## Benjamin Thompson

Sir Benjamin Thompson, Count Rumford (British-American; March 26, 1753 – August 21, 1814) Physicist and inventor whose challenges to established physical theory were part of the 19th century revolution in thermodynamics. Rumford began the quantitative study of the conversion of work into heat by means of his famous cannon-boring experiments. Read more...

## Humphry Davy

Sir Humphry Davy (English; 17 December 1778 – 29 May 1829) Famous for many works including his ice rubbing experiment in which he rubbed two pieces of ice (inside of parallelepiped), stated by some to have occurred in a vacuum, located inside of a room colder than the freezing point of water, together, vigorously, to see if he could generate heat by friction, an idea contrary to the then-prevalent 'caloric theory' of the time. The significance of Davy’s ice-rubbing experiment helped to prove that heat was a mode of motion. Read more...

## Nicolas Léonard Sadi Carnot

Nicolas Léonard Sadi Carnot (French; 1 June 1796 – 24 August 1832) Military engineer and physicist, often described as the "father of thermodynamics". In his only publication, the 1824 monograph Reflections on the Motive Power of Fire, Carnot gave the first successful theory of the maximum efficiency of heat engines. Carnot's work attracted little attention during his lifetime, but it was later used by Rudolf Clausius and Lord Kelvin to formalize the second law of thermodynamics and define the concept of entropy. Read more...

## Julius von Mayer

Julius Robert von Mayer (German; November 25, 1814 – March 20, 1878) Physician and physicist and one of the founders of thermodynamics. He is best known for enunciating in 1841 one of the original statements of the conservation of energy or what is now known as one of the first versions of the first law of thermodynamics, namely that "energy can be neither created nor destroyed." In 1842, Mayer described the vital chemical process now referred to as oxidation as the primary source of energy for any living creature. His achievements were overlooked and priority for the discovery of the mechanical equivalent of heat was attributed to James Joule in the following year. He also proposed that plants convert light into chemical energy. Read more...

## Hermann von Helmholtz

Hermann Ludwig Ferdinand von Helmholtz (German; August 31, 1821 – September 8, 1894) Physician and physicist who made significant contributions to several widely varied areas of modern science. In physics, he is known for his theories on the conservation of energy, work in electrodynamics, chemical thermodynamics, and on a mechanical foundation of thermodynamics. The largest German association of research institutions, the Helmholtz Association, is named after him. Read more...

## Rudolf Clausius

Rudolf Julius Emanuel Clausius (German; 2 January 1822 – 24 August 1888) Physicist and mathematician and is considered one of the central founders of the science of thermodynamics. By his restatement of Sadi Carnot's principle known as the Carnot cycle, he put the theory of heat on a truer and sounder basis. His most important paper, On the Moving Force of Heat, published in 1850, first stated the basic ideas of the second law of thermodynamics. In 1865 he introduced the concept of entropy. In 1870 he introduced the virial theorem which applied to heat. Read more...

## Josiah Willard Gibbs

Josiah Willard Gibbs (American; February 11, 1839 – April 28, 1903) Scientist who made important theoretical contributions to physics, chemistry, and mathematics. His work on the applications of thermodynamics was instrumental in transforming physical chemistry into a rigorous deductive science. Together with James Clerk Maxwell and Ludwig Boltzmann, he created statistical mechanics (a term that he coined), explaining the laws of thermodynamics as consequences of the statistical properties of large ensembles of particles. Gibbs also worked on the application of Maxwell's equations to problems in physical optics. As a mathematician, he invented modern vector calculus (independently of the British scientist Oliver Heaviside, who carried out similar work during the same period). Read more...

## Constantin Carathéodory

Constantin Carathéodory (Greek; 13 September 1873 – 2 February 1950) Mathematician who spent most of his professional career in Germany. He made significant contributions to the theory of functions of a real variable, the calculus of variations, and measure theory. His work also includes important results in conformal representations and in the theory of boundary correspondence. In 1909, Carathéodory pioneered the Axiomatic Formulation of Thermodynamics along a purely geometrical approach. Read more...

## Ludwig Boltzmann

Ludwig Eduard Boltzmann (Austrian; February 20, 1844 – September 5, 1906) Physicist and philosopher whose greatest achievement was in the development of statistical mechanics, which explains and predicts how the properties of atoms (such as mass, charge, and structure) determine the physical properties of matter (such as viscosity, thermal conductivity, and diffusion). Most famous for his equation for Entropy: Read more...

S = K * log(w)

## Gustav Zeuner

Gustav Anton Zeuner (German; 30 November 1828 – 17 October 1907) Physicist, engineer and epistemologist, considered the founder of technical thermodynamics and of the Dresden School of Thermodynamics. The first being his 1859 Fundamentals of the Mechanical Theory of Heat (Grundzüge der Mechanischen Wärmetheorie). His central textbook, deriving from his 1859 paper and intended for his lectures at the Technical High School at Dresden, was the 1887 Technical Thermodynamics, which went through five editions, turning eventually into a two-volume set. Read more...

## Johannes Diderik van der Waals

Johannes Diderik van der Waals (Dutch; 23 November 1837 – 8 March 1923) Theoretical physicist and thermodynamicist famous for his work on an equation of state for gases and liquids. His name is primarily associated with the van der Waals equation of state that describes the behavior of gases and their condensation to the liquid phase. His name is also associated with van der Waals forces (forces between stable molecules), with van der Waals molecules (small molecular clusters bound by van der Waals forces), and with van der Waals radii (sizes of molecules). He became the first physics professor of the University of Amsterdam when in 1877 the old Athenaeum was upgraded to Municipal University. Van der Waals won the 1910 Nobel Prize in physics. Read more...

## James Prescott Joule

James Prescott Joule (English; 24 December 1818 – 11 October 1889) Physicist who studied the nature of heat and its relationship to mechanical work. He worked with Lord Kelvin to develop the absolute scale of temperature, and found the relationship between the flow of current through a resistance and the resulting heat dissipated - this is now called "Joule's law". The "joule" which is named after him is a unit of work with several definitions: The work done, or energy required, to exert a force of one newton for a distance of one meter. The work required to move an electric charge of one coulomb through an electrical potential difference of one volt. The work done to produce the power of one watt continuously for one second. Read more...

## William Thomson, (Lord Kelvin)

William Thomson, 1st Baron Kelvin (Great Britain; 26 June 1824 – 17 December 1907) Mathematical physicist and engineer. He did important work in the mathematical analysis of electricity and thermodynamics, and did much to unify the emerging discipline of physics in its modern form. He is best known for an absolute temperature scale, he developed with James Prescott Joule, called the Kelvin scale. This is a temperature scale in which zero represents the point at which there is absolutely no kinetic energy (or heat energy). He was also a telegraph engineer, and was elected to the board of directors of the Atlantic Telegraph Company in recognition of work he did to help with the problem of transmission rate in the Transatlantic telegraph cable. Thomson had produced a mathematical analysis of the propagation of electrical signals into telegraph cables based on their capacitance and resistance. In higher speed data cables, such as today's Cat 5, it is necessary to factor in inductance as well. Read more...

## James Clerk Maxwell

James Clerk Maxwell (Scottish; 13 June 1831 – 5 November 1879) Mathematical physicist who developed a set of (4) equations that express the basic laws of electricity and magnetism. He is believed to be one of the finest mathematical minds of any theoretical physicist of his time, and is widely regarded as the nineteenth century scientist who had the greatest influence on twentieth century physics. He showed that electric and magnetic fields can travel through the vacuum of space, in the form of waves, and at a constant velocity of 3.0 × 108 m/s (which is known as the speed of light). He also proposed that light was a form of electromagnetic radiation. His (4) equations were based on the previous works of Ampère, Faraday, Gauss, and others. His first equation, called Ampère's Law, predicts the magnetic field that will be created by a given flow of current. The second equation, called Faraday's Law, is essentially the inverse of the first, and calculates the electrical current that will be generated from a changing magnetic field (this is how most electrical power is generated). The third equation, called Gauss' Law, states that a static electrical charge must generate an electrical voltage. The fourth equation, simply called the Fourth Equation, basically asserts that a magnetic charge (or magnetic monopole) cannot exist - the way that an electron can carry an electrical charge. It is believed - though may be disproved in the future - that all magnetic fields have equal and opposing poles. Read more...

## Max Planck

Max Karl Ernst Ludwig Planck, (German; April 23, 1858 – October 4, 1947) Theoretical physicist who originated quantum theory, which won him the Nobel Prize in Physics in 1918. Planck made many contributions to theoretical physics, but his fame rests primarily on his role as originator of the quantum theory. This theory revolutionized human understanding of atomic and subatomic processes, just as Albert Einstein’s theory of relativity revolutionized the understanding of space and time. Together they constitute the fundamental theories of 20th-century physics. Read more...