Born on April 23, 1858 in Kiel, in the Duchy of Holstein (then under Danish rule), Max Karl Ernst Ludwig Planck (1858-1947) grew up in a family of intellectuals and jurists. His father, Julius Wilhelm Planck, was a professor of constitutional law, and his grandfather, Gottlieb Jakob Planck, was a theologian.
Educational journey:
1867-1874: Secondary studies at Maximiliansgymnasium in Munich
1874-1877: Physics studies at the University of Munich
1877-1878: Studies at the University of Berlin under Hermann von Helmholtz and Gustav Kirchhoff
1879: Defended his doctoral thesis on the second law of thermodynamics
1880: Obtained his habilitation with a thesis on equilibrium states of isotropic bodies
The Quantum Revolution (1900)
In December 1900, Planck presented his revolutionary theory of the quantum of action to the German Physical Society:
Problem solved: the "ultraviolet catastrophe" in blackbody radiation
Hypothesis: energy is not emitted continuously but in discrete packets (quanta)
Planck's formula: \( E = h\nu \) where \( h \) is Planck's constant (\( 6.62607015 \times 10^{-34} \) J⋅s)
Planck's law for blackbody radiation: $$ B_\nu(T) = \frac{2h\nu^3}{c^2} \frac{1}{e^{h\nu/kT} - 1} $$
This discovery marks the birth of quantum physics and earned him the Nobel Prize in Physics in 1918.
Major Contributions to Physics
1. Thermodynamics
Before his work on quanta, Planck made fundamental contributions to thermodynamics:
1879: Thesis on the second law of thermodynamics
1882: Concept of irreversibility in thermodynamic processes
1897: Work on entropy and its statistical interpretation
Development of the notion of thermodynamic potential
2. Quantum Theory
After his 1900 discovery, Planck further developed quantum theory:
1906: Introduced the concept of quantum of action as a fundamental constant
1908: Formulated the hypothesis of light quanta (precursor to photons)
1911: First Solvay Conference on quantum theory
1913: Supported Niels Bohr's work on the hydrogen atom
3. Philosophy of Science
Planck was also interested in the philosophy of science:
Reflections on the nature of physical reality
Debates with Einstein on determinism and indeterminism
Works on the relationship between science and religion
Concept of "physical reality" independent of the observer
Academic Career and Engagements
Professional journey:
1885-1889: Privatdozent (lecturer) at the University of Munich
1889-1892: Associate professor at the University of Kiel
1892-1926: Professor of theoretical physics at the University of Berlin
1912-1938: Perpetual secretary of the Prussian Academy of Sciences
1930-1937: President of the Kaiser Wilhelm Society (precursor to the Max Planck Society)
Scientific and social engagements:
Promotion of fundamental research in Germany
Support for young physicists (including Einstein, Bohr, Heisenberg)
Discreet resistance to the Nazi regime (protection of Jewish colleagues)
Reconstruction of German science after World War II
Personal Life and Trials
Planck's life was marked by personal trials:
1909: Death of his first wife Marie Merck (died in childbirth)
1916: Death of his eldest son Karl in the Battle of Verdun
1917: Death of his twin daughters Emma and Grete from tuberculosis
1944: Destruction of his home in Allied bombings
1945: Death of his second son Erwin, executed for his involvement in the plot against Hitler
Despite these tragedies, Planck remained scientifically active until his death on October 4, 1947 in Göttingen.
Scientific Legacy
Planck's legacy is immense:
Founder of quantum physics, basis of:
Quantum mechanics
Atomic and molecular physics
Solid state physics
Particle physics
Posthumous honors:
The Planck constant \( h \) bears his name
The Max Planck Society for the advancement of sciences
The Max Planck Medal for theoretical physics
Asteroid (1069) Planckia
ESA's Planck satellite (2009-2013) for studying the cosmic microwave background
Einstein said about Planck: "He was a man to whom scientific truth was more precious than anything else, and whose personality could not be shaken by external difficulties."
Max Planck's Major Contributions
Field
Year
Contribution
Impact
Thermodynamics
1879
Second law of thermodynamics
Foundation of statistical thermodynamics, understanding of irreversibility
Quantum Physics
1900
Quantum theory
Birth of quantum physics, solution to the blackbody problem
Quantum Physics
1906
Planck constant
Fundamental constant of physics, basis of quantum mechanics
Philosophy
1930s
Reflections on physical reality
Influence on the interpretation of quantum mechanics, debates with Einstein
Institutions
1948
Founding of the Max Planck Society
Promotion of fundamental research in Germany, model for research institutes