# 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.

 Type to find tags:
 shm× 6 shockwave short-circuits× 6 sigma-models× 5 signal-processing× 55 simulation× 210 singularities× 3 for questions about singularities in physical quantities. Use the tag "singularity" for general relativistic singularities such as those inside black holes and at the Big Bang. singularity× 61 si-units× 67 A set of internationally accepted units to aid in communication of measurements. s-matrix-theory× 37 soft-matter× 6 a vast field of research at the interfaces between physics, chemistry and biology. It consists in the study of the physical properties of composite objects described by a characteristic… soft-question× 615 Questions that ask about some aspect of physics research or study which doesn't involve the actual physics. In general, soft questions can be answered without using physical reasoning. software× 110 solar.system solar-sails solar-system× 150 The Sun plus the collection of bodies in orbit around the Sun such as planets, dwarf planets, moons, asteroids, comets, etc. solar-system-exploration× 18 solar-wind× 14 solid-mechanics× 29 solid-state-physics× 352 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… solitary-waves solitons× 24 solstice× 3 sound space× 205 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. space-expansion× 197 space-mission× 28 spacetime× 394 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. spacetime-metric space-travel× 56 special-functions× 5 special-relativity× 1177 The special theory of relativity describes the motion and dynamics of objects moving at significant fractions of the speed of light. specific-reference× 334 for questions seeking a single specific paper or a short, non-open-ended list of references, like "What paper first discovered X?", "Where can I find the original derivation of X?", or "W… spectroscopy× 138 the practice of separating a signal by frequency (or sometimes energy or momentum) and analyzing the resulting spectrum. speed× 121 the magnitude of velocity. speed-of-light× 426 fundamental universal constant that marks the maximum speed at which information can propagate. Its value is $299792458\frac{\mathrm{m}}{\mathrm{s}}$.