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Eugen Goldstein: biography, contributions and discoveries

Eugen Goldstein was a German physicist born in 1850 whose main scientific contribution was the discovery of anode rays, also called channels. His work was also essential for Joseph John Thomson to later present his atomic model, something that Goldstein never did.

Coming from a wealthy family, Goldstein worked at the Berlin Observatory between 1878 and 1890. However, his career developed almost entirely at the Potsdam Observatory, where he served as head of the astrophysics section. In addition, he was a professor of physics at the University of Berlin.

Eugen Goldstein: biography, contributions and discoveries
Eugen Goldstein: biography, contributions and discoveries

His experiments on electric discharges in a vacuum led to the discovery of channel rays. Goldstein presented his work at the Berlin Academy in 1886 and continued his research on the same subject until the early 20th century. His conclusions on the trajectory of these rays led in 1913 to the discovery of isotopes.

The results of these experiments, in addition to other discoveries made, were published in various German magazines. Finally, his articles were gathered for publication in a work called Rayos Canales, in 1830, the same year of his death.


Eugen Goldstein was born on September 5, 1850 in Gleiwitz (the current Polish city of Gliwice), a town then located in Prussian Upper Silesia. His family was dedicated to viticulture, which allowed them to have a very wealthy position.

Hermann von Helmholtz
Hermann von Helmholtz

After studying at the Gymnasium (institute) in Ratibor, in 1869 he entered the University of Breslau. Goldstein later moved to Berlin, at whose university he completed his doctorate under the supervision of the German physicist Hermann von Helmholtz.

Biographical synthesis

Goldstein published his first scientific work in 1876, while the last was published fifty years later. Most of them were dedicated to subjects related to what would be the great interest of their professional life: electric shocks, both in a high vacuum environment and in a moderate one.

The scientist worked at the Berlin observatory between 1878 and 1890. In 1888, he became a professor at the University of Berlin.

Cathophic Ray Tubes, 1890.
Cathophic Ray Tubes, 1890.

With the help of the Academy of Sciences, he conducted a large number of experiments on electric discharges in a vacuum that led to the discovery of channel ratios. His works led him to be awarded the Hughes medal in 1908.

However, most of his professional career was spent at the Potsdam Observatory, Germany. There he held the position of director of the department of astrophysics from 1927. Goldstein also collaborated with the Institute of Technical Physics.

In addition to these scientific activities, Goldstein served as a lawyer on matters related to Jewish immigration, a community of which he was a part.

Eugen Goldstein married at an advanced age, in 1925. Five years later, on December 26, 1930, he died and was buried in the Hebrew Weißensee Cemetery in the city of Berlin.

Eugen Goldstein's grave.
Eugen Goldstein’s grave.

Work and work

Goldstein’s work had as a background the studies carried out by Julius Plücker in the mid-nineteenth century on the light emitted in discharge tubes and the influence that magnetic fields had on glare.

Later, in 1869, Johann Wilhelm Hittorf analyzed the discharge tubes of the energy rays that extend from the cathode, the negative electrode.

Johann Wilhelm Hittorf
Johann Wilhelm Hittorf

Goldsteín had already carried out his own studies on discharge tubes in the 1870s. At that time, he named the light emissions investigated by other scientists as Kathodenstrahlen , or cathode rays.

In 1886, the researcher discovered that perforated cathode discharge tubes also emitted light at the end of the cathode. His conclusion was that, in addition to the already known cathode rays, there were others that moved in the opposite direction, from the negatively charged cathode to the positively charged anode.

The rays discovered by Goldstein passed through the channels of the cathode, which is why they were called kanalstrahlen , or channel rays.

In his time, Goldstein’s find was highly appreciated and became one of the foundations of contemporary physics.

Atomic model of Eugen Goldstein

Despite some confusion on this issue, Goldstein never actually proposed an atomic model of his own. His discoveries, however, were essential for Thomson to develop his.

Something similar happens with the discovery of the proton. Goldstein observed this particle in vacuum tubes during cathode ray experiments, but the scientific community attributes the finding to Ernest Rutherford.

Golsdtein's contributions and discoveries
Golsdtein’s contributions and discoveries

Golsdtein’s contributions and discoveries

Background of his experiments

Goldstein’s first experiments with Crookes tubes were carried out in the 1870s. To do this, the scientist modified the structure that William Crookes had developed decades ago.

The Crookes tube consists of an empty tube made of glass. Gases circulate inside it, the pressure of which can be regulated by moderating the evacuation of the air inside it.

Crookes tube.
Crookes tube.

This structure contains two metal pieces, which act as electrodes. Each of the pieces is located at one end of the tube, both connected to external voltage sources.

When the tube is electrified, the air inside is ionized and becomes a conductor of electricity. This causes the gases to fluoresce by closing the circuit between the two ends.

Crookes claimed that this phenomenon was due to the flow of electrons, which at the time he called cathode rays. Thanks to his experiment, it was possible to demonstrate the existence of negatively charged elementary particles in atoms.

Experiment with modified tubes

In order to carry out his own experiments, Goldstein changed the structure that Crookes had given to his tubes. Thus, he added several perforations to one of the metal cathodes.

Another change was made already during the experiment, when the voltage between the ends of the tube increased by several thousand volts.

The result was a new glow inside the tube, which started from the end where the perforated metal cathode was. However, the highlight was that the new rays were moving in the opposite direction to the cathode ones.

Goldsteín concluded that, in addition to cathode rays, which went from the cathode with a negative charge to the anode with a positive charge, there was another type that traveled in the opposite direction. The scientist called them channel rays.

The behavior of these rays not only differed from the cathode ones in their trajectory. Furthermore, the particles also exhibited opposite behavior in terms of their magnetic field and their electric field.

Goldstein deduced that the electric charge of the channel rays must be the opposite of that of the cathode rays, that is, positive.

Modification of cathode tubes

Eugen Goldstein’s experiments were also essential to learn more about technical notions about cathode rays.

Thanks to his experiments with the empty tubes, the scientist discovered that cathode rays could cast sharp shadows in a direction perpendicular to the area covered by the cathode.

This finding was very useful to be able to modify the design of the cathode tubes that were used until that moment. Thus, concave cathodes could be placed in their corners, in such a way that focused rays appeared. This technique later had a great variety of applications.

On the other hand, channel rays, also called anodic rays or positive rays, depend directly on the physical and chemical characteristics of the gas that is introduced inside the tube.

Among other aspects, the relationship between the mass of the particles and the electrical charge is different depending on the nature of the gas used.

This differentiating factor made it possible to clarify the fact that the particles came out of the interior of the gas, instead of the anode of the electrified tube.

First steps in the discovery of the proton

Although his discovery is sometimes credited to him, Goldstein was only responsible for laying the foundation that led to the confirmation of the existence of positively charged fundamental particles.

Goldstein's experiment
Goldstein’s experiment

In his experiments with modified cathode ray tubes, the scientist observed rays passing through the cathode in the opposite direction to cathode rays.

After studying channel rays, the name given to this new type of ray, Goldstein determined that they were made up of positively charged particles and that their mass was different depending on the gas used.

However, the discovery of the proton was made decades later, when British chemist and physicist Ernest Rutherford conducted similar experiments with nitrogen.

Foundations of modern physics

In addition to the concrete results of his experiments, Goldstein contributed with them the foundations of modern physics. In this way, the discovery of channel rays confirmed the idea that atoms moved with a specific pattern and at great speed.

Both ideas were key to the development of current atomic physics, the field of physics that analyzes the properties and behavior of atoms in all their aspects.

Among other aspects, Goldstein’s work was fundamental for the study of isotopes, in addition to its contribution to other scientific applications that are still in full force today.

Published works

For several decades, Goldstein’s studies appeared in various magazines. Among the most important are Ueber die Reflexion elektrischer Strahlen (1882); Ueber elektrische Leitung im Vakuum (1885); Ueber die durch Kathodenstrahlen hervorgerufenen Färbungen einiger Salze (1897); and Ueber eine noch nicht untersuchte Strahlungsform an der Kathode induzierter Entladungen (1898).

In the same year of his death, 1930, all his writings were brought together to be published in a single volume . The work received the title of Channel Rays.

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