 questions
The study of how the properties of matter arise from its structure at all scales and of how processing can be used to modify those properties (often in pursuit of a specific application).
1620 questions
The universe refers to the cosmos; all of space-time and that which exists as part of it. Alternatively, it can refer to the observable universe, which only contains the part we can see. Questions tag…
1612 questions
for questions which relates with the renormalization, an ensemble of techniques which serves to treat the infinities which appear in quantum field theory or statistical mechanics. Renormal…
1573 questions
should be about computational physics, which is the study of physical situations with the use of software (commercial or in-house). Please note that details of writing and/or …
1571 questions
for questions relating to reflection, the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it origina…
1542 questions
Scattering is a general term for several physical processes in which radiation of some sort changes direction due to an interaction with a particle. Scattering can be classified by the type of radiati…
1524 questions
A convention is a set of agreed, stipulated, or generally accepted norms. It typically helps common efficiency or understanding but is not required, as opposed to a strict standard or protocol.
1524 questions
for questions regarding to Torque which is a measure of the force that can cause an object to rotate about an axis.
1509 questions
Differentiation is the set of techniques and results from Differential Calculus, concerning the calculation of derivatives of functions or distributions.
1505 questions
A pictorial device which analyzes forces present on any body with the use of vectors. Allows easier grasping of problems involving either objects at equilibrium or in motion. Can be used to predict pr…
1490 questions
The central term in the hamiltonian formalism. Can be interpreted as an energy input, or "true" energy.
1489 questions
A unitary linear operator which resolves a function on $\mathbb{R}^N$ into a linear superposition of "plane wave functions". Most often used in physics for calculating the response of a time shift inv…
1480 questions
Use this for questions pertaining to curvature of manifolds. Does not need to be specific to general relativity, but also for curvature of e.g. a Calabi-Yau manifold.
1467 questions