Single-Particle Electrodynamics - Assassination Science

For an elementary particle, the mass m is a constant.
We do not employ the terms “rest mass”, “moving mass”, “longitudinal
mass”, etc., in this thesis.
2.6.2 Four-position
The four-position of a classical point particle is denoted
z ≡ (t, z).
The four-position is a Lorentz-covariant quantity, or simply a covariant quantity,
in the nomenclature of Section A.8.
2.6.3 Three-velocity
The three-velocity v of a classical particle is defined as
v(t) ≡ d t z(t).
The three-velocity is a non-covariant quantity, in the nomenclature of Section
A.8.
2.6.4 Proper time
A most important concept in relativistic mechanics is that of the proper
time, τ. It is the time cumulated in the co-accelerated coördinate system (or
CACS) of the particle.
At any particular instant in time, one may set up a momentarily comoving
Lorentz frame (or MCLF ) for the particle, which is, as its name suggests, a
global Lorentz frame in which the particle is momentarily at rest.
Although the CACS and MCLF have subtle differences in their behaviour,
the differential of the proper-time may in fact be computed around the
rest-instant in the MCLF:
dτ = dt| MCLF
.
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