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Science and Personalities leading to the Development of the Atomic Bomb

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Title: Science and Personalities leading to the Development of the Atomic Bomb


1
Science and Personalities leading to the
Development of the Atomic Bomb
  • Gary Latshaw, Ph.D.

2
Getting Around in the 1900s
3
Physics in 1900
  • Newtons Laws of Motion and Law of Gravity
  • Thermodynamics
  • Maxwells Equations (Electromagnetic Radiation)
  • Concepts of Quantum Mechanics (Planck)

4
Maxwells Equations
  • Electrostatics- Permittivity of Free space (eo)
  • Magnetics Permeability of Free Space (uo)

5
Presumed an Ether Existed
  • Ether contained the properties of permittivity
    (eo) and permeability (uo).
  • Ether sustained the propagation of
    electromagnetic waves much like air sustains the
    propagation of sound.

6
Albert Einstein lt 1905
  • Expelled from Luitpold Gymnasium .. your
    presence in the class is disruptive and affects
    other students
  • Dropout! And Romancer!
  • Passed on Second Attempt the Federal Institute of
    Technologys (FIT) entrance exam
  • Graduated FIT with 3.3, but was refused a
    teaching job due to his independent behavior
  • Help from a friend Technical Expert 3rd Class at
    the Swiss Patent office in Bern

7
Einstein in 1905
  • Photoelectric Effect
  • Brownian Motion
  • Special Relativity
  • Referenced in Nobel Prize in 1921

8
Special Relativity
  • Physical Laws are the same to all
    non-accelerating observers.
  • Speed of Light is measured as the same to all
    observers!

No Ether !!
9
Michelson-Morleys Frustration
  • They had been trying to detect the velocity of
    the ether for over 20 years!

10
1907 E mc2
  • Einstein realized that a consequence of Special
    Relativity was that Mass and Energy were
    manifestations of the same quantity.
  • Mass could be converted to energy and energy to
    mass
  • Motion is a form of energy kinetic energy
  • Collective motion of atoms is revealed as
    temperature!
  • Adding energygtincreases temperature

11
Burning Candle
  • Carbon Oxygen? Carbon Dioxide
  • Loss of Mass approximately
  • 5/10,000,000000 of input masses
  • (5 over 10 billion)

12
In 1930 the Cyclotron Was Invented
  • Nuclear Physics was limited by available energy
    of accelerators.
  • Ernest Lawrence at UC Berkeley invents the
    cyclotron.
  • The cyclotron circulates particles and causes
    them to gain energy with each revolution.

13
First Cyclotron
14
Working Cyclotron
  • Lawrence was known for his salesmanship and
    bringing about big physics.

15
25 years after 1907 Prediction of E mc2
  • Rutherford got a University grant of 1000 to buy
    a 300 kV transformer
  • Walton and Cockcroft split the atom! And Released
    Energy per E mc2

16
Observing E mc2
  • Loss of Mass approximately
  • 3/1000 or 0.3 of input masses
  • (10 million times chemical reactions)

17
Einstein Explains
E mc2
18
Anything Practical?
  • Not yet!
  • All that external energy to cause a relatively
    few reactions, big deal!
  • Accelerator was necessary to overcome
    electrostatic repulsion between the nuclei.

19
Leo Szilards Patent Chain Reaction
  • Hungarian Jew who moved to Berlin.
  • Worked with Einstein in 1919 and shared patents
    on a electromagnetic refrigerator pump.
  • 1932 Hitler elected Chancellor ofGermany 1933
    Hitler obtained Special Powers as Chancellor
    and President
  • 1934 Szilard went to London.

Took out a patent on chain reaction that might
produce electrical energy or possibly an
explosion.
20
Chain Reaction
  • One nuclear reaction entices one or more
    reactions to occur.
  • Thus, nuclear reactions can be sustained.
  • Does nature offer a convenient way to make this
    happen?

21
Meanwhile in Italy..
  • Enrico Fermi was bombarding large nuclei with
    neutrons and observing their reaction products.
  • Typical Reaction Nucleus gains a proton
  • N ZX n ? N1 ZX ? N1 Z1Y e-
  • Chemical Differences expected by increasing the
    atomic number.

22
Then came Uranium
  • Uranium was the largest stable nucleus
  • Fermi thought that he had created a transuranic
    element (element with more protons than uranium)
  • But chemical analysis of the products confusing
  • Work repeated in Berlin by
  • Lise Meitner (female Jew),
  • Fritz Strassmann (refused to join Nazi-associated
    Chemical Society),
  • Otto Hahn (anti-Nazi)

23
Meitner and Frisch concluded
  • 238 92U 1 neutron ? 14256Ba 92 36Kr
    several neutrons
  • More neutrons are released!
  • Energy is released!

24
Fission Reactions
  • These types of reactions provide mass to energy
    conversions
  • Approximately 8/10,000 .08,
  • about one tenth of fusion reactions
  • (one million times chemical reactions)

Fission Reactions could form a basis for Chain
Reactions!
25
Credit for Fission Discovery went solely to Hahn
who received Nobel Prize
  • Initially Hahns refusal to acknowledge the
    contributions of Meitner was consistent with
    political expedience of not associating with a
    Jew.
  • However, he continued to profess fission was his
    discovery.
  • Documentation in letters gives credit to Meitner.

26
Anyway, 6-months after Fission is Discovered
  • American newspapers openly discussed the prospect
    of atomic energy or atomic bombs.
  • Most American physicists doubted practicality of
    atomic energy or atomic bombs.
  • So...

27
Szilard visits Einstein interrupts vacation!
  • July 12, 1939 Eugene Wigner drove Szilard to
    Peconic where Einstein was vacationing
  • Einstein greeted his guest in an undershirt and
    rumpled, rolled-up pants
  • Economist Sachs was consulted by Szilard
  • Later in July, Edward Teller drove on a follow-up
    visit
  • August 2nd, Einstein mailed final draft to
    Szilard

28
Einsteins Letter to Roosevelt
  • September 1, 1939 Germany invaded Poland
  • Sachs delivered the letter to Roosevelt on
    October 11 Roosevelt formed Uranium Committee
    with 6,000 budget
  • This was enough to start experiments by Fermi and
    Szilard
  • Large scale project began December 6th

29
U.S. Army Denies Clearances!
  • US Army denied security clearances to Szilard and
    Fermi
  • Fermi, a refugee from fascism was undoubtedly a
    fascist
  • Szilard, in terror of the Nazis, was very
    pro-German
  • FBI reversed Armys Denial

In 1999/2000 FBI improperly accused Dr. Wen Ho
Lee, a physicist at Los Alamos, of providing
classified data to the Chinese
30
Szilard and Fermi produce Nuclear Reaction
  • Szilard had a very creative mind and could leap
    to conclusions.
  • Fermis thinking process was methodical.
  • Design for the reactor developed in letters the
    two exchanged.

31
Technical Challenge
  • Nuclear Reactor
  • Control fission process so each fissioning
    nucleus creates only ONE other fissioning nucleus
  • Control density, speed of neutrons (slower were
    better)
  • Nuclear Explosion
  • Bring materials together fast enough with enough
    density that the ensuing nuclear reaction stays
    together long enough to produce an explosion

32
December 2, 1942
  • Nuclear Reaction Sustained for 28 minutes
  • Uranium spheres embedded in graphite blocks

33
After the experiment, Szilard and Fermi found
themselves alone in the building
  • On that day, Szilard said to Fermi
  • I thought this day would go down as a black day
    in the history of mankind
  • Arthur Compton reported the results to Washington
    as The Italian navigator has just landed in the
    new world.

34
Manhattan Project
  • All-out effort to develop an Atomic Bomb
  • Lead by
  • General Leslie Groves and
  • UC Berkeley Professor J. Robert Oppenheimer
    Oppy
  • An ambitious hard-driving general and a brilliant
    theoretical physicist

35
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36
Modern Nuclear Power Reactor
37
Tickling the Dragon
  • Fast-moving Uranium Mass drops through hole in a
    larger mass
  • Combined mass for an instant is critical
  • Able to sustain a nuclear chain reaction

38
Major Issue- Fissionable Fuel
  • Acquiring Fissionable Materials
  • Plutonium 239Pu
  • Uranium 235U
  • Plutonium could be produced by nuclear reactor
    with modest concentration of 235 92U
  • First Large Scale Reactor at Hanford, Washington
  • 235 92U was separated by diffusion (UF6)
  • Oak Ridge Facility
  • Experimental Quantities of Material were produced
    by the Berkeley Cyclotron

39
Two Designs for Gadget
  • Gun-Triggered
  • Feasible with 235 92U
  • 235 92U was difficult to obtain
  • Implosion
  • Used 23994Pu
  • Was obtained from Nuclear Reactor

40
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41
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42
Building the Gadget
  • Three Bombs
  • Trinity Los Alamos Test - Pu/Implosion
  • July 16th, 1945
  • Little Boy U/Cannon- Hiroshima-
  • August 6th, 1945
  • Fat Man Pu/Implosion- Nagasaki-
  • August 9th, 1945

43
German Effort Werner Heisenberg
  • Leading German Physicist in charge of German
    effort to develop an atomic bomb
  • Germans acquired a shipment of uranium from South
    Africa
  • Was he truly dedicated to the task?

44
New Letter Asking Not to Use the Atomic Bomb
  • Nazis surrendered on May 7, 1945
  • Leo Szilards motivation for building the bomb
    vanished.
  • Szilard, Einstein, Teller, and many other
    prominent scientist wrote letter to Truman asking
    that the atomic bomb NOT be used.

45
Letter by Szilard and 58 Others
  • We believe that the United States ought NOT to
    resort to the use of atomic bombs in the present
    phase of the war, at least not unless the terms
    which will be imposed upon Japan after the war
    are publicly announced and subsequently Japan is
    given an opportunity to surrender.

46
Truman Gets Letter Late
  • Letter given to Truman after the first bomb had
    been dropped on Hiroshima

47
Trumans Diary
  • I have told the Sec. of War, Mr. Stimson, to
    use it so that military objectives and soldiers
    and sailors are the target and NOT women and
    children. Even if the Japs are savages, ruthless,
    merciless and fanatic, we as the leader of the
    world for the common welfare cannot drop that
    terrible bomb on the old capital or the new.
  • He and I are in accord. The target will be a
    purely military one and we will issue a warning
    statement asking the Japs to surrender and save
    lives. I'm sure they will not do that, but we
    will have given them the chance. It is certainly
    a good thing for the world that Hitler's crowd or
    Stalin's did not discover this atomic bomb.

48
Post-WW II Atomic Bombing
  • United States and the Soviet Union went on to
    develop H-bomb which used fusion and produced
    even larger energy yields.
  • Both countries deployed a total 40,000s nuclear
    weapons.
  • Massive nuclear exchange would release about the
    same as the ancient meteorite impacts that have
    been responsible for severe global climate
    changes resulting any extinction of many
    prehistoric species .

49
Physics 2004, Add
  • Quantum Mechanics
  • General Relativity
  • Existence of Dark Matter and Vacuum Energy
  • Global Constraints
  • Global Warming
  • Exhaustion of Petroleum Resources
  • Genetic Engineering

50
Where will these scientific understandings lead
us?
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