Eugen Goldstein, his discovery of canal rays which led to the discovery of isotopes

Retrato Eugen Goldstein

September 5, 1850, Gliwice (Kingdom of Prussia, now Poland) – December 26, 1930, Berlin (Weimar Republic, now Germany)

He worked at the Potsdam Observatory (Germany) where, in 1927, he became head of the Astrophysics section, he collaborated with the Berlin Observatory (Germany) from 1878 to 1890 and from 1888 he was professor of physics at the University of Berlin.

With the support of the German Academy of Sciences, he carried out numerous experiments on electric discharges in a vacuum that led to the discovery of canal rays, which he first reported to the Berlin Academy in 1886, and continued his research on the same theme until about 1915.

Goldstein observed that, when an electric discharge was produced in a tube containing a rarefied gas, using as a negative electrode (cathode) a metal sheet normal to the axis of the tube and provided with small holes, bright rectilinear lines directed towards to the part opposite to that occupied by the positive electrode (anode). If the gas contained in the tube was air, the stripes were yellow.

Eugen Goldstein_Rayos Catodicos

The rectilinear shape suggested rays that spread in a straight line, which is why Goldstein gave them the name of channel rays. This curious name should have been temporary, pending further study of the nature of the phenomenon, but its use has been imposed and it has become an international scientific vocabulary.

Goldstein postulated that he excluded that the beams could be particles of matter charged with electricity and launched at high speeds because he believed that two beams of canal rays could cross each other without getting in the way and because they did not seem to be influenced by electric or magnetic fields. Over time and more studies it was shown that he was wrong since it is known that the rays are made up of particles whose weight is of the order of an atom and that, formed in the vicinity of the cathode, pass through the small holes at very high speeds and continue to propagate in straight line by inertia.

His discovery was well received in his time and was one of the bases for the construction of contemporary physics. Thanks to the channel rays, swarms of atoms in rapid and orderly movement were available for the first time, the application of which would be very productive in various branches of atomic physics. For example, the study of the paths of such rays would lead Joseph John Thomson and Francis Aston to the discovery of isotopes in 1913.

Access to the best


on Energy and Environment
Go to resources