Lorentz transformations.
Book by T. Matolcsi
Mathematical Preliminaries
A vector is represented as a nx1 matrix (column vector)
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vect(x:List Expression Integer):Matrix Expression Integer == matrix map(y+->[y],x)
Function declaration vect : List(Expression(Integer)) -> Matrix(
Expression(Integer)) has been added to workspace.
Type: Void
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vect [a0,a1,a2,a3]
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Compiling function vect with type List(Expression(Integer)) ->
Matrix(Expression(Integer))
Type: Matrix(Expression(Integer))
Identity
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ID:=diagonalMatrix([1,1,1,1])
Type: Matrix(Integer)
Verification
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possible(x)==subst(x, map(y+->(y=(random(100) - random(100))),variables x) )
Type: Void
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is?(eq:Equation EXPR INT):Boolean == (lhs(eq)-rhs(eq)=0)::Boolean
Function declaration is? : Equation(Expression(Integer)) -> Boolean
has been added to workspace.
Type: Void
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Is?(eq:Equation(Matrix(EXPR(INT)))):Boolean == _
( (lhs(eq)-rhs(eq)) :: Matrix Expression AlgebraicNumber = _
zero(nrows(lhs(eq)),ncols(lhs(eq)))$Matrix Expression AlgebraicNumber )::Boolean
Function declaration Is? : Equation(Matrix(Expression(Integer))) ->
Boolean has been added to workspace.
Type: Void
Lorentz Form (metric) produces a co-vector (represent as a 1xn matrix or row vector)
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G:=diagonalMatrix [-1,1,1,1]
Type: Matrix(Integer)
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g(x)==transpose(x)*G
Type: Void
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g(vect [a0,a1,a2,a3])
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Compiling function g with type Matrix(Expression(Integer)) -> Matrix
(Expression(Integer))
Type: Matrix(Expression(Integer))
Scalar product
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dot(x,y)== (g(x)*y)::Expression Integer
Type: Void
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dot(vect [a0,a1,a2,a3], vect [b0,b1,b2,b3])
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Compiling function dot with type (Matrix(Expression(Integer)),Matrix
(Expression(Integer))) -> Expression(Integer)
Type: Expression(Integer)
Tensor product
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tensor(x,y) == x*g(y)
Type: Void
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tensor(vect [a0,a1,a2,a3], vect [b0,b1,b2,b3])
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Compiling function tensor with type (Matrix(Expression(Integer)),
Matrix(Expression(Integer))) -> Matrix(Expression(Integer))
Type: Matrix(Expression(Integer))
Massive Objects
An object (also referred to as an observer) is represented by a
time-like 4-vector
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P:=vect [sqrt(p1^2+p2^2+p3^2+1),-p1,-p2,-p3];
Type: Matrix(Expression(Integer))
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dot(P,P)
Type: Expression(Integer)
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Q:=vect [sqrt(q1^2+q2^2+q3^2+1),-q1,-q2,-q3];
Type: Matrix(Expression(Integer))
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R:=vect [sqrt(r1^2+r2^2+r3^2+1),-r1,-r2,-r3];
Type: Matrix(Expression(Integer))
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S:=1/sqrt(1-s1^2-s2^2-s3^2)*vect [1,-s1,-s2,-s3]
Type: Matrix(Expression(Integer))
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dot(S,S)
Type: Expression(Integer)
Associated with each such vector is the orthogonal 3-d Euclidean subspace
Relative Velocity
An object P has a unique relative velocity w(P,Q) with respect
to object Q given by
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v(P,Q)==-P/dot(P,Q)-Q
Type: Void
Observer P measures velocity v(Q,P). v(Q,P) is space-like and in .
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dot(P,v(Q,P))
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Compiling function v with type (Matrix(Expression(Integer)),Matrix(
Expression(Integer))) -> Matrix(Expression(Integer))
Type: Expression(Integer)
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possible dot(v(Q,P),v(Q,P))::EXPR Float
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Compiling function possible with type Expression(Integer) ->
Expression(Integer)
Type: Expression(Float)
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dot(Q,v(P,Q))
Type: Expression(Integer)
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possible dot(v(P,Q),v(P,Q))::EXPR Float
Type: Expression(Float)
Lorentz Boost
is a linear bijection that preserves
and maps orthogonal compliments into each other.
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L(P,Q) == ID + tensor(P+Q,P+Q)/(1-dot(P,Q)) - 2*tensor(P,Q)
Type: Void
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Is?(L(P,P) = ID)
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Compiling function L with type (Matrix(Expression(Integer)),Matrix(
Expression(Integer))) -> Matrix(Expression(Integer))
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Compiling function Is? with type Equation(Matrix(Expression(Integer)
)) -> Boolean
Type: Boolean
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Is?(L(P,Q)*L(Q,P) = ID)
Type: Boolean
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Is?(L(P,Q)*Q=P)
Type: Boolean
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Is?(L(P,Q)*v(P,Q) = -v(Q,P))
Type: Boolean
Composition of two Lorentz boosts is not a Lorentz boost
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Is?(L(R,P)*L(P,Q) = L(R,Q))
Type: Boolean
Velocity with respect to observer "at rest"
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v(vect [u0,u1,u2,u3],vect [1,0,0,0])
Type: Matrix(Expression(Integer))
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v(S,vect [1,0,0,0])
Type: Matrix(Expression(Integer))
Lorentz boost with respect to observer "at rest"
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LT:=L(vect [1,0,0,0],vect [u0,-u1,-u2,-u3])
Type: Matrix(Expression(Integer))
Two dimensional Lorentz Transformation
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matrix [[1/sqrt(1-v'^2),v'/sqrt(1-v'^2),0,0],[v'/sqrt(1-v'^2),1/sqrt(1-v'^2),0,0],[0,0,1,0],[0,0,0,1]]
Type: Matrix(Expression(Integer))
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Is?(%=map(x+->eval(x,[u0=1/sqrt(1-v'^2),u1=v'/sqrt(1-v'^2),u2=0,u3=0]),LT))
Type: Boolean