Physlib.Relativity.LorentzGroup.Proper
The Proper Lorentz Group
The proper Lorentz group is the subgroup of the Lorentz group with determinant `1`.
We define the give a series of lemmas related to the determinant of the Lorentz group.
20 declarations
for
Let denote the Lorentz group acting on a -dimensional Minkowski space. For any element , the determinant of its matrix representation is either or . That is,
Discrete topology on
The definition provides a topological space structure on the group (the cyclic group of order 2), where the topology assigned is the discrete topology.
is a discrete space
The topological space defined on the group (the cyclic group of order 2) is a discrete space.
is a topological group
The cyclic group of order 2, , is a topological group when equipped with the discrete topology. This implies that the group multiplication and inversion operations are continuous maps.
Continuous map from to
The function is a continuous map , where the domain is a subset of the real numbers and is the cyclic group of order 2. The map is defined such that is the identity element of (corresponding to ) and is the non-identity element of (corresponding to ).
Continuous determinant map
The continuous map from the Lorentz group to the cyclic group of order 2. For a Lorentz matrix , it maps the determinant to the corresponding element in , where corresponds to the identity element and corresponds to the non-identity element.
For any element in the Lorentz group , the continuous determinant map evaluates to the identity element of if and only if the determinant of the matrix is .
For any element in the Lorentz group acting on -dimensional Minkowski space, the continuous determinant map evaluates to the non-identity element of if and only if the determinant of the matrix representation of is .
For any elements and in the Lorentz group , the values of the continuous determinant map are equal if and only if the determinants of their matrix representations are equal. That is,
Determinant representation
The group homomorphism from the Lorentz group to the cyclic group of order 2. For any Lorentz transformation , the map sends to its determinant , represented as an element of . Specifically, a determinant of corresponds to the identity element of , and a determinant of corresponds to the non-identity element.
The determinant representation is continuous
Let be the -dimensional Lorentz group and be the cyclic group of order 2 equipped with the discrete topology. The determinant representation , which maps a Lorentz transformation to its determinant represented in , is continuous.
for
For any two Lorentz transformations and in the Lorentz group (the group of linear transformations preserving the Lorentz metric in dimensions), if belongs to the same connected component as , then their determinants are equal: .
for in the same connected component as
Let be the Lorentz group in dimensions. For any two Lorentz transformations , if belongs to the same connected component as , then their images under the determinant representation are equal, i.e., .
for Lorentz transformations joined by a path
For any two Lorentz transformations and in the -dimensional Lorentz group, if and are joined by a path, then their determinants are equal: .
Proper Lorentz transformation ()
For a Lorentz transformation in the Lorentz group of dimension , the property holds if the determinant of the matrix representation of is equal to , denoted as .
Decidability of the proper Lorentz transformation predicate ()
For a Lorentz transformation in the Lorentz group of dimension , the property , which is defined by the condition that the determinant of the matrix representation of is equal to (), is a decidable predicate.
Product of proper Lorentz transformations is proper
For any two Lorentz transformations and in the Lorentz group of dimension , if and are proper transformations (meaning and ), then their product is also a proper Lorentz transformation.
For any Lorentz transformation in the Lorentz group of dimension , is a proper Lorentz transformation () if and only if its image under the determinant representation is the identity element .
The Identity Lorentz Transformation is Proper
The identity element of the Lorentz group in dimensions is a proper Lorentz transformation (i.e., its determinant is equal to ).
for Transformations in the Same Connected Component
For any two Lorentz transformations and in the Lorentz group of dimension , if belongs to the same connected component as , then is a proper Lorentz transformation if and only if is a proper Lorentz transformation. A Lorentz transformation is called proper if its determinant is equal to .
