Ștefan Procopiu (; January 19, 1890 – August 22, 1972) was a

Romania Romania is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern and Southeast Europe. It borders Ukraine to the north and east, Hungary to the west, Serbia to the southwest, Bulgaria to the south, Moldova to ...

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

and a titular member of the

Romanian Academy The Romanian Academy ( ) is a cultural forum founded in Bucharest, Romania, in 1866. It covers the scientific, artistic and literary domains. The academy has 181 active members who are elected for life. According to its bylaws, the academy's ma ...

Biography

Procopiu was born in 1890 in

Bârlad Bârlad () is a city in Vaslui County, Romania. It lies on the banks of the river Bârlad (river), Bârlad, which waters the high plains of Western Moldavia. At Bârlad the railway from Iași diverges, one branch skirting the river Siret (river ...

. His father, Emanoil Procopiu, was employed at the Bârlad courthouse. His mother, Ecaterina Tașcă, was the sister of Gheorghe Tașcă (see Tașcă family). He attended the Gheorghe Roșca Codreanu High School in Bârlad from 1901 to 1908, continuing his studies at the Faculty of Sciences of the University of Iași from 1908 to 1912. After graduation he became assistant to Professor Dragomir Hurmuzescu.Diana Iane – Ștefan Procopiu
/ref> In 1919 he obtained a scholarship to continue his studies at the

University of Paris The University of Paris (), known Metonymy, metonymically as the Sorbonne (), was the leading university in Paris, France, from 1150 to 1970, except for 1793–1806 during the French Revolution. Emerging around 1150 as a corporation associated wit ...

, attending courses of famous scientists, such as

Gabriel Lippmann Gabriel Lippmann ( ; 16 August 1845 – 12 July 1921) was a French physicist who received the Nobel Prize in Physics in 1908 "for his method of reproducing colours photographically based on the phenomenon of interference". Early life and educa ...

Marie Curie Maria Salomea Skłodowska-Curie (; ; 7 November 1867 – 4 July 1934), known simply as Marie Curie ( ; ), was a Polish and naturalised-French physicist and chemist who conducted pioneering research on radioactivity. She was List of female ...

Paul Langevin Paul Langevin (23 January 1872 – 19 December 1946) was a French physicist who developed Langevin dynamics and the Langevin equation. He was one of the founders of the '' Comité de vigilance des intellectuels antifascistes'', an anti-fascist ...

, and Aimé Cotton. On 5 March 1924, Procopiu obtained the title of doctor in physics with the thesis "On the electric birefringence of suspensions" presented to a commission including professor Aimé Cotton as coordinator and Charles Fabry and Henri Mouton as cross-examiners.Mihai Olteneanu Ștefan I. Procopiu 1890 – 1972
/ref> After his return to Romania on January 15, 1925, professor of the

gravitation In physics, gravity (), also known as gravitation or a gravitational interaction, is a fundamental interaction, a mutual attraction between all massive particles. On Earth, gravity takes a slightly different meaning: the observed force b ...

heat In thermodynamics, heat is energy in transfer between a thermodynamic system and its surroundings by such mechanisms as thermal conduction, electromagnetic radiation, and friction, which are microscopic in nature, involving sub-atomic, ato ...

and

electricity Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

department of the University of Iași, replacing his former teacher Dragomir Hurmuzescu, who had retired., Procopiu coordinated the department until his retirement in 1962.Ștefan Procopiu (1890—1972)
/ref> At the same time he was appointed professor at the Gheorghe Asachi Polytechnic Institute of Iași In 1939 Ștefan Procopiu published his

treatise A treatise is a Formality, formal and systematic written discourse on some subject concerned with investigating or exposing the main principles of the subject and its conclusions."mwod:treatise, Treatise." Merriam-Webster Online Dictionary. Acc ...

on "

Electricity Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

and

Magnetism Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, ...

", followed in 1948 by his monography on “

Thermodynamics Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed b ...

”. In June 1948 he was appointed corresponding member of the

, being promoted to full membership on July 2, 1955. In 1964 he was awarded the Romanian State Prize. He was also decorated with the Order of Work (Ordinul Muncii),

Order of the Star of Romania The Order of the Star of Romania (Romanian: ''Ordinul Steaua României'') is Romania's highest civil Order and second highest State decoration after the Order of Michael the Brave. It is the oldest Order of Romania. It is awarded by the Preside ...

, and the Order of Scientific Merit. Procopiu was also selected twice as member in the Commission for the award of the

Nobel Prize The Nobel Prizes ( ; ; ) are awards administered by the Nobel Foundation and granted in accordance with the principle of "for the greatest benefit to humankind". The prizes were first awarded in 1901, marking the fifth anniversary of Alfred N ...

. Procopiu was also deeply involved in the cultural life of the city of Iași. He was an active member of the

board of directors A board of directors is a governing body that supervises the activities of a business, a nonprofit organization, or a government agency. The powers, duties, and responsibilities of a board of directors are determined by government regulatio ...

of the Vasile Alecsandri National Theatre. He died on August 22, 1972, in

Iași Iași ( , , ; also known by other #Etymology and names, alternative names), also referred to mostly historically as Jassy ( , ), is the Cities in Romania, third largest city in Romania and the seat of Iași County. Located in the historical ...

, at the age of 82 and was buried in the city's Eternitatea Cemetery.

Scientific activity

Ștefan Procopiu started scientific research even before graduating. He continued this activity while he was assistant professor.

The magnetic moment of the electron

The first important paper by Ștefan Procopiu is "Determining the Molecular Magnetic Moment by M. Planck’s Quantum Theory". After studying Planck’s quantum theory and Langevin’s magnetism theory, he established the

magnetic moment In electromagnetism, the magnetic moment or magnetic dipole moment is the combination of strength and orientation of a magnet or other object or system that exerts a magnetic field. The magnetic dipole moment of an object determines the magnitude ...

of the electron and determined the

physical constant A physical constant, sometimes fundamental physical constant or universal constant, is a physical quantity that cannot be explained by a theory and therefore must be measured experimentally. It is distinct from a mathematical constant, which has a ...

, named magneton.Ștefan Procopiu – ''Determining the Molecular Magnetic Moment by M. Planck’s Quantum Theory'' - Bulletin scientifique de l’Académie roumaine de sciences, Bucharest, 1913 Ștefan Procopiu published his results two years before

Niels Bohr Niels Henrik David Bohr (, ; ; 7 October 1885 – 18 November 1962) was a Danish theoretical physicist who made foundational contributions to understanding atomic structure and old quantum theory, quantum theory, for which he received the No ...

made the same discovery independently.Procopiu, Ștefan (1890–1972)
/ref> Continuing his studies, in 1954 he established a method for the experimental determination of the magneton, which he improved in 1963.
/ref>

Other research before and during World War I

Ștefan Procopiu also worked on wireless communications and in 1913 published a paper on “Experimental Research on Wireless Telegraphy”. In 1916 he invented a device for locating and establishing the depth of bullets in the bodies of the wounded soldiers.

Longitudinal depolarization of light

In 1921, Procopiu discovered and analyzed in the Physics Laboratory of

Sorbonne University Sorbonne University () is a public research university located in Paris, France. The institution's legacy reaches back to the Middle Ages in 1257 when Sorbonne College was established by Robert de Sorbon as a constituent college of the Unive ...

a new optical phenomenon which consisted in the longitudinal depolarization of light by suspensions and colloids. In 1930, the occurrence was designated as "Procopiu Phenomenon" by . Part of this research was included in Procopiu's doctoral thesis.

Electromotive force of galvanic elements

Thus, in 1930, studying the Barkhausen effect, Ștefan Procopiu discovered a circular effect of magnetic discontinuity. In 1951, this effect was named Procopiu Effect. This discovery had important applications in the development of the

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembe ...

computers A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations ('' computation''). Modern digital electronic computers can perform generic sets of operations known as ''programs'', ...

Studies of the Earth's magnetic field

Earth’s magnetism was a continuous concern of Ștefan Procopiu, For 25 years he studied this

phenomenon A phenomenon ( phenomena), sometimes spelled phaenomenon, is an observable Event (philosophy), event. The term came into its modern Philosophy, philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be ...

in Romania and developed the magnetic maps of the country. He also identified the

magnetic anomaly In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying ...

located on the

- Botoșani railway line. In 1947, Procopiu identified a variation of the

Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from structure of Earth, Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from ...

, with a periodicity of approximately 500 years, indicating that, starting 1932 Earth's

increases from the

equator The equator is the circle of latitude that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern Hemispheres of Earth, hemispheres. It is an imaginary line located at 0 degrees latitude, about in circumferen ...

to the

poles Pole or poles may refer to: People *Poles (people), another term for Polish people, from the country of Poland * Pole (surname), including a list of people with the name * Pole (musician) (Stefan Betke, born 1967), German electronic music artist ...

Main works

Library of Congress

References

{{DEFAULTSORT:Procopiu, Stefan 1890 births 1972 deaths People from Bârlad Gheorghe Roșca Codreanu National College alumni Alexandru Ioan Cuza University alumni University of Paris alumni Academic staff of Alexandru Ioan Cuza University Romanian physicists 20th-century Romanian inventors Titular members of the Romanian Academy Recipients of the Order of the Star of Romania Members of the Romanian Academy of Sciences Burials at Eternitatea cemetery