242 RELATIVITY, THE GENERAL THEORYthe personality can unfold itself in the freest possible way.' Then he, too, addressed
the question of the preferred uniform motions in the special theory. 'In my opin-
ion, one could just as well take the opposite view [of Einstein's] and look upon the
preferred position of uniform motion as precisely a very important and valuable
characteristic of the theory'. For, Planck notes, natural laws always imply certain
restrictions on infinitely many possibilities. 'Should we consider Newton's law of
attraction unsatisfactory because the power 2 plays a preferred role?' Could one
perhaps not relate the preferred uniform motion to 'the special privilege which
indeed singles out the straight line among all other spatial curves'?! These are not
impressive comments. However, one must side with Planck when he courteously
and justly chided Einstein, noting that in the latter's general theory not all coor-
dinate systems are on an equal footing anyway, 'as you yourself have proved only
recently.' Planck ended by expressing the hope that the expedition planned to
observe the solar eclipse of August 21, 1914, would provide information about the
bending of light predicted (not yet correctly) by Einstein. These hopes were dashed
by the outbreak of the First World War.
Einstein's productivity was not affected by the deep troubles of the war years,
which, in fact, rank among the most productive and creative in his career. During
this period, he completed the general theory of relativity, found the correct values
for the bending of light and the displacement of the perihelion of Mercury, did
pioneering work on cosmology and on gravitational waves, introduced his A and
B coefficients for radiative transitions, found a new derivation of Planck's radia-
tion law—and ran into his first troubles with causality in quantum physics. Dur-
ing the war he produced, in all, one book and about fifty papers, an outpouring
all the more astounding since he was seriously ill in 1917 and physically weakened
for several years thereafter.
This intense scientific activity did not banish from Einstein's mind a genuine
and intense concern for the tragic events unfolding in the world around him. On
the contrary, the period of 1914-18 marks the public emergence of Einstein the
radical pacifist, the man of strong moral convictions who would never shy away
from expressing his opinions publicly, whether they were popular or not. Early
in the war, he and a few other scholars signed a 'manifesto to Europeans' criticiz-
ing scientists and artists for having 'relinquished any further desire for the contin-
uance of international relations' and calling 'for all those who truly cherish the
culture of Europe to join forces.... We shall endeavor to organize a League of
Europeans' (an effort that came to naught). This appears to be the first political
document to which Einstein lent his name. He also joined the pacifist Bund Neues
Vaterland, League of the New Fatherland.* It gave him joy to find colleagues
who 'stand above the situation and do not let themselves be driven by the murky
* Einstein on Peace by Otto Nathan and Heinz Norden describes in detail Einstein's political activ-
ities during the First World War [Nl]. The quotations from the manifesto are taken from that book,
which contains its full text.