The Revolution and Evolution of Quantum Mechanics

Richard Feynman: A Unique Path
From a child to a world-famous
• Life
• Science
• Teaching
• Born: May 11, 1918 in New York City
Milleve Feynman: “… If it's a boy, he's going
to be a scientist… “
• Early Education: bored with humanity, history,
literature, found spelling “illogical”…;
deeply influenced by his father
met a few good teachers (Mr. Bader,…)
• College: Graduated from MIT
(Senior thesis: “Forces and stresses in molecules”
advisor: John C Slater)
• Graduate School: Princeton (1939-1942)
Thesis: “ The least action
principle in quantum mechanics ”
(Adviser: John A Wheeler)
• First marriage: to Arlene Greenbaum (1942-1945)
• Manhattan project: Los Alamos (1943-1946)
• Cornell Physics Faculty: 1946-1951
• Caltech: Tolman Professor of Physics (1951-death)
• A letter written two years after Arlene’s death:
“…I adore you sweetheart. . . I have met many nice
girls, and I don't want to remain alone-but in two
or three meetings they all turn to ashes. You only
are left for me. You are real. My darling wife, I
adore you….”
“…Please excuse me for not mailing this-but I
don't know your new address."
• Second marriage: to Mary Louise Bell
“He begins working calculus problems in his head as soon as he awakens.
He did calculus while driving in his car, while sitting in the living room, and
while lying in bed at night.”—Mary Louise Bell divorce complaint
• Third marriage: to Gweneth Howarth (1960- )
son (Carl, 1962)
daughter (adopted Michelle,
Feynman on his children:
“I always thought I would be a specially good father because
I wouldn’t try to push my kids into any particular direction.
I wouldn’t try to turn them into scientists or intellectuals if
they didn’t want it. I would be just as happy with them if
they decided to be truck-drivers or guitar-players. In fact I
would even like it better if they went out in the world and
did something real instead of being professor like me. But
they always find a way to hit back at you. My boy Carl for
instance. There he is in his second year at MIT, and all he
wants to do with his life is to become a god-damned
• Nobel prize: 1965 with Schwinger and
Tomonaga (contribution to QED)
• Other recognitions: member of the National Academy
of Science; foreign member of the Royal Society,
London (Great Britain); Albert Einstein Award (1954,
Princeton); Einstein Award (Albert Einstein Award
College of Medicine); Lawrence Award (1962).
• Feynman on honor
• Last part: illness, Challenger, and death
• 1978: first diagnosed with liposarcoma,
underwent operation
• 1981: cancer returned, more operation
• 1986: The Challenger incident committee
"For a successful technology, reality must take
precedence over public relations, for nature
cannot be fooled.”
• 1988 (Feb. 15): woke from a coma”…I’d hate to
die twice. It’s so boring….”
Feynman’s carelessness for formality
(Photo: with other Caltech Nobel Laureates)
• Path integral formulation of QM (1942):
<xA, tA|xB, tB> ~ S(path) exp(2iS/h)
• Bohr’s objection: Feynman, you are crazy…
• Feynman diagram (1948)
The Feynman diagram of the term
• Feynman-Hellman Theorem
• Undergraduate thesis (1939, MIT)
• Most-cited paper of Feynman (> 1800 times!)
• V-A Theory (1958) (Feynman, Gellman, Marshak, Sudarshan)
The first correct theory of Weak Interaction
“…the only law of Nature I could lay a name
• Geometric Model for Laser Operation (his only work in applied physics)
(Feynman, Vernon, Hellwarth: Joun. Appl. Phys., 1957)
• Complete analogy to dynamics (Block Equation) of NMR
• Leading to “Optical Bloch Equation” in Quantum Optics
• Theory of Superfluid Helium (1953-1958)
Feynman (1954)
Feynman and Cohen (1956)
: path integral → partition
• Nanotech Pioneer: “There’s plenty of room at
the bottom…(1959)
“…When we get to the very, very small world -…completely new opportunity for
design. Atoms on a small scale…obey the laws of quantum mechanics…., and we
can expect to do different things….We can use,…system involving quantized energy
level, or interactions of quantized spins, etc.”
Inspiration from biological systems: “ so much information is contained in so tiny
spatial volume (that of a cell) …”
The Feynman prizes: $1000 for building a motor of 1/64 inch cubed
$1000 for shrinking the info of a page of a book by 1/25000
times, and read it with an electron microscope
• Pioneer of Quantum Computing
P. A. Benioff : “ The computer as a physical system: a
microscopic Hamiltonian model of computers as
represented by Turing machines ” (1981)
R. P. Feynman : “ Simulating physics with computers ”
(1982) – “…because Nature is not classical, dammit, and
if you want to make a simulation of Nature, you’d better
make it quantum mechanical…”
R. P. Feynman : “Quantum mechanical computers”
IQEC/CLEO (1984); Opt. News (1985); Found. Phys. (1986) -- ideas of quantum bits (2-state atoms) and quantum
Feynman and the Connection Machine
• Contribution in biology (genetics):
(Is Feynman a “good” teacher?)
• Feynman Lectures on Physics (1961-1963)
• Great Explainer: explanation to layman…
• Diagrams, analogies, gestures, actions,…
“Something I cannot create I do not understand”
"Teaching and students keep life going, I would never accept a
position in which somebody has invented a happy situation
for me where I don't have to teach. Never."
• Challenge: Pauli’s Exclusion Principle
Lecture on “Scientific Method” at
Cornell (1964)
• An address to high school teacher (1966)
• Question: What is  ?
 = s1/d1 = s2/d2 = s3/d3 =…
Richard Feynman on God

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