SUBTLE IS THE LORD 113Proceeding along the same general lines used in the Potsdam experiments, they
built a new interferometer. Great care was taken to minimize perturbative influ-
ences. In August 1887, Michelson wrote to Rayleigh that again a null effect had
been found [M5]. The paper on the Michelson-Morley experiment came out the
following November [M6]. Understandably, the negative outcome of this experi-
ment was initially a disappointment, not only to its authors, but also to Kelvin,
Rayleigh, and Lorentz.
However, more important, the experimental result was accepted. There had to
be a flaw in the theory. In 1892 Lorentz queried Rayleigh: 'Can there be some
point in the theory of Mr Michelson's experiment which had as yet been over-
looked?' [L5]. In a lecture before the Royal Institution on April 27, 1900, Kelvin
referred to the experiment as 'carried out with most searching care to secure a
trustworthy result' and characterized its outcome as a nineteenth century cloud
over the dynamic theory of light [Kl]. In 1904 he wrote in the preface to his
Baltimore lectures: 'Michelson and Morley have by their great experimental work
on the motion of the ether relatively to the earth raised the one and only serious
objection against our dynamical explanations.. ..' [K2].
In later years, Michelson repeated this experiment several times, for the last
time in 1929 [M7]. Others did likewise, notably Dayton Clarence Miller, at one
time a junior colleague of Michelson's at Case. In 1904, Morley and Miller were
the first to do a hilltop experiment: 'Some have thought that [the Michelson-Mor-
ley] experiment only proves that the ether in a certain basement room is carried
along with it. We desire therefore to place the apparatus on a hill to see if an
effect can there be detected' [M8].* Articles in 1933 [M9] and 1955 [S4] give
many technical and historical details of these experiments. No one has done more
to unearth their history than Robert S. Shankland, whose papers are quoted
extensively in this section. For the present purposes, there is no need to discuss
these later developments, except for one interlude which directly involved Einstein.
On April 2, 1921, Einstein arrived for the first time in the United States, for
a two-month visit. In May, he gave four lectures on relativity theory at Princeton
University [El]. While he was there, word reached Princeton that Miller had
found a nonzero aether drift during preliminary experiments performed (on April
8-21 [S4]) at Mount Wilson observatory. Upon hearing this rumor, Einstein
commented: 'Raffiniert ist der Herr Gott, aber boshaft ist er nicht,' Subtle is the
Lord, but malicious He is not. Nevertheless, on May 25, 1921, shortly before his
departure from the United States, Einstein paid a visit to Miller in Cleveland,
where they talked matters over [S5].
There are two postscripts to this story. One concerns transitory events. On April
28, 1925, Miller read a paper before the National Academy of Sciences in Wash-
ington, D.C., in which he reported that an aether drift had definitely been estab-
- Michelson had pointed out earlier that perhaps the aether might be trapped in the basements in
which he had done his experiments [M4].