Edward Morley
Edward Williams Morley | |
|---|---|
| Born | January 29, 1838 Newark, New Jersey, United States |
| Died | February 24, 1923 (aged 85) West Hartford, Connecticut, United States |
| Nationality | American |
| Known for | Michelson–Morley experiment, atomic weight of oxygen, aether drift measurements |
| Scientific career | |
| Fields | Chemistry, Physics |
Edward Williams Morley (29 January 1838 – 24 February 1923) was an American chemist whose name is attached to the most argued-over experiment in modern physics, but whose own reputation in his lifetime rested on something else: he was the most exact analytical chemist of his generation.
Life and chemical work
Morley was born in Newark, New Jersey, the son of a Congregational minister, and was taught at home before entering Williams College. He trained for the ministry at Andover Theological Seminary and was ordained, but was unable to secure a pulpit; in 1869 he took a professorship of chemistry and natural history at Western Reserve College in Hudson, Ohio, moving with the college to Cleveland in 1882. He remained there until his retirement in 1906.
His major chemical work was the determination of the atomic weight of oxygen relative to hydrogen, published in 1895 after more than a decade of work in which he prepared both gases to a purity nobody had previously achieved and weighed the water formed by their combination. The result stood as the standard value for years and is still cited as a model of precision measurement. He also carried out careful studies of the oxygen content of the atmosphere, and served as president of the American Chemical Society in 1899. He was awarded the Davy Medal of the Royal Society in 1907 and the Elliott Cresson Medal in 1912.
The interferometer work
Albert A. Michelson came to Cleveland in 1883 and found in Morley the experimentalist he needed. They collaborated first on a repetition of Fizeau's measurement of the drag of light by moving water, published in 1886, and then on the 1887 experiment for which both are remembered: an interferometer on a stone slab floating in a bath of mercury, turned slowly while an observer walked beside it reading the fringes, looking for a change in the speed of light with the Earth's direction of travel. The expected shift was about four tenths of a fringe. The observed shift was far smaller.
Morley did not treat the matter as closed. After Michelson moved on, Morley continued aether-drift work for another two decades, from 1902 with the young Dayton C Miller. The Morley–Miller experiments used a lighter and larger apparatus and were run at several sites, including elevated ground at Euclid Heights, on the reasoning that an aether might be partially dragged near the Earth's surface — a possibility a basement laboratory could not distinguish from no aether at all. Their results were small but, on their reading, not zero, and it was this thread that Miller carried up to Mount Wilson and pursued until his death.
On this wiki
Morley appears throughout this collection as half of a name, and the substance of what is disputed about the 1887 experiment is gathered at Michelson–Morley experiment, Michelson interferometer and in the "On this wiki" section of Albert A. Michelson. Three threads bear specifically on Morley himself.
The follow-up experiments. The Morley–Miller runs of 1902–1906, and the altitude reasoning behind them, are the direct ancestor of everything Dayton C Miller later did at Mount Wilson. Contributors here who argue the residuals were physical rather than thermal include Reginald T Cahill and James DeMeo; Flavio Tabanelli treats the three data sets as one continuous body of evidence in "Coherence and Continuity of the Non-Null Experimental Results by Michelson, Morley and Miller", and Jean Pierre Vigier in "Relativistic Interpretation (with Non-Zero Photon Mass) of the Small Ether Drift Velocity Detected by Michelson, Morley and Miller". The mainstream position, following the 1955 Shankland reanalysis, is that the residuals are temperature and statistical artefacts.
What the 1887 result was taken to mean. Shannon F Fowler, "1887 Michelson and Morley Null Result"; Bent Kargaard Nielsen, "The Michelson and Morley Experiment Once Again!"; Mohammad Shafiq Khan, "Michelson-Morley Experiment: A Misconceived & Misinterpreted Experiment"; and Thierry De Mees, "The Great Michelson & Morley, Lorentz and Einstein Trap", all dispute the inference from the fringe data to the non-existence of a medium, on different grounds.
What it does not settle. The 1887 experiment constrains the dependence of light speed on direction. It does not by itself constrain the dependence on speed; that requires the Kennedy-Thorndike experiment. Papers here that account for the Morley data by physical contraction alone leave the second constraint unaddressed.
Morley's own view is worth recording: like Michelson, he did not regard the Aether as disposed of, and he went on looking for it.