Torsion may refer to:

Science

Torsion (mechanics) In the field of solid mechanics, torsion is the twisting of an object due to an applied torque. Torsion is expressed in either the pascal (Pa), an SI unit for newtons per square metre, or in pounds per square inch (psi) while torque is expressed ...

, the twisting of an object due to an applied torque * Torsion of spacetime, the field used in

Einstein–Cartan theory In theoretical physics, the Einstein–Cartan theory, also known as the Einstein–Cartan–Sciama–Kibble theory, is a classical theory of gravitation similar to general relativity. The theory was first proposed by Élie Cartan in 1922. Einstein ...

and **

Alternatives to general relativity Founded in 1994, Alternatives, Action and Communication Network for International Development, is a non-governmental, international solidarity organization based in Montreal, Quebec, Canada. Alternatives works to promote justice and equality a ...

Torsion angle A dihedral angle is the angle between two intersecting planes or half-planes. In chemistry, it is the clockwise angle between half-planes through two sets of three atoms, having two atoms in common. In solid geometry, it is defined as the uni ...

, in chemistry

Biology and medicine

* Torsion fracture or spiral fracture, a bone fracture when torque is applied * Organ torsion, twisting that interrupts the blood supply to that organ: ** Splenic torsion, causing

splenic infarction Splenic infarction is a condition in which blood flow supply to the spleen is compromised, leading to partial or complete infarction (tissue death due to oxygen shortage) in the organ. Splenic infarction occurs when the splenic artery or one of i ...

Ovarian torsion Ovarian torsion (OT) or adnexal torsion is an abnormal condition where an ovary twists on its attachment to other structures, such that blood flow is decreased. Symptoms typically include pelvic pain on one side. While classically the pain is su ...

Testicular torsion Testicular torsion occurs when the spermatic cord (from which the testicle is suspended) twists, cutting off the blood supply to the testicle. The most common symptom in children is sudden, severe testicular pain. The testicle may be higher than u ...

* Penile torsion, a congenital condition * Torsion of the digestive tract in some domestic animals: ** Torsion, a type of

horse colic Colic in horses is defined as abdominal pain, but it is a clinical symptom rather than a diagnosis. The term colic can encompass all forms of gastrointestinal conditions which cause pain as well as other causes of abdominal pain not involving the g ...

Gastric torsion Gastric dilatation volvulus (GDV), also known as gastric dilation, twisted stomach, or gastric torsion, is a medical condition that affects dogs in which the stomach becomes overstretched and rotated by excessive gas content. The word bloat is o ...

, or gastric dilatation volvulus *

Torsion (gastropod) Torsion is a gastropod synapomorphy which occurs in all gastropods during larval development. Torsion is the rotation of the visceral mass, mantle, and shell 180˚ with respect to the head and foot of the gastropod. This rotation brings the mantl ...

, a developmental feature of all gastropods

Mathematics

Torsion of a curve In the differential geometry of curves in three dimensions, the torsion of a curve measures how sharply it is twisting out of the osculating plane. Taken together, the curvature and the torsion of a space curve are analogous to the curvature of a ...

Torsion tensor In differential geometry, the notion of torsion is a manner of characterizing a twist or screw of a moving frame around a curve. The torsion of a curve, as it appears in the Frenet–Serret formulas, for instance, quantifies the twist of a curve ...

, in differential geometry *

Torsion (algebra) In mathematics, specifically in ring theory, a torsion element is an element of a module that yields zero when multiplied by some non-zero-divisor of the ring. The torsion submodule of a module is the submodule formed by the torsion elements. A to ...

, in ring theory *

Torsion group In group theory, a branch of mathematics, a torsion group or a periodic group is a group in which every element has finite order. The exponent of such a group, if it exists, is the least common multiple of the orders of the elements. For examp ...

, in group theory and arithmetic geometry *

Tor functor In mathematics, the Tor functors are the derived functors of the tensor product of modules over a ring. Along with the Ext functor, Tor is one of the central concepts of homological algebra, in which ideas from algebraic topology are used to constr ...

, the derived functors of the tensor product of modules over a ring *

Torsion-free module In algebra, a torsion-free module is a module over a ring such that zero is the only element annihilated by a regular element (non zero-divisor) of the ring. In other words, a module is ''torsion free'' if its torsion submodule is reduced to its z ...

, in algebra *

Analytic torsion In mathematics, Reidemeister torsion (or R-torsion, or Reidemeister–Franz torsion) is a topological invariant of manifolds introduced by Kurt Reidemeister for 3-manifolds and generalized to higher dimensions by and . Analytic torsion (or Ray– ...

(Reidemeister torsion, R-torsion, Franz torsion, de Rham torsion, Ray-Singer torsion), a topological invariant of manifolds *

Whitehead torsion In geometric topology, a field within mathematics, the obstruction to a homotopy equivalence f\colon X \to Y of finite CW-complexes being a simple homotopy equivalence is its Whitehead torsion \tau(f) which is an element in the Whitehead group \ope ...

, in geometric topology

Other uses

Torsion field (pseudoscience) A torsion field (also called axion field, spin field, spinor field, and microlepton field) is a feature of pseudoscientific proposals that the quantum spin of particles can be used to cause emanations to carry information through vacuum orders of ...

, a field alleged to make faster-than-light communication and paranormal phenomena possible {{disambiguation, maths