DOCS.

42,

43

DECEMBER 1914-JANUARY

1915

49

42. To

Michael

Polányi

Berlin,

30

December

1914

Dear

Colleague,

From

your

letter

I

see

that

we

do not

quite

understand

each

other

yet.

The

tacit

assumption

in

which I

perceive

a

petitio

principii is

that

to

attain

absolute

zero

your process

needs

infinitely many

stages.[1]

However,

if absolute

zero

can

be reached

through

a

finite

number of

stages

in accordance with

your diagram:

then the

proof

fails, even

though

every positive

value

of parameter

v

at

each

tem-

perature

may correspond

to

a

realizable state.

As

long

as

you

cannot exclude

that

your staged

process progresses

in

the

depicted manner, nothing

can

be inferred

about the

validity

of Nernst’s theorem.

Very respectfully

and

humbly

yours,

A. Einstein.

P.S.

I

do

not

return

now

to

my

comment

on

osmotic

pressure,

because

this

is not

necessary

for

an

assessment of

the

principle

issue.

43.

From

Hendrik

A.

Lorentz

[Haarlem,

between

1

and

23 January

1915][1]

You show in

§12

that

it

is

impossible

to introduce

a

coordinate

system

K'

other than the

one

used

initially,

K,

which

differs

only

within

a

finite

region

E

in such

a

way

that,

like

the

guv's,

the

g'uv’s

connected to

K', together

with

their

derivatives,

are

everywhere

constant.[2]

When

you

nonetheless

find in the

following paragraphs

that

you

can

introduce

in

region

E

coordinate

systems

other

than K

(namely

those which

just like

K

are

adapted to

the

gravitational

field),[3]

this

ought

to

come

from

the

fact

that

in

introducing

such

a

K'

not all derivatives of

guv

remain constant at

the

boundary

of E.

Indeed, you

subject

the

coordinate

systems

adapted

to

the

field

only

to