The history of science records the 1887 ether-drift experiment of Albert Michelson and Edward Morley as a pivotal turning point, where the energetic ether of space was discarded by mainstream physics. Thereafter, the postulate of "empty space" was embraced, along with related concepts which demanded constancy in light-speed, such as Albert Einstein's relativity theory. The now famous Michelson-Morley experiment is widely cited, in nearly every physics textbook, for its claimed "null" or "negative" results. Less known, however, is the far more significant and detailed work of Dayton Miller.

Dayton Miller's 1933 paper in Reviews of Modern Physics details the positive results from over 20 years of experimental research into the question of ether-drift, and remains the most definitive body of work on the subject of light-beam interferometry. Other positive ether-detection experiments have been undertaken, such as the work of Sagnac (1913) and Michelson and Gale (1925), documenting the existence in light-speed variations (c+v c-v), but these were not adequately constructed for detection of a larger cosmological ether-drift, of the Earth and Solar System moving through the background of space. Dayton Miller's work on ether-drift was so constructed, however, and yielded consistently positive results.

Miller's work, which ran from 1906 through the mid-1930s, most strongly supports the idea of an ether-drift, of the Earth moving through a cosmological medium, with calculations made of the actual direction and magnitude of drift. By 1933, Miller concluded that the Earth was drifting at a speed of 208 km/sec. towards an apex in the Southern Celestial Hemisphere, towards Dorado, the swordfish, right ascension 4 hrs 54 min., declination of -70° 33', in the middle of the Great Magellanic Cloud and 7° from the southern pole of the ecliptic. (Miller 1933, p.234) This is based upon a measured displacement of around 10 km/sec. at the interferometer, and assuming the Earth was pushing through a stationary, but Earth-entrained ether in that particular direction, which lowered the velocity of the ether from around 200 to 10 km/sec. at the Earth's surface. Today, however, Miller's work is hardly known or mentioned, as is the case with nearly all the experiments which produced positive results for an ether in space. Modern physics today points instead to the much earlier and less significant 1887 work of Michelson-Morley, as having "proved the ether did not exist".

While Miller had a rough time convincing some of his contemporaries about the reality of his ether-measurements, he clearly could not be ignored in this regard. As a graduate of physics from Princeton University, President of the American Physical Society and Acoustical Society of America, Chairman of the Division of Physical Sciences of the National Research Council, Chairman of the Physics Department of Case School of Applied Science (today Case Western Reserve University), and Member of the National Academy of Sciences well known for his work in acoustics, Miller was no "outsider". While he was alive, he produced a series of papers presenting solid data on the existence of a measurable ether-drift, and he successfully defended his findings to not a small number of critics, including Einstein. His work employed light-beam interferometers of the same type used by Michelson-Morley, but of a more sensitive construction, with a significantly longer light-beam path. He periodically took the device high atop Mt. Wilson (above 6,000' elevation), where Earth-entrained ether-theory predicted the ether would move at a faster speed than close to sea-level. While he was alive, Miller's work could not be fundamentally undermined by the critics. However, towards the end of his life, he was subject to isolation as his ether-measurements were simply ignored by the larger world of physics, then captivated by Einstein's relativity theory.

The basic principles of light-beam interferometry for detection of ether-drift are described in most textbooks, albeit with typical factual errors (ie, the slight positive result of the Michelson-Morley experiment is nearly always misrepresented as a "null" or "zero" result) and so will not be repeated here. However, there were novel methods introduced by Miller into the discussion of ether-drift, along with interferometer construction features and principles of operation which are not widely known - these will be detailed.

Miller's Work with Interferometry

Miller began his work on the question of ether-drift and light-beam interferometry with Edward Morley, from 1902 to 1906, using an apparatus three times as sensitive as the original interferometer used by Michelson-Morley in 1887. In later years, from 1921 through 1928, Miller made additional refinements for sensitivity in his interferometer, obtaining increasingly significant positive results. His interferometer was the most massive and sensitive ever constructed, with iron cross-arms 4.3 meters across, and standing 1.5 meters in height. Four sets of mirrors were mounted on the end of each cross-arm to reflect light beams back and forth 16 times horizontally with a total round-trip light path of 64 meters, starting from the same light-source, and finally recombined to form interference fringes whose movement relative to a pointer was read through a magnifying telescope. The large apparatus was floated inside a circular tank of liquid mercury, providing a frictionless base for rotation. Fringe-shift movements (in tenths of a fringe, plus or minus in direction) were observed by one person who walked around with the apparatus while it turned, speaking out the readings at the ring of bell which automatically sounded when electrodes made contact at 24° intervals (dividing the circle into 15 parts). An assistant then noted the readings on paper. The readings, from consecutive turns of the apparatus were then organized into "sets", which were made at different times of day and at different seasons of year. Data sets were then averaged according to a sidereal time clock, which was correlated with external celestial coordinates. Miller became convinced of an ether Earth-entrainment effect, which necessitated using the apparatus at higher altitudes (to reduce the anticipated entrainment-effect of sea-level environments), and he additionally undertook the experiments in structures where the walls at the level of the light-path were open to the air, covered with canvas. Only glass, or glass and light paper covers were used along the light-beam paths, with all wood or metal shielding removed. By contrast, the original Michelson-Morley interferometer had a round-trip light-path of around 22 meters (Michelson 1927, p.153), and the experiments were undertaken with an opaque wooden cover over the instrument, situated in the basement of one of the large stone buildings at Case School in Cleveland.

In his 1933 paper, Miller published the most comprehensive summary of his work, and the large quantity of data which supported his conclusions. A total of over 200,000 individual readings were made, from over 12,000 individual turns of the interferometer, undertaken at different months of the year, starting in 1902 with Edward Morley at Case School in Cleveland, and ending in 1926 with his Mt. Wilson experiments. These data do not include many rigorous control experiments undertaken at Case School Physics Department from 1922 to 1924. More than half of Miller's readings were made at Mt. Wilson using the most sophisticated and controlled procedures, with the most telling set of experiments in 1925 and 1926. By contrast, we can mention here, the original Michelson-Morley experiment of 1887 involved only six hours of data collection over four days (July 8, 9, 11 and 12 of 1887), with a grand total of only 36 turns of their interferometer. Even so, as shown below, Michelson-Morley originally obtained a slight positive result which has been systematically ignored or misrepresented by modern physics. As stated by Michelson-Morley:

Unfortunately, and in spite of all claims to the contrary, Michelson-Morley never undertook those additional experiments at the different seasonal configurations, to "avoid all uncertainty". However, Miller did. Over many years, he developed increasingly sensitive apparatus, using them at higher altitudes and in open structures, making clear and positive detection of the ether. His experiments yielded systematic periodic effects which pointed to a similar identifiable axis of cosmic ether-drift, though of a variable magnitude, depending upon the season, time of day, density of materials shielding or surrounding the apparatus, and altitude at which the experiment was undertaken. He argued that basement locations, or interferometers shielded with opaque wood or metal housings, yielded the most tiny and insignificant effects, while those undertaken at higher altitudes and in less dense structures yielded more readily observable effects. The Michelson-Morley experiment, by comparison, was undertaken in the basement of a stone building closer to sea-level. Even so, it produced a slight positive result which was in agreement with Miller's results.

Miller's observations were also consistent through the long period of his measurements. He noted, when his data were plotted on sidereal time, they produced "...a very striking consistency of their principal characteristics...for azimuth and magnitude... as though they were related to a common cause... The observed effect is dependent upon sidereal time and is independent of diurnal and seasonal changes of temperature and other terrestrial causes, and...is a cosmical phenomenon." (Miller 1933, p.231)

Michelson, and Others, Confirm an Ether-Drift

Miller's work did finally receive an indirect support from Albert Michelson in 1929, with the publication of "Repetition of the Michelson-Morley Experiment" (Michelson, Pease, Pearson 1929). The paper reported on three attempts to produce ether-drift fringe shifts, using light-beam interferometry similar to that originally employed in the Michelson-Morley (M-M) experiments.

In the first experiment, undertaken in June of 1926, the interferometer was the same dimensions as the original M-M apparatus, with a round-trip light path of around 22 meters. A fringe shift displacement of 0.017 was predicted, but the conclusions stated "No displacement of this order was observed". The second experiment, undertaken on unspecified "autumn" dates in 1927, employed a slightly longer round-trip light path of around 32 meters (given as 53' for an assumed one-way distance). Again, "no displacement of the order anticipated was obtained", and the short report did not give details about the experimental surroundings or locations.

The third experiment was undertaken on an unspecified date (probably 1928) in "a well-sheltered basement room of the Mount Wilson Laboratory". The round-trip light path was further increased to approximately 52 meters (given as 85' for an assumed one-way distance). This time, having moved the apparatus to a higher altitude and using a longer light-path, a small quantity of ether-drift was detected which approximated the result observed by Miller, although the results were unjustifiably reported in negative terms:

One fifteenth of 300 km/sec. is 20 km/sec., a result the authors dismissed as they apparently had discarded the concept of an Earth-entrained ether, which would move more slowly closer to sea level. A similar result of 24 km/sec. was achieved by the team of Kennedy-Thorndike in 1932, however they also dismissed the concept of an entrained ether and, consequently, their own measured result: "In view of relative velocities amounting to thousands of kilometers per second known to exist among the nebulae, this can scarcely be regarded as other than a clear null result". This incredible statement serves to illustrate how deeply ingrained was the concept of a static ether.

Michelson, Pease and Pearson went on to make speed-of-light measurements in a one mile long partially-evacuated steel tube lying flat on the ground, oriented roughly southwest to northeast. While the purpose of these experiments was not to measure any ether-drift or variation in the speed of light, such variations in fact were observed and reported in their paper. (Michelson, Pease, Pearson 1935) A newspaper account of these experiments, published after Michelson's death in 1931 but prior to their final publication of results reported: "Dr. Pease and Mr. Pearson say the entire series of measures, made mostly between the hours of 7 and 9 PM, show fluctuations which suggest a [variation] of about 20 kilometers per second." (Dietz 1933) Miller commented on these results, suggesting they would have measured a stronger ether-drift variation if they had taken their interferometers outside of the basement structures and steel pipes: