Hermann Ludwig Ferdinand von Helmholtz was a German physicist, one of the discoverers of the principle of the conservation of energy. One of the last great universalists of science, he was able not only to unify the practice and teaching of medicine, physiology, anatomy, and physics but to relate these sciences significantly to the fine arts.
Background
Helmholtz was born on August 31, 1821, in Potsdam, Germany. He was the son of the local Gymnasium headmaster, Ferdinand Helmholtz and Caroline Penn. Hermann was the eldest of his parents four children. His childhood had a strong influence on both his character and his later career. In particular, the views on philosophy held by his father restricted Helmholtz's own views.
Ferdinand Helmholtz had served in the Prussian army in the fight against Napoleon. Despite having a good university education in philology and philosophy, he became a teacher at Potsdam Gymnasium. It was a poorly paid job and Hermann was brought up in financially difficult circumstances. Ferdinand was an artistic man and his influence meant that Hermann grew up to have a strong love of music and painting. Caroline Helmholtz was the daughter of an artillery officer.
Education
Hermann attended Potsdam Gymnasium (now Hermann-von-Helmholtz-Gymnasium) where his father taught philology and classical literature. His interests at school were mainly in physics and he would have liked to have studied that subject at university. The financial position of the family, however, meant that he could only study at university if he received a scholarship. Such financial support was only available for particular topics and Hermann's father persuaded him that he should study medicine which was supported by the government.
In 1837 Helmholtz was awarded a government grant to enable him to study medicine at the Royal Friedrich-Wilhelm Institute of Medicine and Surgery in Berlin (now Humboldt University of Berlin). He did not receive the money without strings attached, however, and he had to sign a document promising to work for ten years as a doctor in the Prussian army after graduating. In 1838 he began his studies in Berlin. Although he was officially studying at the Institute of Medicine and Surgery, being in Berlin he had the opportunity of attending courses at the University. He took this chance, attending lectures in chemistry and physiology.
Given Helmholtz's contributions to mathematics later in his career, it would be reasonable to have expected him to have taken mathematics courses at the University of Berlin at this time. However he did not, rather he studied mathematics on his own, reading works by Laplace, Biot, and Daniel Bernoulli. He also read philosophy works at this time, particularly the works of Kant. His research career began in 1841 when he began work on his dissertation. He rejected the direction which physiology had been taking which had been based on vital forces that were not physical in nature. Helmholtz strongly argued for founding physiology completely on the principles of physics and chemistry.
Helmholtz graduated from the Medical Institute in Berlin in 1843 and was assigned to a military regiment at Potsdam, but spent all his spare time doing research.
Career
Helmholtz's first academic position was as a teacher of Anatomy at the Academy of Arts in Berlin in 1848. He then moved to take a post of associate professor of physiology at the Prussian University of Königsberg, where he was appointed in 1849. In 1855 he accepted a full professorship of anatomy and physiology at the University of Bonn. He was not particularly happy in Bonn, however, and three years later he transferred to the University of Heidelberg, in Baden, where he served as professor of physiology. In 1871 he accepted his final university position, as professor of physics at the Humboldt University in Berlin.
The variety of positions he held reflects his interests and competence but does not reflect the way in which his mind worked. He did not start out in medicine, move to physiology, then drift into mathematics and physics. Rather, he was able to coordinate the insights he had acquired from his experience in these disciplines and to apply them to every problem he examined. His greatest work, Handbook of Physiological Optics (1867), was characterized - like all of his scientific works - by a keen philosophical insight, molded by exact physiological investigations, and illustrated with mathematical precision and sound physical principles.
Views
The general theme that runs through most, if not all, of Helmholtz’s work, may be traced to his rejection of Nature philosophy, and the violence of his rejection of this seductive view of the world may well indicate the early attraction it had for him. Nature philosophy derived from Kant, who in the 1780s had suggested that the concepts of time, space, and causation were not products of sense experience but mental attributes by which it was possible to perceive the world. Therefore, the mind did not merely record order in nature, as the Empiricists insisted; rather, the mind organized the world of perceptions so that, reflecting the divine reason, it could deduce the system of the world from a few basic principles. Helmholtz opposed this view by insisting that all knowledge came through the senses. Furthermore, all science could and should be reduced to the laws of classical mechanics, which, in his view, encompassed matter, force, and, later, energy, as the whole of reality.
Helmholtz’s approach to nature was evident in the very first scientific researches he undertook while working for his doctorate in the laboratory of Müller. Like most biologists, Müller was a vitalist who was convinced that it would be impossible ever to reduce living processes to the ordinary mechanical laws of physics and chemistry. The organism as a whole, he insisted, was greater than the sum of its physiological parts. There must be some vital force that coordinated the physiological action of organs to produce the harmonious organic behavior that characterized the living creature. Such a vital force was not susceptible to experimental investigation, and Müller, therefore, concluded that truly experimental physiology was impossible.
In Müller’s laboratory, Helmholtz met a group of young men, among whom were Emil Heinrich Du Bois-Reymond, the founder of experimental neurophysiology, and Ernst Wilhelm von Brücke, who later became an expert on the operations of the human eye. Du Bois-Reymond expressed their opposition to Müller’s views in a statement that fully expressed Helmholtz’s own position. "Brücke and I," Du Bois-Reymond wrote, "we have sworn to each other to validate the basic truth that in an organism no other forces have any effect than the common physiochemical ones."
It was with this attitude that Helmholtz began his doctoral thesis in 1842 on the connection between nerve fibres and nerve cells. This soon led him to a broader field of inquiry, namely, the source of animal heat. Recent publications in France had cast doubt upon the earlier confident assertion that all the heat produced in an animal body was the result of the heats of a combination of the various chemical elements involved, particularly carbon, hydrogen, and oxygen. In 1842 Justus von Liebig attempted to reestablish the mechanical theory of animal heat in his book Animal Chemistry; or, Organic Chemistry in Its Application to Physiology and Pathology. Liebig tried to do this by experiments, whereas Helmholtz took a much more general path. Having mastered both physics and mathematics, Helmholtz could do what no other physiologist of the time could even attempt - subject the problem to mathematical and physical analysis. He supposed that, if vital heat were not the sum of all the heats of the substances involved in chemical reactions within the organic body, there must be some other source of heat not subject to physical laws. This, of course, was precisely what the vitalists argued. But such a source, Helmholtz went on, would permit the creation of a perpetual motion machine if the heat could, somehow, be harnessed. Physics, however, had rejected the possibility of a perpetual motion machine as early as 1775, when the Paris Academy of Sciences had declared itself on the question. Hence, Helmholtz concluded, vital heat must be the product of mechanical forces within the organism. From there he went on to generalize his results to state that all heat was related to ordinary forces and, finally, to state that force itself could never be destroyed. His paper "On the Conservation of Force," which appeared in 1847, marked an epoch in both the history of physiology and the history of physics. For physiology, it provided a fundamental statement about organic nature that permitted physiologists henceforth to perform the same kind of material and energy balances as their colleagues in physics and chemistry. For the physical sciences, it provided one of the first, and certainly the clearest, statements of the principle of the conservation of energy.
In 1850 Helmholtz drove another nail into the coffin of vitalism. Müller had used the nerve impulse as an example of a vital function that would never be submitted to experimental measurement. Helmholtz found that this impulse was perfectly measurable and had a remarkably slow speed of some 90 feet (27 meters) per second. (This measurement was obtained by the invention of the myograph and illustrates Helmholtz’s ability to create new instruments.) The slowness of the nerve impulse further supported those who insisted that it must involve the rearrangement of ponderable molecules, not the mysterious passage of a vital force.
Among Helmholtz’s most valuable inventions were the ophthalmoscope and the ophthalmometer (or keratometer), both made in 1851. While doing work on the eye, and incidentally showing that it was a rather imperfect piece of workmanship not at all consonant with the vitalistic idea of the divine mind at work, Helmholtz discovered that he could focus the light reflected from the retina to produce a sharp image of the tissue. The ophthalmoscope remains one of the most important instruments of the physician, who can use it to examine retinal blood vessels, from which clues to high blood pressure and to arterial disease may be observed. The ophthalmometer permits the measurement of the accommodation of the eye to changing optical circumstances, allowing, among other things, the proper prescription of eyeglasses.
Helmholtz’s researches on the eye were incorporated in his Handbook of Physiological Optics, the first volume of which appeared in 1856. In the second volume (1867), Helmholtz further investigated optical appearances and, more importantly, came to grips with a philosophical problem that was to occupy him for some years - Kant’s insistence that such basic concepts as time and space were not learned by experience but were provided by the mind to make sense of what the mind perceived. The problem had been greatly complicated by Müller’s statement of what he called the law of specific nerve energies. Müller discovered that sensory organs always "report" their own sense no matter how they are stimulated. Thus, for example, a blow to the eye, which has nothing whatsoever to do with optical phenomena, causes the recipient to "see stars." Obviously, the eye is not reporting accurately on the external world, for the reality is the blow, not the stars. How, then, is it possible to have confidence in what the senses report about the external world? Helmholtz examined this question exhaustively in both his work on optics and in his masterly On the Sensation of Tone As a Physiological Basis for the Theory of Music (1863). What he tried to do, without complete success, was to trace sensations through the sensory nerves and anatomical structures (such as the inner ear) to the brain in the hope of laying bare the complete mechanism of sensation. This task, it might be noted, has not been completed, and physiologists are still engaged in solving the mystery of how the mind knows anything about the outside world.
Helmholtz’s detailed investigation of vision permitted him to refute Kant’s theory of space by showing exactly how the sense of vision created the idea of space. Space, according to Helmholtz, was a learned, not an inherent, concept. Moreover, Helmholtz also attacked Kant’s insistence that space was necessarily three-dimensional because that was how the mind had to conceive it. Using his considerable mathematical talents, he investigated the properties of non-Euclidean space and showed that these could be conceived and worked with as easily as the geometry of three dimensions.
Helmholtz’s mathematical talents were not restricted to such theoretical planes as non-Euclidean geometry. He attacked and solved equations that had long frustrated physicists and mathematicians. In 1858 he published the paper "On the Integrals of Hydrodynamic Equations to Which Vortex Motions Conform." This was not only a mathematical tour de force, but, for a brief time, it also seemed to provide a key to the fundamental structure of matter. One of the consequences that flowed from Helmholtz’s mathematical analysis was that vortices of an ideal fluid were amazingly stable; they could collide elastically with one another, intertwine to form complex knotlike structures, and undergo tensions and compressions, all without losing their identities. In 1866 William Thomson (later Lord Kelvin) proposed that these vortices if composed of the ether that was presumed to be the basis for optical, electrical, and magnetic phenomena, could act exactly like primeval atoms of solid matter. Thus the ether would become the only substance in the cosmos, and all physical phenomena could be accounted for in terms of its static and dynamic properties.
Quotations:
"A moving body whose motion was not retarded by any resisting force would continue to move to all eternity."
"A raised weight can produce work, but in doing so it must necessarily sink from its height, and, when it has fallen as deep as it can fall, its gravity remains as before, but it can no longer do work."
"Not that I wish by any means to deny, that the mental life of individuals and peoples is also in conformity with law, as is the object of philosophical, philological, historical, moral, and social sciences to establish."
"Each individual fact, taken by itself, can indeed arouse our curiosity or our astonishment, or be useful to us in its practical applications."
"Reason we call that faculty innate in us of discovering laws and applying them with thought."
"What appeared to the earlier physicists to be the constant quantity of heat is nothing more than the whole motive power of the motion of heat, which remains constant so long as it is not transformed into other forms of work, or results afresh from them."
Personality
From his mother came the calm and reserve that marked Hermann von Helmholtz all his life. From his father came a rich, but mixed, intellectual heritage.
Quotes from others about the person
"Helmholtz devoted his life to seeking the great unifying principles underlying nature. His career began with one such principle, that of energy, and concluded with another, that of least action. No less than the idealistic generation before him, he longed to understand the ultimate, subjective sources of knowledge. That longing found expression in his determination to understand the role of the sense organs, as mediators of experience, in the synthesis of knowledge.
To this continuity with the past, Helmholtz and his generation brought two new elements, a profound distaste for metaphysics and an undeviating reliance on mathematics and mechanism. Helmholtz owed the scope and depth characteristic of his greatest work largely to the mathematical and experimental expertise which he brought to science. ... Helmholtz was the last great scholar whose work, in the tradition of Leibniz, embraced all the sciences, as well as philosophy and the fine arts." - R. Steven Turner.
