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.

Quantum mechanics describes the microscopic properties of nature in a regime where classical mechanics no longer applies. It explains phenomena such as the wave-particle duality, quantization of energ…
30686 questions
Applies to questions of primarily educational value - not only questions that arise from actual homework assignments, but any question where it is preferable to guide the asker to the answer rather th…
23795 questions
Newtonian mechanics discusses the movement of classical bodies under the influence of forces by applying Newton’s three laws. For more general concepts, use [classical-mechanics]. For Newton’s descrip…
The classical theory of electric and magnetic fields, both in the static and dynamic case. It also covers general questions about magnets, electric attraction/repulsion, etc. Distinct from electrical-…
18043 questions
Covers the study of (primarily homogeneous) macroscopic systems from a heat/energy/entropy point of view. Consider also using the tag: [statistical-mechanics].
14697 questions
A theory that describes how matter interacts dynamically with the geometry of space and time. It was first published by Einstein in 1915 and is currently used to study the structure and evolution of t…
13811 questions
Quantum Field Theory (QFT) is the theoretical framework describing the quantisation of classical fields which allows a Lorentz-invariant formulation of quantum mechanics. QFT is used both in high ener…
The special theory of relativity describes the motion and dynamics of objects moving at significant fractions of the speed of light.
for the classical concept of forces, i.e. the quantities causing an acceleration of a body. It expands to the strong/electroweak force only insofar as they act comparable to ‘classical’ fo…
Classical mechanics discusses the behaviour of macroscopic bodies under the influence of forces (without necessarily specifying the origin of these forces). If it's possible, USE MORE SPECIFIC TAGS li…
Electrostatics is concerned with the electrical fields and scalar potentials of stationary electrical charges and charge distributions. Use this for questions about electromagnetic situations in which…
Optics is the study of light, and its interaction with matter. It includes topics such as imaging systems, fiber optics, lasers, quantum optics, and more.
7687 questions
Energy is the conserved quantity associated to time-translation invariance and represents the work a system is capable of doing. Use this tag for questions about energy, and consider adding the [energ…
The quantitative study of how fluids (gases and liquids) move.
The study of large, complicated systems employing statistics and probability theory to extract average properties and to provide a connection between mechanics and thermodynamics.
Particle physics is the study of the fundamental forces of nature as they are embodied in the interactions of elementary and composite particles at high energies and short time and distance scales. DO…
Waves are disturbances that propagate through space and time. Classically, they travelled through a medium, disturbing the particles but not changing their mean position. Electromagnetic waves/particl…
Propagating solutions to Maxwell’s equations in classical electromagnetism and real photons in quantum electrodynamics. A superset of thermal-radiation.
The study of the large-scale structure, history, and future of the universe. Cosmology is about asking and answering questions about the "big picture" - the extent, origin, and fate of everything we k…
For questions involving the Lagrangian formulation of a dynamical system. Namely, the application of an action principle to a suitably chosen Lagrangian or Lagrangian Density in order to obtain the eq…
Gravity is an attractive force that affects and is affected by all mass and - in general relativity - energy, pressure, and stress. Prefer newtonian-gravity or general-relativity if sensible.
A black hole is a region of spacetime from which nothing can escape. More formally, the future light cone of any observer within the black hole is completely contained in the black hole, and the blac…
for questions regarding the Newtonian model of gravity in which the force between two objects is given by $~GMm/r^2~.$ It is a natural phenomenon by which all things with mass or energy – …
Questions related to the perception and measurement of light (primarily in the visible range), its mathematical description, the reproduction of colors by different means, color combinations, etc. Ple…
In physics, an operator is almost always either a square matrix or a linear mapping between two function spaces (defined on, say, $\mathbb R^n$). Operators serve as observables and as time evolution o…
The study of physical properties of condensed phases of matter, including solids and liquids.
for questions relating to Hilbert Space, a vector space equipped with an inner product, an operation that allows defining lengths and angles, and the space is complete. It arises naturally…
For questions that utilize the concept of magnetic fields (commonly denoted by the letter B), or for questions whose answers likely involve magnetic fields. More specific than the [magnetism] tag, as …
An electronic system, with closed loop current flow, and relative electrical potentials present across electrical components.
For questions that utilize the concept of electric fields (commonly denoted by the letter E), or for questions whose answers likely involve electric fields. More specific than the [electricity] tag, a…
The description of the movement of bodies by their position, velocity, acceleration (and possibly higher time derivatives, such as, jerk) without concern for the underlying dynamics/forces/causes.
Mathematical discipline which uses the techniques of calculus to study geometric problems. General relativity is written in this language.
As a consequence of the Lorentz transformations, time and space transform into each other when changing reference frame. This calls for a unified description: Minkowski spacetime.
A tag for questions about the mechanical interactions of rotating objects, including torque and angular momentum.
A reference frame is a particular coordinate system chosen to represent physical entities. The notion is most often used in special and general relativity to denote particular coordinates chosen on th…
The study of the presence and flow of electric charge. Charges, currents, fields, potentials.
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