D O C U M E N T 5 5 F E B R U A R Y 1 9 2 1 4 9
because Tanitchka and Van Aardenne feel like
it,[7]
(4) because it won’t happen in
the end!!!!!!!– (5) because I would like to make as many personal contacts for the
benefit of the Dutch and Russian students, (6) because it’s a kind of “semi-
reversible stepping-outside-of-your-own-skin” which—as you know—I am chron-
ically inclined toward.
——————
I’m going to send your donation to the Zeeman fund together with mine, which
I want to let slide a little longer but not
much![8]
——————
I’ll announce your course “Miscellany from Theoretical Physics” as soon as I
know when you can start, how long you are staying with us, and whether you are
ready to lecture twice a week. As physicists want to come from Amsterdam, Delft,
Utrecht (and perhaps Groningen), it would be nice if that could be taken into
account, e.g., with the following arrangement (roughly!!—you can still suggest
changes)
You speak (as long as you are here) Wednesdays and Saturdays, e.g., from 2 p.m.
sharp to 2:45. Then from 3:00–3:45 “discussion” and from 4:00–4:45 you speak
again.– Possibly Fridays and Saturdays instead of Wednesdays and Saturdays.–
These “discussions” give you the advantage of being able to take a bit of a
“breather” and attain something that is extraordinarily welcome to me: (1) that in
this way the people who come to Leyden because of you come into contact with
one another; (2) you can invite all the people who wish to present something to you
to do so during these “discussion” sessions.
But otherwise you have to help me protect you from being
overrun!!![9]
So that you can speak before a small group of colleagues in the field and no
“public” comes, it is necessary that I be able to announce that your course treats
very specialized issues:
I would be very pleased if you wanted to speak about the following things,
among others: (1) Your arguments for spatial concentration of light
quanta.[10]
(2)
About your photochemical things and in contrast to the things by Lewis and
Perrin.[11]
(3) About reaction
velocities.[12]
(4) About rotation
spectra[13]
(provided
you have thought about that!)–
In case it is unpleasant for you to speak twice a week, take just
Saturdays.[14]
You are completely and entirely free—
You just have to be good!
Your old
Ehrenfest.
We are expecting you with impatience.—This time you’ll be living with us again.
Regards to your wife, Ilse, and Margot.