INTRODUCTION
TO VOLUME
3
I
This volume
presents
Einstein's
writings
for
the
period
from October
1909
through
the end of
1911.
Almost half
of
this material has
not
been
published
before;
the
unpublished
work consists in
large part
of
the notes
Einstein
wrote
as
he
prepared
his lecture
courses
on
several different
subjects.
But the
pub-
lished
scientific
papers
included here
will
also be
full
of
surprises
for
most
readers.
Several
are virtually unknown,
since
they appeared originally
in
Swiss
journals
of rather limited circulation.
Only
two
or
three of
the
papers
in this
volume could be described
as
having
contributed
significantly
to
the
develop-
ment
of
physics
in these
years.
As
a
group
these
writings
differ
sharply
from
the works
that
preceded
them,
the works
presented
in Volume
2.
The
great
papers
of
1905
and
some
of
their
sequels
gave
the reader
an
impression
of
effortless
mastery, as though
Einstein
saw directly
into the
deepest
issues of
his
day.
That
impression largely disappears:
the Einstein
we
meet
here
is
now
evidently working very
hard for his results and
struggling
with
problems
that
do
not
always yield
to his efforts.
Many aspects
of
physics
claim
his
attention,
just
as they
have
since
his student
days,
but
no
central theme
appears
to
guide
his work.
Only
one
paper
in this volume documents his
con-
tinuing
concern
with
gravitation,
but
the
hydralike problems
associated with
quanta
recur
continually.
Those who think of
Einstein
exclusively as
the
lone-
ly
sage
of Princeton
may
well
be astonished
by
the
range
and
depth
of his
knowledge
of
current
experimental
work. This
knowledge
was
maintained
by
his close contacts
with
many experimentalists,
as
demonstrated in his
corre-
spondence
of
this
period,
which
will
be
published
in Volume
5.
II
October
1909
marks
an
epoch
in Einstein's
life.
At the
age
of
thirty
he
left
the
position
as
technical
expert
in
the
Swiss
Patent
Office,
which had
originally
suited him
so
well
and which
he
had
filled
so successfully
for
seven years,
to