1 0 0 D O C . 1 2 R E L A T I V I T Y L E C T U R E N O T E S
if one makes the correction in note 26. This version of the equation, together with Einstein’s boxed
equation immediately above, agrees with, e.g., eqs. (286) of Pauli 1921, p. 662.
[28]Einstein completed his notes for this course after arriving in Zurich, presumably as an aid for
the lecture course on the same topic he gave there (see note 20). The lecture notes on general relativity,
which start on the same page of the notebook as the one on which this phrase is written, are presented
as Doc. 19.
[29]These components of the electromagnetic field tensor should be ,” ,”
and .”
[30]Here should be .”
[31]The first and the third i should be the imaginary unit i. The quantity l, which differs from the
notation used either in Vol. 4, Doc. 1, or in Vol. 6, Doc. 7, is the flux of electromagnetic energy density
which is absorbed by a receiver.
[32]“k” should be .”
[33]The term on this line is equal to the second term in the equation above, , by Maxwell’s
second system of equations. Einstein is deriving the form of the electromagnetic energy-momentum
tensor .
[34]The undeleted term on this line, together with the two terms from the line immediately above,
sum up to (see preceding note). To continue the derivation one moves the term to
the left-hand side. By changing the names of the summation variables μ and σ (hence the superscript
μ indices on the line above, positioned above σ indices), one consolidates terms on both sides and can
divide by two to recover the expression for in the line below. See Einstein 1916b (Vol. 6, Doc. 27),
sec. 2.
[35]For Einstein’s explanation of this formulation of the energy-momentum tensor for a perfect
fluid, see Einstein 1916e (Vol. 6, Doc. 30), p. 811.
[36]The third term should be .”
[37]Einstein deleted the equals sign on this line. Nevertheless, the expressions to the left and right
of the vertical line are equal, if one includes the term written above the line. The expression on
the left of the vertical line was derived from the line above using integration by parts.
fμν f23
= f31

p +
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