Blas Cabrera y Felipe, a renowned physicist in the field of magnetism
Blas Cabrera y Felipe was born on 20 May 1878 in Arrecife, capital of the Canary Island of Lanzarote. He was the eldest of eight children, one of whom, José Cabrera, was an engineer and directed the construction of the first Spanish nuclear power station, which, although it bears his name, is better known as Zorita, after the town in which it is located.
In 1881, the family moved to the city of La Laguna, on the island of Tenerife, where he went to school and high school, and met the love of his life, María Sánchez Real, whom he would marry in 1906 and have three children.
In 1894, he travelled to Madrid to study law, following the family tradition, but he began to attend the gatherings at the Café Suizo, where he met Santiago Ramón y Cajal and decided to switch to science, graduating in 1898 with a degree in Physics and Mathematics from the Central University of Madrid, now the Complutense University. In 1901, he obtained his doctorate in Physical Sciences at this same University; in 1905, he became a professor of Electricity and Magnetism; and in 1931 he was appointed rector.
Blas Cabrera was above all an experimental physicist and developed his greatest activity in the field of the magnetic properties of matter, achieving a singular position in the physics of his time. In 1903 he participated in the founding of the Spanish Society of Physics and Chemistry and the Annals of this Society, where he published his first works, on 7 April 1909, he was elected member of the Royal Academy of Exact, Physical and Natural Sciences, where he held Medal number 22.
In 1910, the Junta para Ampliación de Estudios e Investigaciones Científicas (JAE), an institution created in 1907 to promote scientific research and education in Spain, appointed him director of the recently created Laboratorio de Investigaciones Físicas.
In 1912, with the support of the Junta para Ampliación de Estudios, he travelled to Zurich (Switzerland) to learn the most advanced techniques in magnetism in the laboratories of the great scholar of the time, Pierre Weiss, where he met Albert Einstein. Although he had not applied for enrolment and the laboratory was full, his merit led Professor Weiss to admit him. In 1919, Weiss was appointed director of the Institute of Physics at the University of Strasbourg and Cabrera went with him. The collaboration between the two scientists would last for more than two decades.
He also visited the physics laboratories of the universities of Geneva and Heidelberg as well as the International Bureau of Weights and Measures in Paris (France).
Cabrera's work was recognised internationally, and he was the host of Albert Einstein on his visit to Spain in 1923.
In 1928, he was elected member of the French Academy of Sciences, and received the greatest recognition of his entire career: proposed by Albert Einstein and Marie Curie, he was appointed member of the Scientific Committee of the VI Solvay Conference, the triennial meeting that brought together the most brilliant minds of the time: Schrödinger, Planck, Dirac, Lorentz, Rutherford, Heisenberg, Born....
This conference was held in 1930, the main theme of which was the Spanish physicist's speciality: magnetism. In the official photograph of the participants of the 6th Solvay Congress, Blas Cabrera appears in the front row, third from the right, seated next to Bohr. Albert Einstein and Marie Curie are also there.
His work reached the United States and the Rockefeller Foundation subsidised the creation of the National Institute of Physics and Chemistry with 420,000 dollars. The building christened the Rockefeller Building, was inaugurated in February 1932 and is now occupied by the Rocasolano Institute of Chemistry-Physics of the Spanish National Research Council (CSIC).
In 1933 he was appointed secretary of the International Committee of Weights and Measures based in Paris (France). That same year he took part in the VII Solvay Conference, dedicated on that occasion to the structure of the atomic nucleus, and also participated in the creation of the Santander International Summer University - currently the Menéndez Pelayo International University - a centre of which he was appointed rector the following year.
Cabrera's research work was remarkable. Between 1910 and 1934 he published some one hundred and ten papers, to the point that Pierre Weiss, then director of the Institute of Physics at the University of Strasbourg, commented in 1932 that of the 180 articles on magnetism in the institute's library, 24 came from the Physical Research Laboratory directed by Cabrera.
He established what is called the Cabrera Curve, a law describing the variations in the periodic system of elements in the magnetic moments of atoms of the iron family. He also modified the Curie-Weiss Law, which describes the magnetic susceptibility of a ferromagnetic material in the paramagnetic region beyond the Curie point and derived an equation to describe the magnetic moment of the atom taking into account the effect of temperature. He also improved many experimental devices.
He was the first scientist in Spain to use the methods of error theory and least squares to determine physical constants. Some of his magnetic susceptibility measurements are still the most accurate in existence today.
In 1936, while in Santander, the Civil War broke out and he went to France and from there returned to Madrid, but the atmosphere in the city was not the most favourable for science, and at the end of 1936 Cabrera left Spain for good and settled in Paris.
In 1937, he was appointed secretary of the International Bureau of Weights and Measures, a post he would hold until 1941, and once again participated in the organisation of the 8th Solvay Conference on elementary particles and their interactions, although this was finally suspended as a result of the Second World War.
In February 1939 he was dismissed by Ministerial Order as a professor, along with other colleagues, and in 1941 he was stripped of the awards he had received from the Royal Academy of Exact, Physical and Natural Sciences, along with five other scientists linked to the Second Republic. On 20 December 2018, the Spanish Council of Ministers restored all his academic honours.
He went into exile in Mexico, where he worked as a professor of Atomic Physics and History of Physics at the Faculty of Sciences of the National Autonomous University of Mexico, in 1944 he began to edit the journal Ciencia, published by exiled Spanish scientists.
He died on 1 August 1945 in Mexico of Parkinson's disease, without his wishes to return to Spain and rejoin his longed-for National Institute of Physics and Chemistry being fulfilled.
On 12 October 2022, his remains and those of his family will be repatriated from Mexico to the city of San Cristóbal de La Laguna, the city where he lived.
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