I had just finished reading Graham Farmelo’s biography, The Strangest Man: The Hidden Life of Paul Dirac, Mystic of the Atom (Basic Books, 2009), when the December 2009 issue of Physics Today, arrived, with the interesting review by Babak Ashrafi on page 52. Although I quite agree with Ashrafi that Farmelo’s book is “fascinating” and “thoroughly researched,” since I counted 1494 reference notes distributed across its prologue and 31 chapters, I was consequently astonished to find two significant errors concerning the history of relativistic cosmology in the 1920s.

In chapter 19, after describing Georges Lemaître’s commencing his studies with Arthur Eddington in 1923 and his cosmology work of 1927, Farmelo says, “Quite independently, the Russian mathematician Alexander Friedmann had applied Einstein’s general theory of relativity to the universe as a whole and demonstrated that some mathematical solutions of the equations correspond to an expanding universe, though his work was published only in Russian and at first went unnoticed.” No reference note is given, perhaps because the latter two assertions about Friedmann’s work are incorrect and, in absence of date of publication, possibly misleading with respect to priority of publication.

Friedmann’s first published paper on the subject 1 was written in German and titled “Über die Krümmung des Raumes” (“On the Curvature of Space”). It was not only noticed but criticized later that year by Einstein, who thought Friedmann had made a mistake. 2 Following a visit by Friedmann’s colleague Yuri Krutkov and a letter from Friedmann himself, Einstein withdrew his criticism the following year and accepted Friedmann’s work as “both correct and clarifying.” 3 Although those historical errors have no bearing on Dirac’s life, nevertheless, as he would have emphasized, it is important to get it right.

1.
A.
Friedmann
,
Z. Phys.
10
,
377
(
1922
).
2.
A.
Einstein
,
Z. Phys.
11
,
326
(
1922
).
3.
A.
Einstein
,
Z. Phys.
16
,
228
(
1923
).