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.

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the quantum field theory believed to describe the strong nuclear force.
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Matter not observed directly but inferred to exist based upon its gravitational effects
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A subset of [tag:fluid-dynamics] concerning primarily forces such as lift and drag generated on bodies as they move through gasses or as gasses move through the body (typically air).
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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.
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energy transferred from one system to another by thermal interaction. In contrast to work, heat is always accompanied by a transfer of entropy. Heat flow is characteristic of macroscopic objec…
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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…
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To be used for questions on geometry closely pertaining to physics. Includes differential geometry and euclidean geometry.
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quantify location in space.
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a layer of gases that surround it, permitting life and protecting life by absorbing ultraviolet solar radiation, warming the surface by retaining the heat and mitigating the temp…
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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…
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an almost perfectly symmetric yellow dwarf star [spectral class G2V] which is at the center of our Solar System.
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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.
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A law in Classical Electromagnetism and Newtonian Gravity.
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Polarization characterizes the oscillations in time the electromagnetic field is doing in the plane perpendicular to the propagation direction of a wave
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The time rate of change of energy
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The subfield of optics in which light propagation is approximated in terms of rays. It mainly includes reflection and refraction on surfaces.
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astronomical bodies that are (usually) mainly composed of Hydrogen, Helium, and Lithium. They are massive enough that their gravity compresses the matter to the point where nuclear fusion oc…
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A tag for questions about rotational motion, including angular velocity and angular acceleration.
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The Sun plus the collection of bodies in orbit around the Sun such as planets, dwarf planets, moons, asteroids, comets, etc.
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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…
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for dimensions of a manifold, typically the space-time. DO NOT USE THIS TAG for dimension of a physical quantity.
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particles with an intrinsic angular momentum (i.e. spin) equal to a "half integer" number of fundamental units: $\frac{(2n+1)}{2} \hbar$ for integer $n$. Fermions are required to be in a …
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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…
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A research field within general optical physics concerned with light and its material interaction: where light is modelled by full quantum mechanical description.
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The use of methods from the physical sciences to aid in the study of biological systems. Note that biophysics questions are only allowed if they are mainly about physics.
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Analogous to matter, but with charge of the particles opposite to their ordinary matter counterparts.
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the magnitude of velocity.
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The central term in the hamiltonian formalism. Can be interpreted as an energy input, or "true" energy.