Hermann von Helmholtz
Encyclopedia
Hermann Ludwig Ferdinand von Helmholtz (August 31, 1821 – September 8, 1894) was a German physician
and physicist
who made significant contributions to several widely varied areas of modern science. In physiology
and psychology
, he is known for his mathematics of the eye
, theories of vision, ideas on the visual perception
of space, color vision
research, and on the sensation of tone, perception of sound, and empiricism
. 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
. As a philosopher, he is known for his philosophy of science
, ideas on the relation between the laws of perception and the laws of nature, the science of aesthetics
, and ideas on the civilizing power of science. The largest German association of research institutions, the Helmholtz Association, is named after him.
Gymnasium
headmaster, Ferdinand Helmholtz, who had studied classical
philology
and philosophy
, and who was a close friend of the publisher and philosopher Immanuel Hermann Fichte
. Helmholtz's work is influenced by the philosophy of Fichte
and Kant
. He tried to trace their theories in empirical matters like physiology
.
As a young man, Helmholtz was interested in natural science, but his father wanted him to study medicine at the Charité
because there was financial support for medical students.
Trained primarily in physiology, Helmholtz wrote on many other topics, ranging from theoretical physics, to the age of the Earth
, to the origin of the solar system
.
treatise on the conservation of energy
was written in the context of his medical studies and philosophical background. He discovered the principle of conservation of energy while studying muscle
metabolism
. He tried to demonstrate that no energy is lost in muscle movement, motivated by the implication that there were no vital forces necessary to move a muscle. This was a rejection of the speculative tradition of Naturphilosophie
which was at that time a dominant philosophical paradigm in German physiology.
Drawing on the earlier work of Sadi Carnot
, Émile Clapeyron and James Prescott Joule
, he postulated a relationship between mechanics
, heat
, light
, electricity
and magnetism
by treating them all as manifestations of a single force (energy
in modern terms). He published his theories in his book Über die Erhaltung der Kraft (On the Conservation of Force, 1847). Whether or not Helmholtz knew of Julius Robert von Mayer
's discovery of the law of conservation of energy in the beginning of the 1840s is a point of controversy. Helmholtz did not quote Mayer in his work and was accused by contemporaries of plagiarism
.
In the 1850s and 60s, building on the publications of William Thomson
, Helmholtz and William Rankine popularized the idea of the heat death of the universe
.
, a student of Helmholtz, who is considered one of the founders of experimental psychology
. He, more explicitly than Helmholtz, described his research as a form of empirical philosophy and as a study of the mind as something separate. Helmholtz had, in his early repudiation of Naturphilosophie
, stressed the importance of materialism
, and was focusing more on the unity of "mind" and body.
with the invention of the ophthalmoscope; an instrument used to examine the inside of the human eye
. This made him world famous overnight. Helmholtz's interests at that time were increasingly focused on the physiology of the senses. His main publication, entitled Handbuch der Physiologischen Optik (Handbook of Physiological Optics or Treatise on Physiological Optics), provided empirical theories on depth perception
, color vision
, and motion perception
, and became the fundamental reference work in his field during the second half of the nineteenth century. It was first translated into English under the editorship of James P. C. Southall on behalf of the Optical Society of America
in 1924-5. His theory of accommodation
went unchallenged until the final decade of the 20th century.
Helmholtz continued to work for several decades on several editions of the handbook, frequently updating his work because of his dispute with Ewald Hering
who held opposite views on spatial and color vision. This dispute divided the discipline of physiology during the second half of the 1800s.
as a sensitive timing device, attaching a mirror to the needle to reflect a light beam across the room to a scale which gave much greater sensitivity. Helmholtz reported transmissions speeds in the range of 24.6 - 38.4 meters per second.
to identify the various frequencies
or "tones" present in musical and other sounds containing by multiple tones. Alexander Graham Bell in particular was interested in how Helmholtz used resonators to mimic vowel sounds. Due to not being able to read German, Bell misconstrued Helmholtz' diagrams as meaning that Helmholtz had transmitted vowel sounds over a wire, whereas Helmholtz was merely using electrical stimulation to keep his resonators in motion without manual intervention. Bell reasoned that if vowels could be transmitted, then consonants also should be possible. He tried, and failed, to reproduce what he thought had already been done by Helmholtz. However, Bell was later to say that if he had been able to read German he would probably have given up the task as impossible, but in the event, went on to invent the telephone using the harmonic telegraph as the basis.
The translation by Alexander J. Ellis was first published in 1875 (the first English edition was from the 1870 third German edition; Ellis's second English edition from the 1877 fourth German edition was published in 1885; the 1895 and 1912 third and fourth English editions were reprints of the second).
In 1871 Helmholtz moved from Heidelberg
to Berlin to become a professor in physics. He became interested in electromagnetism
and the Helmholtz equation
is named for him. Although he did not make major contributions to this field, his student Heinrich Rudolf Hertz
became famous as the first to demonstrate electromagnetic radiation
. Oliver Heaviside
criticised Helmholtz's electromagnetic theory because it allowed the existence of longitudinal wave
s. Based on work on Maxwell's equations
, Heaviside pronounced that longitudinal waves could not exist in a vacuum or a homogeneous medium. Heaviside did not note, however, that longitudinal electromagnetic waves can exist at a boundary or in an enclosed space.
--Academic Discourse (Heidelberg 1862)
, Heinrich Kayser
, Eugen Goldstein
, Wilhelm Wien
, Arthur König
, Henry Augustus Rowland
, A. A. Michelson, Wilhelm Wundt
, and Michael I. Pupin. Leo Koenigsberger, who studied at Berlin while Helmholtz was there, wrote the definitive biography of him in 1902.
Physician
A physician is a health care provider who practices the profession of medicine, which is concerned with promoting, maintaining or restoring human health through the study, diagnosis, and treatment of disease, injury and other physical and mental impairments...
and physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
who made significant contributions to several widely varied areas of modern science. In physiology
Physiology
Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...
and psychology
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
, he is known for his mathematics of the eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
, theories of vision, ideas on the visual perception
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...
of space, color vision
Color vision
Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths of the light they reflect, emit, or transmit...
research, and on the sensation of tone, perception of sound, and empiricism
Empiricism
Empiricism is a theory of knowledge that asserts that knowledge comes only or primarily via sensory experience. One of several views of epistemology, the study of human knowledge, along with rationalism, idealism and historicism, empiricism emphasizes the role of experience and evidence,...
. In physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
, he is known for his theories on the conservation of energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
, work in electrodynamics, chemical thermodynamics
Chemical thermodynamics
Chemical thermodynamics is the study of the interrelation of heat and work with chemical reactions or with physical changes of state within the confines of the laws of thermodynamics...
, and on a mechanical
Mechanics
Mechanics is the branch of physics concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment....
foundation of thermodynamics
Thermodynamics
Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
. As a philosopher, he is known for his philosophy of science
Science
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...
, ideas on the relation between the laws of perception and the laws of nature, the science of aesthetics
Aesthetics
Aesthetics is a branch of philosophy dealing with the nature of beauty, art, and taste, and with the creation and appreciation of beauty. It is more scientifically defined as the study of sensory or sensori-emotional values, sometimes called judgments of sentiment and taste...
, and ideas on the civilizing power of science. The largest German association of research institutions, the Helmholtz Association, is named after him.
Early years
Helmholtz was the son of the PotsdamPotsdam
Potsdam is the capital city of the German federal state of Brandenburg and part of the Berlin/Brandenburg Metropolitan Region. It is situated on the River Havel, southwest of Berlin city centre....
Gymnasium
Gymnasium (school)
A gymnasium is a type of school providing secondary education in some parts of Europe, comparable to English grammar schools or sixth form colleges and U.S. college preparatory high schools. The word γυμνάσιον was used in Ancient Greece, meaning a locality for both physical and intellectual...
headmaster, Ferdinand Helmholtz, who had studied classical
Classical philology
Classical philology is the study of ancient Greek and classical Latin. Classical philology has been defined as "the careful study of the literary and philosophical texts of the ancient Greek and Roman worlds." Greek and Latin literature and civilization have traditionally been considered...
philology
Philology
Philology is the study of language in written historical sources; it is a combination of literary studies, history and linguistics.Classical philology is the philology of Greek and Classical Latin...
and philosophy
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...
, and who was a close friend of the publisher and philosopher Immanuel Hermann Fichte
Immanuel Hermann Fichte
Immanuel Hermann von Fichte was a German philosopher and son of Johann Gottlieb Fichte. In his philosophy, he was a theist and strongly opposed to the Hegelian School.-Life:...
. Helmholtz's work is influenced by the philosophy of Fichte
Johann Gottlieb Fichte
Johann Gottlieb Fichte was a German philosopher. He was one of the founding figures of the philosophical movement known as German idealism, a movement that developed from the theoretical and ethical writings of Immanuel Kant...
and Kant
Immanuel Kant
Immanuel Kant was a German philosopher from Königsberg , researching, lecturing and writing on philosophy and anthropology at the end of the 18th Century Enlightenment....
. He tried to trace their theories in empirical matters like physiology
Physiology
Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...
.
As a young man, Helmholtz was interested in natural science, but his father wanted him to study medicine at the Charité
Charité
The Charité - Universitätsmedizin Berlin is the medical school for both the Humboldt University and the Free University of Berlin. After the merger with their fourth campus in 2003, the Charité is one of the largest university hospitals in Europe....
because there was financial support for medical students.
Trained primarily in physiology, Helmholtz wrote on many other topics, ranging from theoretical physics, to the age of the Earth
Age of the Earth
The age of the Earth is 4.54 billion years This age is based on evidence from radiometric age dating of meteorite material and is consistent with the ages of the oldest-known terrestrial and lunar samples...
, to the origin of the solar system
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
.
University posts
Helmholtz's first academic position was 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, also in Prussia. 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 University of Berlin.Mechanics
His first important scientific achievement, an 1847 physicsPhysics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
treatise on the conservation of energy
Conservation of energy
The nineteenth century law of conservation of energy is a law of physics. It states that the total amount of energy in an isolated system remains constant over time. The total energy is said to be conserved over time...
was written in the context of his medical studies and philosophical background. He discovered the principle of conservation of energy while studying muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
metabolism
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
. He tried to demonstrate that no energy is lost in muscle movement, motivated by the implication that there were no vital forces necessary to move a muscle. This was a rejection of the speculative tradition of Naturphilosophie
Naturphilosophie
Naturphilosophie is a term used in English-language philosophy to identify a current in the philosophical tradition of German idealism, as applied to the study of Nature in the earlier 19th century...
which was at that time a dominant philosophical paradigm in German physiology.
Drawing on the earlier work of Sadi Carnot
Nicolas Léonard Sadi Carnot
Nicolas Léonard Sadi Carnot was a French military engineer who, in his 1824 Reflections on the Motive Power of Fire, gave the first successful theoretical account of heat engines, now known as the Carnot cycle, thereby laying the foundations of the second law of thermodynamics...
, Émile Clapeyron and James Prescott Joule
James Prescott Joule
James Prescott Joule FRS was an English physicist and brewer, born in Salford, Lancashire. Joule studied the nature of heat, and discovered its relationship to mechanical work . This led to the theory of conservation of energy, which led to the development of the first law of thermodynamics. The...
, he postulated a relationship between mechanics
Mechanics
Mechanics is the branch of physics concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment....
, heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...
, light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
, electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
and magnetism
Magnetism
Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...
by treating them all as manifestations of a single force (energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
in modern terms). He published his theories in his book Über die Erhaltung der Kraft (On the Conservation of Force, 1847). Whether or not Helmholtz knew of Julius Robert von Mayer
Julius Robert von Mayer
Julius Robert von Mayer was a German physician and physicist and one of the founders of thermodynamics...
's discovery of the law of conservation of energy in the beginning of the 1840s is a point of controversy. Helmholtz did not quote Mayer in his work and was accused by contemporaries of plagiarism
Plagiarism
Plagiarism is defined in dictionaries as the "wrongful appropriation," "close imitation," or "purloining and publication" of another author's "language, thoughts, ideas, or expressions," and the representation of them as one's own original work, but the notion remains problematic with nebulous...
.
William Thomson, 1st Baron Kelvin
William Thomson, 1st Baron Kelvin OM, GCVO, PC, PRS, PRSE, was a mathematical physicist and engineer. At the University of Glasgow he did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics, and did much to unify the emerging...
, Helmholtz and William Rankine popularized the idea of the heat death of the universe
Heat death of the universe
The heat death of the universe is a suggested ultimate fate of the universe, in which the universe has diminished to a state of no thermodynamic free energy and therefore can no longer sustain motion or life. Heat death does not imply any particular absolute temperature; it only requires that...
.
Sensory physiology
The sensory physiology of Helmholtz was the basis of the work of Wilhelm WundtWilhelm Wundt
Wilhelm Maximilian Wundt was a German physician, psychologist, physiologist, philosopher, and professor, known today as one of the founding figures of modern psychology. He is widely regarded as the "father of experimental psychology"...
, a student of Helmholtz, who is considered one of the founders of experimental psychology
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
. He, more explicitly than Helmholtz, described his research as a form of empirical philosophy and as a study of the mind as something separate. Helmholtz had, in his early repudiation of Naturphilosophie
Naturphilosophie
Naturphilosophie is a term used in English-language philosophy to identify a current in the philosophical tradition of German idealism, as applied to the study of Nature in the earlier 19th century...
, stressed the importance of materialism
Materialism
In philosophy, the theory of materialism holds that the only thing that exists is matter; that all things are composed of material and all phenomena are the result of material interactions. In other words, matter is the only substance...
, and was focusing more on the unity of "mind" and body.
Ophthalmic optics
In 1851, Helmholtz revolutionized the field of ophthalmologyOphthalmology
Ophthalmology is the branch of medicine that deals with the anatomy, physiology and diseases of the eye. An ophthalmologist is a specialist in medical and surgical eye problems...
with the invention of the ophthalmoscope; an instrument used to examine the inside of the human eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
. This made him world famous overnight. Helmholtz's interests at that time were increasingly focused on the physiology of the senses. His main publication, entitled Handbuch der Physiologischen Optik (Handbook of Physiological Optics or Treatise on Physiological Optics), provided empirical theories on depth perception
Depth perception
Depth perception is the visual ability to perceive the world in three dimensions and the distance of an object. Depth sensation is the ability to move accurately, or to respond consistently, based on the distances of objects in an environment....
, color vision
Color vision
Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths of the light they reflect, emit, or transmit...
, and motion perception
Motion perception
Motion perception is the process of inferring the speed and direction of elements in a scene based on visual, vestibular and proprioceptive inputs...
, and became the fundamental reference work in his field during the second half of the nineteenth century. It was first translated into English under the editorship of James P. C. Southall on behalf of the Optical Society of America
Optical Society of America
The Optical Society is a scientific society dedicated to advancing the study of light—optics and photonics—in theory and application, by means of publishing, organizing conferences and exhibitions, partnership with industry, and education. The organization has members in more than 100 countries...
in 1924-5. His theory of accommodation
Accommodation reflex
The accommodation reflex is a reflex action of the eye, in response to focusing on a near object, then looking at distant object , comprising coordinated changes in vergence, lens shape and pupil size...
went unchallenged until the final decade of the 20th century.
Helmholtz continued to work for several decades on several editions of the handbook, frequently updating his work because of his dispute with Ewald Hering
Ewald Hering
Karl Ewald Konstantin Hering was a German physiologist who did much research into color vision and spatial perception...
who held opposite views on spatial and color vision. This dispute divided the discipline of physiology during the second half of the 1800s.
Nerve physiology
In 1849, while at Königsberg, Helmholtz measured the speed at which the signal is carried along a nerve fibre. At that time most people believed that nerve signals passed along nerves immeasurably fast. He used a recently dissected sciatic nerve of a frog and the calf muscle to which it attached. He used a galvanometerGalvanometer
A galvanometer is a type of ammeter: an instrument for detecting and measuring electric current. It is an analog electromechanical transducer that produces a rotary deflection of some type of pointer in response to electric current flowing through its coil in a magnetic field. .Galvanometers were...
as a sensitive timing device, attaching a mirror to the needle to reflect a light beam across the room to a scale which gave much greater sensitivity. Helmholtz reported transmissions speeds in the range of 24.6 - 38.4 meters per second.
Acoustics and aesthetics
In 1863 Helmholtz published Die Lehre von den Tonempfindungen als physiologische Grundlage für die Theorie der Musik (On the Sensations of Tone as a Physiological Basis for the Theory of Music), once again demonstrating his interest in the physics of perception. This book influenced musicologists into the twentieth century. Helmholtz invented the Helmholtz resonatorHelmholtz resonance
Helmholtz resonance is the phenomenon of air resonance in a cavity, such as when one blows across the top of an empty bottle. The name comes from a device created in the 1850s by Hermann von Helmholtz, the "Helmholtz resonator", which he, the author of the classic study of acoustic science, used to...
to identify the various frequencies
Audio frequency
An audio frequency or audible frequency is characterized as a periodic vibration whose frequency is audible to the average human...
or "tones" present in musical and other sounds containing by multiple tones. Alexander Graham Bell in particular was interested in how Helmholtz used resonators to mimic vowel sounds. Due to not being able to read German, Bell misconstrued Helmholtz' diagrams as meaning that Helmholtz had transmitted vowel sounds over a wire, whereas Helmholtz was merely using electrical stimulation to keep his resonators in motion without manual intervention. Bell reasoned that if vowels could be transmitted, then consonants also should be possible. He tried, and failed, to reproduce what he thought had already been done by Helmholtz. However, Bell was later to say that if he had been able to read German he would probably have given up the task as impossible, but in the event, went on to invent the telephone using the harmonic telegraph as the basis.
The translation by Alexander J. Ellis was first published in 1875 (the first English edition was from the 1870 third German edition; Ellis's second English edition from the 1877 fourth German edition was published in 1885; the 1895 and 1912 third and fourth English editions were reprints of the second).
Electromagnetism
Helmholtz studied the phenomena of electrical oscillations from 1869 to 1871, and in a lecture delivered to the Nat. Hist. Med. Ver. at Heidelberg on April 30, 1869 titled On Electrical Oscillations he indicated that the perceptible damped electrical oscillations in a coil joined up with a Leyden jar were about 1/50th of a second in duration. In 1871 he announced that the velocity of the propagation of electromagnetic induction was about 314,000 meters per second.In 1871 Helmholtz moved from Heidelberg
Heidelberg
-Early history:Between 600,000 and 200,000 years ago, "Heidelberg Man" died at nearby Mauer. His jaw bone was discovered in 1907; with scientific dating, his remains were determined to be the earliest evidence of human life in Europe. In the 5th century BC, a Celtic fortress of refuge and place of...
to Berlin to become a professor in physics. He became interested in electromagnetism
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...
and the Helmholtz equation
Helmholtz equation
The Helmholtz equation, named for Hermann von Helmholtz, is the elliptic partial differential equation\nabla^2 A + k^2 A = 0where ∇2 is the Laplacian, k is the wavenumber, and A is the amplitude.-Motivation and uses:...
is named for him. Although he did not make major contributions to this field, his student Heinrich Rudolf Hertz
Heinrich Rudolf Hertz
Heinrich Rudolf Hertz was a German physicist who clarified and expanded the electromagnetic theory of light that had been put forth by Maxwell...
became famous as the first to demonstrate electromagnetic radiation
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
. Oliver Heaviside
Oliver Heaviside
Oliver Heaviside was a self-taught English electrical engineer, mathematician, and physicist who adapted complex numbers to the study of electrical circuits, invented mathematical techniques to the solution of differential equations , reformulated Maxwell's field equations in terms of electric and...
criticised Helmholtz's electromagnetic theory because it allowed the existence of longitudinal wave
Longitudinal wave
Longitudinal waves, as known as "l-waves", are waves that have the same direction of vibration as their direction of travel, which means that the movement of the medium is in the same direction as or the opposite direction to the motion of the wave. Mechanical longitudinal waves have been also...
s. Based on work on Maxwell's equations
Maxwell's equations
Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...
, Heaviside pronounced that longitudinal waves could not exist in a vacuum or a homogeneous medium. Heaviside did not note, however, that longitudinal electromagnetic waves can exist at a boundary or in an enclosed space.
Quotations
Whoever in the pursuit of science, seeks after immediate practical utility may rest assured that he seeks in vain.--Academic Discourse (Heidelberg 1862)
Students and associates
Other students and research associates of Helmholtz at Berlin included Max PlanckMax Planck
Max Karl Ernst Ludwig Planck, ForMemRS, was a German physicist who actualized the quantum physics, initiating a revolution in natural science and philosophy. He is regarded as the founder of the quantum theory, for which he received the Nobel Prize in Physics in 1918.-Life and career:Planck came...
, Heinrich Kayser
Heinrich Kayser
Heinrich Gustav Johannes Kayser was a German physicist.He was born at Bingen am Rhein. Kayser's early work was concerned with the characteristics of acoustic waves. He discovered the occurrence of helium in the Earth's atmosphere. Together with Carl Runge, he examined the spectra of chemical...
, Eugen Goldstein
Eugen Goldstein
Eugen Goldstein was a German physicist. He was an early investigator of discharge tubes, the discoverer of anode rays, and is sometimes credited with the discovery of the proton.- Life :...
, Wilhelm Wien
Wilhelm Wien
Wilhelm Carl Werner Otto Fritz Franz Wien was a German physicist who, in 1893, used theories about heat and electromagnetism to deduce Wien's displacement law, which calculates the emission of a blackbody at any temperature from the emission at any one reference temperature.He also formulated an...
, Arthur König
Arthur König
Arthur Peter König devoted his short life to physiological optics. Born with congenital kyphosis he studied in Bonn and Heidelberg, moving to Berlin in the fall of 1879 where he studied under Hermann von Helmholtz, whose assistant he became in 1882...
, Henry Augustus Rowland
Henry Augustus Rowland
Henry Augustus Rowland was a U.S. physicist. Between 1899 and 1901 he served as the first president of the American Physical Society...
, A. A. Michelson, Wilhelm Wundt
Wilhelm Wundt
Wilhelm Maximilian Wundt was a German physician, psychologist, physiologist, philosopher, and professor, known today as one of the founding figures of modern psychology. He is widely regarded as the "father of experimental psychology"...
, and Michael I. Pupin. Leo Koenigsberger, who studied at Berlin while Helmholtz was there, wrote the definitive biography of him in 1902.
See also
- Helmholtz free energyHelmholtz free energyIn thermodynamics, the Helmholtz free energy is a thermodynamic potential that measures the “useful” work obtainable from a closed thermodynamic system at a constant temperature and volume...
- Helmholtz coilHelmholtz coilA Helmholtz coil is a device for producing a region of nearly uniform magnetic field. It is named in honor of the German physicist Hermann von Helmholtz.- Description :A Helmholtz pair consists of two identical circular magnetic...
- Helmholtz pitch notationHelmholtz pitch notationHelmholtz pitch notation is a musical system for naming notes of the Western chromatic scale. Developed by the German scientist Hermann von Helmholtz, it uses a combination of upper and lower case letters , and the sub- and super-prime symbols to describe each individual note of the scale...
- Helmholtz resonanceHelmholtz resonanceHelmholtz resonance is the phenomenon of air resonance in a cavity, such as when one blows across the top of an empty bottle. The name comes from a device created in the 1850s by Hermann von Helmholtz, the "Helmholtz resonator", which he, the author of the classic study of acoustic science, used to...
- Helmholtz theorem
- Helmholtz decompositionHelmholtz decompositionIn physics and mathematics, in the area of vector calculus, Helmholtz's theorem, also known as the fundamental theorem of vector calculus, states that any sufficiently smooth, rapidly decaying vector field in three dimensions can be resolved into the sum of an irrotational vector field and a...
- Helmholtz equationHelmholtz equationThe Helmholtz equation, named for Hermann von Helmholtz, is the elliptic partial differential equation\nabla^2 A + k^2 A = 0where ∇2 is the Laplacian, k is the wavenumber, and A is the amplitude.-Motivation and uses:...
- Helmholtz machineHelmholtz machineThe Helmholtz machine is a name used by Geoff Hinton to describe a class of neural networks which learn the hidden structure of a set of data by being trained to create a generative model which can produce the original set of data...
- Kelvin–Helmholtz instability
- Thévenin's theoremThévenin's theoremIn circuit theory, Thévenin's theorem for linear electrical networks states that any combination of voltage sources, current sources, and resistors with two terminals is electrically equivalent to a single voltage source V and a single series resistor R. For single frequency AC systems the theorem...
- Young–Helmholtz theory, about the trichromatic colour vision
Further reading
- David Cahan (Ed.): Hermann von Helmholtz and the Foundations of Nineteenth-Century Science. Univ. California, Berkeley 1994, ISBN 978-0520083349.
- Gregor Schiemann: Hermann von Helmholtz's Mechanism: The Loss of Certainty. A Study on the Transition from Classical to Modern Philosophy of Nature. Dordrecht: Springer 2009, ISBN 978-1-4020-5629-1.
- Franz Werner: Hermann Helmholtz´ Heidelberger Jahre (1858–1871). (= Sonderveröffentlichungen des Stadtarchivs Heidelberg 8). Mit 52 Abbildungen. Berlin / Heidelberg (Springer) 1997.
External links
- "Hermann von Helmholtz" (Obituary). Royal Society (Great Britain). (1894). Proceedings of the Royal Society of London. London: Printed by Taylor and Francis.
- " Hermann von Helmholtz" by Leo Koenigsberger (Oxford: Clarendon press, 1906) from Internet ArchiveInternet ArchiveThe Internet Archive is a non-profit digital library with the stated mission of "universal access to all knowledge". It offers permanent storage and access to collections of digitized materials, including websites, music, moving images, and nearly 3 million public domain books. The Internet Archive...
- "Hermann von Helmholtz" article by Lydia Patton, Stanford Encyclopedia of Philosophy
- J. G. McKendrick Hermann Ludwig Ferdinand von Helmholtz (London : Unwin, 1899)
- On the Conservation of Force Introduction to a Series of Lectures Delivered at CarlsruheKarlsruheThe City of Karlsruhe is a city in the southwest of Germany, in the state of Baden-Württemberg, located near the French-German border.Karlsruhe was founded in 1715 as Karlsruhe Palace, when Germany was a series of principalities and city states...
in the Winter of 1862–1863, English translation - On the Sensations of Tone as a Physiological Basis for the Theory of Music (downloadable from Google Books) Fourth Edition, By Hermann von Helmholtz, Alexander John Ellis, Published by Longmans, Green, 1912, 575 pages
- Treatise on Physiological Optics 1910, three volumes. English translation by Optical Society of America (1924–5).
- Popular lectures on scientific subjects 1885
- Popular lectures on scientific subjects second series, 1908
- Biography, bibliography and access to digital sources in the Virtual LaboratoryVirtual LaboratoryThe online project Virtual Laboratory. Essays and Resources on the Experimentalization of Life, 1830-1930, located at the Max Planck Institute for the History of Science, is dedicated to research in the history of the experimentalization of life...
of the Max Planck Institute for the History of ScienceMax Planck Institute for the History of ScienceThe Max Planck Institute for the History of Science in Berlin was established in March 1994. Its research is primarily devoted to a theoretically oriented history of science, principally of the natural sciences, but with methodological perspectives drawn from the cognitive sciences and from...
(Die Lehre von den Tonempfindungen)