Title: Science and Personalities leading to the Development of the Atomic Bomb
1Science and Personalities leading to the
Development of the Atomic Bomb
2Getting Around in the 1900s
3Physics in 1900
- Newtons Laws of Motion and Law of Gravity
- Thermodynamics
- Maxwells Equations (Electromagnetic Radiation)
- Concepts of Quantum Mechanics (Planck)
4Maxwells Equations
- Electrostatics- Permittivity of Free space (eo)
- Magnetics Permeability of Free Space (uo)
5Presumed 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.
6Albert 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
7Einstein in 1905
- Photoelectric Effect
- Brownian Motion
- Special Relativity
- Referenced in Nobel Prize in 1921
8Special Relativity
- Physical Laws are the same to all
non-accelerating observers. - Speed of Light is measured as the same to all
observers!
No Ether !!
9Michelson-Morleys Frustration
- They had been trying to detect the velocity of
the ether for over 20 years!
101907 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
11Burning Candle
- Carbon Oxygen? Carbon Dioxide
- Loss of Mass approximately
- 5/10,000,000000 of input masses
- (5 over 10 billion)
12In 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.
13First Cyclotron
14Working Cyclotron
- Lawrence was known for his salesmanship and
bringing about big physics.
1525 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
16Observing E mc2
- Loss of Mass approximately
- 3/1000 or 0.3 of input masses
- (10 million times chemical reactions)
17Einstein Explains
E mc2
18Anything 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.
19Leo 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.
20Chain 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?
21Meanwhile 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.
22Then 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)
23Meitner and Frisch concluded
- 238 92U 1 neutron ? 14256Ba 92 36Kr
several neutrons - More neutrons are released!
- Energy is released!
24Fission 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!
25Credit 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.
26Anyway, 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...
27Szilard 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 -
28Einsteins 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
29U.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
30Szilard 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.
31Technical 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
32December 2, 1942
- Nuclear Reaction Sustained for 28 minutes
- Uranium spheres embedded in graphite blocks
33After 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.
34Manhattan 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
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36Modern Nuclear Power Reactor
37Tickling 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
38Major 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
39Two Designs for Gadget
- Gun-Triggered
- Feasible with 235 92U
- 235 92U was difficult to obtain
- Implosion
- Used 23994Pu
- Was obtained from Nuclear Reactor
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42Building 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
43German 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?
44New 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.
45Letter 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.
46Truman Gets Letter Late
- Letter given to Truman after the first bomb had
been dropped on Hiroshima
47Trumans 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.
48Post-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 .
49Physics 2004, Add
- Quantum Mechanics
- General Relativity
- Existence of Dark Matter and Vacuum Energy
- Global Constraints
- Global Warming
- Exhaustion of Petroleum Resources
- Genetic Engineering
50Where will these scientific understandings lead
us?