310 DOC.
31
ON
THE RELATIVITY PROBLEM
[10]
masses
from each other of the order of
magnitude
10-8.1
Radioactive
processes
are
accompanied
by
the release of
enormous
quantities
of
energy
in
the form of
heat,
which then flow into the
surroundings.
In
accordance
with
the results
presented
above
concerning
the inertia of
energy,
the
decay products
created in the reaction
must,
when taken
together,
have
a
smaller inertial
mass
than
that of the substance
that
was
present
before the
radioactive
decay.
That
change
in
the
inertial
mass
for such reactions where the heat evolved
is
of the relative order of
magnitude
10-4.
If the
gravitational
mass
did
not
change simultaneously
with the
inertial
mass
of the
system,
then the inertial
mass
of various elements would have
to
differ from the
gravitational
mass
far
more
than would be
permitted by
Eötvös's
[11]
experiments. Langevin
was
the first
to
draw attention
to
this
important point.
From the
foregoing
it
follows with
great probability
that the inertial and the
gravitational mass
of closed
systems (at rest)
are
identical; I
think
that, given
the
present
state
of
our
experience,
we
must
stick with the
assumption
of this
identity
unconditionally.
We have
thereby procured
one
of
the
most
important physical
requirements
that
must
be
imposed,
in
my opinion, on a
theory
of
gravitation.
This
requirement
involves
a
far-reaching
restriction
on
theories of
gravitation,
as
one
especially recognizes
if
one
combines
it
with the
principle
of the inertia of
energy.
To
all
energy
there
corresponds
inertial
mass,
and
to
all inertial
mass
there
corresponds gravitational mass;
the
gravitational
mass
of
a
closed
system
must
therefore be determined
by
its
energy.
The
energy
of
a
closed
system
includes
also
the
energy
of its
gravitational
field; thus,
the latter
energy
must
itself contribute
not
only
to
the inertial but also
to
the
gravitational
mass
of the
system.
Theories
of
gravitation
have been
put
forward
by
Abraham
and
Mie.
Abraham's
[12] theory
contradicts the
relativity
principle,
and that of Mie contradicts the
requirement
of the
equality
of
gravitational
and inertial
mass
of closed
systems.
According
to
the
[13]
latter
theory,
the
heating
of
a
body
would increase
its
inertial
mass
in
proportion
to
the
energy
increase,
but
not its
gravitational mass;
in
the
case
of
a
gas,
the latter
[14]
would
even
decrease with
increasing temperature.2
1Eötvös's
experimental
method
is
based
on
the
following.
A
body on
the surface of
the Earth
is
acted
upon by
terrestrial
gravitation
and the
centrifugal
force. The
gravitational
mass
is the
determining
factor for the first
force,
and the inertial
mass
for the second
one.
If
the two did
not
coincide,
then the direction
of
the resultant
of
the two
(apparent
gravitation)
would
depend on
the material of which this
body
consists.
By means
of
his
experiments
with the torsion
balance,
Eötvös
proved
with
great precision
the nonexistence
of
such
a
dependence.
2Owing
to
their
smallness,
these effects
would,
in
fact, not
be accessible
to
experiment.
But it
seems
to
me
that there
is
every reason
to believe that the connection between the
inertial and
gravitational mass
is
maintained
in principle,
regardless
of
what forms of
energy