DOC.
47
253
v/c
of
the relative velocity
to
the
velocity of
light
in
vacuum
appears
in
the first
power.
But
the
negative
result of
Michelson and Morley's
experi-
ment1 showed
that
in
a
particular
case an
effect
of
the
second
order
(proportional to
v2/c2)
was
not present
either,
even though
it should
have
shown
up
in
the
experiment according to
the fundamentals of the Lorentz
theory.
It
is well
known
that this contradiction
between theory and experiment
was
formally
removed
by
the
postulate
of
H. A.
Lorentz
and
FitzGerald,
[4]
according
to which
moving
bodies
experience
a
certain contraction in the
direction of their
motion.
However,
this
ad
hoc
postulate
seemed to
be
only
an
artificial
means
of
saving
the
theory:
Michelson and Morley's experiment
had actually
shown
that
phenomena
agree
with the
principle of
relativity
even
where
this
was
not to
be
expected
from
the Lorentz
theory.
It
seemed
therefore
as
if Lorentz's
theory
should
be abandoned and replaced
by a
theory
whose
foundations
correspond to
the
principle of
relativity,
because
such
a
theory
would readily predict
the
negative
result
of
the
Michelson and
Morley
experiment.
[5]
Surprisingly,
however,
it
turned
out
that
a
sufficiently
sharpened
conception
of time
was
all that
was
needed to
overcome
the difficulty
discussed.
One
had
only to
realize
that
an
auxiliary quantity
introduced
by
H. A.
Lorentz
and
named
by
him
"local
time" could
be
defined
as
"time" in
[6]
general.
If
one
adheres
to
this definition
of
time, the basic
equations
of
Lorentz's
theory correspond to
the
principle of
relativity,
provided
that the
above
transformation
equations
are
replaced
by ones
that
correspond
to
the
new
conception
of time.
H.
A.
Lorentz's
and
FitzGerald's
hypothesis
appears
then
as a
compelling consequence
of
the
theory.
Only
the
conception
of
a
lumini-
ferous ether
as
the carrier of the electric
and
magnetic
forces
does not
fit
into the
theory
described here;
for
electromagnetic
forces
appear
here
not
as
states of
some
substance,
but rather
as
independently
existing things
that
are
similar
to ponderable matter and
share with it
the
feature of inertia.
[7]
The following
is
an
attempt to summarize
the studies that
have
resulted
to
date
from
the
merger
of the
H. A.
Lorentz
theory
and
the
principle of
relativity.
1A.
A.
Michelson and
E.
W.
Morley, Amer.
J.
of
Science
34,
(1887):
333.
[3]