254
THEORY
OF
RELATIVITY
54)
are
discussed in
the
editorial
note,
"Einstein
and
Laub
on
the
Electrodynamics
of
Moving
Media,"
pp.
503-507. Einstein's
Salzburg
talk, Einstein 1909c
(Doc. 60), stating
the relation
between
the
theory
of
relativity
and
Einstein's
views
on
the structure
of
radia-
tion, is also discussed in the editorial
note,
"Einstein's
Early
Work
on
the
Quantum
Hy-
pothesis,"
pp.
147-148, and in the
Introduction,
pp.
xvii-xviii.
In
1913,
Einstein 1905r
(Doc. 23)
and
Einstein
1905s
(Doc. 24) were
reprinted
in Blumenthal
1913.[1]
Strictly speaking,
it
is
anachronistic to
use
the term
"the
theory
of
relativity"
in
dis-
cussing
Einstein's
first
papers
on
the
subject.[2]
In them he referred
to the
"principle
of
relativity" ("Prinzip
der
Relativität"
or "Relativitätsprinzip").[3]
Max
Planck
used the
term
"Relativtheorie"
in 1906 to describe the Lorentz-Einstein
equations
of motion
for
the
electron,
and this
expression
continued to be used from time to time for several
years.[4]
Bucherer
seems
to have
been the
first
person
to
use
the term
"Relativitätstheorie"
in
the
discussion
following
Planck's
lecture.[5] The term
was
used in
an
article
by
Ehrenfest[6]
and
adopted by
Einstein in
1907,
in his
reply.[7]
Although
Einstein used the term from time
to time
thereafter,
for several
years
he continued to
employ
"Relativitätsprinzip"
in the
titles
of
his articles.[8] In 1910 the mathematician Felix Klein
suggested
the
name
"Inva-
riantentheorie,"
but this
suggestion
does not
seem
to have been
adopted
by any
physi-
cist.[9]
In
1915 Einstein started to refer to his earlier work
as
"the
special theory
of
relativ-
ity"
("die
spezielle
Relativitätstheorie") to contrast it with his later
"general
theory"
("allgemeine
Theorie").[10]
In Einstein
1907j
(Doc.
47)
he does
refer
to the need for
gen-
eralizing
the
"principle
of
relativity"
in order to include
gravitation
in the
theory,
but
throughout
the
present
volume the
phrase
"the
theory
of
relativity" is
used to denote
the
special theory.
II
In his 1905
paper,
as
well
as
in his 1907 and 1909 reviews
of
the
theory,
Einstein
described
the
theory
of
relativity as arising
from
a specific problem:
the
apparent
conflict
between
[1]
See Otto
Blumenthal's
foreword
to
Blu-
menthal
1913. Notes added
to
Einstein
1905r
(Doc. 23)
in this
reprint are printed
in editorial
footnotes to that
paper.
For
a
discussion
of
the
authorship
of
these
notes,
see
Einstein
1905r
(Doc. 23),
note 8.
[2]
See Einstein
1905r
(Doc. 23),
1905s
(Doc.
24),
1906e
(Doc. 35),
1906g
(Doc.
36),
and
1907e
(Doc.
41).
[3]
He
also
referred to
"die
Relativitätselek-
trodynamik"
in
Einstein
1907h
(Doc. 45) on
pp.
372, 381,
and
to
"das
Relativitätssystem"
in
Einstein
1907g (Doc. 44) on p.
207.
[4]
See
Planck
1906b,
p.
424.
In
a
critical
re-
view of Kaufmann's
experiments
at the 1906
meeting
of
the Gesellschaft Deutscher Natur-
forscher und
Ärzte,
Planck
compared
the
"Re-
lativtheorie" of
Lorentz and Einstein with the
"Kugeltheorie" ("sphere theory")
of
Abra-
ham. The term
"Relativtheorie"
was
still in
use
in 1910
(see Noether 1910).
Planck continued
to
use
"Prinzip
der
Relativität"
or
"Relativitäts-
prinzip"
to describe the
approaches
of
Lorentz
and
Einstein,
between which he did not distin-
guish.
See
Planck
1906a,
1907a.
[5]
For
Bucherer's
comment, see
Discussion/
Planck
1906,
p.
760.
[6]
Ehrenfest
1907, p.
205.
[7]
See
Einstein
1907g (Doc. 44), pp. 206,
207;
see
also
Einstein
1907j (Doc.
47),
p.
439.
[8]
He did
not
use
"Relativitätstheorie"
in
a
title until
Einstein
191le.
[9]
See Klein,
F.
1910, p.
287.
[10]
See
Einstein
1915b,
p.
778.