Julius Robert von Mayer | |
|---|---|
.jpg) Mayer in 1868 | |
| Born | Julius Robert Mayer[a] 25 November 1814 |
| Died | 20 March 1878(1878-03-20) (aged 63) Heilbronn, Kingdom of Württemberg,German Empire |
| Alma mater | University of Tübingen |
| Known for | First law of thermodynamics Mechanical equivalent of heat Mayer's reagent Mayer's relation |
| Awards | Copley Medal (1871) Poncelet Prize (1869) |
| Scientific career | |
| Fields | Physics |
Julius Robert von Mayer (25 November 1814 – 20 March 1878) was a Germanphysician,chemist, andphysicist and one of the founders ofthermodynamics. He is best known for enunciating in 1841 one of the original statements of theconservation of energy or what is now known as one of the first versions of thefirst law of thermodynamics, namely that "energy can be neither created nor destroyed".[1][2] In 1842, Mayer described the vitalchemical process now referred to asoxidation as the primary source ofenergy for anyliving creature. He also proposed thatplants convert light into chemical energy.
His achievements were overlooked and priority for the discovery in 1842 of themechanical equivalent of heat was attributed toJames Joule in the following year.
Mayer was born on 25 November 1814 inHeilbronn,Württemberg (Baden-Württemberg, modern day Germany), the son of apharmacist. He grew up in Heilbronn. After completing hisAbitur, he studied medicine at theUniversity of Tübingen, where he was a member of theCorps Guestphalia, aGerman Student Corps. During 1838 he attained his doctorate as well as passing theStaatsexamen. After a stay in Paris (1839/40) he left as a ship's physician on aDutch three-mastsailing ship for a journey toJakarta.
Although he had hardly been interested before this journey inphysical phenomena, his observation that storm-whipped waves are warmer than the calm sea started him thinking about thephysical laws, in particular about the physical phenomenon of warmth and the questionwhether the directly developed heat alone (theheat of combustion), or the sum of the quantities of heat developed in direct and indirect ways are to be accounted for in the burning process. After his return in February 1841 Mayer dedicated his efforts to solve this problem.
In 1841 he settled inHeilbronn and married.
Even as a young child, Mayer showed an intense interest with various mechanical mechanisms. He was a young man who performed various experiments of the physical and chemical variety. In fact, one of his favorite hobbies was creating various types of electrical devices and air pumps. It was obvious that he was intelligent. Hence, Mayer attended Eberhard-Karls University in May 1832. He studied medicine during his time there.
In 1837, he and some of his friends were arrested for wearing thecouleurs of a forbidden organization. The consequences for this arrest included a one year expulsion from the college and a brief period of incarceration. This diversion sent Mayer traveling to Switzerland, France, and theDutch East Indies. Mayer drew some additional interest in mathematics and engineering from his friend Carl Baur through private tutoring. In 1841, Mayer returned to Heilbronn to practice medicine, but physics became his new passion.
In June 1841 he completed his first scientific paper entitled "On the Quantitative and Qualitative Determination of Forces". It was largely ignored by other professionals in the area. Then, Mayer became interested in the area of heat and its motion. He presented a value in numerical terms for the mechanical equivalent of heat. He also was the first person to describe the vital chemical process now referred to as oxidation as the primary source of energy for any living creature.
In 1848 he calculated that in the absence of a source of energy the Sun would cool down in only 5000 years, and he suggested that the impact of meteorites kept it hot.[3]
Since he was not taken seriously at the time, his achievements were overlooked and credit was given toJames Joule. Mayer almost committed suicide after he discovered this fact. He spent some time in mental institutions to recover from this and the loss of some of his children. Several of his papers were published due to the advanced nature of the physics and chemistry. He was awarded an honorary doctorate in 1859 by the philosophical faculty at theUniversity of Tübingen. His overlooked work was revived in 1862 by fellow physicistJohn Tyndall in a lecture at the London Royal Institution. In July 1867 Mayer published "Die Mechanik der Wärme." This publication dealt with the mechanics of heat and its motion. On 5 November 1867 Mayer was awarded personal nobility by theKingdom of Württemberg (von Mayer) which is the German equivalent of a British knighthood. von Mayer died in Germany in 1878.
After Sadi Carnot stated it for caloric[clarification needed], Mayer was the first person to state the law of the conservation of energy, one of the most fundamental tenets of modern day physics. The law of the conservation of energy states that the total mechanical energy of a system remains constant in any isolated system of objects that interact with each other only by way of forces that areconservative.Mayer's first attempt at stating the conservation of energy was a paper he sent toJohann Christian Poggendorff'sAnnalen der Physik, in which he postulated a conservation of force (Erhaltungssatz der Kraft). However, owing to Mayer's lack of advanced training inphysics, it contained some fundamental mistakes and was not published. Mayer continued to pursue the idea steadfastly and argued with theTübingen physics professorJohann Gottlieb Nörremberg, who rejected hishypothesis. Nörremberg did, however, give Mayer a number of valuable suggestions on how the idea could be examined experimentally; for example, ifkinetic energy transforms into heat energy, water should be warmed byvibration.
Mayer not only performed this demonstration, but determined also the quantitative factor of the transformation, calculating the mechanical equivalent of heat. The result of his investigations was published 1842 in the May edition ofJustus von Liebig'sAnnalen der Chemie und Pharmacie.[4][5] It was translated asRemarks on the Forces of Inorganic Nature[6] In his bookletDie organische Bewegung im Zusammenhang mit dem Stoffwechsel (The Organic Movement in Connection with the Metabolism, 1845) he specified the numerical value of the mechanical equivalent of heat: at first as 365kgf·m/kcal,[7] later as 425 kgf·m/kcal; the modern values are 4.184kJ/kcal (426.6 kgf·m/kcal) for the thermochemical calorie and 4.1868 kJ/kcal (426.9 kgf·m/kcal) for the international steam table calorie.
This relation implies that, although work and heat are different forms of energy, they can be transformed into one another. This law is now called thefirst law of thermodynamics, and led to the formulation of the general principle ofconservation of energy, definitively stated byHermann von Helmholtz in 1847.
Mayer derived a relation between specific heat at constant pressure and the specific heat at constant volume for an ideal gas. The relation is:
,
whereCP,m is themolar specific heat at constantpressure,CV,m is the molar specific heat at constantvolume andR is thegas constant.
Mayer was aware of the importance of his discovery, but his inability to express himself scientifically led to degrading[clarification needed] speculation and resistance from the scientific establishment. Contemporary physicists rejected his principle of conservation of energy, and even acclaimed physicistsHermann von Helmholtz andJames Prescott Joule viewed his ideas with hostility. The former doubted Mayer's qualifications in physical questions, and a bitter dispute over priority developed with the latter.
In 1848 two of his children died rapidly in succession, and Mayer'smental health deteriorated. He attempted suicide on 18 May 1850 and was committed to a mental institution.[citation needed] After he was released, he was a broken man and only timidly re-entered public life in 1860. However, in the meantime, his scientific fame had grown and he received a late appreciation of his achievement, although perhaps at a stage where he was no longer able to enjoy it.
He continued to work vigorously as a physician until his death.
In chemistry, he inventedMayer's reagent which is used in detecting alkaloids.
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