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Galilean Transformation




, ed. 2002 ISBN 0-7624-1348-4
The topic was motivated by Galileo 's description of the motion of a Ball rolling down a Ramp , by which he measured the numerical value for the Acceleration of Gravity , at the surface of the Earth . The descriptions below are another Mathematical Notation for this concept.


TRANSLATION (ONE DIMENSION)

The Galilean transformation is nothing more than careful addition and subtraction of velocity vectors.

Unlike the Galilean transformation, the Relativistic Lorentz Transformation can be shown to apply at all velocities so far measured, and the Galilean transformation can be regarded as a low-velocity approximation to the Lorentz transformation.

The notation below describes the relationship of two coordinate systems (''x''′ and ''x'') in constant relative motion ( Velocity ''u'') in the ''x''-direction. All other parameters (''t'', ''y'', ''z'') are unchanged in the transformation from ''x''′ to ''x'' coordinates.

:\begin{align}t'&=t \
x'&=x-ut \
y'&=y \
z'&=z \end{align}

of an accelerating observer.

Vertical direction indicates time. Horizontal indicates distance, the dashed line is the Spacetime trajectory of the observer. The lower half of the diagram shows events in the past. Upper half shows future events. The small dots are arbitrary events in spacetime.

The slope of the world line (deviation from being vertical) gives the relative velocity to the observer. Note how the view of spacetime Shears when the observer accelerates.]]


GALILEAN TRANSFORMATIONS

Under the Erlangen Program , the space-time (no longer Spacetime ) of nonrelativistic physics is described by the Symmetry Group generated by Galilean transformations, spatial and time translations and rotations.

The Galilean symmetries (interpreted as Active Transformation s):

Spatial translations:
:t ightarrow t \,\!
: ec{x} ightarrow ec{x}+ ec{a} \,\!

Time translations:
:t ightarrow t+ au \,\!
: ec{x} ightarrow ec{x} \,\!

Shears :
:t ightarrow t \,\!
: ec{x} ightarrow ec{x}+ ec{v}t \,\!

Rotations:
:t ightarrow t \,\!
: ec{x} ightarrow \mathbf{R} ec{x} \,\!

where R is an Orthogonal Matrix .


CENTRAL EXTENSION OF THE GALILEAN GROUP

The . It's easy to extend the results to the Lie Group . The Lie algebra of L is Spanned by E, Pi, Ci and Lij ( Antisymmetric Tensor ) subject to Commutator s ( Operator s of the form {Link without Title} ), where
: {Link without Title} =0 \,\!
: {Link without Title} =0 \,\!
: {Link without Title} =0 \,\!
: {Link without Title} =0 \,\!
: [\delta_{ik}L_{jl}-\delta_{il}L_{jk}-\delta_{jk}L_{il}+\delta_{jl}L_{ik} \,\!
: {Link without Title} =i\hbar {Link without Title} \,\!
: {Link without Title} =i\hbar {Link without Title} \,\!
: {Link without Title} =i\hbar P_i \,\!
: {Link without Title} =0 \,\!

We can now give it a Central Extension into the Lie algebra spanned by E', P'i, C'i, L'ij (antisymmetric Tensor ), M such that M Commute s with everything (i.e. lies in the Center , that's why it's called a central extension) and
: {Link without Title} =0 \,\!
: {Link without Title} =0 \,\!
: {Link without Title} =0 \,\!
: {Link without Title} =0 \,\!
: [\delta_{ik}L'_{jl}-\delta_{il}L'_{jk}-\delta_{jk}L'_{il}+\delta_{jl}L'_{ik} \,\!
: {Link without Title} =i\hbar {Link without Title} \,\!
: {Link without Title} =i\hbar {Link without Title} \,\!
: {Link without Title} =i\hbar P'_i \,\!
: {Link without Title} =i\hbar M\delta_{ij} \,\!


NOTES



SEE ALSO