Giovanni Giorgi (November 27, 1871 – August 19, 1950) was an Italian

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 ca ...

and

electrical engineer Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the ...

who proposed the ''Giorgi system'' of measurement, the precursor to the International System of Units (SI).

Early Life

Giovanni Giorgi was born in

Lucca Lucca ( , ) is a city and ''comune'' in Tuscany, Central Italy, on the Serchio River, in a fertile plain near the Ligurian Sea. The city has a population of about 89,000, while its province has a population of 383,957. Lucca is known as ...

on November 27, 1871.

Career

Giorgi studied

engineering Engineering is the use of scientific method, scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad rang ...

at the Institute of Technology of Rome, he worked at Fornaci Giorgi in

Ferentino Ferentino is a town and ''comune'' in Italy, in the province of Frosinone, Lazio, southeast of Rome. It is situated on a hill above sea level, in the Monti Ernici area. History ''Ferentinum'' was a town of the Hernici; it was captured from th ...

, then was the director of the Technology Office of Rome between 1906 and 1923. He also taught at the University of Rome between 1913 and 1939. During

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

he moved to

. He was an Invited Speaker of the ICM in 1924 in Toronto, in 1928 in Bologna, and in 1932 in Zurich.

Personal life

He was engaged to Laura Pisati, his former master's student who became the first woman invited to deliver a lecture at the fourth

International Congress of Mathematicians The International Congress of Mathematicians (ICM) is the largest conference for the topic of mathematics. It meets once every four years, hosted by the International Mathematical Union (IMU). The Fields Medals, the Nevanlinna Prize (to be rename ...

(ICM), but she died in 1908 shortly before both her talk and their intended wedding.

Death

Giorgi died on August 19, 1950, in Castiglioncello, Livorno at the age of 78.

The ''Giorgi system''

Toward the end of the 19th century, after

James Clerk Maxwell James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematician and scientist responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism and ligh ...

's discoveries, it was clear that electric measurements could not be explained in terms of the three base units of length, mass and time, and that some irrational coefficients appeared in the equations without any logical physical reason. In 1901, Giorgi proposed to the (AEI) that the MKS system (which used the

metre The metre ( British spelling) or meter ( American spelling; see spelling differences) (from the French unit , from the Greek noun , "measure"), symbol m, is the primary unit of length in the International System of Units (SI), though its p ...

kilogram The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially ...

and second as its base units) should be extended with a fourth unit to be chosen from the units of

electromagnetism In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions o ...

, solving also the presence of the irrational coefficients. In 1935 this was adopted by the

International Electrotechnical Commission The International Electrotechnical Commission (IEC; in French: ''Commission électrotechnique internationale'') is an international standards organization that prepares and publishes international standards for all electrical, electronic and ...

(IEC) as the ''M.K.S. System of Giorgi'' without specifying which electromagnetic unit would be the fourth base unit. In 1946 the

International Committee for Weights and Measures The General Conference on Weights and Measures (GCWM; french: Conférence générale des poids et mesures, CGPM) is the supreme authority of the International Bureau of Weights and Measures (BIPM), the intergovernmental organization established ...

(CIPM) approved a proposal to use the

ampere The ampere (, ; symbol: A), often Clipping (morphology), shortened to amp,SI supports only the use of symbols and deprecates the use of abbreviations for units. is the unit of electric current in the International System of Units (SI). One amp ...

as that unit in a four-dimensional system, the MKSA system. The ''Giorgi system'' was thus the precursor of the International System of Units (SI) adopted in 1960, which was based on six base units: metre, kilogram, second, ampere,

kelvin The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based engineer and ph ...

, and

candela The candela ( or ; symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous t ...

. The mole was added as a seventh base unit in 1971.

Works

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Notes

References

# # {{DEFAULTSORT:Giorgi, Giovanni 1871 births 1950 deaths Italian electrical engineers 20th-century Italian physicists Metrologists nl:Giovanni Giorgi