Quantum Geography: Who Was Where & When

Track the movements of the quantum revolution's key players between research centres. Based on K. Schönhammer's “Göttingen and Quantum Mechanics”.

1925Slide to explore years

Track:

Key Events: The Road to Quantum Mechanics

1900

BerlinPlanck: black-body radiation, energy quanta E = nhν

1905

BerlinEinstein: light quanta (photons), photoelectric effect

1913

CopenhagenBohr: quantised orbits, E_n = -E_R/n², Balmer series explained

1915

MunichSommerfeld: quantisation of classical action for multiple periodic systems

1921

GöttingenBorn appointed director, Franck appointed to experimental physics

1922

GöttingenBohr’s Wolfskehl lectures (“Bohr Festival”) — Heisenberg asks crucial question

1924

GöttingenBorn’s “Vorlesungen über Atommechanik” — presents the crisis; Vol. 2 promised

1925

HelgolandMay–June: Heisenberg retreats to Helgoland; breakthrough on anharmonic oscillator

1925

GöttingenJune 21–July 9: Heisenberg’s four letters to Pauli showing ups and downs

1925

GöttingenMid-July: Heisenberg gives paper to Born (“finish or burn it”); Born recognises MATRIX MULTIPLICATION

1925

GöttingenSept 27: Born & Jordan submit “Zur Quantenmechanik” — commutation relation pq−qp = ħ/i in print

1925

HamburgOct: Pauli solves hydrogen atom via Laplace–Runge–Lenz vector in matrix form

1925

CambridgeNov 7: Dirac submits “Fundamental equations” using Poisson brackets [A,B] ↔ iħ{A,B}

1925

GöttingenNov 25: Dreimännerarbeit (Born, Heisenberg, Jordan) — state of the art of matrix mechanics

1926

ZürichJan 27: Schrödinger submits wave equation & hydrogen solution

1926

GöttingenJune: Born uses Schrödinger equation for scattering; |ψ|² = probability (Born rule)

1926

CambridgeDec: Dirac & Jordan independently submit transformation theory

Heisenberg's Four Letters to Pauli (June–July 1925)

The emotional arc of the quantum breakthrough, as Heisenberg wrote from Göttingen:

June 21

"My attempts to formulate a quantum mechanics progress rather slowly..."

June 24

"I don't want to write about my work because most of it is still unclear to me..."

June 29

"I made some progress and in my heart I am now convinced that this quantum mechanics is quite correct..."

July 9

"I feel guilty to ask you to send back my draft within 2–3 days, as I want to finish or burn it before leaving... I am convinced about the negative critical part, but the positive one I judge as rather formal and meager, maybe more gifted people are able to make something reasonable out of it."

Source: W. Pauli, Scientific Correspondence with Bohr, Einstein, Heisenberg a.o., K. von Meyenn (ed.), Springer 1985

“I have tried several times to read the paper that Heisenberg wrote on returning from Helgoland, and, although I think I understand quantum mechanics, I have never understood Heisenberg's motivation for the mathematical steps in his paper... Heisenberg's paper was pure magic.”

— Steven Weinberg, Dreams of a Final Theory (1992)

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