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Physlib.Relativity.Tensors.RealTensor.Vector.Basic

81 declarations

instance

Vectord\text{Vector}_d is an additive commutative monoid

#instAddCommMonoid

For a given spatial dimension dd, the space of Lorentz vectors Vectord\text{Vector}_d, which are defined as functions from the index set Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d to the real numbers R\mathbb{R}, forms an additive commutative monoid. This structure provides an associative and commutative addition operation and a zero element.

instance

Vectord\text{Vector}_d is a vector space over R\mathbb{R}

#instModuleReal

For a given spatial dimension dd, the space of Lorentz vectors Vectord\text{Vector}_d, defined as the set of functions mapping the index set Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d to the real numbers R\mathbb{R}, forms a vector space (module) over the field of real numbers R\mathbb{R}.

instance

Vectord\text{Vector}_d is an additive commutative group

#instAddCommGroup

For a given spatial dimension dd, the space of Lorentz vectors Vectord\text{Vector}_d, defined as the set of functions from the index set Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d to the real numbers R\mathbb{R}, 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).

instance

Vectord\text{Vector}_d is finite-dimensional over R\mathbb{R}

#instFiniteDimensionalReal

For any spatial dimension dd, the space of Lorentz vectors Vectord\text{Vector}_d, defined as the set of functions from the index set Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d to the real numbers R\mathbb{R}, is a finite-dimensional vector space over R\mathbb{R}.

definition

Linear equivalence VectordEuclideanSpace(R,Fin 1Fin d)\text{Vector}_d \cong \text{EuclideanSpace}(\mathbb{R}, \text{Fin } 1 \oplus \text{Fin } d)

#equivEuclid

For a given spatial dimension dd, the map `equivEuclid` defines a linear isomorphism (linear equivalence) between the space of Lorentz vectors Vectord\text{Vector}_d and the Euclidean space R1+d\mathbb{R}^{1+d}, specifically represented as EuclideanSpace R(Fin 1Fin d)\text{EuclideanSpace } \mathbb{R} (\text{Fin } 1 \oplus \text{Fin } d). This equivalence identifies the components of a Lorentz vector with the coordinates of a vector in (1+d)(1+d)-dimensional Euclidean space.

theorem

(equivEuclid d(v))i=vi(\text{equivEuclid } d (v))_i = v_i

#equivEuclid_apply

For any spatial dimension dNd \in \mathbb{N}, Lorentz vector vVectordv \in \text{Vector}_d, and index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, the value of the linear isomorphism equivEuclid d\text{equivEuclid } d applied to vv and evaluated at index ii is equal to the ii-th component of vv, i.e., (equivEuclid d(v))i=vi(\text{equivEuclid } d (v))_i = v_i.

instance

Euclidean norm on Vectord\text{Vector}_d

#instNorm

For a given spatial dimension dd, the norm \|\cdot\| on the space of Lorentz vectors Vectord\text{Vector}_d is defined such that for any vVectordv \in \text{Vector}_d, its norm v\|v\| is equal to the standard Euclidean norm of its image under the linear isomorphism equivEuclidd:VectordR1+d\text{equivEuclid}_d : \text{Vector}_d \cong \mathbb{R}^{1+d}. This defines a positive-definite norm based on the components of the vector in the underlying Euclidean space.

theorem

v=equivEuclidd(v)\|v\| = \|\text{equivEuclid}_d(v)\|

#norm_eq_equivEuclid

For any spatial dimension dNd \in \mathbb{N} and any Lorentz vector vVectordv \in \text{Vector}_d, the norm v\|v\| is equal to the Euclidean norm of its image under the linear isomorphism equivEuclidd\text{equivEuclid}_d, which maps the space of Lorentz vectors to the Euclidean space R1+d\mathbb{R}^{1+d} (represented as EuclideanSpace R(Fin 1Fin d)\text{EuclideanSpace } \mathbb{R} (\text{Fin } 1 \oplus \text{Fin } d)).

theorem

viv|v_i| \leq \|v\| for Lorentz vectors

#abs_component_le_norm

For any Lorentz vector vv in 1+d1+d dimensions and any index ii in the set Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d, the absolute value of the ii-th component of the vector is less than or equal to its Euclidean norm, i.e., viv|v_i| \leq \|v\|. Here, the norm v\|v\| is defined as the standard Euclidean norm of the vector's components in R1+d\mathbb{R}^{1+d}.

instance

Vectord\text{Vector}_d is a normed additive commutative group

#isNormedAddCommGroup

For a given spatial dimension dd, the space of Lorentz vectors Vectord\text{Vector}_d is a normed additive commutative group. This structure integrates the additive commutative group properties of Vectord\text{Vector}_d with its Euclidean norm \|\cdot\|, such that the distance between two vectors x,yVectordx, y \in \text{Vector}_d is defined by the norm of their difference, dist(x,y)=xydist(x, y) = \|x - y\|.

instance

Vectord\text{Vector}_d is a normed space over R\mathbb{R}

#isNormedSpace

For a given spatial dimension dd, the space of Lorentz vectors Vectord\text{Vector}_d is a normed vector space over the field of real numbers R\mathbb{R}. This structure signifies that the Euclidean norm \|\cdot\| on Vectord\text{Vector}_d is compatible with scalar multiplication, such that for any scalar αR\alpha \in \mathbb{R} and any vector vVectordv \in \text{Vector}_d, the property αv=αv\|\alpha v\| = |\alpha| \|v\| holds.

instance

Real inner product on Vectord\text{Vector}_d

#instInnerReal

For a given spatial dimension dd, the space of Lorentz vectors Vectord\text{Vector}_d is equipped with an inner product structure over the real numbers R\mathbb{R}. The inner product of two Lorentz vectors v,wVectordv, w \in \text{Vector}_d, denoted by v,wR\langle v, w \rangle_{\mathbb{R}}, is defined as the standard Euclidean inner product of their representations in the (1+d)(1+d)-dimensional Euclidean space R1+d\mathbb{R}^{1+d} 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.

theorem

v,wR=equivEuclid(v),equivEuclid(w)R\langle v, w \rangle_{\mathbb{R}} = \langle \text{equivEuclid}(v), \text{equivEuclid}(w) \rangle_{\mathbb{R}}

#inner_eq_equivEuclid

For any spatial dimension dNd \in \mathbb{N} and any two Lorentz vectors v,wVectordv, w \in \text{Vector}_d, the real inner product v,wR\langle v, w \rangle_{\mathbb{R}} is equal to the standard Euclidean inner product of their images under the linear equivalence equivEuclid ⁣:VectordR1+d\text{equivEuclid} \colon \text{Vector}_d \cong \mathbb{R}^{1+d}. That is, v,wR=equivEuclid(v),equivEuclid(w)R\langle v, w \rangle_{\mathbb{R}} = \langle \text{equivEuclid}(v), \text{equivEuclid}(w) \rangle_{\mathbb{R}}.

instance

Vectord\text{Vector}_d is a real inner product space

#innerProductSpace

For a given spatial dimension dNd \in \mathbb{N}, the space of Lorentz vectors Vectord\text{Vector}_d is equipped with the structure of an inner product space over the real numbers R\mathbb{R}. This inner product ,R\langle \cdot, \cdot \rangle_{\mathbb{R}} is the standard Euclidean inner product (distinct from the Minkowski metric) and is defined via the linear equivalence between Vectord\text{Vector}_d and the Euclidean space R1+d\mathbb{R}^{1+d}. It satisfies the axioms of a real inner product space, including symmetry, linearity in the first argument, and the identity v2=v,vR\|v\|^2 = \langle v, v \rangle_{\mathbb{R}} for any vector vVectordv \in \text{Vector}_d.

instance

Vectord\text{Vector}_d is a Charted Space modeled on itself

#instChartedSpace

The space of Lorentz vectors Vectord\text{Vector}_d is a charted space (manifold) modeled on the vector space Vectord\text{Vector}_d itself. This structure equips the space with a manifold atlas where the local charts are identity maps from Vectord\text{Vector}_d to Vectord\text{Vector}_d.

instance

Lorentz vector vv as a function of its components ivii \mapsto v_i

#instCoeFunForallSumFinOfNatNatReal

A Lorentz vector vv in dd spatial dimensions can be treated as a function that maps an index ii from the set {0,1,,d}\{0, 1, \dots, d\} (represented formally by the sum type Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d) to its corresponding real-valued component viRv_i \in \mathbb{R}. This coercion allows the notation v(i)v(i) to be used to access the ii-th component of the vector.

theorem

(cv)i=cvi(c \cdot v)_i = c \cdot v_i for Lorentz vectors

#apply_smul

For any spatial dimension dd, given a scalar cRc \in \mathbb{R}, a Lorentz vector vVectordv \in \text{Vector}_d, and an index i{0,1,,d}i \in \{0, 1, \dots, d\} (represented by the sum type Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d), the ii-th component of the scalar multiple cvc \cdot v is equal to the product of cc and the ii-th component of vv. That is, (cv)i=cvi(c \cdot v)_i = c \cdot v_i.

theorem

(v+w)i=vi+wi(v + w)_i = v_i + w_i for Lorentz vectors

#apply_add

For any spatial dimension dd, given two Lorentz vectors vv and ww in Vectord\text{Vector}_d and an index i{0,1,,d}i \in \{0, 1, \dots, d\}, the ii-th component of the sum of the vectors is equal to the sum of their individual ii-th components. That is, (v+w)i=vi+wi(v + w)_i = v_i + w_i.

theorem

(vw)i=viwi(v - w)_i = v_i - w_i for Lorentz vectors

#apply_sub

For any spatial dimension dNd \in \mathbb{N}, given two Lorentz vectors v,wVectordv, w \in \text{Vector}_d and an index i{0,1,,d}i \in \{0, 1, \dots, d\}, the ii-th component of the difference of the vectors is equal to the difference of their individual ii-th components. That is, (vw)i=viwi (v - w)_i = v_i - w_i

theorem

(jvj)i=j(vj)i(\sum_j v_j)_i = \sum_j (v_j)_i for Lorentz vectors

#apply_sum

For any spatial dimension dNd \in \mathbb{N}, given a finite index set ι\iota, a family of Lorentz vectors f:ιVectordf : \iota \to \text{Vector}_d, and an index i{0,1,,d}i \in \{0, 1, \dots, d\}, the ii-th component of the sum of these vectors is equal to the sum of the ii-th components of each individual vector. That is, (jιf(j))i=jιf(j)i \left( \sum_{j \in \iota} f(j) \right)_i = \sum_{j \in \iota} f(j)_i

theorem

(v)i=vi(-v)_i = -v_i for Lorentz vectors

#neg_apply

For any spatial dimension dNd \in \mathbb{N}, given a Lorentz vector vVectordv \in \text{Vector}_d and an index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, the ii-th component of the negated vector v-v is equal to the negation of the ii-th component of vv. That is, (v)i=vi (-v)_i = -v_i

theorem

The ii-th component of the zero Lorentz vector is 00

#zero_apply

For any spatial dimension dNd \in \mathbb{N} and any index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, the ii-th component of the zero Lorentz vector 0Vectord0 \in \text{Vector}_d is 00.

definition

Continuous linear map vviv \mapsto v_i of a Lorentz vector

#coordCLM

For a spatial dimension dNd \in \mathbb{N} and an index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, this is the continuous linear map from the space of Lorentz vectors Vectord\text{Vector}_d to the real numbers R\mathbb{R} that maps each vector vv to its ii-th component viv_i.

theorem

coordCLMi(v)=vi\text{coordCLM}_i(v) = v_i

#coordCLM_apply

For a spatial dimension dNd \in \mathbb{N}, an index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, and a Lorentz vector vVectordv \in \text{Vector}_d, the application of the continuous linear map coordCLMi\text{coordCLM}_i to the vector vv is equal to its ii-th component viv_i.

theorem

The map vviv \mapsto v_i is continuous for Lorentz vectors

#coord_continuous

For a spatial dimension dNd \in \mathbb{N} and an index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, the map vviv \mapsto v_i from the space of Lorentz vectors Vectord\text{Vector}_d to the real numbers R\mathbb{R} is continuous.

theorem

The coordinate map of Lorentz vectors is CnC^n smooth

#coord_contDiff

For any spatial dimension dNd \in \mathbb{N} and any index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, the coordinate map from the space of Lorentz vectors Vectord\text{Vector}_d to the real numbers R\mathbb{R}, defined by vviv \mapsto v_i, is nn-times continuously differentiable (CnC^n) over R\mathbb{R} for any nn.

theorem

Coordinate Functions of Lorentz Vectors are Differentiable

#coord_differentiable

For a spatial dimension dNd \in \mathbb{N} and an index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, the coordinate function vviv \mapsto v_i, which maps a Lorentz vector vVectordv \in \text{Vector}_d to its ii-th component in R\mathbb{R}, is differentiable over R\mathbb{R}.

theorem

The coordinate map vviv \mapsto v_i is differentiable at vv

#coord_differentiableAt

For a given spatial dimension dNd \in \mathbb{N}, an index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, and a Lorentz vector vVectordv \in \text{Vector}_d, the map vviv \mapsto v_i that sends a vector to its ii-th component is differentiable at vv over the field of real numbers R\mathbb{R}.

definition

Continuous linear equivalence VectordEuclideanSpace(R,Fin 1Fin d)\text{Vector}_d \cong \text{EuclideanSpace}(\mathbb{R}, \text{Fin } 1 \oplus \text{Fin } d)

#euclidCLE

For a given spatial dimension dd, the map `euclidCLE` defines a continuous linear equivalence (a topological vector space isomorphism) between the space of Lorentz vectors Vectord\text{Vector}_d and the (1+d)(1+d)-dimensional Euclidean space, represented as EuclideanSpace R(Fin 1Fin d)\text{EuclideanSpace } \mathbb{R} (\text{Fin } 1 \oplus \text{Fin } d). This map is the continuous version of the linear equivalence `equivEuclid`.

definition

Continuous linear equivalence VectordL,RiR\text{Vector}_d \simeq_{L,\mathbb{R}} \prod_{i} \mathbb{R}

#equivPi

For a given spatial dimension dd, this definition provides the continuous linear equivalence between the space of Lorentz vectors Vectord\text{Vector}_d and the space of functions (the product type) from the index set Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d to the real numbers R\mathbb{R}, denoted as iFin 1Fin dR\prod_{i \in \text{Fin } 1 \oplus \text{Fin } d} \mathbb{R}. This map is a bijective linear transformation that is continuous in both directions, identifying Lorentz vectors with their component representations.

theorem

The ii-th component of equivPi(v)\text{equivPi}(v) is equal to viv_i

#equivPi_apply

For any spatial dimension dd, let vVectordv \in \text{Vector}_d be a Lorentz vector and iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d be an index. The application of the continuous linear equivalence equivPi\text{equivPi} to vv, evaluated at the index ii, is equal to the ii-th component viv_i.

theorem

Component-wise continuity implies continuity of Lorentz vector-valued functions

#continuous_of_apply

Let dd be a natural number and α\alpha be a topological space. For a function f:αVectordf : \alpha \to \text{Vector}_d mapping into the space of Lorentz vectors, if for every index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d the component function xf(x)ix \mapsto f(x)_i is continuous, then the function ff is continuous.

theorem

ff is differentiable     \iff all components fif_i are differentiable for f:αVectordf : \alpha \to \text{Vector}_d

#differentiable_apply

For a spatial dimension dNd \in \mathbb{N}, let Vectord\text{Vector}_d be the space of Lorentz vectors. Let α\alpha be a normed space over R\mathbb{R}. A function f:αVectordf : \alpha \to \text{Vector}_d is differentiable if and only if for every index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, the component function fi:αRf_i : \alpha \to \mathbb{R} (defined by x(f(x))ix \mapsto (f(x))_i) is differentiable.

theorem

f:αVectordf: \alpha \to \text{Vector}_d is CnC^n iff its components are CnC^n

#contDiff_apply

Let α\alpha be a real normed vector space and dd be a natural number representing the spatial dimensions. For any nN{}n \in \mathbb{N} \cup \{\infty\}, a function f:αVectordf: \alpha \to \text{Vector}_d is nn-times continuously differentiable (CnC^n) if and only if for every index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, the scalar-valued component function xf(x)ix \mapsto f(x)_i is nn-times continuously differentiable.

theorem

(Df(x)dt)ν=D(fν)(x)dt(Df(x) \cdot dt)_\nu = D(f_\nu)(x) \cdot dt

#fderiv_apply

Let dNd \in \mathbb{N} be the spatial dimension and α\alpha be a real normed space. For any differentiable function f:αVectordf: \alpha \to \text{Vector}_d, any point xαx \in \alpha, direction dtαdt \in \alpha, and index νFin 1Fin d\nu \in \text{Fin } 1 \oplus \text{Fin } d, the ν\nu-th component of the Fréchet derivative of ff at xx in the direction dtdt is equal to the Fréchet derivative of the component function fν:αRf_\nu: \alpha \to \mathbb{R} (where fν(y)=f(y)νf_\nu(y) = f(y)_\nu) at xx in the direction dtdt. Mathematically, this is expressed as: \[ (Df(x) \cdot dt)_\nu = D(f_\nu)(x) \cdot dt \]

theorem

The Fréchet derivative of vvμv \mapsto v_\mu is coordCLM μ\text{coordCLM } \mu

#fderiv_coord

For a given number of spatial dimensions dNd \in \mathbb{N} and an index μFin 1Fin d\mu \in \text{Fin } 1 \oplus \text{Fin } d, the Fréchet derivative of the function that maps a Lorentz vector vVectordv \in \text{Vector}_d to its μ\mu-th component vμv_\mu is equal to the continuous linear map coordCLM μ\text{coordCLM } \mu, which evaluates the μ\mu-th coordinate of its argument.

definition

Index equivalence for Lorentz vectors Fin(1)Fin(d)\cong \text{Fin}(1) \oplus \text{Fin}(d)

#indexEquiv

For a spacetime with dd spatial dimensions, the type of component indices for a Lorentz vector (a tensor with a single contravariant index) is equivalent to the disjoint union Fin(1)Fin(d)\text{Fin}(1) \oplus \text{Fin}(d). This equivalence maps the single index of the vector to either the temporal component (index 00 in Fin(1)\text{Fin}(1)) or one of the dd spatial components (indices in Fin(d)\text{Fin}(d)).

instance

Vectord\text{Vector}_d is tensorial with a single upper index

#tensorial

For a given number of spatial dimensions dNd \in \mathbb{N}, this definition establishes that the space of Lorentz vectors Vectord\text{Vector}_d 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 Vectord\text{Vector}_d and the formal tensor space associated with the color sequence [up][ \text{up} ]. 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 Fin(1)Fin(d)\text{Fin}(1) \oplus \text{Fin}(d), representing the temporal and spatial components respectively.

theorem

Component-wise evaluation of the inverse `toTensor` map for Lorentz vectors

#toTensor_symm_apply

Let dd be the number of spatial dimensions. For any real Lorentz tensor pp with a single contravariant (upper) index, the image of pp under the inverse isomorphism toTensor1\text{toTensor}^{-1} (which maps tensors back to the space of Lorentz vectors Vectord\text{Vector}_d) is the function that assigns to each index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d the coordinate of pp with respect to the canonical tensor basis, where the tensor's multi-indices are identified with Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d via the index equivalence map.

theorem

Components of the Lorentz vector toTensor1(p)\text{toTensor}^{-1}(p) for rank-1 pure tensors

#toTensor_symm_pure

Let dd be the number of spatial dimensions. For any pure tensor pp of rank 1 with a single contravariant (upper) index, let p0p_0 be its constituent vector in the representation space. For any index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, the ii-th component of the Lorentz vector obtained from pp via the inverse isomorphism toTensor1\text{toTensor}^{-1} is given by: (toTensor1(p.toTensor))i=repr(p0)j (\text{toTensor}^{-1}(p.\text{toTensor}))_i = \text{repr}(p_0)_{j} where repr(p0)\text{repr}(p_0) denotes the coordinate representation of the vector p0p_0 with respect to the standard contravariant basis, and jj is the index in the representation space corresponding to ii via the index equivalence map.

definition

Standard basis for Vectord\text{Vector}_d indexed by Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d

#basis

For a given spatial dimension dNd \in \mathbb{N}, this provides the standard coordinate basis for the space of Lorentz vectors Vectord\text{Vector}_d over the field of real numbers R\mathbb{R}. The basis is indexed by the set Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d, which represents the combination of one temporal and dd spatial dimensions. A basis vector indexed by μ\mu corresponds to the function that yields 11 at index μ\mu and 00 for all other indices ν\nu.

theorem

The components of the standard basis for Vectord\text{Vector}_d are δμν\delta_{\mu\nu}

#basis_apply

For a given spatial dimension dNd \in \mathbb{N}, let basis μ\text{basis } \mu denote the μ\mu-th vector of the standard coordinate basis for the space of Lorentz vectors Vectord\text{Vector}_d, where the indices μ,ν\mu, \nu belong to the set Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d. The ν\nu-th component of the μ\mu-th basis vector is given by: (basis μ)ν={1if μ=ν0if μν (\text{basis } \mu)_\nu = \begin{cases} 1 & \text{if } \mu = \nu \\ 0 & \text{if } \mu \neq \nu \end{cases}

theorem

toTensor1\text{toTensor}^{-1} maps the canonical tensor basis to the Lorentz vector basis

#toTensor_symm_basis

For a spacetime with dd spatial dimensions, let Vectord\text{Vector}_d be the space of Lorentz vectors and let Tensorup\text{Tensor}_{\text{up}} be the space of real Lorentz tensors with a single contravariant (upper) index. Let toTensor:VectordTensorup\text{toTensor} : \text{Vector}_d \cong \text{Tensor}_{\text{up}} be the linear isomorphism that identifies a Lorentz vector with its tensorial representation. Let eμe_\mu be the μ\mu-th basis vector of the standard coordinate basis for Vectord\text{Vector}_d, where μFin 1Fin d\mu \in \text{Fin } 1 \oplus \text{Fin } d, and let EbE_b be the canonical basis for the tensor space indexed by component indices bb. Then, the inverse of the isomorphism toTensor\text{toTensor} maps the tensor basis element associated with μ\mu to the corresponding Lorentz vector basis vector: toTensor1(Eϕ(μ))=eμ \text{toTensor}^{-1}(E_{\phi(\mu)}) = e_\mu where ϕ\phi is the equivalence map (`indexEquiv.symm`) from the physical index set Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d to the tensor component index set.

theorem

toTensor\text{toTensor} maps the Lorentz vector basis to the canonical tensor basis

#toTensor_basis_eq_tensor_basis

For a spacetime with dd spatial dimensions, let Vectord\text{Vector}_d be the space of Lorentz vectors and let Tensorup\text{Tensor}_{\text{up}} be the space of real Lorentz tensors with a single contravariant (upper) index. Let toTensor:VectordTensorup\text{toTensor} : \text{Vector}_d \cong \text{Tensor}_{\text{up}} be the linear isomorphism that identifies a Lorentz vector with its tensorial representation. Let eμe_\mu be the μ\mu-th basis vector of the standard coordinate basis for Vectord\text{Vector}_d, where μFin 1Fin d\mu \in \text{Fin } 1 \oplus \text{Fin } d, and let EbE_b be the canonical basis for the tensor space indexed by component indices bb. Then, the isomorphism toTensor\text{toTensor} maps the μ\mu-th basis vector of the Lorentz vector space to the corresponding basis vector in the tensor space: toTensor(eμ)=Eϕ(μ) \text{toTensor}(e_\mu) = E_{\phi(\mu)} where ϕ\phi is the equivalence map (`indexEquiv.symm`) from the physical index set Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d to the tensor component index set.

theorem

basis=reindex ϕ(toTensor1(Tensor.basis))\text{basis} = \text{reindex } \phi (\text{toTensor}^{-1}(\text{Tensor.basis}))

#basis_eq_map_tensor_basis

For a spacetime with dd spatial dimensions, let Vectord\text{Vector}_d be the space of Lorentz vectors and {eμ}μFin 1Fin d\{e_\mu\}_{\mu \in \text{Fin } 1 \oplus \text{Fin } d} be its standard coordinate basis. Let Tensorup\text{Tensor}_{\text{up}} be the space of real Lorentz tensors with a single contravariant (upper) index, and let {Eb}\{E_b\} be its canonical basis indexed by component indices bb. Given the linear isomorphism toTensor:VectordTensorup\text{toTensor} : \text{Vector}_d \cong \text{Tensor}_{\text{up}} and the index equivalence ϕ:ComponentIdx(up)Fin 1Fin d\phi : \text{ComponentIdx}(\text{up}) \cong \text{Fin } 1 \oplus \text{Fin } d, the basis for Lorentz vectors is equal to the tensor basis mapped through the inverse isomorphism toTensor1\text{toTensor}^{-1} and reindexed by ϕ\phi: e=reindexϕ(toTensor1(E)) e = \text{reindex}_\phi (\text{toTensor}^{-1}(E)) Specifically, for each μFin 1Fin d\mu \in \text{Fin } 1 \oplus \text{Fin } d, the basis vector eμe_\mu is the image of the tensor basis element Eϕ1(μ)E_{\phi^{-1}(\mu)} under the map toTensor1\text{toTensor}^{-1}.

theorem

toTensor1(Tensor.basis)=reindex ϕ1(basis)\text{toTensor}^{-1}(\text{Tensor.basis}) = \text{reindex } \phi^{-1}(\text{basis})

#tensor_basis_map_eq_basis_reindex

For a spacetime with dd spatial dimensions, let Vectord\text{Vector}_d be the space of Lorentz vectors and let TupT_{\text{up}} be the space of real Lorentz tensors with a single contravariant (upper) index. Let toTensor:VectordTup\text{toTensor} : \text{Vector}_d \cong T_{\text{up}} be the canonical linear isomorphism between these spaces. Let EE be the canonical basis of TupT_{\text{up}} indexed by bComponentIdx(up)b \in \text{ComponentIdx}(\text{up}), and let ee be the standard coordinate basis of Vectord\text{Vector}_d indexed by μFin 1Fin d\mu \in \text{Fin } 1 \oplus \text{Fin } d. Given the index equivalence ϕ:ComponentIdx(up)Fin 1Fin d\phi : \text{ComponentIdx}(\text{up}) \cong \text{Fin } 1 \oplus \text{Fin } d, the image of the tensor basis under the inverse isomorphism toTensor1\text{toTensor}^{-1} is equal to the Lorentz vector basis reindexed by the inverse equivalence ϕ1\phi^{-1}: toTensor1(E)=reindexϕ1(e) \text{toTensor}^{-1}(E) = \text{reindex}_{\phi^{-1}}(e) Specifically, for each tensor component index bb, the image of the bb-th tensor basis vector under toTensor1\text{toTensor}^{-1} is the ϕ(b)\phi(b)-th Lorentz vector basis vector.

theorem

(Tensor.basis.repr (toTensor p))μ=p(indexEquiv μ)(\text{Tensor.basis.repr } (\text{toTensor } p))_\mu = p(\text{indexEquiv } \mu)

#tensor_basis_repr_toTensor_apply

For a spacetime with dd spatial dimensions, let pVectordp \in \text{Vector}_d be a Lorentz vector and let toTensor(p)\text{toTensor}(p) be its representation as a rank-1 tensor with a single contravariant (upper) index. For any tensor component index μ\mu, the coordinate of toTensor(p)\text{toTensor}(p) with respect to the canonical tensor basis at index μ\mu is equal to the value of the vector pp evaluated at the corresponding spacetime index indexEquiv(μ)Fin 1Fin d\text{indexEquiv}(\mu) \in \text{Fin } 1 \oplus \text{Fin } d.

theorem

basis.repr pμ=pμ\text{basis.repr } p \mu = p \mu for Lorentz vectors

#basis_repr_apply

For any spatial dimension dNd \in \mathbb{N}, let pp be a Lorentz vector in Vectord\text{Vector}_d and μFin 1Fin d\mu \in \text{Fin } 1 \oplus \text{Fin } d be a spacetime index. The μ\mu-th coordinate of pp with respect to the standard basis is equal to the component value p(μ)p(\mu).

theorem

Matrix representation of linear maps on Lorentz vectors f(p)=Mfpf(p) = M_f p

#map_apply_eq_basis_mulVec

For a spatial dimension dNd \in \mathbb{N}, let f:VectordVectordf: \text{Vector}_d \to \text{Vector}_d be an R\mathbb{R}-linear map and pVectordp \in \text{Vector}_d be a Lorentz vector. The application of the map ff to the vector pp is equal to the matrix-vector product of the matrix representation of ff (with respect to the standard basis) and the vector pp. That is, f(p)=Mfpf(p) = M_f \cdot p, where MfM_f is the matrix of ff relative to the standard basis.

theorem

μfμbasisμ=0    μ,fμ=0\sum_{\mu} f_\mu \cdot \text{basis}_{\mu} = 0 \iff \forall \mu, f_\mu = 0 for Lorentz vectors

#sum_basis_eq_zero_iff

For a spatial dimension dNd \in \mathbb{N}, let f:Fin 1Fin dRf: \text{Fin } 1 \oplus \text{Fin } d \to \mathbb{R} be a collection of real coefficients. The linear combination of the standard basis vectors for the space of Lorentz vectors, μf(μ)basisμ\sum_{\mu} f(\mu) \cdot \text{basis}_{\mu}, is equal to zero if and only if f(μ)=0f(\mu) = 0 for all μFin 1Fin d\mu \in \text{Fin } 1 \oplus \text{Fin } d.

theorem

f0basis0+ifibasisi=0    f0=0i,fi=0f_0 \cdot \text{basis}_0 + \sum_i f_i \cdot \text{basis}_i = 0 \iff f_0 = 0 \land \forall i, f_i = 0 for Lorentz vectors

#sum_inl_inr_basis_eq_zero_iff

For a spatial dimension dNd \in \mathbb{N}, let f0Rf_0 \in \mathbb{R} and f:Fin dRf: \text{Fin } d \to \mathbb{R} be coefficients. The linear combination of the temporal basis vector and the spatial basis vectors in the space of Lorentz vectors Vectord\text{Vector}_d, given by f0basis(inl 0)+ifibasis(inr i)f_0 \cdot \text{basis}(\text{inl } 0) + \sum_{i} f_i \cdot \text{basis}(\text{inr } i), is equal to zero if and only if f0=0f_0 = 0 and fi=0f_i = 0 for all iFin di \in \text{Fin } d.

theorem

(Λp)i=jΛijpj(\Lambda \cdot p)_i = \sum_j \Lambda_{ij} p_j

#smul_eq_sum

For a spacetime with dd spatial dimensions, let Λ\Lambda be a Lorentz transformation and pp be a Lorentz vector in Vectord\text{Vector}_d. For any index iFin 1Fin di \in \text{Fin } 1 \oplus \text{Fin } d, the ii-th component of the vector resulting from the action of Λ\Lambda on pp is given by the sum over all indices jj: (Λp)i=jΛijpj (\Lambda \cdot p)_i = \sum_{j} \Lambda_{ij} p_j where Λij\Lambda_{ij} represents the (i,j)(i, j)-th entry of the matrix representation of the Lorentz transformation Λ\Lambda, and pjp_j is the jj-th component of the vector pp.

theorem

Lorentz action Λp\Lambda \cdot p equals matrix-vector product Λvp\Lambda \mathbf{v}_p

#smul_eq_mulVec

For any spatial dimension dd, let Λ\Lambda be a Lorentz transformation in the Lorentz group and pp be a Lorentz vector in Vectord\text{Vector}_d. The action of Λ\Lambda on pp, denoted by Λp\Lambda \cdot p, is equal to the matrix-vector product Λvp\Lambda \mathbf{v}_p, where Λ\Lambda is represented by its underlying matrix and vp\mathbf{v}_p is the vector of components of pp.

theorem

Λ(p+q)=Λp+Λq\Lambda \cdot (p + q) = \Lambda \cdot p + \Lambda \cdot q

#smul_add

For any spatial dimension dNd \in \mathbb{N}, let Λ\Lambda be a Lorentz transformation in the Lorentz group and p,qp, q be two Lorentz vectors in Vectord\text{Vector}_d. The action of Λ\Lambda on the sum of the two vectors satisfies the distributive property, such that Λ(p+q)=Λp+Λq\Lambda \cdot (p + q) = \Lambda \cdot p + \Lambda \cdot q.

theorem

Λ(pq)=ΛpΛq\Lambda \cdot (p - q) = \Lambda \cdot p - \Lambda \cdot q

#smul_sub

For any spatial dimension dNd \in \mathbb{N}, let Λ\Lambda be a Lorentz transformation in the Lorentz group and p,qp, q be two Lorentz vectors in Vectord\text{Vector}_d. The action of Λ\Lambda on the difference of the two vectors satisfies the distributive property, such that Λ(pq)=ΛpΛq\Lambda \cdot (p - q) = \Lambda \cdot p - \Lambda \cdot q.

theorem

Λ0=0\Lambda \cdot 0 = 0

#smul_zero

For a spacetime with dd spatial dimensions, let Λ\Lambda be a Lorentz transformation in the Lorentz group and 0Vectord0 \in \text{Vector}_d be the zero Lorentz vector. The action of Λ\Lambda on the zero vector is the zero vector: Λ0=0\Lambda \cdot 0 = 0

theorem

Λ(p)=(Λp)\Lambda \cdot (-p) = -(\Lambda \cdot p)

#smul_neg

For a spacetime with dd spatial dimensions, let Λ\Lambda be a Lorentz transformation in the Lorentz group and pp be a Lorentz vector. The action of Λ\Lambda on the additive inverse (negation) of pp is equal to the negation of the result of Λ\Lambda acting on pp: Λ(p)=(Λp)\Lambda \cdot (-p) = -(\Lambda \cdot p)

theorem

(Λ)p=(Λp)(-\Lambda) \cdot p = -(\Lambda \cdot p)

#neg_smul

For a spacetime with dd spatial dimensions, let Λ\Lambda be a Lorentz transformation and pp be a Lorentz vector. The action of the negated Lorentz transformation Λ-\Lambda on the vector pp is equal to the negation of the result of the action of Λ\Lambda on pp: (Λ)p=(Λp)(-\Lambda) \cdot p = -(\Lambda \cdot p)

definition

Lorentz action on Vectord\text{Vector}_d as a continuous linear map

#actionCLM

For a given spatial dimension dd and a Lorentz transformation Λ\Lambda in the Lorentz group, this definition represents the action of Λ\Lambda on the space of Lorentz vectors Vectord\text{Vector}_d as a continuous linear map from Vectord\text{Vector}_d to itself, which sends a vector vv to the transformed vector Λv\Lambda \cdot v.

theorem

actionCLM(Λ)(p)=Λp\text{actionCLM}(\Lambda)(p) = \Lambda \cdot p for Lorentz vectors

#actionCLM_apply

For any spatial dimension dNd \in \mathbb{N}, any Lorentz transformation Λ\Lambda in the Lorentz group, and any Lorentz vector pVectordp \in \text{Vector}_d, the application of the continuous linear map actionCLM(Λ)\text{actionCLM}(\Lambda) to the vector pp is equal to the group action of Λ\Lambda on pp, denoted as Λp\Lambda \cdot p.

theorem

The action of ΛLorentzGroupd\Lambda \in \text{LorentzGroup}_d on Vectord\text{Vector}_d is injective

#actionCLM_injective

For any spatial dimension dNd \in \mathbb{N} and any Lorentz transformation Λ\Lambda in the Lorentz group, the continuous linear map actionCLM Λ:VectordVectord\text{actionCLM } \Lambda : \text{Vector}_d \to \text{Vector}_d (which maps a vector vv to Λv\Lambda \cdot v) is injective.

theorem

The Lorentz action on Vectord\text{Vector}_d is surjective

#actionCLM_surjective

For any spatial dimension dd and any Lorentz transformation Λ\Lambda in the Lorentz group, the continuous linear map actionCLM Λ:VectordVectord\text{actionCLM } \Lambda: \text{Vector}_d \to \text{Vector}_d, which maps a Lorentz vector vv to its transformed version Λv\Lambda \cdot v, is surjective.

theorem

Λbasisμ=νΛνμbasisν\Lambda \cdot \text{basis}_\mu = \sum_\nu \Lambda_{\nu\mu} \text{basis}_\nu

#smul_basis

For a given spatial dimension dd, let Λ\Lambda be a Lorentz transformation and eμe_\mu denote the μ\mu-th basis vector of the standard basis for the space of Lorentz vectors Vectord\text{Vector}_d, where the index μFin 1Fin d\mu \in \text{Fin } 1 \oplus \text{Fin } d. The action of the Lorentz transformation on this basis vector is given by the linear combination: Λeμ=νΛνμeν \Lambda \cdot e_\mu = \sum_{\nu} \Lambda_{\nu\mu} e_\nu where Λνμ\Lambda_{\nu\mu} represents the (ν,μ)(\nu, \mu)-th entry of the matrix representing the Lorentz transformation Λ\Lambda.

abbrev

Spatial part of a Lorentz vector vv

#spatialPart

For a Lorentz vector vv in (1+d)(1+d)-dimensional Minkowski spacetime, the spatial part is the vector in the dd-dimensional Euclidean space Rd\mathbb{R}^d obtained by extracting the components of vv corresponding to the spatial indices. Specifically, the ii-th component of the resulting vector in Rd\mathbb{R}^d is given by viv^i for i{1,,d}i \in \{1, \dots, d\}.

theorem

The ii-th component of the spatial part of vv equals viv^i

#spatialPart_apply_eq_toCoord

For a Lorentz vector vv in (1+d)(1+d)-dimensional Minkowski spacetime and any spatial index i{1,,d}i \in \{1, \dots, d\}, the ii-th component of the spatial part of vv is equal to the component of the vector vv at the corresponding spatial index. That is, (spatialPart v)i=vi(\text{spatialPart } v)_i = v^i.

theorem

The jj-th component of the spatial part of the ii-th spatial basis vector is δij\delta_{ij}

#spatialPart_basis_sum_inr

For a given spatial dimension dNd \in \mathbb{N} and any spatial indices i,jFin di, j \in \text{Fin } d, let basis(inr i)\text{basis}(\text{inr } i) denote the ii-th spatial basis vector of the (1+d)(1+d)-dimensional Lorentz vector space. The jj-th component of the spatial part of this basis vector is equal to 11 if i=ji = j and 00 otherwise. That is, (spatialPart(basis(inr i)))j=δij (\text{spatialPart}(\text{basis}(\text{inr } i)))_j = \delta_{ij} where δij\delta_{ij} is the Kronecker delta.

theorem

The ii-th spatial component of the temporal basis vector is 00

#spatialPart_basis_sum_inl

For any spatial dimension dNd \in \mathbb{N} and any spatial index i{0,,d1}i \in \{0, \dots, d-1\}, let e0e_0 be the basis vector of the Lorentz vector space Vectord\text{Vector}_d corresponding to the temporal dimension (represented by the index Sum.inl 0\text{Sum.inl } 0). The ii-th component of the spatial part of this temporal basis vector is zero, denoted as: (spatialPart e0)i=0 (\text{spatialPart } e_0)_i = 0

definition

Continuous linear map of the spatial part of a Lorentz vector

#spatialCLM

For a spatial dimension dNd \in \mathbb{N}, this continuous linear map from the Lorentz vector space Vectord\text{Vector}_d to the dd-dimensional Euclidean space Rd\mathbb{R}^d extracts the spatial components of a Lorentz vector vv. Specifically, for any vVectordv \in \text{Vector}_d, the map returns a vector in Rd\mathbb{R}^d whose ii-th component is v(inr i)v(\text{inr } i) for i{0,,d1}i \in \{0, \dots, d-1\}.

theorem

(spatialCLMd(v))i=(spatialPart v)i(\text{spatialCLM}_d(v))_i = (\text{spatialPart } v)_i

#spatialCLM_apply_eq_spatialPart

For any spatial dimension dNd \in \mathbb{N}, Lorentz vector vVectordv \in \text{Vector}_d, and spatial index i{0,,d1}i \in \{0, \dots, d-1\}, the ii-th component of the vector resulting from the application of the continuous linear map spatialCLMd\text{spatialCLM}_d to vv is equal to the ii-th component of the spatial part of vv. That is, (spatialCLMd(v))i=(spatialPart v)i (\text{spatialCLM}_d(v))_i = (\text{spatialPart } v)_i

theorem

spatialCLMd(e0)=0\text{spatialCLM}_d(e_0) = 0

#spatialCLM_basis_sum_inl

For any spatial dimension dNd \in \mathbb{N}, let e0e_0 be the basis vector of the Lorentz vector space Vectord\text{Vector}_d corresponding to the temporal dimension (indexed by Sum.inl 0\text{Sum.inl } 0). The continuous linear map spatialCLMd\text{spatialCLM}_d, which extracts the spatial components of a Lorentz vector, maps e0e_0 to the zero vector in the dd-dimensional Euclidean space Rd\mathbb{R}^d: spatialCLMd(e0)=0\text{spatialCLM}_d(e_0) = 0

theorem

spatialCLMd(einr i)=ei\text{spatialCLM}_d(e_{\text{inr } i}) = \mathbf{e}_i

#spatialCLM_basis_sum_inr

For any spatial dimension dNd \in \mathbb{N} and any spatial index i{0,,d1}i \in \{0, \dots, d-1\}, let einr ie_{\text{inr } i} be the basis vector of the Lorentz vector space Vectord\text{Vector}_d corresponding to the ii-th spatial dimension. The continuous linear map spatialCLMd\text{spatialCLM}_d, which extracts the spatial components of a Lorentz vector, maps einr ie_{\text{inr } i} to the ii-th standard basis vector of the dd-dimensional Euclidean space Rd\mathbb{R}^d. That is, spatialCLMd(einr i)=ei\text{spatialCLM}_d(e_{\text{inr } i}) = \mathbf{e}_i where ei\mathbf{e}_i is the ii-th basis function of Rd\mathbb{R}^d.

abbrev

Time component of a Lorentz vector vv

#timeComponent

For a Lorentz vector vv in a Minkowski space with dd spatial dimensions, the function returns its temporal component v0Rv^0 \in \mathbb{R}, which corresponds to the component indexed by the first element (the "0-th" index) of the underlying representation.

theorem

The temporal component of a spatial basis vector is 00

#timeComponent_basis_sum_inr

For any spatial dimension dNd \in \mathbb{N} and any spatial index iFin di \in \text{Fin } d, the temporal component of the ii-th spatial basis vector in the standard basis of the Lorentz vector space Vectord\text{Vector}_d is 00.

theorem

The time component of the temporal basis vector is 11

#timeComponent_basis_sum_inl

For any spatial dimension dNd \in \mathbb{N}, the time component of the standard basis vector corresponding to the temporal dimension (indexed by Sum.inl 0\text{Sum.inl } 0) in the space of Lorentz vectors Vectord\text{Vector}_d is equal to 11.

definition

Temporal component continuous linear map

#temporalCLM

For a given spatial dimension dd, the map temporalCLM\text{temporalCLM} is the continuous linear map from the space of Lorentz vectors Vectord\text{Vector}_d to the real numbers R\mathbb{R} that maps a vector vv to its temporal component, which corresponds to the index 00 in the temporal dimension (represented formally as v(Sum.inl 0)v(\text{Sum.inl } 0)).

theorem

temporalCLMd(v)=v0\text{temporalCLM}_d(v) = v^0 for Lorentz vectors

#temporalCLM_apply_eq_timeComponent

For any spatial dimension dNd \in \mathbb{N} and any Lorentz vector vVectordv \in \text{Vector}_d, the result of applying the temporal continuous linear map temporalCLMd\text{temporalCLM}_d to vv is equal to the vector's time component v0v^0.

theorem

The temporal component of spatial basis vectors is zero

#temporalCLM_basis_sum_inr

For a given spatial dimension dNd \in \mathbb{N}, let basis(μ)\text{basis}(\mu) denote the μ\mu-th vector of the standard coordinate basis for the space of Lorentz vectors Vectord\text{Vector}_d, where the indices μ\mu belong to the set Fin 1Fin d\text{Fin } 1 \oplus \text{Fin } d. Let temporalCLMd\text{temporalCLM}_d be the continuous linear map that extracts the temporal component of a Lorentz vector (the component corresponding to the index Sum.inl 0\text{Sum.inl } 0). For any spatial index iFin di \in \text{Fin } d (represented by Sum.inr i\text{Sum.inr } i), the temporal component of the ii-th spatial basis vector is zero: temporalCLMd(basis(Sum.inr i))=0 \text{temporalCLM}_d(\text{basis}(\text{Sum.inr } i)) = 0

theorem

The temporal component of the temporal basis vector is 11

#temporalCLM_basis_sum_inl

For any spatial dimension dNd \in \mathbb{N}, the temporal component of the temporal basis vector basis(Sum.inl 0)\text{basis}(\text{Sum.inl } 0) is equal to 11.

definition

Smooth manifold structure on Vectord\text{Vector}_d

#asSmoothManifold

For a given spatial dimension dNd \in \mathbb{N}, the space of Lorentz vectors Vectord\text{Vector}_d is equipped with a smooth manifold structure over the real numbers R\mathbb{R}. This is represented by the identity model with corners I(R,Vectord)\mathcal{I}(\mathbb{R}, \text{Vector}_d), which models the space Vectord\text{Vector}_d on itself, providing the standard smooth structure associated with its vector space properties.

theorem

basis μ,pR=pμ\langle \text{basis } \mu, p \rangle_{\mathbb{R}} = p_\mu

#basis_inner

For a given spatial dimension dNd \in \mathbb{N}, let pVectordp \in \text{Vector}_d be a Lorentz vector and let basis μ\text{basis } \mu be the μ\mu-th standard basis vector for the space, where the index μFin 1Fin d\mu \in \text{Fin } 1 \oplus \text{Fin } d. The real inner product (Euclidean inner product) of basis μ\text{basis } \mu and pp is equal to the μ\mu-th component of pp. That is, basis μ,pR=pμ \langle \text{basis } \mu, p \rangle_{\mathbb{R}} = p_\mu

theorem

p,basis μR=pμ\langle p, \text{basis } \mu \rangle_{\mathbb{R}} = p_\mu

#inner_basis

For any spatial dimension dNd \in \mathbb{N}, let pVectordp \in \text{Vector}_d be a Lorentz vector and let basis μ\text{basis } \mu be the μ\mu-th vector of the standard coordinate basis for Vectord\text{Vector}_d, where μFin 1Fin d\mu \in \text{Fin } 1 \oplus \text{Fin } d. The real inner product of pp and basis μ\text{basis } \mu is equal to the μ\mu-th component of pp: p,basis μR=pμ\langle p, \text{basis } \mu \rangle_{\mathbb{R}} = p_\mu