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Max Planck
1858–1947 · Theoretical Physicist
In 1900, Planck introduced discrete energy elements proportional to frequency while deriving his law of black-body radiation, helping launch quantum theory.
“Science cannot solve the ultimate mystery of nature. And that is because, in the last analysis, we ourselves are a part of the mystery that we are trying to solve.”
Why is this scientist famous?
Introducing the quantum of action while deriving his black-body radiation law, helping launch quantum theory.
Planck's 1900 work introduced a new relationship between energy and frequency involving the constant now called Planck's constant. His proposal became the starting point for quantum theory, which was later developed by scientists including Albert Einstein, Niels Bohr, Werner Heisenberg and Erwin Schrödinger. Quantum mechanics now underpins technologies including semiconductors and lasers.
Max's story
Early Life
Born in Kiel, Germany, in 1858 to a family of scholars, Planck was the son of a professor of constitutional law. He showed talent in music and physics. After entering the University of Munich in 1874, Planck asked physics professor Philipp von Jolly about the prospects for research and was told that physics appeared to be essentially complete, with little prospect of major new developments. Planck chose physics anyway.
The Ultraviolet Catastrophe
In the late 1890s, Planck studied black-body radiation: the pattern of wavelengths emitted by an ideal heated object. Existing formulas matched only parts of the observed spectrum. In October 1900 he proposed a new radiation law that matched the measurements, and in December he presented a theoretical derivation that required discrete energy elements. The later phrase "ultraviolet catastrophe" described the failure of classical theory at short wavelengths.
The Quantum Leap
In December 1900, Planck presented a derivation in which the energy of oscillators occurred in multiples of hν, where h is now called Planck's constant and ν represents frequency. Planck described the procedure as an act of desperation and spent years trying to reconcile the quantum of action with classical physics. His work nevertheless became the starting point for quantum theory.
Einstein and the Quantum
It was Albert Einstein, in 1905, who first took Planck’s quanta seriously as a physical reality rather than a mathematical convenience. Einstein used the idea to explain the photoelectric effect — light itself was quantised into particles called photons. Planck was one of Einstein’s earliest supporters, and the two became close friends despite living through some of the darkest years of German history together.
Personal Tragedy
Planck’s later life was marked by devastating loss. His first wife died in 1909. His eldest son was killed at the Battle of Verdun in 1916. Both of his twin daughters died in childbirth. His other son was implicated in the July 1944 plot to assassinate Hitler and was executed by the Gestapo in 1945. Through all of this, Planck, a deeply patriotic German, stayed in his homeland and tried to preserve German science from within.
Legacy
Planck lived to see quantum mechanics developed by a new generation of physicists including Heisenberg, Bohr, Schrödinger and Dirac. He died in 1947 at the age of 89. The Kaiser Wilhelm Society, which he had led, was succeeded after the war by the Max Planck Society, named in his honour. Planck's constant remains one of the fundamental constants of quantum physics.
What did they discover?
Planck’s Constant
The fundamental constant h that relates a quantum of energy to its frequency — the number that sets the scale of the entire quantum world and appears in every equation of quantum mechanics.
Quantum Theory
Introduced discrete energy elements in his derivation of the black-body radiation law, providing the starting point for quantum theory.
Black-Body Radiation Law
Developed a formula that accurately described the distribution of radiation emitted by an ideal black body across different frequencies.
Planck Units
A system of natural units based on fundamental physical constants, used by physicists to this day as the simplest way to express equations in quantum gravity and cosmology.
Amazing facts
Planck described the procedure that led to his quantum interpretation as an "act of despair" and spent years trying to reconcile the quantum of action with classical physics.
After entering the University of Munich in 1874, Planck asked professor Philipp von Jolly about the prospects for physics research and was told there was little left to discover.
He was an exceptionally gifted pianist and considered becoming a professional musician before choosing physics.
His son Erwin was executed by the Gestapo in 1945 for involvement in the plot to assassinate Hitler.
His second wife's twin sister married his first wife's brother — making the two families doubly intertwined.
Planck was 42 when he published his quantum theory in 1900, proving that major discoveries do not always come from the young.
The Planck space telescope, launched by ESA in 2009, measured the cosmic microwave background with unprecedented precision using principles rooted in his work.
His house in Berlin was destroyed in an Allied bombing raid in 1944, along with most of his papers and possessions.
Max Born said of him: "He was a man of absolute honesty, unaffected modesty, and a deeply religious spirit."
Timeline
Born in Kiel, Germany
Began studying physics at the University of Munich
Earned his doctorate with a thesis on thermodynamics
Appointed associate professor of theoretical physics at the University of Kiel
Appointed associate professor of theoretical physics at the University of Berlin
Appointed full professor at the University of Berlin
Published the quantum theory of energy
Awarded the Nobel Prize in Physics
Became president of the Kaiser Wilhelm Society
His Berlin home and many of his papers were destroyed following an air raid
His son Erwin was executed by the Gestapo for involvement in the plot to kill Hitler
Named honorary president of the Kaiser Wilhelm Society, which was later succeeded by the Max Planck Society
Died in Göttingen, Germany, age 89
