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The Strangest Man - Dirac

John Anderson

The Academy Class “The Ghost Particle”

mi

His view that fundamental

physics could be gleaned

from elegant mathematics

now permeates a whole

field of inquiry into the

reality of nature, string

theory.

•Swiss father, Charles, taught French at

English School - well regarded teacher

•Mother, Flo, was English - 12 years

younger (and Methodist)

•Father wanted Paul to speak only

French (Paul would stay silent)

•One sister, Betty, one brother, Felix

• Father a bit of a charlatan

X - Lied on resume

X - Hid large amounts of income

X - Had long term secret affair

X - Lied to Paul about financial aid

Early Life

Paul

Family in 1907

Charles later on.

•Rivalry between older brothers - would

pass in streets without speaking

•Wanted to go into medicine. No money

so mech. eng. at local tech college

•Took a dull job as draftsman in

Wolverhampton

•Took up Buddhism, found a guru, had a

girlfriend (family split on meeting her)

•Suicide 1925, two months after quitting

•Ravaged family, especially father

•Paul resolved never to take his own life

Brother Felix

Felix

1921

“My parents were terribly distressed. I

didn’t know they cared so much…

I never knew that parents ought to care

for their children, but from then on I

knew.” P. Dirac

•Extrovert from Hungary. Wigner’s sister

•Divorced with 2 children. (Judith,

Gabriel)

•Met in Princeton lunch counter, 1934

•They had 2 daughters (Mary Elizabeth

and Florence Monica)

Wife - Margit Wigner

Manci 1963

When asked by Manci what

he would say if she left, the

sweet-talking Paul said “I

would say good-bye dear.” Judy, MIA

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&uact=8&docid=otqQvmLu7y--pM&tbnid=yG4icTUrWuCE1M:&ved=0CAcQjRw&url=http://en.wikipedia.org/wiki/Paul_Dirac&ei=RYk4VNKcKYOeyASrpoDgDg&bvm=bv.77161500,d.aWw&psig=AFQjCNGAzAXNNMeNz9gi0gxIuvz_55YpsA&ust=1413077784856665

•Honeymoon at the shore, conventional Brighton.

Family Photos

Education

• Starts out slow. Scholarship exam

success at Bishop Road School

• Outshines brother in high school,

college, relationship strained

• Completes degree at Bristol, only bad

mark in OJT internship at factory

•Studies general relativity

•J.S. Mill’s philosophy of science

• Applies to Cambridge - Needs money

• More study at Bristol - Projective

geometry, Q.M., Hamiltonian mechanics

• British citizenship in 1919

• Cambridge - Re-applies. Gets

money

• In the big time now

Education Bristol

• Merchant Venturers’ Technical

College in Bristol

• Grade school with Archibald Leach

Cambridge Education

•Terse cards home to mother

•Cavendish Lab connections

•Patrick Blackett - (cosmic rays,

cloud chambers, Nobel 1948)

•Pyotr Kapitza (Soviet Ideology,

super-fluidity, Nobel 1978)

• Dirac is a passive listener

• Ralph Fowler urges Dirac to

publish

•Dirac stories begin in earnest.

•“It is not now raining.”

• Brother Felix commits suicide

•Paul sees parents grief (Paul’s

emotional blindness)

• Heisenberg, Bohr speak at Kapitza

club

•Early work: 5 good papers, and then,

• Kapitsa at Cambridge educates Dirac on

Soviet ideology

• Kapitsa club at Cambridge (Bohr guest)

• Climbed Mt. Elbrus in Caucasus mountains

• Attended conferences in Soviet Union

• Gets roughed up at border, held 3 days

• No MI-5 file

Russian Affinity

Peter Kapitsa

1894-1984 Nobel 1978

Mt. Elbrus, 18,510 ft. Tough climb.

Igor Tamm

1895-1971 Nobel 1958

Making a Name

•First Really Major Paper - 1925

•Born astonished:

“This was -- I remember well -- one of the

greatest surprises of my scientific life. For the

name Dirac was completely unknown to me, the

author appeared to be a youngster, yet

everything was perfect in its way and admirable.”

•Niels Bohr in Copenhagen - 1926

• Next Born in Göttingen, then Leiden,

then Brussels for Solvay Conference of

1927.

European Tour

Quantum Revolution Over - 1927

First row: I. Langmuir, M. Planck, M. Curie, H. A. Lorentz, A. Einstein, P. Langevin, C. E. Guye, C. T. R. Wilson, O. W. Richardson.

Second row, left to right: P. Debye, M. Knudsen, W. L. Bragg, H. A. Kramers, P. A. M. Dirac, A. H. Compton, L. V. de Broglie, M. Born, N. Bohr.

Standing: A. Piccard, E. Henriot, P. Ehrenfest, E. Herzen, T. De Donder, E. Schroedinger, E. Verschaffelt, W. Pauli, W. Heisenberg, R. H. Fowler, L. Brillouin.

Fifth Solvay Conference – Changing of the Guard

P. A. M. Dirac

How to incorporate Special

Relativity into Quantum Mechanics

Dirac has recalled a conversation with Bohr during the 1927 Solvay

conference.

Bohr: ‘What are you working on?’

Dirac: ‘I’m trying to get a relativistic theory of the electron.’

Bohr: ‘But Klein has already solved that problem.’

Dirac disagreed.

Ingredients to Build QFT

Quantum Mechanics

Strong Force

Electroweak

Force

Einstein’s Relativity

Principle Locality (no action at a

distance – emission and

absorption of particles)

QFT

Classical

Field

Theory

Dirac

merges

The Dirac Equation - 1928

0

xmxeA

x i

Dirac gets first order equation

mi Feynman slash notation

No electromagnetic field

In Westminster Abbey Plaque

Shorthand

yields

concise

equation

“Our

equations

are smarter

than we are.”

4x4 matrices,

way to factor

equations

Electron matter field.

Special Relativity - Results

•Dirac succeeds in adding Relativity to Quantum Mechanics.

•Coefficients are really matrices not numbers.

•Two positive energy solutions

•Correct magnetic moment Wow!

•Correct Thomas factor in Coulomb field

•Ordinary Schrödinger Eq. if E

Golden Years Timeline

Graduates High School - 1918 at 16

Graduates Bristol Univ. 1921,

Engineer

Bristol Univ. for 2 More Years,1923

• Advanced math and physics

Enters Cambridge. PhD 1926.

• Ceremony in Latin. Paul doesn’t

understand.

Lucasian Professor - 1932 - 1968

• Finally earning some money

Nobel Prize - 1933

• Shared with Schrödinger

Dirac, Heisenberg and Schrödinger

in Stockholm

Early Builders of QFT

Wolfgang Pauli

1929- Team w/Heisenberg

Lagrangian formulation of

QFT.

1928 – w/Jordan shows relativity compatible with

QED time commutators.

J. Robert Oppenheimer

1929 – 3rd part of Heisenberg- Pauli paper (Coulomb Gauge

precursor) in Göttingen,

Germany.

Werner Heisenberg

1929- Team w/Pauli

Lagrangian formulation of

QFT.

1932 – First to apply QM principles to nucleus.

Builders - Continuity Post War

Feynman picked up Dirac’s Lagrangian

approach and developed path integrals in PhD

thesis (1942).

In Warsaw, Poland 1962

Relativity Conference

Particle and Field Concepts Evolve

Phase I - Classical View

“Your old fashioned ideas are no

damn good.” Feynman

Phase II – Quantum Mechanics

1. Particle spreads like wave

2. Particle impacts like classical particle

3. It carries its own probability info about

where it is likely to impact

Phase III – Quantum Field Theory

1. Particle is a quantum of the permanent field

2. Forces via exchange of particles

3. Fields are fundamental - particles

secondary!!!

“Duality”

D

i

s

t

i

n

c

t

Quantum

of Field

Point Particle

Wave/Field

Field/P