3 4 D O C U M E N T S 2 9 , 3 0 M A Y 1 9 2 3

29. To Mileva Einstein-Maric

Berlin, 18 May 1923

Dear Mileva,

I agree about buying the

house.[1]

But be well advised regarding the price and

conditions, most preferably by Albert Karr. I’ll have the money sent out as soon as

I have heard from you. But it’s still unclear to me in whose name the remainder is

to be deposited. Do inform yourselves at last about the capital

tax.[2]

If all of you

are persuaded on the basis of careful consideration, then close immediately and, if

need be, have Karr pay the money out to you in advance. He, in turn, will get it im-

mediately back from Stockholm. In a hurry, yours,

Albert.

I’ll be writing the boys in tranquility as soon as I have time.

30. From Hermann Weyl[1]

Zurich, 52 Bolley St., 18 May 1923

Dear Colleague,

In the correction proof I had forwarded a short note to you which, among other

things, contains a somewhat precipitous criticism of your new approach and which

I will suppress, provided it is still

possible.[2]

By way of an apology I would like to

indicate that I had earlier made a similar attempt following

Eddington[3]

and then

did not notice enough the difference between your approach and my earlier one. In

the interim I calculated a little further and obviously cannot help it that, according

to your new theory, the dynamic effect of the electromagnetic field always only re-

sults from a small cosmological magnitude.

In order to perform approximation calculations, I assume is small compared

to and write, in order to express this, instead of .[4]

The reciprocal matter

(riαrαk

is, developed from powers of ε,

. Through substitution in the definition equation in paren-

theses and comparison there then result the relations

, , .

If the juggling with the indices is determined by , then the designation is

correct, and one has

ϕik

giκ gik εϕik + rik = gik ϕik +

rik δik)

=

gik εϕik – ε2γik… + =

giαgαk

δik =

giαϕαk ϕiαgαk

=

giαγαk ϕiαϕαk

=

gik

ϕik