Rotation in three dimensions | Spinors
In geometry and physics, spinors /spɪnər/ are elements of a complex vector space that can be associated with Euclidean space. Like geometric vectors and more general tensors, spinors transform linearly when the Euclidean space is subjected to a slight (infinitesimal) rotation. Unlike vectors and tensors, a spinor transforms to its negative when the space is continuously rotated through a complete turn from 0° to 360° (see picture). This property characterizes spinors: spinors can be viewed as the "square roots" of vectors (although this is inaccurate and may be misleading; they are better viewed as "square roots" of sections of vector bundles – in the case of the exterior algebra bundle of the cotangent bundle, they thus become "square roots" of differential forms). It is also possible to associate a substantially similar notion of spinor to Minkowski space, in which case the Lorentz transformations of special relativity play the role of rotations. Spinors were introduced in geometry by Élie Cartan in 1913. In the 1920s physicists discovered that spinors are essential to describe the intrinsic angular momentum, or "spin", of the electron and other subatomic particles. Spinors are characterized by the specific way in which they behave under rotations. They change in different ways depending not just on the overall final rotation, but the details of how that rotation was achieved (by a continuous path in the rotation group). There are two topologically distinguishable classes (homotopy classes) of paths through rotations that result in the same overall rotation, as illustrated by the belt trick puzzle. These two inequivalent classes yield spinor transformations of opposite sign. The spin group is the group of all rotations keeping track of the class. It doubly covers the rotation group, since each rotation can be obtained in two inequivalent ways as the endpoint of a path. The space of spinors by definition is equipped with a (complex) linear representation of the spin group, meaning that elements of the spin group act as linear transformations on the space of spinors, in a way that genuinely depends on the homotopy class. In mathematical terms, spinors are described by a double-valued projective representation of the rotation group SO(3). Although spinors can be defined purely as elements of a representation space of the spin group (or its Lie algebra of infinitesimal rotations), they are typically defined as elements of a vector space that carries a linear representation of the Clifford algebra. The Clifford algebra is an associative algebra that can be constructed from Euclidean space and its inner product in a basis-independent way. Both the spin group and its Lie algebra are embedded inside the Clifford algebra in a natural way, and in applications the Clifford algebra is often the easiest to work with. A Clifford space operates on a spinor space, and the elements of a spinor space are spinors. After choosing an orthonormal basis of Euclidean space, a representation of the Clifford algebra is generated by gamma matrices, matrices that satisfy a set of canonical anti-commutation relations. The spinors are the column vectors on which these matrices act. In three Euclidean dimensions, for instance, the Pauli spin matrices are a set of gamma matrices, and the two-component complex column vectors on which these matrices act are spinors. However, the particular matrix representation of the Clifford algebra, hence what precisely constitutes a "column vector" (or spinor), involves the choice of basis and gamma matrices in an essential way. As a representation of the spin group, this realization of spinors as (complex) column vectors will either be irreducible if the dimension is odd, or it will decompose into a pair of so-called "half-spin" or Weyl representations if the dimension is even. (Wikipedia).
Learn the basics for simplifying an expression using the rules of exponents
👉 Learn how to simplify expressions using the quotient rule of exponents. The quotient rule of exponents states that the quotient of powers with a common base is equivalent to the power with the common base and an exponent which is the difference of the exponents of the term in the numerat
From playlist Simplify Using the Rules of Exponents | Quotient Rule
Simplify a large numeric expression by applying the order of operations
👉 Learn how to simplify mathematics expressions. A mathematis expression is a finite combination of numbers and symbols formed following a set of operations or rules. To simplify a mathematics expression means to reduce the expression into simpler form. For expressions having parenthesis
From playlist Simplify Expressions Using Order of Operations
Simplifying an exponent using the power to power rule and rational powers
👉 Learn how to simplify rational powers using the power rule. There are some laws of exponents which might come handy when simplifying expressions with exponents. Some of the laws include the power rule which states that when an expression with an exponent is raised to another exponent tha
From playlist Raise an Exponent to a Fraction
What is a Four-Vector? Is a Spinor a Four-Vector? | Special Relativity
In special relativity, we are dealing a lot with four-vectors, but what exactly is a four-vector? A four-vector is an object with four entries, which get transformed and changed in a very special way after we change our frame of reference. More precisely, a four-vector transforms like a (1
From playlist Special Relativity, General Relativity
Jean-Pierre Bourguignon: Revisiting the question of dependence of spinor fields and Dirac [...]
Find this video and other talks given by worldwide mathematicians on CIRM's Audiovisual Mathematics Library: http://library.cirm-math.fr. And discover all its functionalities: - Chapter markers and keywords to watch the parts of your choice in the video - Videos enriched with abstracts, b
From playlist Geometry
Applying the rules of exponents to simplify an expression with numbers
👉 Learn about the rules of exponents. An exponent is a number which a number is raised to, to produce a power. It is the number of times which a number will multiply itself in a power. There are several rules used in evaluating exponents. Some of the rules includes: the product rule, which
From playlist Simplify Using the Rules of Exponents
Simplify an expression by applying quotient rule of exponents
👉 Learn how to simplify expressions using the quotient rule of exponents. The quotient rule of exponents states that the quotient of powers with a common base is equivalent to the power with the common base and an exponent which is the difference of the exponents of the term in the numerat
From playlist Simplify Using the Rules of Exponents | Quotient Rule
Simplify a rational expression
Learn how to simplify rational expressions. A rational expression is an expression in the form of a fraction where the numerator and/or the denominator are/is an algebraic expression. To simplify a rational expression, we factor completely the numerator and the denominator of the rational
From playlist Simplify Rational Expressions (Binomials) #Rational
Simplifying an expression using properties of exponents
👉 Learn how to simplify expressions using the quotient rule of exponents. The quotient rule of exponents states that the quotient of powers with a common base is equivalent to the power with the common base and an exponent which is the difference of the exponents of the term in the numerat
From playlist Simplify Using the Rules of Exponents | Quotient Rule
Quantum Mechanics 12b - Dirac Equation II
Here we explore solutions to the Dirac equation corresponding to electrons at rest, in uniform motion and within a hydrogen atom. Part 1: https://youtu.be/OCuaBmAzqek
From playlist Quantum Mechanics
Spinor Normalization | Solving the Dirac Equation
In this video, we will show you how to normalize a spinor. This is actually a very delicate question, and unfortunately there are infinitely many allowed ways to normalize a spinor. But some normalizations are more useful than others. Contents: 00:00 Setup 00:45 Constraint 02:00 Two Conv
From playlist Quantum Mechanics, Quantum Field Theory
Quantum Mechanics 12a - Dirac Equation I
When quantum mechanics and relativity are combined to describe the electron the result is the Dirac equation, presented in 1928. This equation predicts electron spin and the existence of anti-matter.
From playlist Quantum Mechanics
Applying the power rule to simplify an expression with a rational power
👉 Learn how to simplify rational powers using the power rule. There are some laws of exponents which might come handy when simplifying expressions with exponents. Some of the laws include the power rule which states that when an expression with an exponent is raised to another exponent tha
From playlist Raise an Exponent to a Fraction
Spinor Lorentz Transformations | How to Boost a Spinor
In this video, we will show you how a Dirac spinor transforms under a Lorentz transformation. Contents: 00:00 Our Goal 00:38 Determining S 01:23 Determining T 02:30 Finite Transformation References: [1] Peskin, Schroeder, "An Introduction to Quantum Field Theory". Follow us on Insta
From playlist Quantum Mechanics, Quantum Field Theory
Simplify rational expression using the rules of exponents
👉 Learn how to simplify expressions using the quotient rule of exponents. The quotient rule of exponents states that the quotient of powers with a common base is equivalent to the power with the common base and an exponent which is the difference of the exponents of the term in the numerat
From playlist Simplify Using the Rules of Exponents | Quotient Rule
Supersymmetry and Superspace, Part 1 - Jon Bagger
Supersymmetry and Superspace, Part 1 Jon Bagger Johns Hopkins University July 19, 2010
From playlist PiTP 2010
Rudolf Zeidler - Scalar and mean curvature comparison via the Dirac operator
I will explain a spinorial approach towards a comparison and rigidity principle involving scalar and mean curvature for certain warped products over intervals. This is motivated by recent scalar curvature comparison questions of Gromov, in particular distance estimates under lower scalar c
From playlist Talks of Mathematics Münster's reseachers
Spinors and the Clutching Construction
What’s the connection between spinors and the clutching construction? Chapters: 00:00 Why should we care? 00:32 Spinors in pop culture 01:34 Graph 03:15 Wall 03:42 Tome 04:18 Sir Roger Penrose 04:53 Hopf fibration 06:23 Paul Dirac 07:12 The belt trick 08:54 Exterior derivative 09:49 Deter
From playlist Summer of Math Exposition Youtube Videos
Sir Michael Atiyah, What is a Spinor ?
Sir Michael Atiyah, University of Edinburgh What is a Spinor?
From playlist Conférence en l'honneur de Jean-Pierre Bourguignon
What is the definition of an exponent
👉 Learn how to apply the rules of exponents to simplify an expression. We will focus on applying the product rule, quotient rule as well as power rule. We will then explore multiple properties such as power to product, power to quotient and negative exponents. 👏SUBSCRIBE to my channel h
From playlist Simplify Using the Rules of Exponents