Adolfo Bartoli (19 March 1851 – 18 July 1896) 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 cau ...

, who is best known for introducing the concept of

radiation pressure Radiation pressure (also known as light pressure) is mechanical pressure exerted upon a surface due to the exchange of momentum between the object and the electromagnetic field. This includes the momentum of light or electromagnetic radiation of ...

from thermodynamical considerations. Born in

Florence Florence ( ; ) is the capital city of the Italy, Italian region of Tuscany. It is also the most populated city in Tuscany, with 362,353 inhabitants, and 989,460 in Metropolitan City of Florence, its metropolitan province as of 2025. Florence ...

, Bartoli studied

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

and

mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

at the

University of Pisa The University of Pisa (, UniPi) is a public university, public research university in Pisa, Italy. Founded in 1343, it is one of the oldest universities in Europe. Together with Scuola Normale Superiore di Pisa and Sant'Anna School of Advanced S ...

until 1874. He was a professor of physics at the Technical Institute of

Arezzo Arezzo ( , ; ) is a city and ''comune'' in Italy and the capital of the Province of Arezzo, province of the same name located in Tuscany. Arezzo is about southeast of Florence at an elevation of Above mean sea level, above sea level. As of 2 ...

from 1876, at the

University of Sassari The University of Sassari (, UniSS) is a public university located in Sassari, Italy. It was founded in 1562 and is organized in 13 departments. The University of Sassari earned first place in the rankings for the best “medium-sized” Italian ...

from 1878, at the Technical Institute of Firenze from 1879, at the

University of Catania The University of Catania () is a university located in Catania, Sicily. Founded in 1434, it is the oldest university in Sicily, the 13th oldest in Italy, and the 29th oldest in the world. With over 38,000 enrolled students, it is the largest uni ...

from 1886 to 1893, and at the

University of Pavia The University of Pavia (, UNIPV or ''Università di Pavia''; ) is a university located in Pavia, Lombardy, Italy. There was evidence of teaching as early as 1361, making it one of the List of oldest universities in continuous operation, oldest un ...

from 1893. In 1874

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

found out that the existence of tensions in the ether, in other words

, follows from his

electromagnetic theory In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interact ...

. In 1876 Bartoli derived the existence of radiation pressure from

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 ...

, and his derivation influenced Boltzmann. Like how the thermodynamics of gas is independent of microscopic details of what gas is, his derivation does not depend on a theory of what light is, such as Maxwell's electromagnetism. In contrast, Maxwell predicted radiation pressure directly from his theory of electromagnetism. Therefore, radiation pressure was also called "Maxwell-Bartoli pressure". Later the radiation pressure played an important role in the work of

Albert Einstein Albert Einstein (14 March 187918 April 1955) was a German-born theoretical physicist who is best known for developing the theory of relativity. Einstein also made important contributions to quantum mechanics. His mass–energy equivalence f ...

in connection with

mass–energy equivalence In physics, mass–energy equivalence is the relationship between mass and energy in a system's rest frame. The two differ only by a multiplicative constant and the units of measurement. The principle is described by the physicist Albert Einstei ...

and the

photoelectric effect The photoelectric effect is the emission of electrons from a material caused by electromagnetic radiation such as ultraviolet light. Electrons emitted in this manner are called photoelectrons. The phenomenon is studied in condensed matter physi ...

. Einstein lived in

Pavia Pavia ( , ; ; ; ; ) is a town and comune of south-western Lombardy, in Northern Italy, south of Milan on the lower Ticino (river), Ticino near its confluence with the Po (river), Po. It has a population of c. 73,086. The city was a major polit ...

at that time (1895), when Bartoli held the Physics chair at the local University. However, it is unknown whether Einstein was directly influenced by Bartoli. Bartoli died in

in 1896.

Bartoli's argument for radiation pressure

Consider a perfectly reflexive piston with a mirror in the middle, and two black bodies connected to two heat baths at its two ends. One body is hot at temperature

T_1

, and the other is cold at temperature

T_0

. Now, consider the following heat-engine cycle: * Move the mirror towards the hot body. The hot body would be forced to absorb photons, while the cold body would be forced to emit more photons to fill the space. * Insert another mirror in the middle. * Remove the first mirror, and wait for the radiation trapped between the two mirrors to reach equilibrium with the hot body. With one cycle, we have pumped energy away from the cold body. Since the energy has nowhere else to go, it must have ended up in the hot body. If light has no pressure, then this transports

energy Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and l ...

from a colder to a hotter body. To avoid this violation of the second law of thermodynamics, it is necessary that light imparts pressure to the mirror.

Selected publications

* with G. Poloni: * * * * with E. Stracciati: * with E. Stracciati: * with E. Stracciati: * * with E. Stracciati: * * * with E. Stracciati & G. Raffo:

References

External links

* Paths of Physics
Anthology of Italian Physics - Adolfo Bartoli
* Mathpages

* Bevilacqua, Bordoni, Fregonese

{{DEFAULTSORT:Bartoli, Adolfo 1851 births 1896 deaths Scientists from Florence 19th-century Italian physicists University of Pisa alumni Academic staff of the University of Sassari Academic staff of the University of Catania Academic staff of the University of Pavia