# 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.

The conserved quantity arising from a rotational invariance. Combine with rotational-dynamics for the classical mechanics approach and quantum-mechanics for the QM interpretation
3517 questions
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…
3507 questions
For questions about design, process, data, or analysis of experiments and observations.
3466 questions
A complex scalar field that describes a quantum mechanical system. The square of the modulus of the wave function gives the probability of the system to be found in a particular state. DO NOT USE THIS…
3292 questions
for questions relating to pressure, in the physical sciences, the perpendicular force per unit area, or the stress at a point within a confined fluid.
3232 questions
In introductory mechanics, the momentum of a particle is its mass times its velocity. In electrodynamics, the momentum of a field is proportional to the cross-product of the electric field with the ma…
3175 questions
Solid-state physics studies how macroscopic properties of solids (mechanical, electrical, optical, etc.) result from their microscopic structure. It usually deals with the scale where quantum properti…
3065 questions
Negatively charged particle with spin 1/2. A component of mundane terrestrial matter, and part of all neutral atoms and molecules. It has a mass about 1/1800 that of a proton. Its antiparticle is the…
3021 questions
It's the physical property that indicates the degree/intensity of heat present in a substance or an object. It can be expressed and measured according to various scales.
3009 questions
Quantum information is the study of the informational content of quantum states. The most common object of study is the "qubit", the information in a two-state quantum system such as spin-1/2 or photo…
2987 questions
The variables used in general relativity to describe the shape of spacetime. If your question is about metric units, use the tag "units", and/or "si-units" if it is about the SI system specifically.
2975 questions
The law of conservation of energy, which states that the amount of energy in a system is constant. For questions about Earth's environment, see the climate-science tag instead.
2965 questions
The property of an object that determines how much it responds to a force in Newtonian mechanics, and how much it interacts with gravity in the Newtonian framework. Mass also refers to the intrinsic e…
2958 questions
A measure of the rate at which electric charge is transported (especially through a circuit), it has units of charge/time.
2921 questions
Nuclear physics is the study of the composition, behavior and interaction of atomic nuclei and their constituent parts.
2891 questions
A fundamental property of matter which causes it to experience electromagnetic forces.
2880 questions
The statement that a property of a system does not change if the system is isolated.
2737 questions
The rate of change of velocity of a body per unit of time.
2732 questions
Scalar and vector potentials in electromagnetism. The scalar potential is potential energy per unit charge. For potential energy, use the [potential-energy] tag.
2729 questions
We say that something is symmetric if there is some transformation we can perform on that object that leaves some property unchanged. The set of symmetry transformations of an object form a group, and…
2722 questions
The product of the force on an object and the displacement the object undergoes along the direction of the force.
2652 questions
Atomic physics is the field of physics that studies atoms as an isolated system of electrons and an atomic nucleus. It is primarily concerned with the arrangement of electrons around the nucleus and t…
2637 questions
The speed of light is a fundamental universal constant that marks the maximum speed at which energy and information can propagate. Its value is $299792458\frac{\mathrm{m}}{\mathrm{s}}$.
2569 questions
An important extensive property of all systems in thermodynamics, statistical mechanics, and information theory, quantifying their disorder (randomness), i.e., our lack of information about them. It …
2541 questions
A set of numbers used to quantify location in space.
2529 questions
For questions where the dynamical variables are fields, that is, functions of several variables (typically, one time coordinate and several space coordinates). Comprises both classical field theory an…
2513 questions
Partial differential equation which describes the time evolution of the wavefunction of a quantum system. It is one of the first and most fundamental equations of quantum mechanics.
2509 questions
Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. Applications of acoust…
2495 questions
A class of theories that attempt to explain all existing particles (including force carriers) as vibrational modes of extended objects, such as the 1-dimensional fundamental string. PLEASE DO NOT USE …
2464 questions
to electrical resistance and resistors. DO NOT USE THIS TAG for non-electrical resistance.
2445 questions
The application of physical theory to celestial systems such as stars, planets, galaxies, supernovae, and black holes. Astrophysics proper is concerned with explaining phenomena more so than making ob…
2443 questions
Fundamental characteristic property of particles which together with orbital angular momentum acts as the generator of rotations and which doesn't have a classical equivalent but is sometimes compared…
2432 questions
The resistance a surface or object encounters when moving over another.
2426 questions
Potential energy is the energy of a body or a system due to the position of the body or the arrangement of the particles of the system.
2311 questions
The path a body takes while moving through space under the influence of the gravitational forces of other bodies
2259 questions
Tensor calculus (tensor analysis) is a systematic extension of vector calculus to multivector and tensor fields in a form that is independent of the choice of coordinates on the relevant manifold, but…
2254 questions