D O C U M E N T 1 6 A P R I L 1 9 2 3 2 1
First, I would like to congratulate you most heartily on the brilliant confirmation
by W. W. Campbell (of the Lick Observatory) of your light deflection
formula.[4]
Yesterday, I only received a preliminary message that the mean value from 12
plates comes to approximately 1”.75 (reduced to the Sun’s limb). I am soon going
to be officially receiving all the details from Campbell (for my Relativity Commit-
tee of the Internation. Astron. Union, composed of Michelson, Dayton Miller,
Kasner, and
me);[5]
but even now I do not doubt that the result has been found to
be very near to 1”.75, and with much better photographic material than by Dyson
in
1919.[6]
I can vividly imagine how much you must be looking forward to it (de-
spite your having once said to me that you would be very surprised if 1”.75 did not
result; but basically, you will be pleased, since nothing can guarantee us that Nature
will slavishly follow even the finest of theoretical formulas in every respect. (You
surely don’t seriously let yourself in for such mystical concepts as “rationality of
Nature.”) I shan’t write anymore about this because you have probably already re-
ceived the good news. If I should receive from Campbell more than one copy of the
photographs, I will send you one.
Second, I would like to inform you that Michelson is continuing to work unceas-
ingly on his rot. terrestr. opt. experiment .
[7]
He has already brought the
light path to 6,5000 feet and has increased the measurement precision 5-fold. (He
is now in a position to distinguish a “fringe width” of 0’01.) It turned out, however,
that the interference fringes tremble so energetically in the open air that one cannot
measure anything, and we are occupied with collecting funds in order to guide the
light (all around) in (12-inch-diameter) tubes. The installation of this 6,000 or
7,000-foot-long piping system will hopefully begin next June, at
Yerkes.[8]
Michelson writes me very often and has not suffered any loss of zeal for the
experiment. Lorentz, in whose honor a colloquium was held in Madison, also gave
us much encouragement on it. A memorial book for Lorentz, with my article on the
-experiment, is now being printed.
Third, I would like to request that you enlighten me in regard to a new and mag-
nificent relativity paper attributed to you. Dr. Campbell from New York (whom I in-
troduced to you at
Princeton[9]
) told me recently that he had read about it in the pa-
pers and that your paper on this is appearing imminently in the proc[eedings] of the
Berlin Academy. Now I would also like to ask you, provided this is true, to send me
a reprint of your new paper (we receive the proceedings here with great delay), as
soon as
possible.[10]
I am now writing the 2nd edition of my London Relativity, of