Note: this is Euclidean relativity, not Minkowski.
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Writing the Minkowski 4-vector for energy-momentum
 |
(12) |
or alternatively
 |
(13) |
in Euclidean form yields:
 |
(14) |
The Euclidean form becomes transparent if the identity
is used:
 |
(15) |
saying that the 4D momentum is the vector sum of spatial and proper time momentum.
Equation (14) does however not yield an invariant. The factor
, resulting from the Minkowski 4-velocity prohibits this.
The Euclidean relativistic Lagrangian for a freely moving particle in 4D,
 |
(16) |
is a constant of motion as a result of the universal velocity magnitude
for the free particle in 4D space-time (see also the derivation of Montanus in [2]). This shows that, just as in the Euclidean 4-velocity,
must be left out in the Euclidean form, which again yields
as an invariant:
 |
(17) |
Note that the invariance of the 4D momentum is also consistent with the invariance of the acceleration
that was discussed in the previous Section. Since the acceleration is always orthogonal to the velocity, the magnitude of the momentum vector will not change.
Figure 5:
Minkowski and Euclidean components for energy-momentum.
![\begin{figure}\centerline{\includegraphics[width=0.5\textwidth]{4vecfig5.eps}}\end{figure}](img56.gif) |
Figure 5 again visualizes the geometries.
Note: this is Euclidean relativity, not Minkowski.
Next: 5 Current density
Up: Minkowski versus Euclidean 4-vectors
Previous: 3 Acceleration
© Copyright 2005-2006 R.F.J. van Linden