DOC.
47 THE RELATIVITY
PRINCIPLE 487
defines the
mass
M
of
a body as
the limit
of
its
momentum divided
by
its
velocity as
the veloc
ity approaches zero
(see
ibid.,
p.
564).
Applied
to
blackbody
radiation, this
gives
M
=
(E0
+
pV0)/c2,
which
is
Planck's
eq. (48).
[66]
See
Cockcroft
and
Walton 1932 for the
first
reported
verification
of
the
massenergy re
lationship
in
a
nuclear reaction.
[67]
See
Planck
1907a,
§
18,
pp.
568569, for
a
discussion
of
the
relationship
of
inertial and
gravitational mass.
[68]
See Eötvös 1890 for
a report
of
the most
accurate tests
of
this
proportionality
then avail
able.
[69]
The
"Xa" should
be
"X'a."
[70]
The
"e2"
should
be
"c2."
[71]
The
following
discussion
is based
on
Ein
stein 1907h
(Doc.
45),
§
1.
[72]
Einstein
1907h
(Doc. 45);
the reference
should be
to
§
1.
[73]
The
"q"
on
the
lefthand side
of
this
equa
tion should be
"G."
[74]
Planck derived results
equivalent
to the
following
two
equations
from
a
variational
prin
ciple
in
Planck
1907a,
§ 11
and
§
12.
[75]
Planck derived transformation
equations
for volume and
pressure by
different methods in
Planck
1907a,
§
5
and
§
6.
[76]
The
u
should be omitted from this
equa
tion.
[77]
See
Mosengeil
1907 for
a
discussion
of
this
system
not
involving
the
theory
of
relativity.
Planck
1907a,
§
1,
summarizes
Mosengeil's
re
sults;
§
15
shows how
to
obtain them with the
help
of
the relativistic transformation laws.
[78] The
"E0"
should be "E0/c2."
[79]
The
"c2"
should be "V0."
[80]
In
a
reprint
copy
(see note 34),
Einstein
crossed out the factor
"4/3"
in this
equation.
See also
Einstein
1908b
(Doc. 49).
[81]
Einstein
1907h
(Doc. 45).
[82]
In
a
reprint
copy
(see note 34),
Einstein
corrected the term "
q
dQ" to
"
q
dG."
[83]
Planck
1907a. The
quotation
is
from
p.
552. Planck used S
as
a symbol
for the
entropy
throughout
his text.
[84]
Planck's
text
(see
note 81)
has
"dasje
nige"
where
Einstein's
quotation
has
"das."
[85]
Planck's
text
(see
note
81)
has
"Bezugs
system"
following
"ungestrichene."
[86]
Planck's
text
(see
note 81)
has
"S'1S1,"
where
Einstein's
quotation
has
"n'1n1."
[87]
The "T"
in this
equation
should be
"T0."
[88]
Planck
gave a
different derivation
of
this
result in
Planck
1907a,
§
6. Einstein returned to
the
question
of
the transformation law for
tem
perature
many years
later,
and arrived
at
a
dif
ferent result:

T/T0
=
Vl

v2/c2
(see
Einstein
to
Max
von
Laue,
27
January
1952).
[89]
Planck
1907a.
[90]
In
a
reprint
copy
(see note 34),
Einstein
corrected
the coefficient
of
dz to
Fz,
and the
coefficient
of
T to
dn.
See also Einstein 1908b
(Doc. 49).
[91]
In
a reprint copy (see
note
34),
Einstein
corrected
the term
"x dG"
to
"x
dGx."
See also
Einstein 1908b
(Doc. 49).
[92]
See
Planck
1907a,
§
2. The definition
of
the kinetic
potential
H
is
given on p.
549,
and its
relationship
to the
energy
E
on p.
550.
[93]
See
Einstein
1908b
(Doc. 49),
p.
99, for
a
clarification
of
the
meaning
of
constant acceler
ation.
[94]
This
paragraph
contains
Einstein's
first
formulation
of
what he later termed the
equiva
lence
principle
(see
Einstein
1912b,
p.
365).
[95]
In
a reprint copy
(see
note
34),
Einstein
crossed
out
"nutzbar"
and
wrote
"ersetzbar."
See also
Einstein
1908b
(Doc. 49).
[96]
See
p.
413
of
the text
above,
and note
6.
The first
equation on p.
457
corresponds
to Lo
rentz's
original
definition
of
the local time
("Ortszeit").
[97]
In
a reprint copy (see
note
34),
Einstein
corrected
"gleichen" to "gleicher."
[98]
The reference
to
eq.
(29)
should
be to
eq.
(12).
[99]
See
Einstein
1908b
(Doc. 49), p. 99,
for
a
comment
on
this
equation.
[100]
Einstein
evidently
calculated the
gravita
tional
potential
at the surface
of
the
sun
and
di
vided it
by c2.
This is
Einstein's
first
prediction
of
what
came
to
be known
as
the
gravitational
red shift
of
spectral
lines.
His next
paper
on
gravitation
contains
a
discussion
of
this effect
that differs
from the
one given
here
(see
Einstein
1911g,
p.
905).
[101]
In
a reprint copy (see
note
34),
Einstein
corrected
"d/dt" on
the
righthand
side
of
this
equation to
"d/da"
See also
Einstein
1908b
(Doc. 49),
p.
99.
[102]
In
a
reprint
copy
(see
note
34),
Einstein
added
"u"
following
the
closing parenthesis
in