Goldstein, E
NAME: Goldstein, Eugen
ACHIEVEMENT(S): Cathode rays
NICKNAME/ALIAS: None
DATE/PLACE OF BIRTH: 5 September 1850, at Gleiwitz, Upper Silesia (now
Gliwice, Poland)
DATE/PLACE/AGE AT DEATH: 25 December 1930, in Berlin, Germany. Aged 80
DISCIPLINE: Physicist
FIELD: Physics
LANGUAGE: German
PARENTS: Julius Goldstein and Bertha Neumann
SIBLINGS: Unknown
SPOUSE: Laura Kempe
CHILDREN: Unknown
EDUCATION: Ratibor Gymnasium, 1862-69; University of Breslau, 1869-70;
University of Berlin, 1870-81
MAJOR WORK: 'Uber eine noch nicht untersuchte Strahlungsform an der Kathode
inducirter Entladungen', 1886
LIFE AND TIMES: At the University of Berlin Goldstein worked with the physicist and physiologist <assistant to> Helmholtz* first as his student and then as his assistant. From 1871, Goldstein made a series of experiments on electrical discharges in gases, and coined the name “cathode ray” to explain the glow first observed in a vacuum tube by <explained glow seen by> Plucker* in 1858.
In 1876 he published his first paper on this work, in which he demonstrated that cathode rays could cast sharp shadows and that the rays are emitted at right angles to the cathode surface.
He then made a concave cathode to produce concentrated or focused rays, an instrument which proved fundamental to a wide range of new and useful experiments.
In 1878, at the Potsdam Observatory, Goldstein continued his investigations into cathode rays, and conducted a series of experiments which demonstrated how they could be deflected by magnetic fields (a phenomenon first discovered by Julius Plucker and <proved theory of> Hittorf*, and later investigated by <work developed by> Lenard*).
The idea then prevailing among German physicists was that the rays consisted of some form of electromagnetic radiation, or waves (not unlike light), while many British physicists - including <work related to> Crookes*, who suggested in the 1879 that the rays were charged "molecular torrents" rebounding from the cathode - thought that the rays were streams of negative particles.
Although his work during the 1870s had cast some doubt on the German view, in 1880 Goldstein conducted a series of experiments to counter Crookes' ideas, and show that cathode rays emitted light that showed little if any Doppler shift.
(P.G. Tait had pointed out that year that if cathode rays were molecules travelling at high speed, then the light emitted by these molecules should be shifted, by the <work related to> Doppler* effect, to wavelengths higher or lower than that which they ordinarily emitted).
Goldstein's many contributions aided the conclusion, made eventually by <anticipated> J.J. Thomson* in 1897, that cathode rays were fast moving negative particles, or electrons.
In the course of his continued investigations during the 1880s, Goldstein studied many different arrangements of anode and cathode discharge circuits. In an experiment of 1886, he perforated the anode and observed glowing yellow streamers behind the anode coming from the perforations. Since the rays were to the holes or channels, he named them “canal rays”, and showed that they always moved away from the anode.
In 1898, Goldstein's student, Wilhelm Wien, showed by a series of experiments that these canal rays could be deflected by electric and magnetic fields in such a way that they appeared to be positively charged. Wien also calculated the charge-to-mass ratio of the rays, and found this to be approximately 10,000 times greater than the corresponding ratio for cathode rays.
In 1911, J.J. Thomson named them “positive” rays and, by a series of investigations, led the way to their identification as ionized molecules or atoms of the gaseous contents of the discharge tube. From his detection of different charge-to-mass ratios in tubes with different contents, Thomson concluded that the different contents had formed different positive ions, and this research was then continued by Francis W. Aston, who in 1919 developed the mass spectrograph to separate positive rays.
In 1905, another of Goldstein's students, Johannes Stark, used light from canal rays to demonstrate for the first time an optical Doppler shift in a terrestrial, rather than a stellar, source of light.
During this period, Goldstein himself continued to publish papers on various canal-ray topics, including studies of the wavelengths of light emitted by various metals and oxides when struck by canal rays, during which he discovered that the alkali metals, when hit by the rays, emit their characteristic bright spectral lines. He also found that a constriction in a discharge tube could function as a source of positive rays.
Goldstein’s last paper, published in 1928, reported a significant new discovery, which as for a long period largely ignored, that in a discharge tube containing nitrogen and hydrogen and possibly other gases, Goldstein observed that a trace of ammonia was
present after the discharge.
More than 30 years later, investigations along these lines were begun in order to test if biologically important molecules (and so, life) could have originated in this way.
ASSESSMENT: His identification of cathode rays greatly advanced the study of physics.
EXTRA CONNECTIONS: He influenced the work of <influenced> Roentgen*
ONELINER: Eugen Goldstein, who named cathode rays
BIBLIOGRAPHY: DSB, EB
Anderson, David L., The Discovery of the Electron, Princeton, New Jersey: D. van Nostrand Company Inc., 1964
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