Thomson, Joseph John

1995/08/02 Azkune Mendia, Iñaki - Elhuyar Fundazioa | Kaltzada, Pili - Elhuyar Zientziaren Komunikazioa

• Biografiak

(1856-1940)

British physicist born in Cheetham Hille, near Manchester on December 18, 1856. At the age of fourteen he begins school engineering studies in Manchester, but soon he is given the tendency to physics.

In 1876 he travelled to Cambridge with a fellowship and there he spent the years until his death. He finished his career as a mathematician. Then in 1884, when he was only twenty-six, he was professor of physics for the retirement of John Rayleigh. He took responsibility for the Cavendish laboratory and was a good director in subatomic physics in the twentieth century. At the beginning of the twentieth century Britain was a pioneer.

Thomson began working on the theory of Maxwell's electromagnetic radiations and from there he reached cathodic rays. These rays were a new form of radiation, since they were not electromagnetic. William Crookes and other physicists showed that cathodic rays were negatively charged particles, since the magnetic field diverted the rays. This test was not complete. For this purpose, the electric field also had to divert the rays if they were formed by really charged particles.

Thomson demonstrated in 1897 that the electric field diverted cathodic rays using the tubes with the most perfect failure possible. Since then, cathodic rays have been considered to be negatively charged particles. Thomson also measured the relationship between the load and mass of the particles of cathodic rays.

According to Faraday's electrochemical laws, if the electric charge was the minimum of the ions, the mass of the particle of the cathodic rays was much lower than that of the hydrogen atom. Therefore, the particles of the cathodic rays were much smaller than the atoms, and for the first time we could start talking about subatomic particles.

These subatomic particles were accepted as electric current units. George Stoney had proposed the word electron for the hypothetical electrical unit and Hendrik Lorentz applied it to the particles of cathodic rays. As the last essay to demonstrate the presence of these particles in cathodic rays was conducted by Thomson, who showed that the size of the particles was less and less than the atom, the discovery of the electron is attributed to Thomson. Today we also know that the mass of the electron is 1,837 times smaller than that of the hydrogen atom.

For Thomson the electron was a universal component of matter, so he formulated one of the first theories on the internal structure of the atom. For Thomson the atom was a sphere of positive electricity in which negative electrons were located neutralizing the positive charge. This initial theory was soon replaced by another devised by Ernest Rutherford, a student of Thomson. Rutherford's theory was, logically, more complete and useful.

In 1906 Thomson received the Nobel Prize in Physics for his work with the electron. In 1908 he obtained the title of Sir. In the field of the awards it must be said that Thomson taught famous students and seven of them were to receive the Nobel Prize.

Since 1906 he took over the Thomson ray channels, the rays that Eugen Goldstein found twenty years earlier. By forming a positively charged ion flow, he called them positive rays.

Thomson diverted these channels by magnetic and electric fields. The ions with different load/mass ratio printed different aspects of the photographic plate. In 1912 he was able to verify that the ions of the neon gas fell to two different points, as if it were a mixture of ions of two types: the charge, the mass or both, as a mixture of different ions. Frederick Soddy suggested there could be isotopes. Isotopes are atoms whose mass is exclusively atomic.

Thomson collected in his essay the traces of what the neon could contain isotopes. Later, his student Francis William Aston gave continuity to these investigations, demonstrating clearly the existence of isotopes.

Thomson was you on August 30, 1940 at Cambridge, the eve of the famous battle of England. His body was buried at Westminster Abbey, next to Newton's tomb.