Max Planck

Max Planck

Overview
Max Karl Ernst Ludwig Planck, ForMemRS
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

, (April 23, 1858 – October 4, 1947) was a German
Germans
The Germans are a Germanic ethnic group native to Central Europe. The English term Germans has referred to the German-speaking population of the Holy Roman Empire since the Late Middle Ages....

 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 actualized the quantum physics, initiating a revolution in natural science and philosophy. He is regarded as the founder of the quantum theory
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...

, for which he received the Nobel Prize in Physics
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...

 in 1918.

Planck came from a traditional, intellectual family. His paternal great-grandfather and grandfather were both theology
Theology
Theology is the systematic and rational study of religion and its influences and of the nature of religious truths, or the learned profession acquired by completing specialized training in religious studies, usually at a university or school of divinity or seminary.-Definition:Augustine of Hippo...

 professor
Professor
A professor is a scholarly teacher; the precise meaning of the term varies by country. Literally, professor derives from Latin as a "person who professes" being usually an expert in arts or sciences; a teacher of high rank...

s in Göttingen; his father was a law
Law
Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...

 professor in Kiel
University of Kiel
The University of Kiel is a university in the city of Kiel, Germany. It was founded in 1665 as the Academia Holsatorum Chiloniensis by Christian Albert, Duke of Holstein-Gottorp and has approximately 23,000 students today...

 and Munich; and his pater
Father
A father, Pop, Dad, or Papa, is defined as a male parent of any type of offspring. The adjective "paternal" refers to father, parallel to "maternal" for mother...

nal uncle was a judge
Judge
A judge is a person who presides over court proceedings, either alone or as part of a panel of judges. The powers, functions, method of appointment, discipline, and training of judges vary widely across different jurisdictions. The judge is supposed to conduct the trial impartially and in an open...

.


Planck was born in Kiel
Kiel
Kiel is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 238,049 .Kiel is approximately north of Hamburg. Due to its geographic location in the north of Germany, the southeast of the Jutland peninsula, and the southwestern shore of the...

, Holstein
Holstein
Holstein is the region between the rivers Elbe and Eider. It is part of Schleswig-Holstein, the northernmost state of Germany....

, to Johann Julius Wilhelm Planck and his second wife, Emma Patzig.
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Unanswered Questions
Quotations

We have no right to assume that any physical laws exist, or if they have existed up to now, that they will continue to exist in a similar manner in the future.

The Universe in the Light of Modern Physics (1931)

I regard consciousness as fundamental. I regard matter as derivative from consciousness. We cannot get behind consciousness. Everything that we talk about, everything that we regard as existing, postulates consciousness.

The Observer (January 25th, 1931)

Anybody who has been seriously engaged in scientific work of any kind realizes that over the entrance to the gates of the temple of science are written the words: Ye must have faith. It is a quality which the scientist cannot dispense with.

Where Is Science Going? (1932)

Both Religion and science require a belief in God. For believers, God is in the beginning, and for physicists He is at the end of all considerations… To the former He is the foundation, to the latter, the crown of the edifice of every generalized world view.

Religion and Natural Science (Lecture Given 1937) Scientific Autobiography and Other Papers, trans. F. Gaynor (New York, 1949), pp. 184

New scientific ideas never spring from a communal body, however organized, but rather from the head of an individually inspired researcher who struggles with his problems in lonely thought and unites all his thought on one single point which is his whole world for the moment.

Address on the 25th anniversary of the Kaiser-Wilhelm Gesellschaft, 10/11 January 1936. Quoted in Macrakis, Kristie Surviving the Swastika: Scientific Research in Nazi Germany (Oxford, 1993) ISBN 0-19-507010-0.
Encyclopedia
Max Karl Ernst Ludwig Planck, ForMemRS
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

, (April 23, 1858 – October 4, 1947) was a German
Germans
The Germans are a Germanic ethnic group native to Central Europe. The English term Germans has referred to the German-speaking population of the Holy Roman Empire since the Late Middle Ages....

 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 actualized the quantum physics, initiating a revolution in natural science and philosophy. He is regarded as the founder of the quantum theory
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...

, for which he received the Nobel Prize in Physics
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...

 in 1918.

Life and career


Planck came from a traditional, intellectual family. His paternal great-grandfather and grandfather were both theology
Theology
Theology is the systematic and rational study of religion and its influences and of the nature of religious truths, or the learned profession acquired by completing specialized training in religious studies, usually at a university or school of divinity or seminary.-Definition:Augustine of Hippo...

 professor
Professor
A professor is a scholarly teacher; the precise meaning of the term varies by country. Literally, professor derives from Latin as a "person who professes" being usually an expert in arts or sciences; a teacher of high rank...

s in Göttingen; his father was a law
Law
Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...

 professor in Kiel
University of Kiel
The University of Kiel is a university in the city of Kiel, Germany. It was founded in 1665 as the Academia Holsatorum Chiloniensis by Christian Albert, Duke of Holstein-Gottorp and has approximately 23,000 students today...

 and Munich; and his pater
Father
A father, Pop, Dad, or Papa, is defined as a male parent of any type of offspring. The adjective "paternal" refers to father, parallel to "maternal" for mother...

nal uncle was a judge
Judge
A judge is a person who presides over court proceedings, either alone or as part of a panel of judges. The powers, functions, method of appointment, discipline, and training of judges vary widely across different jurisdictions. The judge is supposed to conduct the trial impartially and in an open...

.


Planck was born in Kiel
Kiel
Kiel is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 238,049 .Kiel is approximately north of Hamburg. Due to its geographic location in the north of Germany, the southeast of the Jutland peninsula, and the southwestern shore of the...

, Holstein
Holstein
Holstein is the region between the rivers Elbe and Eider. It is part of Schleswig-Holstein, the northernmost state of Germany....

, to Johann Julius Wilhelm Planck and his second wife, Emma Patzig. He was baptised with the name of Karl Ernst Ludwig Marx Planck; of his given names, Marx (a now obsolete variant of Markus or maybe simply an error for Max, which is actually short for Maximilian) was indicated as the primary name. However, by the age of ten he signed with the name Max and used this for the rest of his life.

He was the sixth child in the family, though two of his siblings were from his father's first marriage. Among his earliest memories was the marching of Prussian
Kingdom of Prussia
The Kingdom of Prussia was a German kingdom from 1701 to 1918. Until the defeat of Germany in World War I, it comprised almost two-thirds of the area of the German Empire...

 and Austrian
Austrian Empire
The Austrian Empire was a modern era successor empire, which was centered on what is today's Austria and which officially lasted from 1804 to 1867. It was followed by the Empire of Austria-Hungary, whose proclamation was a diplomatic move that elevated Hungary's status within the Austrian Empire...

 troops into Kiel during the Danish-Prussian war of 1864. In 1867 the family moved to Munich
Munich
Munich The city's motto is "" . Before 2006, it was "Weltstadt mit Herz" . Its native name, , is derived from the Old High German Munichen, meaning "by the monks' place". The city's name derives from the monks of the Benedictine order who founded the city; hence the monk depicted on the city's coat...

, and Planck enrolled in the Maximilians 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...

 school, where he came under the tutelage of Hermann Müller, a mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....

 who took an interest in the youth, and taught him astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 and 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....

 as well as mathematics. It was from Müller that Planck first learned the principle of conservation of energy. Planck graduated early, at age 17. This is how Planck first came in contact with the field of physics.

Planck was gifted when it came to music
Music
Music is an art form whose medium is sound and silence. Its common elements are pitch , rhythm , dynamics, and the sonic qualities of timbre and texture...

. He took singing lessons and played piano
Piano
The piano is a musical instrument played by means of a keyboard. It is one of the most popular instruments in the world. Widely used in classical and jazz music for solo performances, ensemble use, chamber music and accompaniment, the piano is also very popular as an aid to composing and rehearsal...

, organ
Organ (music)
The organ , is a keyboard instrument of one or more divisions, each played with its own keyboard operated either with the hands or with the feet. The organ is a relatively old musical instrument in the Western musical tradition, dating from the time of Ctesibius of Alexandria who is credited with...

 and cello
Cello
The cello is a bowed string instrument with four strings tuned in perfect fifths. It is a member of the violin family of musical instruments, which also includes the violin, viola, and double bass. Old forms of the instrument in the Baroque era are baryton and viol .A person who plays a cello is...

, and composed song
Song
In music, a song is a composition for voice or voices, performed by singing.A song may be accompanied by musical instruments, or it may be unaccompanied, as in the case of a cappella songs...

s and opera
Opera
Opera is an art form in which singers and musicians perform a dramatic work combining text and musical score, usually in a theatrical setting. Opera incorporates many of the elements of spoken theatre, such as acting, scenery, and costumes and sometimes includes dance...

s. However, instead of music he chose to study 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...

.
The Munich physics professor Philipp von Jolly
Philipp von Jolly
Johann Philipp Gustav von Jolly was a German physicist and mathematician.Born in Mannheim as the son of merchant Louis Jolly and Marie Eleonore Jolly, he studied science in Heidelberg, Vienna and Berlin. After his studies, he was appointed professor of mathematics in Heidelberg in 1839 and in...

 advised Planck against going into physics, saying, "in this field, almost everything is already discovered, and all that remains is to fill a few holes." Planck replied that he did not wish to discover new things, but only to understand the known fundamentals of the field, and so began his studies in 1874 at the University of Munich. Under Jolly's supervision, Planck performed the only experiments of his scientific career, studying the diffusion
Diffusion
Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...

 of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 through heated platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...

, but transferred to theoretical physics
Theoretical physics
Theoretical physics is a branch of physics which employs mathematical models and abstractions of physics to rationalize, explain and predict natural phenomena...

.

In 1877 he went to Berlin
Humboldt University of Berlin
The Humboldt University of Berlin is Berlin's oldest university, founded in 1810 as the University of Berlin by the liberal Prussian educational reformer and linguist Wilhelm von Humboldt, whose university model has strongly influenced other European and Western universities...

 for a year of study with physicists Hermann von Helmholtz
Hermann von Helmholtz
Hermann Ludwig Ferdinand von Helmholtz was a German physician and physicist who made significant contributions to several widely varied areas of modern science...

 and Gustav Kirchhoff
Gustav Kirchhoff
Gustav Robert Kirchhoff was a German physicist who contributed to the fundamental understanding of electrical circuits, spectroscopy, and the emission of black-body radiation by heated objects...

 and mathematician Karl Weierstrass
Karl Weierstrass
Karl Theodor Wilhelm Weierstrass was a German mathematician who is often cited as the "father of modern analysis".- Biography :Weierstrass was born in Ostenfelde, part of Ennigerloh, Province of Westphalia....

. He wrote that Helmholtz was never quite prepared, spoke slowly, miscalculated endlessly, and bored his listeners, while Kirchhoff spoke in carefully prepared lectures which were dry and monotonous. He soon became close friends with Helmholtz. While there he undertook a program of mostly self-study of Clausius's
Rudolf Clausius
Rudolf Julius Emanuel Clausius , was a German 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...

 writings, which led him to choose heat theory as his field.

In October 1878 Planck passed his qualifying exams and in February 1879 defended his dissertation, Über den zweiten Hauptsatz der mechanischen Wärmetheorie (On the second law of thermodynamics). He briefly taught mathematics and physics at his former school in Munich.

In June 1880 he presented his habilitation
Habilitation
Habilitation is the highest academic qualification a scholar can achieve by his or her own pursuit in several European and Asian countries. Earned after obtaining a research doctorate, such as a PhD, habilitation requires the candidate to write a professorial thesis based on independent...

 thesis, Gleichgewichtszustände isotroper Körper in verschiedenen Temperaturen (Equilibrium states of isotropic bodies at different temperatures).

Academic career


With the completion of his habilitation thesis, Planck became an unpaid private lecturer in Munich, waiting until he was offered an academic position. Although he was initially ignored by the academic community, he furthered his work on the field of heat theory
Theory of heat
In the history of science, the theory of heat or mechanical theory of heat was a theory, introduced predominantly in 1824 by the French physicist Sadi Carnot, that heat and mechanical work are equivalent. It is related to the mechanical equivalent of heat...

 and discovered one after another the same thermodynamic
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...

al formalism as Gibbs
Josiah Willard Gibbs
Josiah Willard Gibbs was an American theoretical physicist, chemist, and mathematician. He devised much of the theoretical foundation for chemical thermodynamics as well as physical chemistry. As a mathematician, he invented vector analysis . Yale University awarded Gibbs the first American Ph.D...

 without realizing it. Clausius's ideas on entropy
Entropy
Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...

 occupied a central role in his work.

In April 1885 the University of Kiel
University of Kiel
The University of Kiel is a university in the city of Kiel, Germany. It was founded in 1665 as the Academia Holsatorum Chiloniensis by Christian Albert, Duke of Holstein-Gottorp and has approximately 23,000 students today...

 appointed Planck as associate professor of theoretical physics
Theoretical physics
Theoretical physics is a branch of physics which employs mathematical models and abstractions of physics to rationalize, explain and predict natural phenomena...

. Further work on entropy and its treatment, especially as applied in physical chemistry
Physical chemistry
Physical chemistry is the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of physical laws and concepts...

, followed. He proposed a thermodynamic basis for Svante Arrhenius
Svante Arrhenius
Svante August Arrhenius was a Swedish scientist, originally a physicist, but often referred to as a chemist, and one of the founders of the science of physical chemistry...

's theory of electrolytic
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....

 dissociation
Dissociation (chemistry)
Dissociation in chemistry and biochemistry is a general process in which ionic compounds separate or split into smaller particles, ions, or radicals, usually in a reversible manner...

.

Within four years he was named the successor to Kirchhoff's position at the University of Berlin — presumably thanks to Helmholtz's intercession — and by 1892 became a full professor. In 1907 Planck was offered Boltzmann
Ludwig Boltzmann
Ludwig Eduard Boltzmann was an Austrian physicist famous for his founding contributions in the fields of statistical mechanics and statistical thermodynamics...

's position in Vienna
Vienna
Vienna is the capital and largest city of the Republic of Austria and one of the nine states of Austria. Vienna is Austria's primary city, with a population of about 1.723 million , and is by far the largest city in Austria, as well as its cultural, economic, and political centre...

, but turned it down to stay in Berlin. During 1909, as University of Berlin professor, eight of his lectures were used by the Ernest Kempton Adams Fund for Physical Research in Theoretical Physics at Columbia University
Columbia University
Columbia University in the City of New York is a private, Ivy League university in Manhattan, New York City. Columbia is the oldest institution of higher learning in the state of New York, the fifth oldest in the United States, and one of the country's nine Colonial Colleges founded before the...

 in New York City
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

 for a series of lectures translated by Columbia University professor A. P. Wills. He retired from Berlin on January 10, 1926, and was succeeded by Erwin Schrödinger
Erwin Schrödinger
Erwin Rudolf Josef Alexander Schrödinger was an Austrian physicist and theoretical biologist who was one of the fathers of quantum mechanics, and is famed for a number of important contributions to physics, especially the Schrödinger equation, for which he received the Nobel Prize in Physics in 1933...

.

Family


In March 1887 Planck married Marie Merck (1861–1909), sister of a school fellow, and moved with her into a sublet apartment in Kiel. They had four children: Karl (1888–1916), the twins Emma (1889–1919) and Grete (1889–1917), and Erwin
Erwin Planck
Erwin Planck was a German politician, and a resistance fighter in the Third Reich.Born in Berlin, Erwin Planck was theoretical physicist Max Planck's and his first wife's fourth child. After his Abitur in 1911, Planck went into the military and pursued a career as an officer...

 (1893–1945).

After the apartment in Berlin, the Planck family lived in a villa in Berlin-Grunewald, Wangenheimstraße 21. Several other professors of Berlin University lived nearby, among them theologian Adolf von Harnack
Adolf von Harnack
Adolf von Harnack , was a German theologian and prominent church historian.He produced many religious publications from 1873-1912....

, who became a close friend of Planck. Soon the Planck home became a social and cultural centre. Numerous well-known scientists, such as Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

, Otto Hahn
Otto Hahn
Otto Hahn FRS was a German chemist and Nobel laureate, a pioneer in the fields of radioactivity and radiochemistry. He is regarded as "the father of nuclear chemistry". Hahn was a courageous opposer of Jewish persecution by the Nazis and after World War II he became a passionate campaigner...

 and Lise Meitner
Lise Meitner
Lise Meitner FRS was an Austrian-born, later Swedish, physicist who worked on radioactivity and nuclear physics. Meitner was part of the team that discovered nuclear fission, an achievement for which her colleague Otto Hahn was awarded the Nobel Prize...

 were frequent visitors. The tradition of jointly performing music had already been established in the home of Helmholtz
Hermann von Helmholtz
Hermann Ludwig Ferdinand von Helmholtz was a German physician and physicist who made significant contributions to several widely varied areas of modern science...

.

After several happy years, in July 1909 Marie Planck died, possibly from tuberculosis
Tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

. In March 1911 Planck married his second wife, Marga von Hoesslin (1882–1948); in December his third son Hermann was born.

During the First World War Planck's second son Erwin was taken prisoner by the French in 1914, while his oldest son Karl was killed in action at Verdun
Battle of Verdun
The Battle of Verdun was one of the major battles during the First World War on the Western Front. It was fought between the German and French armies, from 21 February – 18 December 1916, on hilly terrain north of the city of Verdun-sur-Meuse in north-eastern France...

. Grete died in 1917 while giving birth to her first child. Her sister died the same way two years later, after having married Grete's widower. Both granddaughters survived and were named after their mothers. Planck endured these losses stoically.

In January 1945, Erwin
Erwin Planck
Erwin Planck was a German politician, and a resistance fighter in the Third Reich.Born in Berlin, Erwin Planck was theoretical physicist Max Planck's and his first wife's fourth child. After his Abitur in 1911, Planck went into the military and pursued a career as an officer...

, to whom he had been particularly close, was sentenced to death by the Nazi Volksgerichtshof
People's Court (German)
The People's Court was a court established in 1934 by German Chancellor Adolf Hitler, who had been dissatisfied with the outcome of the Reichstag Fire Trial . The "People's Court" was set up outside the operations of the constitutional frame of law...

 because of his participation in the failed attempt to assassinate Hitler
July 20 Plot
On 20 July 1944, an attempt was made to assassinate Adolf Hitler, Führer of the Third Reich, inside his Wolf's Lair field headquarters near Rastenburg, East Prussia. The plot was the culmination of the efforts of several groups in the German Resistance to overthrow the Nazi-led German government...

 in July 1944. Erwin was executed on 23 January 1945.
  • Wives: Marie Merck (m. 1887), Marga von Hoesslin (m. 1910)
  • Children: Karl (1888–1916), twins Emma (1889–1919) and Grete (1889–1917), Erwin
    Erwin Planck
    Erwin Planck was a German politician, and a resistance fighter in the Third Reich.Born in Berlin, Erwin Planck was theoretical physicist Max Planck's and his first wife's fourth child. After his Abitur in 1911, Planck went into the military and pursued a career as an officer...

     (1893–1945), Hermann (1911–1954)

Professor at Berlin University


In Berlin, Planck joined the local Physical Society. He later wrote about this time: "In those days I was essentially the only theoretical physicist there, whence things were not so easy for me, because I started mentioning entropy, but this was not quite fashionable, since it was regarded as a mathematical spook". Thanks to his initiative, the various local Physical Societies of Germany merged in 1898 to form the German Physical Society (Deutsche Physikalische Gesellschaft
Deutsche Physikalische Gesellschaft
The Deutsche Physikalische Gesellschaft is the world's largest organization of physicists. The DPG's worldwide membership is cited as 60,000, as of 2011...

, DPG); from 1905 to 1909 Planck was the president.

Planck started a six-semester course of lectures on theoretical physics, "dry, somewhat impersonal" according to Lise Meitner
Lise Meitner
Lise Meitner FRS was an Austrian-born, later Swedish, physicist who worked on radioactivity and nuclear physics. Meitner was part of the team that discovered nuclear fission, an achievement for which her colleague Otto Hahn was awarded the Nobel Prize...

, "using no notes, never making mistakes, never faltering; the best lecturer I ever heard" according to an English participant, James R. Partington
J. R. Partington
James Riddick Partington MBE was a British chemist and historian of chemistry.- Life and work :Partington was born in Bolton, Lancashire and was educated at the University of Manchester, where he obtained First Class Honours...

, who continues: "There were always many standing around the room. As the lecture-room was well heated and rather close, some of the listeners would from time to time drop to the floor, but this did not disturb the lecture". Planck did not establish an actual "school"; the number of his graduate students was only about 20, among them:
1897 Max Abraham
Max Abraham
Max Abraham was a German physicist.Abraham was born in Danzig, Imperial Germany to a family of Jewish merchants. His father was Moritz Abraham and his mother was Selma Moritzsohn. Attending the University of Berlin, he studied under Max Planck. He graduated in 1897...

 (1875–1922)
1904 Moritz Schlick
Moritz Schlick
Friedrich Albert Moritz Schlick was a German philosopher, physicist and the founding father of logical positivism and the Vienna Circle.-Early life and works:...

 (1882–1936)
1906 Walther Meißner
Walther Meißner
Fritz Walther Meißner was a German technical physicist.Meissner was born in Berlin to Waldemar Meissner and Johanna Greger. He studied mechanical engineering and physics at the Technical University of Berlin, his doctoral supervisor being Max Planck...

 (1882–1974)
1906 Max von Laue
Max von Laue
Max Theodor Felix von Laue was a German physicist who won the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals...

 (1879–1960)
1907 Fritz Reiche
Fritz Reiche
Fritz Reiche was a student of Max Planck and a colleague of Albert Einstein,who was active in, and made important contributions to the early development of quantum mechanics including co-authoring the Thomas-Reiche-Kuhn sum rule....

 (1883–1960)
1912 Walter Schottky (1886–1976)
1914 Walther Bothe
Walther Bothe
Walther Wilhelm Georg Bothe was a German nuclear physicist, who shared the Nobel Prize in Physics in 1954 with Max Born....

 (1891–1957)

Black-body radiation


In 1894 Planck turned his attention to the problem of black-body radiation
Black body
A black body is an idealized physical body that absorbs all incident electromagnetic radiation. Because of this perfect absorptivity at all wavelengths, a black body is also the best possible emitter of thermal radiation, which it radiates incandescently in a characteristic, continuous spectrum...

. He had been commissioned by electric companies to create maximum light from lightbulbs with minimum energy. The problem had been stated by Kirchhoff in 1859: "how does the intensity of the electromagnetic radiation emitted by a black body
Black body
A black body is an idealized physical body that absorbs all incident electromagnetic radiation. Because of this perfect absorptivity at all wavelengths, a black body is also the best possible emitter of thermal radiation, which it radiates incandescently in a characteristic, continuous spectrum...

 (a perfect absorber, also known as a cavity radiator) depend on the frequency
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...

 of the radiation (i.e., the color of the light) and the temperature of the body?". The question had been explored experimentally, but no theoretical treatment agreed with experimental values. 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...

 proposed Wien's law, which correctly predicted the behaviour at high frequencies, but failed at low frequencies. The Rayleigh–Jeans law, another approach to the problem, created what was later known as the "ultraviolet catastrophe
Ultraviolet catastrophe
The ultraviolet catastrophe, also called the Rayleigh–Jeans catastrophe, was a prediction of late 19th century/early 20th century classical physics that an ideal black body at thermal equilibrium will emit radiation with infinite power....

", but contrary to many textbooks this was not a motivation for Planck.

Planck's first proposed solution to the problem in 1899 followed from what Planck called the "principle of elementary disorder", which allowed him to derive Wien's law from a number of assumptions about the entropy of an ideal oscillator, creating what was referred-to as the Wien–Planck law. Soon it was found that experimental evidence did not confirm the new law at all, to Planck's frustration. Planck revised his approach, deriving the first version of the famous Planck black-body radiation law, which described the experimentally observed black-body spectrum well. It was first proposed in a meeting of the DPG on October 19, 1900 and published in 1901. This first derivation did not include energy quantisation, and did not use statistical mechanics
Statistical mechanics
Statistical mechanics or statistical thermodynamicsThe terms statistical mechanics and statistical thermodynamics are used interchangeably...

, to which he held an aversion. In November 1900, Planck revised this first approach, relying on Boltzmann
Ludwig Boltzmann
Ludwig Eduard Boltzmann was an Austrian physicist famous for his founding contributions in the fields of statistical mechanics and statistical thermodynamics...

's statistical interpretation of the second law of thermodynamics
Second law of thermodynamics
The second law of thermodynamics is an expression of the tendency that over time, differences in temperature, pressure, and chemical potential equilibrate in an isolated physical system. From the state of thermodynamic equilibrium, the law deduced the principle of the increase of entropy and...

 as a way of gaining a more fundamental understanding of the principles behind his radiation law. As Planck was deeply suspicious of the philosophical and physical implications of such an interpretation of Boltzmann's approach, his recourse to them was, as he later put it, "an act of despair ... I was ready to sacrifice any of my previous convictions about physics."

The central assumption behind his new derivation, presented to the DPG on 14 December 1900, was the supposition, now known as the Planck postulate
Planck postulate
The Planck Postulate , one of the fundamental principles of quantum mechanics, is the postulate that the energy of oscillators in a black body is quantized, and is given byE=nh\nu\,,...

, that electromagnetic energy could be emitted only in quantized
Quantization (physics)
In physics, quantization is the process of explaining a classical understanding of physical phenomena in terms of a newer understanding known as "quantum mechanics". It is a procedure for constructing a quantum field theory starting from a classical field theory. This is a generalization of the...

 form, in other words, the energy could only be a multiple of an elementary unit , where is Planck's constant, also known as Planck's action quantum (introduced already in 1899), and (the Greek letter nu, not the Roman letter v) is the frequency of the radiation. Note that the elementary units of energy discussed here are represented by and not simply by . Physicists now call these quanta photons, and a photon of frequency will have its own specific and unique energy. The amplitude of energy at that frequency is then a function of the number of photons of that frequency being produced per unit of time.
At first Planck considered that quantisation was only "a purely formal assumption ... actually I did not think much about it..."; nowadays this assumption, incompatible with classical physics
Classical physics
What "classical physics" refers to depends on the context. When discussing special relativity, it refers to the Newtonian physics which preceded relativity, i.e. the branches of physics based on principles developed before the rise of relativity and quantum mechanics...

, is regarded as the birth of quantum physics and the greatest intellectual accomplishment of Planck's career (Ludwig Boltzmann
Ludwig Boltzmann
Ludwig Eduard Boltzmann was an Austrian physicist famous for his founding contributions in the fields of statistical mechanics and statistical thermodynamics...

 had been discussing in a theoretical paper in 1877 the possibility that the energy states of a physical system could be discrete). Further interpretation of the implications of Planck's work was advanced by Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

 in 1905 in connection with his work on the photoelectric effect
Photoelectric effect
In the photoelectric effect, electrons are emitted from matter as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength, such as visible or ultraviolet light. Electrons emitted in this manner may be referred to as photoelectrons...

—for this reason, the philosopher and historian of science Thomas Kuhn
Thomas Kuhn
Thomas Samuel Kuhn was an American historian and philosopher of science whose controversial 1962 book The Structure of Scientific Revolutions was deeply influential in both academic and popular circles, introducing the term "paradigm shift," which has since become an English-language staple.Kuhn...

 argued that Einstein should be given credit for quantum theory more so than Planck, since Planck did not understand in a deep sense that he was "introducing the quantum" as a real physical entity. Be that as it may, it was in recognition of Planck's monumental accomplishment that he was awarded the Nobel Prize in Physics
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...

 in 1918.

The discovery of Planck's constant enabled him to define a new universal set of physical units
Planck units
In physics, Planck units are physical units of measurement defined exclusively in terms of five universal physical constants listed below, in such a manner that these five physical constants take on the numerical value of 1 when expressed in terms of these units. Planck units elegantly simplify...

 (such as the Planck length and the Planck mass), all based on fundamental physical constant
Physical constant
A physical constant is a physical quantity that is generally believed to be both universal in nature and constant in time. It can be contrasted with a mathematical constant, which is a fixed numerical value but does not directly involve any physical measurement.There are many physical constants in...

s.

Subsequently, Planck tried to grasp the meaning of energy quanta, but to no avail. "My unavailing attempts to somehow reintegrate the action quantum into classical theory extended over several years and caused me much trouble." Even several years later, other physicists like Rayleigh, Jeans, and Lorentz
Hendrik Lorentz
Hendrik Antoon Lorentz was a Dutch physicist who shared the 1902 Nobel Prize in Physics with Pieter Zeeman for the discovery and theoretical explanation of the Zeeman effect...

 set Planck's constant to zero in order to align with classical physics, but Planck knew well that this constant had a precise nonzero value. "I am unable to understand Jeans' stubbornness — he is an example of a theoretician as should never be existing, the same as Hegel was for philosophy. So much the worse for the facts if they don't fit."

Max Born
Max Born
Max Born was a German-born physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a number of notable physicists in the 1920s and 30s...

 wrote about Planck: "He was by nature and by the tradition of his family conservative, averse to revolutionary novelties and skeptical towards speculations. But his belief in the imperative power of logical thinking based on facts was so strong that he did not hesitate to express a claim contradicting to all tradition, because he had convinced himself that no other resort was possible."

Einstein and the theory of relativity


In 1905 the three epochal papers of the hitherto completely unknown Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

 were published in the journal Annalen der Physik
Annalen der Physik
Annalen der Physik is one of the oldest physics journals worldwide. The journal publishes original, peer-reviewed papers in the areas of experimental, theoretical, applied and mathematical physics and related areas...

. Planck was among the few who immediately recognized the significance of the special theory of relativity. Thanks to his influence this theory was soon widely accepted in Germany. Planck also contributed considerably to extend the special theory of relativity.

Einstein's hypothesis of light quanta (photons), based on Philipp Lenard
Philipp Lenard
Philipp Eduard Anton von Lenard , known in Hungarian as Lénárd Fülöp Eduárd Antal, was a Hungarian - German physicist and the winner of the Nobel Prize for Physics in 1905 for his research on cathode rays and the discovery of many of their properties...

's 1902 discovery of the photoelectric effect
Photoelectric effect
In the photoelectric effect, electrons are emitted from matter as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength, such as visible or ultraviolet light. Electrons emitted in this manner may be referred to as photoelectrons...

, was initially rejected by Planck. He was unwilling to discard completely Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

's theory of electrodynamics. "The theory of light would be thrown back not by decades, but by centuries, into the age when Christian Huygens dared to fight against the mighty emission theory of Isaac Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...

 ..."

In 1910 Einstein pointed out the anomalous behavior of specific heat at low temperatures as another example of a phenomenon which defies explanation by classical physics. Planck and Nernst
Walther Nernst
Walther Hermann Nernst FRS was a German physical chemist and physicist who is known for his theories behind the calculation of chemical affinity as embodied in the third law of thermodynamics, for which he won the 1920 Nobel Prize in chemistry...

, seeking to clarify the increasing number of contradictions, organized the First Solvay Conference
Solvay Conference
The International Solvay Institutes for Physics and Chemistry, located in Brussels, were founded by the Belgian industrialist Ernest Solvay in 1912, following the historic invitation-only 1911 Conseil Solvay, the turning point in world physics...

 (Brussels 1911). At this meeting Einstein was able to convince Planck.

Meanwhile Planck had been appointed dean of Berlin University, whereby it was possible for him to call Einstein to Berlin and establish a new professorship for him (1914). Soon the two scientists became close friends and met frequently to play music together.

World War I


At the onset of the First World War Planck endorsed the general excitement of the public, writing that, "Besides much that is horrible, there is also much that is unexpectedly great and beautiful: the smooth solution of the most difficult domestic political problems by the unification of all parties (and) ... the extolling of everything good and noble."

Nonetheless, Planck refrained from the extremes of nationalism. In 1915, at a time when Italy was about to join the Allied Powers
Allies of World War I
The Entente Powers were the countries at war with the Central Powers during World War I. The members of the Triple Entente were the United Kingdom, France, and the Russian Empire; Italy entered the war on their side in 1915...

, he voted successfully for a scientific paper from Italy, which received a prize from the Prussian Academy of Sciences
Prussian Academy of Sciences
The Prussian Academy of Sciences was an academy established in Berlin on 11 July 1700, four years after the Akademie der Künste or "Arts Academy", to which "Berlin Academy" may also refer.-Origins:...

, where Planck was one of four permanent presidents.

Planck also signed the infamous "Manifesto of the 93 intellectuals
Manifesto of the Ninety-Three
The "Manifesto of the Ninety-Three" is the name commonly given to a 1914 proclamation endorsed by 93 prominent German scientists, scholars and artists, declaring their unequivocal support of German military actions in the early period of World War I. These actions were elsewhere called the Rape of...

", a pamphlet of polemic war propaganda (while Einstein retained a strictly pacifistic attitude which almost led to his imprisonment, being spared by his Swiss
Swiss (people)
The Swiss are citizens or natives of Switzerland. The demonym derives from the toponym of Schwyz and has been in widespread use to refer to the Old Swiss Confederacy since the 16th century....

 citizenship). But in 1915 Planck, after several meetings with Dutch physicist Lorentz
Hendrik Lorentz
Hendrik Antoon Lorentz was a Dutch physicist who shared the 1902 Nobel Prize in Physics with Pieter Zeeman for the discovery and theoretical explanation of the Zeeman effect...

, revoked parts of the Manifesto. Then in 1916 he signed a declaration against German annexationism.

Post War and Weimar Republic


In the turbulent post-war years, Planck, now the highest authority of German physics, issued the slogan "persevere and continue working" to his colleagues.

In October 1920 he and Fritz Haber
Fritz Haber
Fritz Haber was a German chemist, who received the Nobel Prize in Chemistry in 1918 for his development for synthesizing ammonia, important for fertilizers and explosives. Haber, along with Max Born, proposed the Born–Haber cycle as a method for evaluating the lattice energy of an ionic solid...

 established the Notgemeinschaft der Deutschen Wissenschaft
Notgemeinschaft der Deutschen Wissenschaft
Notgemeinschaft der Deutschen Wissenschaft was founded on 30 October 1920 on the initiative of leading members of the Preußischen Akademie der Wissenschaften – Fritz Haber, Max Planck, and Ernst von Harnack – and the former Preußischen...

(Emergency Organization of German Science), aimed at providing financial support for scientific research. A considerable portion of the monies the organization would distribute were raised abroad.

Planck also held leading positions at Berlin University, the Prussian Academy of Sciences, the German Physical Society and the Kaiser-Wilhelm-Gesellschaft
Kaiser Wilhelm Institute
The Kaiser Wilhelm Society for the Advancement of Science was a German scientific institution established in 1911. It was implicated in Nazi science, and after the Second World War was wound up and its functions replaced by the Max Planck Society...

 (which in 1948 became the Max-Planck-Gesellschaft). During this time economic conditions in Germany were such that he was hardly able to conduct research.

During the interwar period, Planck became a member of the Deutsche Volks-Partei (German People's Party
German People's Party
The German People's Party was a national liberal party in Weimar Germany and a successor to the National Liberal Party of the German Empire.-Ideology:...

), the party of Nobel Peace Prize laureate Gustav Stresemann
Gustav Stresemann
was a German politician and statesman who served as Chancellor and Foreign Minister during the Weimar Republic. He was co-laureate of the Nobel Peace Prize in 1926.Stresemann's politics defy easy categorization...

, which aspired to liberal aims for domestic policy and rather revisionistic aims for international politics.

Planck disagreed with the introduction of universal suffrage
Universal suffrage
Universal suffrage consists of the extension of the right to vote to adult citizens as a whole, though it may also mean extending said right to minors and non-citizens...

 and later expressed the view that the Nazi dictatorship resulted from "the ascent of the rule of the crowds".

Quantum mechanics


At the end of the 1920s Bohr
Niels Bohr
Niels Henrik David Bohr was a Danish physicist who made foundational contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922. Bohr mentored and collaborated with many of the top physicists of the century at his institute in...

, Heisenberg
Werner Heisenberg
Werner Karl Heisenberg was a German theoretical physicist who made foundational contributions to quantum mechanics and is best known for asserting the uncertainty principle of quantum theory...

 and Pauli
Wolfgang Pauli
Wolfgang Ernst Pauli was an Austrian theoretical physicist and one of the pioneers of quantum physics. In 1945, after being nominated by Albert Einstein, he received the Nobel Prize in Physics for his "decisive contribution through his discovery of a new law of Nature, the exclusion principle or...

 had worked out the Copenhagen interpretation
Copenhagen interpretation
The Copenhagen interpretation is one of the earliest and most commonly taught interpretations of quantum mechanics. It holds that quantum mechanics does not yield a description of an objective reality but deals only with probabilities of observing, or measuring, various aspects of energy quanta,...

 of quantum mechanics, but it was rejected by Planck, as well as Schrödinger
Erwin Schrödinger
Erwin Rudolf Josef Alexander Schrödinger was an Austrian physicist and theoretical biologist who was one of the fathers of quantum mechanics, and is famed for a number of important contributions to physics, especially the Schrödinger equation, for which he received the Nobel Prize in Physics in 1933...

, Laue
Max von Laue
Max Theodor Felix von Laue was a German physicist who won the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals...

, and Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

. Planck expected that wave mechanics would soon render quantum theory—his own child—unnecessary. This was not to be the case, however. Further work only cemented quantum theory, even against his and Einstein's philosophical revulsions. Planck experienced the truth of his own earlier observation from his struggle with the older views in his younger years: "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it."

Nazi dictatorship and The Second World War


When the Nazis seized power in 1933, Planck was 74. He witnessed many Jewish friends and colleagues expelled from their positions and humiliated, and hundreds of scientists emigrated from Germany. Again he tried the "persevere and continue working" slogan and asked scientists who were considering emigration to remain in Germany.
He hoped the crisis would abate soon and the political situation would improve. There was also a deeper argument against emigration. Emigrating German non-Jewish scientists would need to look for academic positions abroad, but these positions better served Jewish scientists, who had no chance of continuing to work in Germany.

Hahn
Otto Hahn
Otto Hahn FRS was a German chemist and Nobel laureate, a pioneer in the fields of radioactivity and radiochemistry. He is regarded as "the father of nuclear chemistry". Hahn was a courageous opposer of Jewish persecution by the Nazis and after World War II he became a passionate campaigner...

 asked Planck to gather well-known German professors in order to issue a public proclamation against the treatment of Jewish professors, but Planck replied, "If you are able to gather today 30 such gentlemen, then tomorrow 150 others will come and speak against it, because they are eager to take over the positions of the others." Under Planck's leadership, the Kaiser-Wilhelm-Gesellschaft
Kaiser Wilhelm Institute
The Kaiser Wilhelm Society for the Advancement of Science was a German scientific institution established in 1911. It was implicated in Nazi science, and after the Second World War was wound up and its functions replaced by the Max Planck Society...

 (KWG) avoided open conflict with the Nazi regime, except concerning Fritz Haber
Fritz Haber
Fritz Haber was a German chemist, who received the Nobel Prize in Chemistry in 1918 for his development for synthesizing ammonia, important for fertilizers and explosives. Haber, along with Max Born, proposed the Born–Haber cycle as a method for evaluating the lattice energy of an ionic solid...

. Planck tried to discuss the issue with Adolf Hitler
Adolf Hitler
Adolf Hitler was an Austrian-born German politician and the leader of the National Socialist German Workers Party , commonly referred to as the Nazi Party). He was Chancellor of Germany from 1933 to 1945, and head of state from 1934 to 1945...

 but was unsuccessful. In the following year, 1934, Haber died in exile.

One year later, Planck, having been the president of the KWG since 1930, organized in a somewhat provocative style an official commemorative meeting for Haber. He also succeeded in secretly enabling a number of Jewish scientists to continue working in institutes of the KWG for several years. In 1936, his term as president of the KWG ended, and the Nazi government pressured him to refrain from seeking another term.

As the political climate in Germany gradually became more hostile, Johannes Stark
Johannes Stark
Johannes Stark was a German physicist, and Physics Nobel Prize laureate who was closely involved with the Deutsche Physik movement under the Nazi regime.-Early years:...

, prominent exponent of Deutsche Physik
Deutsche Physik
Deutsche Physik or Aryan Physics was a nationalist movement in the German physics community in the early 1930s against the work of Albert Einstein, labeled "Jewish Physics"...

 ("German Physics", also called "Aryan Physics") attacked Planck, Sommerfeld
Arnold Sommerfeld
Arnold Johannes Wilhelm Sommerfeld was a German theoretical physicist who pioneered developments in atomic and quantum physics, and also educated and groomed a large number of students for the new era of theoretical physics...

 and Heisenberg for continuing to teach the theories of Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

, calling them "white Jews." The "Hauptamt Wissenschaft" (Nazi government office for science) started an investigation of Planck's ancestry, but all they could find out was that he was "1/16 Jewish."

In 1938 Planck celebrated his 80th birthday. The DPG held a celebration, during which the Max-Planck medal (founded as the highest medal by the DPG in 1928) was awarded to French physicist Louis de Broglie. At the end of 1938 the Prussian Academy lost its remaining independence and was taken over by Nazis (Gleichschaltung
Gleichschaltung
Gleichschaltung , meaning "coordination", "making the same", "bringing into line", is a Nazi term for the process by which the Nazi regime successively established a system of totalitarian control and tight coordination over all aspects of society. The historian Richard J...

). Planck protested by resigning his presidency. He continued to travel frequently, giving numerous public talks, such as his talk on Religion and Science, and five years later he was sufficiently fit to climb 3,000-meter peaks in the Alps.

During the Second World War, the increasing number of Allied bombing campaigns against Berlin forced Planck and his wife to leave the city temporarily and live in the countryside. In 1942 he wrote: "In me an ardent desire has grown to persevere this crisis and live long enough to be able to witness the turning point, the beginning of a new rise." In February 1944 his home in Berlin was completely destroyed by an air raid, annihilating all his scientific records and correspondence. Finally, he got into a dangerous situation in his rural retreat because of the rapid advance of the Allied armies from both sides. After the end of the war he was brought to a relative in Göttingen
Göttingen
Göttingen is a university town in Lower Saxony, Germany. It is the capital of the district of Göttingen. The Leine river runs through the town. In 2006 the population was 129,686.-General information:...

.

Planck endured many personal tragedies after the age of 50. In 1909, his first wife died after 22 years of marriage, leaving him with two sons and twin daughters. Planck's oldest son, Karl, was killed in action in 1916. His daughter Margarete died in childbirth in 1917, and another daughter, Emma, married her late sister's husband and then also died in childbirth, in 1919. During World War II, Planck's house in Berlin was completely destroyed by bombs in 1944 and his youngest son, Erwin
Erwin Planck
Erwin Planck was a German politician, and a resistance fighter in the Third Reich.Born in Berlin, Erwin Planck was theoretical physicist Max Planck's and his first wife's fourth child. After his Abitur in 1911, Planck went into the military and pursued a career as an officer...

, was implicated in the attempt made on Hitler's life in the July 20 plot
July 20 Plot
On 20 July 1944, an attempt was made to assassinate Adolf Hitler, Führer of the Third Reich, inside his Wolf's Lair field headquarters near Rastenburg, East Prussia. The plot was the culmination of the efforts of several groups in the German Resistance to overthrow the Nazi-led German government...

. Consequently, Erwin died at the hands of the Gestapo in 1945. Erwin's death destroyed Planck's will to live. By the end of the war, Planck, his second wife and his son by her, moved to Göttingen where he died on October 4, 1947.

Religious view



Planck was very tolerant towards alternative views and religions, and so was discontented with the Nazi church organizations' demands for unquestioning belief.

In a lecture on 1937 entitled "Religion und Naturwissenschaft" he suggested the importance of these symbols and rituals related directly with a believer's ability to worship God, but that one must be mindful that the symbols provide an imperfect illustration of divinity. He criticised atheism for being focussed on the derision of such symbols, while at the same time warned of the over-estimation of the importance of such symbols by believers.

Max Planck said "All matter originates and exists only by virtue of a force which brings the particle of an atom to vibration and holds this most minute solar system of the atom together. We must assume behind this force the existence of a conscious and intelligent mind. This mind is the matrix of all matter" in 1944, indicating that he believed in some kind of God.

Planck regarded the scientist as a man of imagination and faith, "faith" interpreted as being similar to "having a working hypothesis". For example the causality principle
Causality
Causality is the relationship between an event and a second event , where the second event is understood as a consequence of the first....

 isn't true or false, it is an act of faith. Thereby Planck may have indicated a view that points toward Imre Lakatos
Imre Lakatos
Imre Lakatos was a Hungarian philosopher of mathematics and science, known for his thesis of the fallibility of mathematics and its 'methodology of proofs and refutations' in its pre-axiomatic stages of development, and also for introducing the concept of the 'research programme' in his...

' research programs process descriptions, where falsification is mostly tolerable, in faith of its future removal.

On the other hand, Planck wrote, "...'to believe' means 'to recognize as a truth,' and the knowledge of nature, continually advancing on incontestably safe tracks, has made it utterly impossible for a person possessing some training in natural science to recognize as founded on truth the many reports of extraordinary contradicting the laws of nature, of miracles which are still commonly regarded as essential supports and confirmations of religious doctrines, and which formerly used to be accepted as facts pure and simple, without doubt or criticism.. The belief in miracles must retreat step by step before relentlessly and reliably progressing science and we cannot doubt that sooner or later it must vanish completely."

Six months before his death a rumour started that Planck had converted to Catholicism
Catholicism
Catholicism is a broad term for the body of the Catholic faith, its theologies and doctrines, its liturgical, ethical, spiritual, and behavioral characteristics, as well as a religious people as a whole....

, but when questioned what had brought him to make this step, he declared that, although he had always been deeply religious, he did not believe "in a personal God, let alone a Christian God."

Honors and awards


  • "Pour le Mérite
    Pour le Mérite
    The Pour le Mérite, known informally as the Blue Max , was the Kingdom of Prussia's highest military order for German soldiers until the end of World War I....

    " for Science and Arts 1915 (in 1930 he became chancellor of this order)
  • Nobel Prize in Physics
    Nobel Prize in Physics
    The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...

     1918 (awarded 1919)
  • Lorentz Medal
    Lorentz Medal
    Lorentz Medal is a prize awarded every four years by the Royal Netherlands Academy of Arts and Sciences. It was established in 1925 on the occasion of the 50th anniversary of the doctorate of Hendrik Lorentz. This solid gold medal is given for important contributions to theoretical physics, though...

     1927
  • Franklin Medal
    Franklin Medal
    The Franklin Medal was a science and engineering award presented by the Franklin Institute, of Philadelphia, PA, USA.-Laureates:*1915 - Thomas Alva Edison *1915 - Heike Kamerlingh Onnes *1916 - John J...

     (1927)
  • Adlerschild des Deutschen Reiches (1928), an award from the German Reich President
  • Max Planck medal
    Max Planck medal
    The Max Planck medal is an award for extraordinary achievements in theoretical physics. It is awarded annually by the Deutsche Physikalische Gesellschaft , the world's largest organization of physicists.-List of recipients:...

     (1929, together with Einstein
    Albert Einstein
    Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

    )
  • Copley Medal
    Copley Medal
    The Copley Medal is an award given by the Royal Society of London for "outstanding achievements in research in any branch of science, and alternates between the physical sciences and the biological sciences"...

     (1929)
  • Planck received honorary doctorates from the universities of Frankfurt, Munich (TH
    Technische Hochschule
    Technische Hochschule is what an Institute of Technology used to be called in German-speaking countries, as well as in the Netherlands, before most of them changed their name to Technische Universität or Technische Universiteit in the 1970s and in the...

    ), Rostock, Berlin (TH), Graz, Athens, Cambridge, London, and Glasgow.
  • The asteroid 1069
    1069 Planckia
    1069 Planckia is an asteroid. It was discovered by Max Wolf on January 28, 1927. Its provisional designation was 1927 BC. It was named after physicist Max Planck....

     was named "Stella Planckia" by the International Astronomical Union
    International Astronomical Union
    The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...

     (1938)

Publications


See also

  • Planck units
    Planck units
    In physics, Planck units are physical units of measurement defined exclusively in terms of five universal physical constants listed below, in such a manner that these five physical constants take on the numerical value of 1 when expressed in terms of these units. Planck units elegantly simplify...

    • Planck length
    • Planck mass
    • Planck time
      Planck time
      In physics, the Planck time, , is the unit of time in the system of natural units known as Planck units. It is the time required for light to travel, in a vacuum, a distance of 1 Planck length...

    • Planck temperature
      Planck temperature
      Planck temperature is the greatest physically-possible temperature, according the set of theories proposed by the German physicist Max Planck. It's part of a system of five natural units known as Planck units, based on universal physical constants....

    • Planck charge
      Planck charge
      In physics, the Planck charge , is one of the base units in the system of natural units called Planck units. It is a quantity of electric charge defined in terms of fundamental physical constants.The Planck charge is defined as:...

  • Derived Planck units
    • Planck current
    • Planck power
      Planck power
      The Planck energy divided by the Planck time is the Planck power, equal to about 3.62831 × 1052 W. This is an extremely large unit; even gamma-ray bursts, the most luminous phenomena known, have output on the order of 1 × 1045 W, less than one ten-millionth of the Planck power.In terms of the...

    • Planck density
  • Planck's law of black body radiation
    Planck's law of black body radiation
    In physics, Planck's law describes the amount of energy emitted by a black body in radiation of a certain wavelength . The law is named after Max Planck, who originally proposed it in 1900. The law was the first to accurately describe black body radiation, and resolved the ultraviolet catastrophe...

  • Planck epoch
    Planck epoch
    In physical cosmology, the Planck epoch , named after Max Planck, is the earliest period of time in the history of the universe, from zero to approximately 10−43 seconds , during which, it is believed, quantum effects of gravity were significant...

  • Planck particle
    Planck particle
    A Planck particle, named after physicist Max Planck, is a hypothetical particle defined as a tiny black hole whose Compton wavelength is comparable to its Schwarzschild radius. Its mass is thus approximately the Planck mass, and its Compton wavelength and Schwarzschild radius are about the Planck...

  • Planck postulate
    Planck postulate
    The Planck Postulate , one of the fundamental principles of quantum mechanics, is the postulate that the energy of oscillators in a black body is quantized, and is given byE=nh\nu\,,...

  • Max-Planck-Gesellschaft
  • Planck (crater)
    Planck (crater)
    Planck is a huge lunar crater that is located in the southern hemisphere of the Moon, on the far side as seen from the Earth. It lies to the west of the walled plain Poincaré, another enormous formation only slightly larger than Planck. Both formations are larger than the walled plain Bailly, the...

  • Max Planck Society
    Max Planck Society
    The Max Planck Society for the Advancement of Science is a formally independent non-governmental and non-profit association of German research institutes publicly funded by the federal and the 16 state governments of Germany....

  • Planck Surveyor
    Planck Surveyor
    Planck is a space observatory of the European Space Agency and designed to observe the anisotropies of the cosmic microwave background over the entire sky, at a high sensitivity and angular resolution...

  • Photon polarization
    Photon polarization
    Photon polarization is the quantum mechanical description of the classical polarized sinusoidal plane electromagnetic wave. Individual photons are completely polarized...

  • German inventors and discoverers
    German inventors and discoverers
    This is a list of German inventors and discoverers. The following list comprises people from Germany or German-speaking Europe, also of people of predominantly German heritage, in alphabetical order of the surname. The main section includes existing articles, indicated by blue links, and possibly...


  • Biographies


    Articles