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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Light Amplification by Stimulated Emission of Radiation. A means of creating coherent light by either driving an atomic or molecular transition in an optical cavity or firing a beam of electrons throu…
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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.
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standards of measurement used for different types of quantities.
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Object moving through space due to the exertion of a force.
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The ability of an object to store electric charge.
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A nucleus made of protons and neutrons surrounded by a cloud of electrons equal in number to the protons.
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The near-vacuum extending between the planets and stars, containing small amounts of gas and dust. Also called outer space to refer to the physical universe beyond the Earth's atmosphere.
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Celestial body that orbits following an elliptical path around a star or stellar remnant.
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the transmission of current with no resistive losses, and is one of the most active areas of condensed matter physics research.
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The tendency of a force to rotate an object about an arbitrary axis.
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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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the unit of measurement for electronic potential, from one point location to another.
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Change in the direction of propagation of a wave when its transmitting medium changes.
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is used in situations where the question is either about how some term or concept is define or where the validity of an answer depends on a subtle definition of some term or concept…
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Study of macroscopic and microscopic phenomena in chemical systems in terms of physical laws and concepts [thermodynamics, statistical mechanics, kinetic theory, quantum mechanics...].
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questions concerning measurements, experiments, and activities that demonstrate physics and are safe to do at home, require at most one tool or ingredient not readily available, and can be interpreted…
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for questions about the exact nature of wavefunction collapse.
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"Faster-than-light", also known as superluminal velocities, refers to any sort of travel at a speed greater than the speed of light. Prohibited in mainstream physics due to the Special theory of …
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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 [tag:calabi-yau] manifold.
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The temperature-dependant emission of electromagnetic waves. Combine this tag with [tag:thermodynamics] for a macroscopic view or [tag:quantum-mechanics] for a microscopic explanation.
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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 calcalating the response of a time shift inv…
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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 region of space devoid of any fluid molecules resulting in a zero pressure in ideal cases. In practice, even space has a small but finite number of molecules.
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the quantum field theory believed to describe the strong nuclear force.
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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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The double slit experiment involves passing light through two parallel slits to demonstrate that the light from one slit interferes with that from the other.
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the rate of repetitive aspect in the amplitude over a given dimension.
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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 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).