From Electrical Engineering to QuantumFrom Electrical Engineering to QuantumFrom Electrical Engineering to Quantum From Electrical Engineering to Quantum Physics: The Case of Nishina YoshioPhysics: The Case of Nishina Yoshio

Kenji ItojHQ_3 Conference July 1, 2010

Max Planck Institute for the History of Science B liBerlin

Beginning of QM in JapanBeginning of QM in Japang g pg g p

Yukawa HidekiTomoanga Sin-itiroSakata ShoichiEsaki ReonaNambu YoichiroNambu Yoichiro

Nishina Yoshio 1890Nishina Yoshio 1890--19511951

The first generation f Jof Japanese quantum

physicistEssential in introducing quantum mechanics into JapanTrained as an electrical engineer

Nishina Yoshio’s earlier careerNishina Yoshio’s earlier career

6th higher school: EngineeringTokyo Imperial University: College of Engineering, Dept. of Electrical Engineering1918 Riken and Grad School1921 Europe1921 Europe1923 Copenhagen1928 R t t J1928 Return to Japan

Goal of the paperGoal of the paperp pp p

Possible connections between electrical engineering and

t h i i Jquantum mechanics in Japan

ArgumentArgumentgg

Electrical engineering was one of the bases for quantum physical research to be motivatedresearch to be motivated, legitimized, and sustained in Japan.

I d l iIt prepared at least one important figure in quantum physics research g q p yin Japan through its conceptual ffi itaffinity.

Larger projectLarger projectg p jg p j

Quantum mechanics in socio-cultural context i Jin Japan– 1. social-institutional levels

– 2. conceptual-cultural levels.

Social and institutional levelsSocial and institutional levels

What social and institutional resources d d l f i / lsupported development of atomic/nuclear

physics in Japan– What were personal motivations for

physicists?

– What legitimized such research in society?

– How was such research sustained in society?How was such research sustained in society?

Conceptual dimensionConceptual dimensionpp

What were conceptual and cultural resources il blavailable

– Pedagogical traditions

– Conceptual resources in related disciplines

Background considerationsBackground considerationsgg

Perception of values of atomic physics was diff i l 20th J ( h diddifferent in early 20th century Japan (they did not expect atomic power/bomb)Did not know what kind of knowledge and training would be needed for atomic physics research

Note 1Note 1Focus on the first generationA f th d ti diff tAs for the second generation, different considerations would be necessary

Notes 2Notes 2

Mathematical physics and engineering ( as in h f h S f ld h l)the case of the Sommerfeld school).

Spectroscopy and X-ray

1930s: Cosmic ray research and airplane1930s: Cosmic ray research and airplane1940s: Atomic bomb project

Outline of the paperOutline of the paperp pp p

Social and cultural backgroundConceptual connections– Electrical engineering education that Nishina g g

received

– Quantum physics research of NishinaQuantum physics research of Nishina

• Derivation of Klein-Nishina formula

I SocioI Socio c lt ral backgro ndc lt ral backgro ndI. SocioI. Socio--cultural backgroundcultural background

1. Primacy of Engineering1. Primacy of Engineeringy g gy g g

Engineering had higher priority and more i h h i i l 20thprestige than physics in early 20th century

JapanModernization of Japan since the Meiji Era (1868-)– Early inclusion of engineering in higher

education: The Imperial college of engineeringp g g g

– Need of engineers to build modern infrastructureinfrastructure

2. Atomic theory and Electron2. Atomic theory and Electronyy

Atomic physics as a basis of electrical i iengineering

– Physics provided basic understanding of electric theory

– Electron was the main focus of atomic physics as it was introduced into Japan in early 20th centuryy y

– Education and training (textbooks)

Physicists’ self description (Popular– Physicists self-description (Popular writings)

NagaokaNagaoka HantaroHantaro (1865(1865--1950)1950)

Tokyo Imperial U i iUniversitySaturnian model of atom

Studies of Electricity T d (1912)Today (1912)– Popular account of

l delectricity studies

– Includes atomic h iphysics

Mizuno Mizuno ToshinojoToshinojo (1861(1861--1944)1944)

Imperial University f Kof Kyoto

More focused on electronThe Electron Theoryy(1912)

Aichi Keiichi (1880Aichi Keiichi (1880--1923)1923)

Theoretical physicist T h k I i lat Tohoku Imperial

UniversityAutobiography of an Electron (1923)– Popular account of

atomic physics

Physics and electricityPhysics and electricityy yy y

Connecting physics with electricitySeeking popular support and interestEducation of electrical engineers or teachers of gelectrical engineeringResearch related to electricityResearch related to electricity

Study of ElectronStudy of Electronyy

Nishina’s early career was consistent as a i f k l d b lpursuit of knowledge about electron

Commented by his relatives about his stay in Europe as “research of electron”

II Ph sical and Concept alII Ph sical and Concept alII. Physical and ConceptualII. Physical and Conceptual

QuestionQuestion

What Nishina learned from electrical i iengineering

How could that be related to quantum physics conceptually

1. Nishina’s EE training1. Nishina’s EE traininggg

Ho Hidetaro (1882-1931)– Professor of electrical engineering at Tokyo

Imperial University and Nishina’s first advisor

– Introduction of Steinmetz’ theory of alternating current theory to Japang y p

– Ho-Thévenin’s theorem

Steinmetz Steinmetz

Charles Proteus Steinmetz 1865-1923Theorization of alternating current

HoHo--Thévenin’sThévenin’s theoremtheorem

Principle of SuperpositionPrinciple of Superpositionp p pp p p

Principle of Superposition in Electrical Circuit– Configuration A: voltage source E1 at A but

none at B

– Configuration B: voltage source E2 at B but not A

– Configuration C: voltage source E1 at A and E2 at BE2 at B

– The solution to configuration C by adding up the solutions to Configurations A and Bthe solutions to Configurations A and B

HoHo--Thévenin’sThévenin’s theoremtheorem

2. Nishina’s B. A. Thesis2. Nishina’s B. A. Thesis

“Effects of Unbalanced Single-Phase Loads on P l Ph M hi d Ph B l i ”Poly-Phase Machinery and Phase Balancing,” B. A. Thesis, Tokyo Imperial University, 1918.The question of how unbalanced loads would affect an alternator, a motor, or a rotary transformer in poly-phase system.Applied the principle of superpositionpp p p p p“An unbalanced polyphase system can be resolved into two balanced components ofresolved into two balanced components of opposite phase rotations, one positive and the other negative”other negative

3. QM and Superposition3. QM and Superpositionp pp p

The principle ofThe principle of superposition in QMDirac’s textbookDirac s textbook Japanese translation in the 1930 (b T d1930s (by Tomonaga and others)

4. The Klein4. The Klein--Nishina formulaNishina formulaKlein & Nishina, “Über die Streuung durch freie Elektronen nach der neuen relativstischenfreie Elektronen nach der neuen relativstischen Quantendynamik von Dirac,” Zeitschrift f`ür Physik 52 853 868Physik, 52, 853-868. Earliest application of Dirac’s theoryExperimental confirmationIncludes negative energy contributions (I. g gy (Waller, 1930)

KleinKlein--Nishina formulaNishina formula

Yazaki, Y. (1992). “How was the Klein-Nishina formula derived?: Based mainly on the source materials of Y. Nishina in RIKEN,” Kagakushi Kenkyu, 31, (I) 81-91; (II)129-137 (in Japanese).

Outline of DerivationOutline of Derivation

Semiclassical treatment of Compton scattering f ll i G d d Di i Di ’following Gordon and Dirac, using Dirac’s relativistic theory of electron

1. Solutions of Dirac equation for a free electron and an electron in a monochromatic radiation

2. Current density 3. Vector potential and Magnetic field vector3. Vector potential and Magnetic field vector5. Intensity

Dirac EquationDirac Equationqq

Free electron solutionsFree electron solutions

Incoming radiationIncoming radiationgg

SolutionsSolutions

Electric and current densityElectric and current densityyy

Outgoing radiationOutgoing radiationg gg g

Outgoing radiation (According to Gordon)From initial state u(p) v(p) to u(p’) v(p’)

Magnetic fieldMagnetic fieldgg

IntensityIntensityyy

ResultResult

Archival research Archival research

Yazaki, Y. (1992). “How was the Klein-Ni hi f l d i d? B d i l hNishina formula derived?: Based mainly on the source materials of Y. Nishina in RIKEN,” K k hi K k 31 (I) 81 91 (II)129 137 (iKagakushi Kenkyu, 31, (I) 81-91; (II)129-137 (in Japanese)

Initial/final states and AverageInitial/final states and Average/ g/ g

Calculating averageCalculating averageg gg g

Assumptions– The final state contains two independent

state with the same strength (superposition)

– Take average over phase

ResultsResults

Concl sionConcl sionConclusionConclusion

Electrical Engineering and QMElectrical Engineering and QMg gg g

No causal claim– It would be ridiculous to claim that Nishina

worked on quantum mechanics because he studied electrical engineering