EINSTEIN'S COLLABORATORS 487
- Adriaan Daniel Fokker. b. 1887, Buitenzorg, Dutch East Indies, (now
Bogor, Indonesia). PhD in 1913 with Lorentz in Leiden on the Brownian motion
of an electron in a radiation field [F3]. This work led to the Fokker-Planck equa-
tion for Gaussian Markov processes. Fokker worked with Einstein in Zurich dur-
ing the winter semester in 1913-14. Their joint paper on the Nordstrom theory
of gravitation [El5] was discussed in Section 13b. In later years, Fokker wrote
several papers on relativity as well as a Dutch textbook on that subject. He became
the curator of the Teyler Foundation in Haarlem and concurrently held a profes-
sorship at Leiden. He was a passionate advocate of 31-tone music and of the
purity of the Dutch language, d. 1972, Beekbergen, Holland.
- Wander Johannes de Haas. b. 1878, Lisse, Holland. PhD in 1912 with
Kamerlingh Onnes in Leiden. Soon after obtaining this degree, de Haas and his
wife (nee Geertruida Luberta Lorentz, the oldest of the three children of H. A.
Lorentz) went to Berlin, where he worked first in the laboratory of Henri du Bois
and then with Einstein at the Physikalisch Technische Reichsanstalt. This led to
the discovery of the Einstein-de Haas effect, as described'in Section 14b. In 1925
de Haas succeeded Kamerlingh Onnes at Leiden. He was a leading and produc-
tive figure in experimental low-temperature physics. He retired from his Leiden
position in 1948. d. 1960, Bilthoven, Holland.
7 7. Jakob Grommer. b. Brest-Litovsk, a Russian town in the year (not known
to me) of Grommer's birth, a Polish town from 1921 to 1939 (Grommer held a
Polish passport at one time), now Brest in the U.S.S.R. As a young man, Grom-
mer devoted himself exclusively to the study of the Talmud.* A burning interest
in mathematics brought him to Goettingen. According to Helen Dukas, Grommer
spoke only Yiddish when he arrived in Germany. In Goettingen 'he aroused the
curiosity of the mathematicians soon after his arrival. In an incredibly short time,
he not only acquired a deep knowledge of mathematics but also managed to write
a doctoral thesis which is considered outstanding by insiders. ... If one considers
that he was disfigured as the result of a malignant disease** and that he was,
moreover, physically weak, then one can appreciate how uncommon the talents
were which this man brought along into this world' [E16].
Grommer worked with Einstein for ten years, the longest period any person
collaborated with him. The first mention of him is in Einstein's 1917 paper on
cosmology [E17]. Six years later, they published a joint paper in which it was
shown that the Kaluza theory does not admit centrally symmetric singularity-free
solutions [E18]. Shortly thereafter, Einstein mentioned Grommer's work again in
one of his own papers [E19]. In 1925 Einstein wrote that Grommer had 'faithfully
assisted me in recent years with all calculations in the area of general relativity
"This was stated by Einstein in a note written in 1953 [E16J at the request of an Israeli committee
that was preparing a book on the history of the Jews of Brest-Litovsk [Cl].
**Grommer suffered from acromegaly. Einstein mentioned that this affliction often made Grommer
irritable.
