Physlib.Relativity.Tensors.RealTensor.Vector.Basic
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is an additive commutative monoid
#instAddCommMonoidFor a given spatial dimension , the space of Lorentz vectors , which are defined as functions from the index set to the real numbers , forms an additive commutative monoid. This structure provides an associative and commutative addition operation and a zero element.
is a vector space over
#instModuleRealFor a given spatial dimension , the space of Lorentz vectors , defined as the set of functions mapping the index set to the real numbers , forms a vector space (module) over the field of real numbers .
is an additive commutative group
#instAddCommGroupFor a given spatial dimension , the space of Lorentz vectors , defined as the set of functions from the index set to the real numbers , forms an additive commutative group. This structure defines the addition of vectors, the existence of a zero vector, and the existence of additive inverses (negation).
is finite-dimensional over
#instFiniteDimensionalRealFor any spatial dimension , the space of Lorentz vectors , defined as the set of functions from the index set to the real numbers , is a finite-dimensional vector space over .
Linear equivalence
#equivEuclidFor a given spatial dimension , the map `equivEuclid` defines a linear isomorphism (linear equivalence) between the space of Lorentz vectors and the Euclidean space , specifically represented as . This equivalence identifies the components of a Lorentz vector with the coordinates of a vector in -dimensional Euclidean space.
For any spatial dimension , Lorentz vector , and index , the value of the linear isomorphism applied to and evaluated at index is equal to the -th component of , i.e., .
Euclidean norm on
#instNormFor a given spatial dimension , the norm on the space of Lorentz vectors is defined such that for any , its norm is equal to the standard Euclidean norm of its image under the linear isomorphism . This defines a positive-definite norm based on the components of the vector in the underlying Euclidean space.
For any spatial dimension and any Lorentz vector , the norm is equal to the Euclidean norm of its image under the linear isomorphism , which maps the space of Lorentz vectors to the Euclidean space (represented as ).
for Lorentz vectors
#abs_component_le_normFor any Lorentz vector in dimensions and any index in the set , the absolute value of the -th component of the vector is less than or equal to its Euclidean norm, i.e., . Here, the norm is defined as the standard Euclidean norm of the vector's components in .
is a normed additive commutative group
#isNormedAddCommGroupFor a given spatial dimension , the space of Lorentz vectors is a normed additive commutative group. This structure integrates the additive commutative group properties of with its Euclidean norm , such that the distance between two vectors is defined by the norm of their difference, .
is a normed space over
#isNormedSpaceFor a given spatial dimension , the space of Lorentz vectors is a normed vector space over the field of real numbers . This structure signifies that the Euclidean norm on is compatible with scalar multiplication, such that for any scalar and any vector , the property holds.
Real inner product on
#instInnerRealFor a given spatial dimension , the space of Lorentz vectors is equipped with an inner product structure over the real numbers . The inner product of two Lorentz vectors , denoted by , is defined as the standard Euclidean inner product of their representations in the -dimensional Euclidean space via the linear equivalence `equivEuclid`. This inner product is distinct from the Minkowski inner product and is used to define the topological and normed space structure of the vector space.
For any spatial dimension and any two Lorentz vectors , the real inner product is equal to the standard Euclidean inner product of their images under the linear equivalence . That is, .
is a real inner product space
#innerProductSpaceFor a given spatial dimension , the space of Lorentz vectors is equipped with the structure of an inner product space over the real numbers . This inner product is the standard Euclidean inner product (distinct from the Minkowski metric) and is defined via the linear equivalence between and the Euclidean space . It satisfies the axioms of a real inner product space, including symmetry, linearity in the first argument, and the identity for any vector .
is a Charted Space modeled on itself
#instChartedSpaceThe space of Lorentz vectors is a charted space (manifold) modeled on the vector space itself. This structure equips the space with a manifold atlas where the local charts are identity maps from to .
Lorentz vector as a function of its components
#instCoeFunForallSumFinOfNatNatRealA Lorentz vector in spatial dimensions can be treated as a function that maps an index from the set (represented formally by the sum type ) to its corresponding real-valued component . This coercion allows the notation to be used to access the -th component of the vector.
for Lorentz vectors
#apply_smulFor any spatial dimension , given a scalar , a Lorentz vector , and an index (represented by the sum type ), the -th component of the scalar multiple is equal to the product of and the -th component of . That is, .
for Lorentz vectors
#apply_addFor any spatial dimension , given two Lorentz vectors and in and an index , the -th component of the sum of the vectors is equal to the sum of their individual -th components. That is, .
for Lorentz vectors
#apply_subFor any spatial dimension , given two Lorentz vectors and an index , the -th component of the difference of the vectors is equal to the difference of their individual -th components. That is,
for Lorentz vectors
#apply_sumFor any spatial dimension , given a finite index set , a family of Lorentz vectors , and an index , the -th component of the sum of these vectors is equal to the sum of the -th components of each individual vector. That is,
for Lorentz vectors
#neg_applyFor any spatial dimension , given a Lorentz vector and an index , the -th component of the negated vector is equal to the negation of the -th component of . That is,
The -th component of the zero Lorentz vector is
#zero_applyFor any spatial dimension and any index , the -th component of the zero Lorentz vector is .
Continuous linear map of a Lorentz vector
#coordCLMFor a spatial dimension and an index , this is the continuous linear map from the space of Lorentz vectors to the real numbers that maps each vector to its -th component .
For a spatial dimension , an index , and a Lorentz vector , the application of the continuous linear map to the vector is equal to its -th component .
The map is continuous for Lorentz vectors
#coord_continuousFor a spatial dimension and an index , the map from the space of Lorentz vectors to the real numbers is continuous.
The coordinate map of Lorentz vectors is smooth
#coord_contDiffFor any spatial dimension and any index , the coordinate map from the space of Lorentz vectors to the real numbers , defined by , is -times continuously differentiable () over for any .
Coordinate Functions of Lorentz Vectors are Differentiable
#coord_differentiableFor a spatial dimension and an index , the coordinate function , which maps a Lorentz vector to its -th component in , is differentiable over .
The coordinate map is differentiable at
#coord_differentiableAtFor a given spatial dimension , an index , and a Lorentz vector , the map that sends a vector to its -th component is differentiable at over the field of real numbers .
Continuous linear equivalence
#euclidCLEFor a given spatial dimension , the map `euclidCLE` defines a continuous linear equivalence (a topological vector space isomorphism) between the space of Lorentz vectors and the -dimensional Euclidean space, represented as . This map is the continuous version of the linear equivalence `equivEuclid`.
Continuous linear equivalence
#equivPiFor a given spatial dimension , this definition provides the continuous linear equivalence between the space of Lorentz vectors and the space of functions (the product type) from the index set to the real numbers , denoted as . This map is a bijective linear transformation that is continuous in both directions, identifying Lorentz vectors with their component representations.
The -th component of is equal to
#equivPi_applyFor any spatial dimension , let be a Lorentz vector and be an index. The application of the continuous linear equivalence to , evaluated at the index , is equal to the -th component .
Component-wise continuity implies continuity of Lorentz vector-valued functions
#continuous_of_applyLet be a natural number and be a topological space. For a function mapping into the space of Lorentz vectors, if for every index the component function is continuous, then the function is continuous.
is differentiable all components are differentiable for
#differentiable_applyFor a spatial dimension , let be the space of Lorentz vectors. Let be a normed space over . A function is differentiable if and only if for every index , the component function (defined by ) is differentiable.
is iff its components are
#contDiff_applyLet be a real normed vector space and be a natural number representing the spatial dimensions. For any , a function is -times continuously differentiable () if and only if for every index , the scalar-valued component function is -times continuously differentiable.
Let be the spatial dimension and be a real normed space. For any differentiable function , any point , direction , and index , the -th component of the Fréchet derivative of at in the direction is equal to the Fréchet derivative of the component function (where ) at in the direction . Mathematically, this is expressed as: \[ (Df(x) \cdot dt)_\nu = D(f_\nu)(x) \cdot dt \]
The Fréchet derivative of is
#fderiv_coordFor a given number of spatial dimensions and an index , the Fréchet derivative of the function that maps a Lorentz vector to its -th component is equal to the continuous linear map , which evaluates the -th coordinate of its argument.
Index equivalence for Lorentz vectors
#indexEquivFor a spacetime with spatial dimensions, the type of component indices for a Lorentz vector (a tensor with a single contravariant index) is equivalent to the disjoint union . This equivalence maps the single index of the vector to either the temporal component (index in ) or one of the spatial components (indices in ).
is tensorial with a single upper index
#tensorialFor a given number of spatial dimensions , this definition establishes that the space of Lorentz vectors is tensorial with respect to the species of real Lorentz tensors with a single contravariant (upper) index. This is achieved by providing a linear isomorphism between and the formal tensor space associated with the color sequence . Specifically, the isomorphism identifies a Lorentz vector with its components in the canonical tensor basis, where the index set is equivalent to the disjoint union , representing the temporal and spatial components respectively.
Component-wise evaluation of the inverse `toTensor` map for Lorentz vectors
#toTensor_symm_applyLet be the number of spatial dimensions. For any real Lorentz tensor with a single contravariant (upper) index, the image of under the inverse isomorphism (which maps tensors back to the space of Lorentz vectors ) is the function that assigns to each index the coordinate of with respect to the canonical tensor basis, where the tensor's multi-indices are identified with via the index equivalence map.
Components of the Lorentz vector for rank-1 pure tensors
#toTensor_symm_pureLet be the number of spatial dimensions. For any pure tensor of rank 1 with a single contravariant (upper) index, let be its constituent vector in the representation space. For any index , the -th component of the Lorentz vector obtained from via the inverse isomorphism is given by: where denotes the coordinate representation of the vector with respect to the standard contravariant basis, and is the index in the representation space corresponding to via the index equivalence map.
Standard basis for indexed by
#basisFor a given spatial dimension , this provides the standard coordinate basis for the space of Lorentz vectors over the field of real numbers . The basis is indexed by the set , which represents the combination of one temporal and spatial dimensions. A basis vector indexed by corresponds to the function that yields at index and for all other indices .
The components of the standard basis for are
#basis_applyFor a given spatial dimension , let denote the -th vector of the standard coordinate basis for the space of Lorentz vectors , where the indices belong to the set . The -th component of the -th basis vector is given by:
maps the canonical tensor basis to the Lorentz vector basis
#toTensor_symm_basisFor a spacetime with spatial dimensions, let be the space of Lorentz vectors and let be the space of real Lorentz tensors with a single contravariant (upper) index. Let be the linear isomorphism that identifies a Lorentz vector with its tensorial representation. Let be the -th basis vector of the standard coordinate basis for , where , and let be the canonical basis for the tensor space indexed by component indices . Then, the inverse of the isomorphism maps the tensor basis element associated with to the corresponding Lorentz vector basis vector: where is the equivalence map (`indexEquiv.symm`) from the physical index set to the tensor component index set.
maps the Lorentz vector basis to the canonical tensor basis
#toTensor_basis_eq_tensor_basisFor a spacetime with spatial dimensions, let be the space of Lorentz vectors and let be the space of real Lorentz tensors with a single contravariant (upper) index. Let be the linear isomorphism that identifies a Lorentz vector with its tensorial representation. Let be the -th basis vector of the standard coordinate basis for , where , and let be the canonical basis for the tensor space indexed by component indices . Then, the isomorphism maps the -th basis vector of the Lorentz vector space to the corresponding basis vector in the tensor space: where is the equivalence map (`indexEquiv.symm`) from the physical index set to the tensor component index set.
For a spacetime with spatial dimensions, let be the space of Lorentz vectors and be its standard coordinate basis. Let be the space of real Lorentz tensors with a single contravariant (upper) index, and let be its canonical basis indexed by component indices . Given the linear isomorphism and the index equivalence , the basis for Lorentz vectors is equal to the tensor basis mapped through the inverse isomorphism and reindexed by : Specifically, for each , the basis vector is the image of the tensor basis element under the map .
For a spacetime with spatial dimensions, let be the space of Lorentz vectors and let be the space of real Lorentz tensors with a single contravariant (upper) index. Let be the canonical linear isomorphism between these spaces. Let be the canonical basis of indexed by , and let be the standard coordinate basis of indexed by . Given the index equivalence , the image of the tensor basis under the inverse isomorphism is equal to the Lorentz vector basis reindexed by the inverse equivalence : Specifically, for each tensor component index , the image of the -th tensor basis vector under is the -th Lorentz vector basis vector.
For a spacetime with spatial dimensions, let be a Lorentz vector and let be its representation as a rank-1 tensor with a single contravariant (upper) index. For any tensor component index , the coordinate of with respect to the canonical tensor basis at index is equal to the value of the vector evaluated at the corresponding spacetime index .
for Lorentz vectors
#basis_repr_applyFor any spatial dimension , let be a Lorentz vector in and be a spacetime index. The -th coordinate of with respect to the standard basis is equal to the component value .
Matrix representation of linear maps on Lorentz vectors
#map_apply_eq_basis_mulVecFor a spatial dimension , let be an -linear map and be a Lorentz vector. The application of the map to the vector is equal to the matrix-vector product of the matrix representation of (with respect to the standard basis) and the vector . That is, , where is the matrix of relative to the standard basis.
for Lorentz vectors
#sum_basis_eq_zero_iffFor a spatial dimension , let be a collection of real coefficients. The linear combination of the standard basis vectors for the space of Lorentz vectors, , is equal to zero if and only if for all .
for Lorentz vectors
#sum_inl_inr_basis_eq_zero_iffFor a spatial dimension , let and be coefficients. The linear combination of the temporal basis vector and the spatial basis vectors in the space of Lorentz vectors , given by , is equal to zero if and only if and for all .
For a spacetime with spatial dimensions, let be a Lorentz transformation and be a Lorentz vector in . For any index , the -th component of the vector resulting from the action of on is given by the sum over all indices : where represents the -th entry of the matrix representation of the Lorentz transformation , and is the -th component of the vector .
Lorentz action equals matrix-vector product
#smul_eq_mulVecFor any spatial dimension , let be a Lorentz transformation in the Lorentz group and be a Lorentz vector in . The action of on , denoted by , is equal to the matrix-vector product , where is represented by its underlying matrix and is the vector of components of .
For any spatial dimension , let be a Lorentz transformation in the Lorentz group and be two Lorentz vectors in . The action of on the sum of the two vectors satisfies the distributive property, such that .
For any spatial dimension , let be a Lorentz transformation in the Lorentz group and be two Lorentz vectors in . The action of on the difference of the two vectors satisfies the distributive property, such that .
For a spacetime with spatial dimensions, let be a Lorentz transformation in the Lorentz group and be the zero Lorentz vector. The action of on the zero vector is the zero vector:
For a spacetime with spatial dimensions, let be a Lorentz transformation in the Lorentz group and be a Lorentz vector. The action of on the additive inverse (negation) of is equal to the negation of the result of acting on :
For a spacetime with spatial dimensions, let be a Lorentz transformation and be a Lorentz vector. The action of the negated Lorentz transformation on the vector is equal to the negation of the result of the action of on :
Lorentz action on as a continuous linear map
#actionCLMFor a given spatial dimension and a Lorentz transformation in the Lorentz group, this definition represents the action of on the space of Lorentz vectors as a continuous linear map from to itself, which sends a vector to the transformed vector .
for Lorentz vectors
#actionCLM_applyFor any spatial dimension , any Lorentz transformation in the Lorentz group, and any Lorentz vector , the application of the continuous linear map to the vector is equal to the group action of on , denoted as .
The action of on is injective
#actionCLM_injectiveFor any spatial dimension and any Lorentz transformation in the Lorentz group, the continuous linear map (which maps a vector to ) is injective.
The Lorentz action on is surjective
#actionCLM_surjectiveFor any spatial dimension and any Lorentz transformation in the Lorentz group, the continuous linear map , which maps a Lorentz vector to its transformed version , is surjective.
For a given spatial dimension , let be a Lorentz transformation and denote the -th basis vector of the standard basis for the space of Lorentz vectors , where the index . The action of the Lorentz transformation on this basis vector is given by the linear combination: where represents the -th entry of the matrix representing the Lorentz transformation .
Spatial part of a Lorentz vector
#spatialPartFor a Lorentz vector in -dimensional Minkowski spacetime, the spatial part is the vector in the -dimensional Euclidean space obtained by extracting the components of corresponding to the spatial indices. Specifically, the -th component of the resulting vector in is given by for .
The -th component of the spatial part of equals
#spatialPart_apply_eq_toCoordFor a Lorentz vector in -dimensional Minkowski spacetime and any spatial index , the -th component of the spatial part of is equal to the component of the vector at the corresponding spatial index. That is, .
The -th component of the spatial part of the -th spatial basis vector is
#spatialPart_basis_sum_inrFor a given spatial dimension and any spatial indices , let denote the -th spatial basis vector of the -dimensional Lorentz vector space. The -th component of the spatial part of this basis vector is equal to if and otherwise. That is, where is the Kronecker delta.
The -th spatial component of the temporal basis vector is
#spatialPart_basis_sum_inlFor any spatial dimension and any spatial index , let be the basis vector of the Lorentz vector space corresponding to the temporal dimension (represented by the index ). The -th component of the spatial part of this temporal basis vector is zero, denoted as:
Continuous linear map of the spatial part of a Lorentz vector
#spatialCLMFor a spatial dimension , this continuous linear map from the Lorentz vector space to the -dimensional Euclidean space extracts the spatial components of a Lorentz vector . Specifically, for any , the map returns a vector in whose -th component is for .
For any spatial dimension , Lorentz vector , and spatial index , the -th component of the vector resulting from the application of the continuous linear map to is equal to the -th component of the spatial part of . That is,
For any spatial dimension , let be the basis vector of the Lorentz vector space corresponding to the temporal dimension (indexed by ). The continuous linear map , which extracts the spatial components of a Lorentz vector, maps to the zero vector in the -dimensional Euclidean space :
For any spatial dimension and any spatial index , let be the basis vector of the Lorentz vector space corresponding to the -th spatial dimension. The continuous linear map , which extracts the spatial components of a Lorentz vector, maps to the -th standard basis vector of the -dimensional Euclidean space . That is, where is the -th basis function of .
Time component of a Lorentz vector
#timeComponentFor a Lorentz vector in a Minkowski space with spatial dimensions, the function returns its temporal component , which corresponds to the component indexed by the first element (the "0-th" index) of the underlying representation.
The temporal component of a spatial basis vector is
#timeComponent_basis_sum_inrFor any spatial dimension and any spatial index , the temporal component of the -th spatial basis vector in the standard basis of the Lorentz vector space is .
The time component of the temporal basis vector is
#timeComponent_basis_sum_inlFor any spatial dimension , the time component of the standard basis vector corresponding to the temporal dimension (indexed by ) in the space of Lorentz vectors is equal to .
Temporal component continuous linear map
#temporalCLMFor a given spatial dimension , the map is the continuous linear map from the space of Lorentz vectors to the real numbers that maps a vector to its temporal component, which corresponds to the index in the temporal dimension (represented formally as ).
for Lorentz vectors
#temporalCLM_apply_eq_timeComponentFor any spatial dimension and any Lorentz vector , the result of applying the temporal continuous linear map to is equal to the vector's time component .
The temporal component of spatial basis vectors is zero
#temporalCLM_basis_sum_inrFor a given spatial dimension , let denote the -th vector of the standard coordinate basis for the space of Lorentz vectors , where the indices belong to the set . Let be the continuous linear map that extracts the temporal component of a Lorentz vector (the component corresponding to the index ). For any spatial index (represented by ), the temporal component of the -th spatial basis vector is zero:
The temporal component of the temporal basis vector is
#temporalCLM_basis_sum_inlFor any spatial dimension , the temporal component of the temporal basis vector is equal to .
Smooth manifold structure on
#asSmoothManifoldFor a given spatial dimension , the space of Lorentz vectors is equipped with a smooth manifold structure over the real numbers . This is represented by the identity model with corners , which models the space on itself, providing the standard smooth structure associated with its vector space properties.
For a given spatial dimension , let be a Lorentz vector and let be the -th standard basis vector for the space, where the index . The real inner product (Euclidean inner product) of and is equal to the -th component of . That is,
For any spatial dimension , let be a Lorentz vector and let be the -th vector of the standard coordinate basis for , where . The real inner product of and is equal to the -th component of :
