Quantum hypothesis: energy emitted in discrete quanta (1900)
Presented to the German Physical Society on 14 December 1900, the birth of quantum theory
Science · Physics
Max Planck
1858–1947 · German
Theoretical physics; thermodynamics and quantum theory
Max Planck, born in Kiel, founded quantum theory in 1900 when, to explain black-body radiation, he proposed that energy is emitted in discrete packets (quanta) proportional to frequency. The constant h in E = hν bears his name. He won the 1918 Nobel Prize in Physics and was the elder statesman of German science through two world wars.
How to spot them
- ▸Quantum hypothesis of 14 December 1900; E = hν
- ▸Planck's constant, Planck length and Planck units
- ▸Black-body radiation law; his 'act of desperation'
- ▸The Max Planck Society; ESA's Planck satellite
- ▸Told as a student that physics was almost complete
Key discoveries & works
Black-body radiation law (1900)
Formula correctly describing the spectrum of radiation from a hot body at all frequencies
Natural units of length, mass, time and temperature (1899)
Units built from fundamental constants, e.g. the Planck length
Treatise on Thermodynamics (1897)
Influential textbook reflecting his early work on entropy
Scientific Autobiography (1948 (posthumous))
Contains his remark that new scientific truths win because opponents eventually die
Key ideas
- Energy of a quantum equals h times frequency (E = hν)
- The quantum of action h is a fundamental constant of nature (about 6.626 × 10⁻³⁴ joule-seconds)
- Planck's principle: a new scientific truth triumphs not by convincing opponents but because they die and a new generation grows up familiar with it
Quick-fire facts
- •Born in Kiel on 23 April 1858; died in Göttingen on 4 October 1947
- •His Munich teacher Philipp von Jolly advised him against physics because almost everything had been discovered
- •Succeeded Gustav Kirchhoff as professor at the University of Berlin
- •Awarded the 1918 Nobel Prize in Physics (presented in 1919) for his discovery of energy quanta
- •An early champion of Einstein's special relativity
- •A gifted pianist who considered a career in music
- •His son Erwin was executed in 1945 for involvement in the July 1944 plot against Hitler
- •President of the Kaiser Wilhelm Society, renamed the Max Planck Society in his honour in 1948
- •Since 2019 the kilogram has been defined by fixing the exact value of Planck's constant
Drill it — 7 cards
1 / 7new card
Sources
- Nobel Prize Outreach — Max Planck – Biographical
- MacTutor History of Mathematics, University of St Andrews — Max Planck