History of thermodynamics

In the mid- to late 18th century,

Joseph Black and

Carl Wilhelm Scheele distinguished heat transfer by thermal radiation (radiant heat) from that by convection and conduction in 1777.

In the 17th century, it came to be believed that all materials had an identical conductivity and that differences in sensation arose from their different

In 1791,

In the 19th century, scientists abandoned the idea of a physical caloric. The first substantial experimental challenges to the caloric theory arose in a work by Benjamin Thompson's (Count Rumford) from 1798, in which he showed that boring cast iron cannons produced great amounts of heat which he ascribed to friction. His work was among the first to undermine the caloric theory.

As a result of his experiments in 1798, Thompson suggested that heat was a form of motion, though no attempt was made to reconcile theoretical and experimental approaches, and it is unlikely that he was thinking of the vis viva principle.

Although early steam engines were crude and inefficient, they attracted the attention of the leading scientists of the time. One such scientist was

Though it had come to be suspected from Scheele's work, in 1831

John Herapath independently formulated a kinetic theory in 1820, but mistakenly associated temperature with momentum rather than vis viva or kinetic energy. His work ultimately failed peer review, even from someone as well-disposed to the kinetic principle as Humphry Davy, and was neglected.

John James Waterston in 1843 provided a largely accurate account, again independently, but his work received the same reception, failing peer review.

Further progress in kinetic theory started only in the middle of the 19th century, with the works of Rudolf Clausius, James Clerk Maxwell, and Ludwig Boltzmann.

Quantitative studies by Joule from 1843 onwards provided soundly reproducible phenomena, and helped to place the subject of thermodynamics on a solid footing. In 1843, Joule experimentally found the mechanical equivalent of heat. In 1845, Joule reported his best-known experiment, involving the use of a falling weight to spin a paddle-wheel in a barrel of water, which allowed him to estimate a mechanical equivalent of heat of 819 ft·lbf/Btu (4.41 J/cal). This led to the theory of conservation of energy and explained why heat can do work.

The idea of absolute zero was generalised in 1848 by Lord Kelvin.

In March 1851, while grappling to come to terms with the work of Joule, Lord Kelvin started to speculate that there was an inevitable loss of useful heat in all processes. The idea was framed even more dramatically by Hermann von Helmholtz in 1854, giving birth to the spectre of the heat death of the universe.

In 1854,

In 1865, Clausius coined the term "entropy" (das Wärmegewicht, symbolized S) to denote heat lost or turned into waste.^[15][16] ("Wärmegewicht" translates literally as "heat-weight"; the corresponding English term stems from the Greek τρέπω, "I turn".) Clausius used the concept to develop his classic statement of the second law of thermodynamics the same year.^[17]

In his 1857 work On the nature of the motion called heat, Clausius for the first time clearly states that heat is the average kinetic energy of molecules.

Clausius' above statement interested the Scottish mathematician and physicist James Clerk Maxwell, who in 1859 derived the momentum distribution later named after him. The Austrian physicist Ludwig Boltzmann subsequently generalized this distribution for the case of gases in external fields. In association with Clausius, in 1871, Maxwell formulated a new branch of thermodynamics called statistical thermodynamics, which functions to analyze large numbers of particles at equilibrium, i.e., systems where no changes are occurring, such that only their average properties as temperature T, pressure P, and volume V become important.

Boltzmann is perhaps the most significant contributor to kinetic theory, as he introduced many of the fundamental concepts in the theory. Besides the Maxwell–Boltzmann distribution mentioned above, he also associated the kinetic energy of particles with their degrees of freedom. The Boltzmann equation for the distribution function of a gas in non-equilibrium states is still the most effective equation for studying transport phenomena in gases and metals. By introducing the concept of thermodynamic probability as the number of microstates corresponding to the current macrostate, he showed that its logarithm is proportional to entropy.

In 1875, the Austrian physicist Ludwig Boltzmann formulated a precise connection between entropy S and molecular motion:

${\displaystyle S=k\log W\,}$

being defined in terms of the number of possible states W that such motion could occupy, where k is the Boltzmann constant.

In 1876, chemical engineer

Gibbs also originated the concept we now know as enthalpy H, calling it "a heat function for constant pressure".^[18] The modern word enthalpy would be coined many years later by Heike Kamerlingh Onnes,^[19] who based it on the Greek word enthalpein meaning to warm.

In 1900 Max Planck found an accurate formula for the spectrum of black-body radiation. Fitting new data required the introduction of a new constant, known as the Planck constant, the fundamental constant of modern physics. Looking at the radiation as coming from a cavity oscillator in thermal equilibrium, the formula suggested that energy in a cavity occurs only in multiples of frequency times the constant. That is, it is quantized. This avoided a divergence to which the theory would lead without the quantization.

In 1906, Walther Nernst stated the third law of thermodynamics.

Building on the foundations above, Lars Onsager, Erwin Schrödinger, Ilya Prigogine and others, brought these engine "concepts" into the thoroughfare of almost every modern-day branch of science.

The following list is a rough disciplinary outline of the major branches of thermodynamics and their time of inception:

• Thermochemistry – 1780s
• Classical thermodynamics
  – 1824
• Chemical thermodynamics – 1876
• Statistical mechanics – c. 1880s
• Equilibrium thermodynamics
• Engineering thermodynamics
• Chemical engineering thermodynamics – c. 1940s
• Non-equilibrium thermodynamics – 1941
• Small systems thermodynamics – 1960s
• Biological thermodynamics – 1957
• Ecosystem thermodynamics – 1959
• Relativistic thermodynamics – 1965
• Rational thermodynamics – 1960s
• Quantum thermodynamics – 1968
• Black hole thermodynamics – c. 1970s
• Theory of critical phenomena and use of renormalization group theory in statistical physics – 1966-1974
• Geological thermodynamics – c. 1970s
• Biological evolution thermodynamics – 1978
• Geochemical thermodynamics – c. 1980s
• Atmospheric thermodynamics – c. 1980s
• Natural systems thermodynamics – 1990s
• Supramolecular thermodynamics – 1990s
• Earthquake thermodynamics – 2000
• Drug-receptor thermodynamics – 2001
• Pharmaceutical systems thermodynamics – 2002

Concepts of thermodynamics have also been applied in other fields, for example:

• Thermoeconomics – c. 1970s

• History of chemistry
• Timeline of heat engine technology
• Timeline of low-temperature technology
• Timeline of thermodynamics

Further reading

• Cardwell, D.S.L. (1971). From Watt to Clausius: The Rise of Thermodynamics in the Early Industrial Age. London: Heinemann.
  ISBN 978-0-435-54150-7
  .
• Leff, H.S.; Rex, A.F., eds. (1990). Maxwell's Demon: Entropy, Information and Computing. Bristol: Adam Hilger.
  ISBN 978-0-7503-0057-5
  .

External links

Wikimedia Commons has media related to History of thermodynamics.

• History of Thermodynamics – University of Waterloo
• Thermodynamic History Notes – WolframScience.com
• Brief History of Thermodynamics – Berkeley [PDF]