DOC.
42 SPECIAL AND GENERAL RELATIVITY
283
38
Relativity
This
system
of
equations
is
often termed the “Galilei
trans-
formation.”
The
Galilei transformation
can
be obtained
from
the Lorentz transformation
by substituting
an
infinitely
large
value
for
the
velocity
of
light
c
in the latter transformation.
Aided
by
the
following illustration,
we
can
readily
see
that,
in
accordance with the Lorentz
transformation,
the
law
of the
transmission
of
light
in
vacuo
is satisfied both
for
the reference-
body
K and
for
the
reference-body
K'. A
light-signal
is
sent
[16]
along
the
positive x-axis,
and this
light-stimulus
advances
in
accordance with the
equation.
x
=
ct,
i.e.
with the
velocity
c.
According to
the
equations
of the
Lorentz
transformation,
this
simple
relation between
x
and
t
involves
a
relation between x' and
t'.
In
point
of
fact,
if
we
substitute
for
x
the
value
ct
in
the
first
and fourth
equations
of
the Lorentz
transformation,
we
obtain:
X
L.
(c
-
v)t
N~c2
(1 nt
J4~
C)
41
V2