Volume 4: The Swiss Years: Writings 1912-1914 (English translation supplement) Page 231 (243 of 326)

DOC.
19
LECTURE ON
ELECTRICITY
&
MAGNETISM
231
Doc.
19
Lecture
Notes
for
Course
on
Electricity
and
Magnetism
at the
ETH,
Winter Semester
1913/1914
Please
see
the
documentary
edition. This document consists
mostly
of
equations
and
is therefore
not
translated.

Previous Page Next Page

Extracted Text (may have errors)

DOC.
19
LECTURE ON
ELECTRICITY
&
MAGNETISM
231
Doc.
19
Lecture
Notes
for
Course
on
Electricity
and
Magnetism
at the
ETH,
Winter Semester
1913/1914
Please
see
the
documentary
edition. This document consists
mostly
of
equations
and
is therefore
not
translated.

Help

230
DOC.
18
DISCUSSION OF DOC.
16
experiment,
and
it
would be
interesting
to
hear how this
matter
is viewed
by
the
astronomers
present
here.
Einstein: It
is
outside
my competence
to
lay
down the details of how the
astronomers
should do that. It involves the
photographing
of the fixed
stars
near
the
Sun
during a
total solar
eclipse,
so as
to decide whether
or
not
the
nearness
of the
Sun influences the
apparent
locations of the
stars.
Jäger:
Are
astrophysicists
not
of
the
opinion
that
changes
in the
pictures
of
the
fixed
stars
occur
depending
on
whether the Sun
is
nearby
or
not,
and that the
changes
looked for
by
Einstein
completely
vanish in
comparison?
Einstein:
Experts
will have
to decide about
that;
for the time
being,
we
have
to
wait and
see
how the
photographs
will
turn out.
Mie: I would like
to
draw attention
to
another
experimental consequence
of the
various theories
of
gravitation. According
to
Einstein's
theory,
the oscillation
periods
of
atoms at
a
place
of
high gravitational
potential
must
be
different from those where
the
gravitational potential
is
zero.
Hence the lines of
a
line
spectrum
from
a
fixed
star
of
large
mass
must
be shifted with
respect
to
the lines observed
on
the Earth.
[23]
According
to
my theory,
this
is not
so.
My theory,
as
I would
like
to
note
here,
is
based
on a specific principle.
To be
sure,
I
have abandoned the
principle
of
the
identity
of
gravitational
and inertial
mass,
and
I
also believe that
one
cannot
base
any
theory
on
it.
Instead,
I
have the
principle
that the absolute
value
of
the
gravitational
potential
has
no
effect whatsoever
on
physical phenomena.
I call this the
principle
of
the
relativity
of the
gravitational potential.
Thus,
according
to
my theory
the shifts
of the
spectral
lines
predicted by
Einstein's
theory are
not to
be
expected.
Einstein:
Yes,
that's
right; according
to
my theory,
and also
according
to that of
Nordström,
this
must
take
place;
an
oscillator
transported
from here
to
the Sun
must
oscillate slower there. It
is
unfortunately
true that other
causes
also
produce
line
shifts,
and it is therefore
very
difficult
to
check whether
such
a
shift is
produced
[24]
exactly by
this
cause.

Previous Page Next Page

232 DOC.
20
THEORETICAL ATOMISM
Doc.
20
Theoretical
Atomism
by
A.
Einstein
[In
Die Kultur der
Gegenwart.
Ihre
Entwicklung
und Ihre
Ziele,
ed.
Paul
Hinneberg,
Part
3, sec. 3,
vol.
1,
Physik,
ed.
Emil
Warburg, Leipzig:
Teubner,
1915,
pp.
251-263]
The development of
the
modem theory of heat
in
general,
as
well as the development
of the molecular-kinetic theory of heat, was initiated primarily
by
the establishment
of
the
energy principle. Let us first dwell briefly on the latter in order
to
consider the
relationship of this principle
to
physical experience. We will carry out this
consideration
using
a
very simple comparison
so as
to
let neither the
multifaceted
nature
of the
topic
nor
habits
or
convictions
get
in
the
way.
I
have before
me
two
vessels
G1
and
G2,
which
are
open
at
the
top
and
partly
filled with
water,
and which communicate with each other via
a
flexible hose
through
which the
water
can
flow from the lowest
layer
of
one
of the vessels into that of the
other;
this will
always
continue until the levels
in
the
two
vessels
(taken absolutely)
have the
same
height.
Let the vessel
G1
have
transparent
walls,
so
that its
water
level
can
be observed from the
outside,
and let it
be
firmly
fixed
at
a
certain
height.
Let
the walls of the second vessel be
opaque,
and let
it be
absolutely impossible
to
perceive
the
water
level in
this
vessel
directly;
but this vessel shall be
adjustable
in
the vertical
direction,
and there shall
be
some
way
of
determining
the
weight
of the
second vessel
together
with
its contents at
every height.
After each
adjustment
of
G2,
once
equilibrium
has been
established,
an
observer shall determine the
water
level
h
in
G1
with
respect
to
the walls of this
vessel,
as
well
as
the
corresponding weight
g
of
G2,
restricting
himself
to
those
settings
of
G2
in
which there is
water
in
G1
as
well
as
in
G2.
If vessel
G1
is
cylindrical,
this observer will find
a
simple relationship,
namely
that-given
an appropriate
choice of the numerical factor
a-the
quantity
ah
+ g
is
independent
of the
height
at which
G2
has been
set.
If the observer knows the
laws of
hydrostatics
and knows that
the vessels contain
a
liquid,
he will find these
experiments uninteresting.
But let
our
observer know
nothing
about the
contents
of
the
vessels;
for him the result
concerning
the
physical
system
he
has been
studying
represents
a
scientific
discovery.
He will
say:
"The
water
level
h
of
G1
and the
weight
g
of
G2
are
equivalent quantities,
since
a
specific change
of the
water
level
h
of
G1
always
results
in
a
wholly
determinate,
opposite change
of
g;
the
quantity
ah
+ g
measures an
invariant
quantity
characteristic of the
system."
Repeated findings
of
an
analogous
kind
are
what led
physicists
to
the
principle
of the conservation of
energy.
It
was
first discovered
in
the domain of
pure
A
Comparison
Illustrating the
Relation of the
Energy
Principle
to
Experiment.

Previous Page Next Page

Page 1Texts click to expand contents

Extracted Text (may have errors)

Help

loading