|
|
|
last edited 10 years ago by Bill Page |
Edit detail for SandBoxLorentzTransformation revision 23 of 30
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | ||
|
Editor: page
Time: 2013/10/05 09:34:56 GMT+0 |
||
| Note: relative velocities | ||
added: sinhcosh := rule ?c*exp(a)+?c*exp(-a) == 2*c*cosh(a) ?c*exp(a)-?c*exp(-a) == 2*c*sinh(a) added: map(x+->sinhcosh(x),U) changed: -map(simplify,v(U,V)) map(x+->htrigs sinhcosh simplify x,v(U,V)) changed: -map(simplify, v(U,vect [1,0,0,0])) map(x+->htrigs sinhcosh simplify x, v(U,vect [1,0,0,0]))
Lorentz transformations.
Book by T. Matolcsi
Mathematical Preliminaries
A vector is represented as a 
matrix (column vector)
fricas
Scalar := Expression Integer
 | (1) |
Type: Type
fricas
vect(x:List Scalar):Matrix Scalar == matrix map(y+->[y],x)
Function declaration vect : List(Expression(Integer)) -> Matrix( Expression(Integer)) has been added to workspace.
Type: Void
fricas
vect [a0,a1, a2, a3]
fricas
Compiling function vect with type List(Expression(Integer)) ->
Matrix(Expression(Integer))![\label{eq2}\left[
\begin{array}{c}
a 0
\
a 1
\
a 2
\
a 3](images/1362409580171013215-16.0px.png "\label{eq2}\left[
\begin{array}{c}
a 0
\
a 1
\
a 2
\
a 3") | (2) |
Type: Matrix(Expression(Integer))
Identity
fricas
ID:=diagonalMatrix([1,1, 1, 1])
![\label{eq3}\left[
\begin{array}{cccc}
1 & 0 & 0 & 0
\
0 & 1 & 0 & 0
\
0 & 0 & 1 & 0
\
0 & 0 & 0 & 1](images/8334690762880839438-16.0px.png "\label{eq3}\left[
\begin{array}{cccc}
1 & 0 & 0 & 0
\
0 & 1 & 0 & 0
\
0 & 0 & 1 & 0
\
0 & 0 & 0 & 1") | (3) |
Type: Matrix(Integer)
Verification
fricas
possible(x)==subst(x,map(y+->(y=(random(100) - random(100))), variables x) )
Type: Void
fricas
is?(eq:Equation Scalar):Boolean == (lhs(eq)-rhs(eq)=0)::Boolean
Function declaration is? : Equation(Expression(Integer)) -> Boolean has been added to workspace.
Type: Void
fricas
Is?(eq:Equation(Matrix(Scalar))):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
fricas
sinhcosh := rule ?c*exp(a)+?c*exp(-a) == 2*c*cosh(a) ?c*exp(a)-?c*exp(-a) == 2*c*sinh(a)
![\label{eq4}\begin{array}{@{}l}
\displaystyle
\left\{{{{c \ {{e}^{a}}}+{c \ {{e}^{- a}}}+ \%B}\mbox{\rm = =}{{2 \ c \ {\cosh \left({a}\right)}}+ \%B}}, \: \right.
\
\
\displaystyle
\left.{{{c \ {{e}^{a}}}-{c \ {{e}^{- a}}}+ \%C}\mbox{\rm = =}{{2 \ c \ {\sinh \left({a}\right)}}+ \%C}}\right\}](images/5441485291728437091-16.0px.png "\label{eq4}\begin{array}{@{}l}
\displaystyle
\left\{{{{c \ {{e}^{a}}}+{c \ {{e}^{- a}}}+ \%B}\mbox{\rm = =}{{2 \ c \ {\cosh \left({a}\right)}}+ \%B}}, \: \right.
\
\
\displaystyle
\left.{{{c \ {{e}^{a}}}-{c \ {{e}^{- a}}}+ \%C}\mbox{\rm = =}{{2 \ c \ {\sinh \left({a}\right)}}+ \%C}}\right\}") | (4) |
Type: Ruleset(Integer,
Lorentz Form (metric)
fricas
G:=diagonalMatrix [-1,1, 1, 1]
![\label{eq5}\left[
\begin{array}{cccc}
- 1 & 0 & 0 & 0
\
0 & 1 & 0 & 0
\
0 & 0 & 1 & 0
\
0 & 0 & 0 & 1](images/1775388585705312935-16.0px.png "\label{eq5}\left[
\begin{array}{cccc}
- 1 & 0 & 0 & 0
\
0 & 1 & 0 & 0
\
0 & 0 & 1 & 0
\
0 & 0 & 0 & 1") | (5) |
Type: Matrix(Integer)
applied to a vector produces a co-vector (represent as a 
matrix or row vector)
fricas
g(x) == transpose(x)*G
Type: Void
fricas
g(vect [a0,a1, a2, a3])
fricas
Compiling function g with type Matrix(Expression(Integer)) -> Matrix
(Expression(Integer)) | (6) |
Type: Matrix(Expression(Integer))
Scalar product
fricas
dot(x,y) == (g(x)*y)::Scalar
Type: Void
fricas
dot(vect [a0,a1, a2, a3], vect [b0, b1, b2, b3])
fricas
Compiling function dot with type (Matrix(Expression(Integer)),Matrix (Expression(Integer))) -> Expression(Integer)
 | (7) |
Type: Expression(Integer)
Tensor product
fricas
tensor(x,y) == x*g(y)
Type: Void
fricas
tensor(vect [a0,a1, a2, a3], vect [b0, b1, b2, b3])
fricas
Compiling function tensor with type (Matrix(Expression(Integer)),Matrix(Expression(Integer))) -> Matrix(Expression(Integer))
![\label{eq8}\left[
\begin{array}{cccc}
-{a 0 \ b 0}&{a 0 \ b 1}&{a 0 \ b 2}&{a 0 \ b 3}
\
-{a 1 \ b 0}&{a 1 \ b 1}&{a 1 \ b 2}&{a 1 \ b 3}
\
-{a 2 \ b 0}&{a 2 \ b 1}&{a 2 \ b 2}&{a 2 \ b 3}
\
-{a 3 \ b 0}&{a 3 \ b 1}&{a 3 \ b 2}&{a 3 \ b 3}](images/3812898827285370281-16.0px.png "\label{eq8}\left[
\begin{array}{cccc}
-{a 0 \ b 0}&{a 0 \ b 1}&{a 0 \ b 2}&{a 0 \ b 3}
\
-{a 1 \ b 0}&{a 1 \ b 1}&{a 1 \ b 2}&{a 1 \ b 3}
\
-{a 2 \ b 0}&{a 2 \ b 1}&{a 2 \ b 2}&{a 2 \ b 3}
\
-{a 3 \ b 0}&{a 3 \ b 1}&{a 3 \ b 2}&{a 3 \ b 3}") | (8) |
Type: Matrix(Expression(Integer))
Massive Objects
A material object (also referred to as an observer) is represented by a time-like 4-vector
fricas
P:=vect [sqrt(p1^2+p2^2+p3^2+1),-p1, -p2, -p3];
Type: Matrix(Expression(Integer))
fricas
dot(P,P)
 | (9) |
Type: Expression(Integer)
fricas
Q:=vect [sqrt(q1^2+q2^2+q3^2+1),-q1, -q2, -q3];
Type: Matrix(Expression(Integer))
fricas
R:=vect [sqrt(r1^2+r2^2+r3^2+1),-r1, -r2, -r3];
Type: Matrix(Expression(Integer))
fricas
S:=1/sqrt(1-s1^2-s2^2-s3^2)*vect [1,-s1, -s2, -s3]
![\label{eq10}\left[
\begin{array}{c}
{1 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}
\
-{s 1 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}
\
-{s 2 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}
\
-{s 3 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}](images/4004990098889856667-16.0px.png "\label{eq10}\left[
\begin{array}{c}
{1 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}
\
-{s 1 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}
\
-{s 2 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}
\
-{s 3 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}") | (10) |
Type: Matrix(Expression(Integer))
fricas
dot(S,S)
 | (11) |
Type: Expression(Integer)
fricas
T:=1/sqrt(1-t1^2-t2^2-t3^2)*vect [1,-t1, -t2, -t3]
![\label{eq12}\left[
\begin{array}{c}
{1 \over{\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}
\
-{t 1 \over{\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}
\
-{t 2 \over{\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}
\
-{t 3 \over{\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}](images/1327830887957006770-16.0px.png "\label{eq12}\left[
\begin{array}{c}
{1 \over{\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}
\
-{t 1 \over{\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}
\
-{t 2 \over{\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}
\
-{t 3 \over{\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}") | (12) |
Type: Matrix(Expression(Integer))
fricas
U:=vect [(exp(a)+exp(-a))/2,(exp(a)-exp(-a))/2, 0, 0]
![\label{eq13}\left[
\begin{array}{c}
{{{{e}^{a}}+{{e}^{- a}}}\over 2}
\
{{{{e}^{a}}-{{e}^{- a}}}\over 2}
\
0
\
0](images/8890225341644312964-16.0px.png "\label{eq13}\left[
\begin{array}{c}
{{{{e}^{a}}+{{e}^{- a}}}\over 2}
\
{{{{e}^{a}}-{{e}^{- a}}}\over 2}
\
0
\
0") | (13) |
Type: Matrix(Expression(Integer))
fricas
V:=vect [(exp(b)+exp(-b))/2,(exp(b)-exp(-b))/2, 0, 0]
![\label{eq14}\left[
\begin{array}{c}
{{{{e}^{b}}+{{e}^{- b}}}\over 2}
\
{{{{e}^{b}}-{{e}^{- b}}}\over 2}
\
0
\
0](images/9107244589333885837-16.0px.png "\label{eq14}\left[
\begin{array}{c}
{{{{e}^{b}}+{{e}^{- b}}}\over 2}
\
{{{{e}^{b}}-{{e}^{- b}}}\over 2}
\
0
\
0") | (14) |
Type: Matrix(Expression(Integer))
fricas
map(x+->sinhcosh(x),U)
![\label{eq15}\left[
\begin{array}{c}
{\cosh \left({a}\right)}
\
{\sinh \left({a}\right)}
\
0
\
0](images/8894902454489381359-16.0px.png "\label{eq15}\left[
\begin{array}{c}
{\cosh \left({a}\right)}
\
{\sinh \left({a}\right)}
\
0
\
0") | (15) |
Type: Matrix(Expression(Integer))
fricas
simplify dot(U,U)
 | (16) |
Type: Expression(Integer)
Observer "at rest"
fricas
vect [1,0, 0, 0]
![\label{eq17}\left[
\begin{array}{c}
1
\
0
\
0
\
0](images/1415495408323897621-16.0px.png "\label{eq17}\left[
\begin{array}{c}
1
\
0
\
0
\
0") | (17) |
Type: Matrix(Expression(Integer))
fricas
dot(%,%)
 | (18) |
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
fricas
v(P,Q)==-P/dot(P, Q)-Q
Type: Void
fricas
v(P,Q)
fricas
Compiling function v with type (Matrix(Expression(Integer)),Matrix( Expression(Integer))) -> Matrix(Expression(Integer))
![\label{eq19}\left[
\begin{array}{c}
{{{{\left({p 3 \ q 3}+{p 2 \ q 2}+{p 1 \ q 1}\right)}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}+{{\left(-{{q 3}^{2}}-{{q 2}^{2}}-{{q 1}^{2}}\right)}\ {\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}}}\over{{{\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ q 3}-{p 2 \ q 2}-{p 1 \ q 1}}}
\
{{{q 1 \ {\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ q 1 \ q 3}-{p 2 \ q 1 \ q 2}-{p 1 \ {{q 1}^{2}}}- p 1}\over{{{\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ q 3}-{p 2 \ q 2}-{p 1 \ q 1}}}
\
{{{q 2 \ {\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ q 2 \ q 3}-{p 2 \ {{q 2}^{2}}}-{p 1 \ q 1 \ q 2}- p 2}\over{{{\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ q 3}-{p 2 \ q 2}-{p 1 \ q 1}}}
\
{{{q 3 \ {\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ {{q 3}^{2}}}+{{\left(-{p 2 \ q 2}-{p 1 \ q 1}\right)}\ q 3}- p 3}\over{{{\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ q 3}-{p 2 \ q 2}-{p 1 \ q 1}}}](images/3851011753316030127-16.0px.png "\label{eq19}\left[
\begin{array}{c}
{{{{\left({p 3 \ q 3}+{p 2 \ q 2}+{p 1 \ q 1}\right)}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}+{{\left(-{{q 3}^{2}}-{{q 2}^{2}}-{{q 1}^{2}}\right)}\ {\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}}}\over{{{\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ q 3}-{p 2 \ q 2}-{p 1 \ q 1}}}
\
{{{q 1 \ {\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ q 1 \ q 3}-{p 2 \ q 1 \ q 2}-{p 1 \ {{q 1}^{2}}}- p 1}\over{{{\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ q 3}-{p 2 \ q 2}-{p 1 \ q 1}}}
\
{{{q 2 \ {\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ q 2 \ q 3}-{p 2 \ {{q 2}^{2}}}-{p 1 \ q 1 \ q 2}- p 2}\over{{{\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ q 3}-{p 2 \ q 2}-{p 1 \ q 1}}}
\
{{{q 3 \ {\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ {{q 3}^{2}}}+{{\left(-{p 2 \ q 2}-{p 1 \ q 1}\right)}\ q 3}- p 3}\over{{{\sqrt{{{p 3}^{2}}+{{p 2}^{2}}+{{p 1}^{2}}+ 1}}\ {\sqrt{{{q 3}^{2}}+{{q 2}^{2}}+{{q 1}^{2}}+ 1}}}-{p 3 \ q 3}-{p 2 \ q 2}-{p 1 \ q 1}}}") | (19) |
Type: Matrix(Expression(Integer))
fricas
v(S,T)
![\label{eq20}\left[
\begin{array}{c}
{{{{t 3}^{2}}-{s 3 \ t 3}+{{t 2}^{2}}-{s 2 \ t 2}+{{t 1}^{2}}-{s 1 \ t 1}}\over{{\left({s 3 \ t 3}+{s 2 \ t 2}+{s 1 \ t 1}- 1 \right)}\ {\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}}
\
{{-{s 1 \ {{t 3}^{2}}}+{s 3 \ t 1 \ t 3}-{s 1 \ {{t 2}^{2}}}+{s 2 \ t 1 \ t 2}- t 1 + s 1}\over{{\left({s 3 \ t 3}+{s 2 \ t 2}+{s 1 \ t 1}- 1 \right)}\ {\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}}
\
{{-{s 2 \ {{t 3}^{2}}}+{s 3 \ t 2 \ t 3}+{{\left({s 1 \ t 1}- 1 \right)}\ t 2}-{s 2 \ {{t 1}^{2}}}+ s 2}\over{{\left({s 3 \ t 3}+{s 2 \ t 2}+{s 1 \ t 1}- 1 \right)}\ {\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}}
\
{{{{\left({s 2 \ t 2}+{s 1 \ t 1}- 1 \right)}\ t 3}-{s 3 \ {{t 2}^{2}}}-{s 3 \ {{t 1}^{2}}}+ s 3}\over{{\left({s 3 \ t 3}+{s 2 \ t 2}+{s 1 \ t 1}- 1 \right)}\ {\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}}](images/8331760300205224683-16.0px.png "\label{eq20}\left[
\begin{array}{c}
{{{{t 3}^{2}}-{s 3 \ t 3}+{{t 2}^{2}}-{s 2 \ t 2}+{{t 1}^{2}}-{s 1 \ t 1}}\over{{\left({s 3 \ t 3}+{s 2 \ t 2}+{s 1 \ t 1}- 1 \right)}\ {\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}}
\
{{-{s 1 \ {{t 3}^{2}}}+{s 3 \ t 1 \ t 3}-{s 1 \ {{t 2}^{2}}}+{s 2 \ t 1 \ t 2}- t 1 + s 1}\over{{\left({s 3 \ t 3}+{s 2 \ t 2}+{s 1 \ t 1}- 1 \right)}\ {\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}}
\
{{-{s 2 \ {{t 3}^{2}}}+{s 3 \ t 2 \ t 3}+{{\left({s 1 \ t 1}- 1 \right)}\ t 2}-{s 2 \ {{t 1}^{2}}}+ s 2}\over{{\left({s 3 \ t 3}+{s 2 \ t 2}+{s 1 \ t 1}- 1 \right)}\ {\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}}
\
{{{{\left({s 2 \ t 2}+{s 1 \ t 1}- 1 \right)}\ t 3}-{s 3 \ {{t 2}^{2}}}-{s 3 \ {{t 1}^{2}}}+ s 3}\over{{\left({s 3 \ t 3}+{s 2 \ t 2}+{s 1 \ t 1}- 1 \right)}\ {\sqrt{-{{t 3}^{2}}-{{t 2}^{2}}-{{t 1}^{2}}+ 1}}}}") | (20) |
Type: Matrix(Expression(Integer))
fricas
map(x+->htrigs sinhcosh simplify x,v(U, V))
![\label{eq21}\left[
\begin{array}{c}
{{-{\cosh \left({{2 \ b}- a}\right)}+{\cosh \left({a}\right)}}\over{2 \ {\cosh \left({b - a}\right)}}}
\
{{-{\sinh \left({{2 \ b}- a}\right)}+{\sinh \left({a}\right)}}\over{2 \ {\cosh \left({b - a}\right)}}}
\
0
\
0](images/8980483919812364021-16.0px.png "\label{eq21}\left[
\begin{array}{c}
{{-{\cosh \left({{2 \ b}- a}\right)}+{\cosh \left({a}\right)}}\over{2 \ {\cosh \left({b - a}\right)}}}
\
{{-{\sinh \left({{2 \ b}- a}\right)}+{\sinh \left({a}\right)}}\over{2 \ {\cosh \left({b - a}\right)}}}
\
0
\
0") | (21) |
Type: Matrix(Expression(Integer))
Observer P measures velocity v(Q,P). v(Q,P) is space-like
fricas
dot(v(P,vect [1, 0, 0, 0]), v(P, vect [1, 0, 0, 0]))
 | (22) |
Type: Expression(Integer)
and in 
fricas
dot(P,v(Q, P))
 | (23) |
Type: Expression(Integer)
fricas
possible dot(v(Q,P), v(Q, P))::EXPR Float
fricas
Compiling function possible with type Expression(Integer) ->
Expression(Integer) | (24) |
Type: Expression(Float)
fricas
dot(Q,v(P, Q))
 | (25) |
Type: Expression(Integer)
fricas
possible dot(v(P,Q), v(P, Q))::EXPR Float
 | (26) |
Type: Expression(Float)
Velocity with respect to observer "at rest"
fricas
v(vect [u0,u1, u2, u3], vect [1, 0, 0, 0])
![\label{eq27}\left[
\begin{array}{c}
0
\
{u 1 \over u 0}
\
{u 2 \over u 0}
\
{u 3 \over u 0}](images/5220628976960289948-16.0px.png "\label{eq27}\left[
\begin{array}{c}
0
\
{u 1 \over u 0}
\
{u 2 \over u 0}
\
{u 3 \over u 0}") | (27) |
Type: Matrix(Expression(Integer))
fricas
v(R,vect [1, 0, 0, 0])
![\label{eq28}\left[
\begin{array}{c}
0
\
-{r 1 \over{\sqrt{{{r 3}^{2}}+{{r 2}^{2}}+{{r 1}^{2}}+ 1}}}
\
-{r 2 \over{\sqrt{{{r 3}^{2}}+{{r 2}^{2}}+{{r 1}^{2}}+ 1}}}
\
-{r 3 \over{\sqrt{{{r 3}^{2}}+{{r 2}^{2}}+{{r 1}^{2}}+ 1}}}](images/302633975438516848-16.0px.png "\label{eq28}\left[
\begin{array}{c}
0
\
-{r 1 \over{\sqrt{{{r 3}^{2}}+{{r 2}^{2}}+{{r 1}^{2}}+ 1}}}
\
-{r 2 \over{\sqrt{{{r 3}^{2}}+{{r 2}^{2}}+{{r 1}^{2}}+ 1}}}
\
-{r 3 \over{\sqrt{{{r 3}^{2}}+{{r 2}^{2}}+{{r 1}^{2}}+ 1}}}") | (28) |
Type: Matrix(Expression(Integer))
fricas
v(S,vect [1, 0, 0, 0])
![\label{eq29}\left[
\begin{array}{c}
0
\
- s 1
\
- s 2
\
- s 3](images/4741283703918282737-16.0px.png "\label{eq29}\left[
\begin{array}{c}
0
\
- s 1
\
- s 2
\
- s 3") | (29) |
Type: Matrix(Expression(Integer))
fricas
map(x+->htrigs sinhcosh simplify x,v(U, vect [1, 0, 0, 0]))
![\label{eq30}\left[
\begin{array}{c}
0
\
{{\sinh \left({a}\right)}\over{\cosh \left({a}\right)}}
\
0
\
0](images/885959658725494425-16.0px.png "\label{eq30}\left[
\begin{array}{c}
0
\
{{\sinh \left({a}\right)}\over{\cosh \left({a}\right)}}
\
0
\
0") | (30) |
Type: Matrix(Expression(Integer))
Non-reciprocal velocities
fricas
v(vect [1,0, 0, 0], S)
![\label{eq31}\left[
\begin{array}{c}
{{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}}\over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}
\
{s 1 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}
\
{s 2 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}
\
{s 3 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}](images/7917952599014407387-16.0px.png "\label{eq31}\left[
\begin{array}{c}
{{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}}\over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}
\
{s 1 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}
\
{s 2 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}
\
{s 3 \over{\sqrt{-{{s 3}^{2}}-{{s 2}^{2}}-{{s 1}^{2}}+ 1}}}") | (31) |
Type: Matrix(Expression(Integer))
fricas
v(vect [1,0, 0, 0], R)
![\label{eq32}\left[
\begin{array}{c}
{{-{{r 3}^{2}}-{{r 2}^{2}}-{{r 1}^{2}}}\over{\sqrt{{{r 3}^{2}}+{{r 2}^{2}}+{{r 1}^{2}}+ 1}}}
\
r 1
\
r 2
\
r 3](images/4343337828186764728-16.0px.png "\label{eq32}\left[
\begin{array}{c}
{{-{{r 3}^{2}}-{{r 2}^{2}}-{{r 1}^{2}}}\over{\sqrt{{{r 3}^{2}}+{{r 2}^{2}}+{{r 1}^{2}}+ 1}}}
\
r 1
\
r 2
\
r 3") | (32) |
Type: Matrix(Expression(Integer))
fricas
is?(dot(v(P,Q), v(P, Q))=dot(v(Q, P), v(Q, P)))
fricas
Compiling function is? with type Equation(Expression(Integer)) ->
Boolean | (33) |
Type: Boolean
Lorentz Boost
is a linear bijection 
that preserves
and maps orthogonal compliments into each other.
fricas
L(P,Q) == ID + tensor(P+Q, P+Q)/(1-dot(P, Q)) - 2*tensor(P, Q)
Type: Void
fricas
Is?(L(P,P) = ID)
fricas
Compiling function L with type (Matrix(Expression(Integer)),Matrix( Expression(Integer))) -> Matrix(Expression(Integer))
fricas
Compiling function Is? with type Equation(Matrix(Expression(Integer)
)) -> Boolean | (34) |
Type: Boolean
fricas
Is?(L(P,Q)*L(Q, P) = ID)
 | (35) |
Type: Boolean
fricas
Is?(L(P,Q)*Q=P)
 | (36) |
Type: Boolean
fricas
Is?(L(P,Q)*v(P, Q) = -v(Q, P))
 | (37) |
Type: Boolean
Composition of two Lorentz boosts is not a Lorentz boost unless all three observers are in the same plane.
fricas
Is?(L(R,P)*L(P, Q) = L(R, Q))
 | (38) |
Type: Boolean
fricas
RQ:=a*R+b*Q;
Type: Matrix(Expression(Integer))
fricas
rq:=solve(dot(RQ,RQ)=-1, b); #rq
 | (39) |
Type: PositiveInteger?
fricas
RQ1:=eval(RQ,rq.1);
Type: Matrix(Expression(Integer))
fricas
dot(RQ1,RQ1)
 | (40) |
Type: Expression(Integer)
fricas
Is?(L(R,RQ1)*L(RQ1, Q) = L(R, Q))
 | (41) |
Type: Boolean
fricas
RQ2:=eval(RQ,rq.2);
Type: Matrix(Expression(Integer))
fricas
Is?(RQ1=RQ2)
 | (42) |
Type: Boolean
fricas
dot(RQ2,RQ2)
 | (43) |
Type: Expression(Integer)
fricas
Is?(L(R,RQ2)*L(RQ2, Q) = L(R, Q))
 | (44) |
Type: Boolean
but the composition does preserve observers and magnitudes
fricas
LRPQ := L(R,P)*L(P, Q);
Type: Matrix(Expression(Integer))
fricas
Is?(LRPQ*Q = L(R,Q)*Q)
 | (45) |
Type: Boolean
fricas
is?(dot(LRPQ*v(S,Q), LRPQ*v(S, Q))=dot(L(R, Q)*v(S, Q), L(R, Q)*v(S, Q)))
 | (46) |
Type: Boolean
Lorentz boost with respect to observer "at rest"
fricas
map(simplify,L(vect [1, 0, 0, 0], U))
![\label{eq47}\left[
\begin{array}{cccc}
{{{{e}^{a}}+{{e}^{- a}}}\over 2}&{{-{{e}^{a}}+{{e}^{- a}}}\over 2}& 0 & 0
\
{{-{{e}^{a}}+{{e}^{- a}}}\over 2}&{{{{e}^{2 \ a}}+{2 \ {{e}^{a}}}+{2 \ {{e}^{- a}}}+{{e}^{-{2 \ a}}}+ 2}\over{{2 \ {{e}^{a}}}+{2 \ {{e}^{- a}}}+ 4}}& 0 & 0
\
0 & 0 & 1 & 0
\
0 & 0 & 0 & 1](images/5478502696124231556-16.0px.png "\label{eq47}\left[
\begin{array}{cccc}
{{{{e}^{a}}+{{e}^{- a}}}\over 2}&{{-{{e}^{a}}+{{e}^{- a}}}\over 2}& 0 & 0
\
{{-{{e}^{a}}+{{e}^{- a}}}\over 2}&{{{{e}^{2 \ a}}+{2 \ {{e}^{a}}}+{2 \ {{e}^{- a}}}+{{e}^{-{2 \ a}}}+ 2}\over{{2 \ {{e}^{a}}}+{2 \ {{e}^{- a}}}+ 4}}& 0 & 0
\
0 & 0 & 1 & 0
\
0 & 0 & 0 & 1") | (47) |
Type: Matrix(Expression(Integer))
fricas
LT:=L(vect [1,0, 0, 0], vect [u0, -u1, -u2, -u3])
![\label{eq48}\left[
\begin{array}{cccc}
u 0 & u 1 & u 2 & u 3
\
u 1 &{{{{u 1}^{2}}+ u 0 + 1}\over{u 0 + 1}}&{{u 1 \ u 2}\over{u 0 + 1}}&{{u 1 \ u 3}\over{u 0 + 1}}
\
u 2 &{{u 1 \ u 2}\over{u 0 + 1}}&{{{{u 2}^{2}}+ u 0 + 1}\over{u 0 + 1}}&{{u 2 \ u 3}\over{u 0 + 1}}
\
u 3 &{{u 1 \ u 3}\over{u 0 + 1}}&{{u 2 \ u 3}\over{u 0 + 1}}&{{{{u 3}^{2}}+ u 0 + 1}\over{u 0 + 1}}](images/1248682259228083354-16.0px.png "\label{eq48}\left[
\begin{array}{cccc}
u 0 & u 1 & u 2 & u 3
\
u 1 &{{{{u 1}^{2}}+ u 0 + 1}\over{u 0 + 1}}&{{u 1 \ u 2}\over{u 0 + 1}}&{{u 1 \ u 3}\over{u 0 + 1}}
\
u 2 &{{u 1 \ u 2}\over{u 0 + 1}}&{{{{u 2}^{2}}+ u 0 + 1}\over{u 0 + 1}}&{{u 2 \ u 3}\over{u 0 + 1}}
\
u 3 &{{u 1 \ u 3}\over{u 0 + 1}}&{{u 2 \ u 3}\over{u 0 + 1}}&{{{{u 3}^{2}}+ u 0 + 1}\over{u 0 + 1}}") | (48) |
Type: Matrix(Expression(Integer))
Two dimensional Lorentz Transformation
fricas
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]]
![\label{eq49}\left[
\begin{array}{cccc}
{1 \over{\sqrt{-{{v'}^{2}}+ 1}}}&{v' \over{\sqrt{-{{v'}^{2}}+ 1}}}& 0 & 0
\
{v' \over{\sqrt{-{{v'}^{2}}+ 1}}}&{1 \over{\sqrt{-{{v'}^{2}}+ 1}}}& 0 & 0
\
0 & 0 & 1 & 0
\
0 & 0 & 0 & 1](images/3314286836853991411-16.0px.png "\label{eq49}\left[
\begin{array}{cccc}
{1 \over{\sqrt{-{{v'}^{2}}+ 1}}}&{v' \over{\sqrt{-{{v'}^{2}}+ 1}}}& 0 & 0
\
{v' \over{\sqrt{-{{v'}^{2}}+ 1}}}&{1 \over{\sqrt{-{{v'}^{2}}+ 1}}}& 0 & 0
\
0 & 0 & 1 & 0
\
0 & 0 & 0 & 1") | (49) |
Type: Matrix(Expression(Integer))
fricas
Is?(%=map(x+->eval(x,[u0=1/sqrt(1-v'^2), u1=v'/sqrt(1-v'^2), u2=0, u3=0]), LT))
 | (50) |
Type: Boolean