Bond of Bombs:
The story of atomic bomb
Chung Wen Kao
Department of Physics
Chung Yuan Christian University, Taiwan
Colloquium @ NCTU 18/11/2010
1
Modern Alchemistry
In 1919 Rutherford became
the first person to transmute
one element into another
when he converted nitrogen
into oxygen through the
nuclear reaction
14N + α → 17O + p.
For centuries, alchemists had
searched for something that
would turn less valuable
metals into gold. They called
this the "philosopher's stone."
Finally, Rutherford had
discovered how to transmute
the elements.
2
The first accelerator
During the early 1930s Ernest Walton and John
Cockcroft collaborated to build an apparatus
that split the nuclei of lithium atoms by
bombarding them with a stream of protons
accelerated inside a high-voltage tube (700
kilovolts). The splitting of the lithium nuclei
produced helium nuclei. This was experimental
verification of theories about atomic structure
that had been proposed earlier by Rutherford.
The successful apparatus - a type of particle
accelerator now called the Cockcroft-Walton
generator - helped to usher in an era of particleaccelerator-based experimental nuclear physics.
It was this research at Cambridge in the early
1930s that won Walton and Cockcroft the Nobel
Prize in physics in 1951.
3
Discovery of neutron (I)
Walther Wilhelm
Georg Bothe
(B.1891 – D.1957 )
was a German
nuclear physicist,
who shared the
Nobel Prize in
Physics in 1954
with Max Born.
In 1931 Walther Bothe and Herbert Becker in Germany found
that if the very energetic alpha particles emitted from
polonium fell on certain light elements, specifically beryllium,
boron, or lithium, an unusually penetrating radiation was
produced. At first this radiation was thought to be gamma
radiation, although it was more penetrating than any gamma
rays known, and the details of experimental results were very
difficult to interpret on this basis
4
Discovery of neutron(II)
The next important contribution was
reported in 1932 by Irène Joliot-Curie and
Frédéric Joliot in Paris. They showed that
if this unknown radiation fell on paraffin or
any other hydrogen-containing compound
it ejected protons of very high energy.
This was not in itself inconsistent with the
assumed gamma ray nature of the new
radiation, but detailed quantitative
analysis of the data became increasingly
difficult to reconcile with such a
hypothesis.
Paraffin Wax
5
Another Curie and her husband…
Irène Joliot-Curie (B.1897 – D.1956) was a French scientist, the
daughter of Marie Skłodowska-Curie and Pierre Curie and the wife
of Frédéric Joliot-Curie. Jointly with her husband, Joliot-Curie was
awarded the Nobel Prize for chemistry in 1935 for their discovery of
artificial radioactivity. This made the Curies the family with most
Nobel laureates to date.
Jean Frédéric Joliot-Curie (B.1900 – D. 1958) was a French
physicist and Nobel laureate. In 1925 he became an assistant to Marie
Curie, at the Radium Institute. He fell in love with Irène Curie, and
soon after their marriage in 1926 they both changed their surnames to
Joliot-Curie. At the time of the Nazi invasion in 1940, Joliot-Curie
managed to smuggle his working documents. During the French
occupation he took an active part in the French Resistance as a
member of the National Front.
6
Discovery of neutron (III)
Chadwick reported the Joliot-Curie's
experiment to Rutherford, who did not
believe that gamma rays could account for
the protons from the wax. He and Chadwick
were convinced that the beryllium was
emitting neutrons. Neutrons have nearly the
same mass as protons, so should knock
protons from a wax block fairly easily.
Chadwick's neutron chamber
containing parallel disks of radioactive
polonium and beryllium. Radiation is
emitted from an aluminium window at
the chamber's end
"The lions den" of the
Cavendish: Rutherford,
foreground, with colleagues;
Chadwick is at right.
7
Discovery of neutron (IV)
Chadwick was able to prove that
the neutral particle could not be
a photon by bombarding targets
other than hydrogen, including
nitrogen, oxygen, helium and
argon. Not only were these
inconsistent with photon
emission on energy grounds, the
cross-section for the interactions
was orders of magnitude greater
than that for Compton scattering
by photons.
8
Who is Chadwick?
Sir James Chadwick
(B.1891 – D.1974)
was an English Nobel laureate in physics awarded for his
discovery of the neutron. In 1913 Chadwick went and worked
with Hans Geiger at Berlin. He was in Germany at the start of
World War I and was interned in Ruhleben P.O.W. Camp just
outside Berlin. While he was interned, he had the freedom to
set up a laboratory in the stables. He spent most of the war
years in Ruhleben until Geiger's laboratory interceded for his
release. For this discovery he was awarded the Nobel Prize
for Physics in 1935.
Ruhleben Gefangenenlager (British Civilian Internment Camp) was
established after the outbreak of the First World War at a racetrack in
Spandau, a suburb of Berlin, and remained in operation until Armistice
Day, 1918.
9
Playing with neutrons
10
Create new elements
In 1934, Italian
physicists Enrico Fermi
and his group at Rome
bombarded uranium
with neutrons and
postulated that
transuranic elements
might have been
produced and which
was widely accepted for
a few years. He
received 1938 Nobel
Physics Prize
11
Who is Fermi?
Enrico Fermi (B. 1901 – D.1954)
was an Italian physicist, particularly remembered for his
work on the development of the first nuclear reactor, and
for his contributions to the development of quantum theory,
nuclear and particle physics, and statistical mechanics.
Awarded the Nobel Prize in Physics in 1938 for his work on
induced radioactivity, Fermi is widely regarded as one of
the leading scientists of the 20th century, highly
accomplished in both theory and experiment. Fermium, a
synthetic element created in 1952, the Fermi National
Accelerator Lab, the Fermi Gamma-ray Space Telescope,
and a type of particles called fermions are named after him.
12
Criticism from chemist
Ida Noddack (B.1896 – D.1978),
was a German chemist and
physicist. With her husband Walter
Noddack she discovered element
75 rhenium. She was nominated
three times for Nobel Prize in
Chemistry.
Ida Noddack criticized Enrico Fermi's chemical
proofs in his 1934 neutron bombardment
experiments. Her paper, "On Element 93" suggested
a number of possibilities, centering around Fermi's
failure to chemically eliminate all lighter than
uranium elements in his proofs. She suggested the
possibility that "it is conceivable that the nucleus
breaks up into several large fragments, which would
of course be isotopes of known elements but would
not be neighbors of the irradiated element."
However Noddack offered no theoretical basis for
this possibility, the paper was generally ignored.
13
Discovery of Nuclear Fission
In December 1938, when Otto Hahn and Fritz Strassman
looked for transuranium elements in a uranium sample that
had been bombarded with neutrons, they found traces of
barium. On 22 December 1938, they sent a manuscript to
Naturwissenschaften reporting their radiochemical results,
which were the irrefutable proof that the uranium had been
split into fragments consisting of lighter elements;
simultaneously, they communicated these results to Lise
Meitner, who had escaped out of Germany earlier that year
and was then in Sweden. Meitner, and her nephew, the
young physicist Otto Robert Frisch, correctly interpreted
these results as being nuclear fission, a term coined by
Frisch, which subsequently became internationally known.
Frisch confirmed this experimentally on 13 January 1939.
14
Who is Hahn?
Otto Hahn (B. 1879 – D. 1968) was a
German chemist and Nobel laureate
who pioneered the fields of radioactivity
and radiochemistry. He is regarded as
"the father of nuclear chemistry" and the
"founder of the atomic age". From 1948
to 1960 Otto Hahn was the founding
President of the newly formed Max
Planck Society for the Advancement of
Science, which through his tireless
activity and his worldwide respected
personality succeeded in regaining the
renown once enjoyed by the Kaiser
Wilhelm Society.
Nuclear fission experimental
setup, reconstructed at the
Deutsches Museum, Munich
Otto Hahn's notebook
15
Hahn after WWII
Safe House, Farm
Hall.
At the end of World War II in 1945 Hahn was suspected of
working on the German nuclear energy project to develop an
atomic reactor or an atomic bomb. But his only connection was
the discovery of fission, he did not work on the program. Hahn
and nine German physicists (including Max von Laue, Werner
Heisenberg and Carl Friedrich von Weizsäcker) were interned
at Farm Hall, Godmanchester, near Cambridge, England from 3
July 1945 to 3 January 1946. While they were there, the
German scientists learned of the dropping of the American
atom bombs on Hiroshima and Nagasaki . Hahn was on the
brink of despair, as he felt that because he had discovered
nuclear fission he shared responsibility for the death and
suffering of hundreds of thousands of Japanese people. Early
in January 1946, the group was allowed to return to Germany.
16
Who is Lise Meitner?
Lise Meitner (B. 1878 – D. 1968) was an Austrian-born,
later Swedish physicist who worked on radioactivity and
nuclear physics. Meitner was part of the team that
discovered nuclear fission, an achievement for which her
colleague Otto Hahn was awarded the Nobel Prize. Meitner
is often mentioned as one of the most glaring examples of
women's scientific achievement overlooked by the Nobel
committee. Meitner also first realized that Einstein's famous
equation E = mc2, explained the source of the tremendous
releases of energy in atomic decay, by the conversion of
the mass into energy. She and Frisch had discovered the
reason that no stable elements beyond uranium (in atomic
number) existed naturally; the electrical repulsion of so
many protons overcame the "strong" nuclear force. The
element 109 was named meitnerium in her honour.
17
Lise Meitner as a refugee
Dirk Coster (B.1889– D.1950),
was a Dutch physicist known as
the co-discoverer of Hafnium.
Adriaan Daniël Fokker
(B1887 – D.1972), was a
Dutch physicist and
musician. In his 1913 thesis,
he derived the FokkerPlanck equation along
with Max Planck
When Adolf Hitler came to power in 1933,
Meitner was acting director of the Institute for
Chemistry. In July 1938, Meitner, with help from
the Dutch physicists Dirk Coster and Adriaan
Fokker, escaped to Holland. She was forced to
travel under cover to the Dutch border, where
Coster persuaded German immigration officers
that she had permission to travel to the
Netherlands. She reached safety, though
without her possessions. Meitner later said that
she left Germany forever with 10 marks in her
purse. Before she left, Otto Hahn had given her
a diamond ring he had inherited from his mother:
this was to be used to bribe the frontier guards if
required. It was not required, and Meitner's
nephew's wife later wore it.
18
Who is Strassmann?
Friedrich Wilhelm "Fritz" Straßmann (B.1902 – D.1980)
was a German chemist who, with Otto Hahn in 1938, identified
barium in the residue after bombarding uranium with neutrons,
which led to the interpretation of their results as being from
nuclear fission. In 1933 he resigned from the Society of
German Chemists when it became part of a Nazi-controlled
public corporation. He was blacklisted. Hahn and Meitner
found an assistantship for him at half pay. Strassmann
considered himself fortunate, for "despite my affinity for
chemistry, I value my personal freedom so highly that to
preserve it I would break stones for a living." During the war
he and his wife Maria Heckter Strassmann concealed a
Jewish friend in their apartment for months, putting
themselves and their three year old son at risk. Strassmann
was recognized by Yad Vashem Holocaust Memorial as
Righteous Among the Nations.
19
Who is Frisch?
Otto Robert Frisch (B. 1904, Vienna – D.1979),
Austrian-British physicist. Frisch was Jewish, born in
Vienna, Austria in 1904, the son of a painter and a
concert pianist. He himself was talented at both but also
had inherited his aunt Lise Meitner's love of physics .
The accession of Adolf Hitler to the chancellorship of
Germany in 1933 made Otto Robert Frisch make the
decision to move to London, England where he worked
with the physicist Blackett on cloud chamber technology
and artificial radioactivity. He followed this with a five
year stint in Copenhagen with Niels Bohr where he
increasingly specialized in nuclear physics, particularly
in neutron physics. Later he played a very important role
in the design of the atomic bomb.
20
Nuclear chain reaction
A nuclear chain reaction occurs when
one nuclear reaction causes an average of
one or more nuclear reactions, thus
leading to a self-propagating number of
these reactions. The specific nuclear
reaction may be the fission of heavy
isotopes (e.g. 235U) or the fusion of light
isotopes (e.g. 2H and 3H). The nuclear
chain reaction is unique since it releases
several million times more energy per
reaction than any chemical reaction. The
concept of a nuclear chain reaction was
first realized by Hungarian scientist Leó
Szilárd in 1933. He filed a patent for his
idea of a simple nuclear reactor the
following year.
21
Who is Szilard?
Leó Szilárd (B.1898 – D.1964) was a Hungarian physicist who
conceived the nuclear chain reaction and worked on the
Manhattan Project. Szilárd was born into a Jewish family of
Budapest at the time of the Austro-Hungarian monarchy before
World War I as the son of a civil engineer. During his time in Berlin
he was working on numerous technical inventions. 1928 German
patent application on the linear accelerator, 1929 German patent
application on the cyclotron, since 1926 work with Einstein on the
construction of a refrigerator without moving parts (US patent
1,781,541 on November 11, 1930).
In 1873 Buda and Pest were officially
merged into Budapest. Due to the
prosperity and the large Jewish
community of the city, Budapest was often
called as the "Jewish Mecca
22
Very poor and inefficient way
During 1933 Szilárd fled to London to escape Nazi
persecution, where he read an article in The Times
summarizing a speech given by Ernest Rutherford which
rejected the possibility of using atomic energy for
practical purposes:
We might in these processes obtain very much more
energy than the proton supplied, but on the average we
could not expect to obtain energy in this way. It was a
very poor and inefficient way of producing energy, and
anyone who looked for a source of power in the
transformation of the atoms was talking moonshine. But
the subject was scientifically interesting because it gave
insight into the atoms.
23
Concept of chain reaction
Although nuclear fission had not yet been discovered, Szilárd was reportedly
so annoyed at this dismissal that he conceived of the idea of the nuclear chain
reaction while walking to work at St Bartholomew's Hospital waiting for traffic
lights to change on Southampton Row in Bloomsbury, though his friend Jacob
Bronowski notes that he never knew Szilárd to wait for traffic lights. The
following year he filed for a patent on the concept.
St Bartholomew's Hospital
The King Henry VIII Gate at Barts, which
was constructed in 1702. Note Henry VIII
above the
24
Szilárd and Fermi
An image from the Fermi–Szilárd
"neutronic reactor" patent
During 1938 Szilárd accepted an offer to conduct
research at Columbia University in Manhattan, and
moved to New York, and was soon joined by Fermi.
After learning about the successful nuclear fission
experiment conducted during 1939 in Germany by
Otto Hahn, Fritz Strassmann, Lise Meitner, and Otto
Robert Frisch, Szilárd and Fermi concluded that
uranium would be the element capable of sustaining
a chain reaction. Szilárd and Fermi conducted a
simple experiment at Columbia and discovered
significant neutron multiplication in uranium, proving
that the chain reaction was possible and enabling
nuclear weapons. Szilárd later described the event:
"We turned the switch and saw the flashes. We
watched them for a little while and then we switched
everything off and went home."
25
Nazi Germany and coming war
On 30 January 1933, Adolf Hitler was
appointed Chancellor of Germany by
Hindenburg . At Hindenburg's death on 2
August 1934, the Nazi-controlled
Reichstag merged the offices of
Reichspräsident and Reichskanzler and
reinstalled Hitler with the new title Führer.
By the time the Nuremberg Laws were
passed in 1935, Jews were stripped of
their German citizenship and denied
government employment. With growing
threat from Nazi Germany World war II
becomes inevitable in 1939.
26
Einstein–Szilárd letter
The Einstein–Szilárd letter was a letter sent to
United States President Franklin D. Roosevelt
on August 2, 1939, that was signed by Albert
Einstein but largely written by Leó Szilárd. The
letter advised Roosevelt that Nazi Germany
might be researching the use of nuclear fission
to create atomic bombs and suggested that the
U.S. should begin studying the possibility itself.
He later regretted signing the letter.
Albert Einstein and Leo Szilard
in1939, reenacting the signing of
their letter to President Roosevelt
warning him that Germany may be
building an atomic bomb.
27
Content of the letter
……In the course of the last four months it has been made probable — through
the work of Joliot in France as well as Fermi and Szilard in America — that it
may become possible to set up a nuclear chain reaction in a large mass of
uranium, by which vast amounts of power and large quantities of new radiumlike elements would be generated. Now it appears almost certain that this could
be achieved in the immediate future.
This new phenomenon would also lead to the construction of bombs, and it is
conceivable — though much less certain — that extremely powerful bombs of a
new type may thus be constructed. A single bomb of this type, carried by boat
and exploded in a port, might very well destroy the whole port together with
some of the surrounding territory. However, such bombs might very well prove
to be too heavy for transportation by air……….
28
Content of the letter
The United States has only very poor ores of uranium in moderate quantities.
There is some good ore in Canada and the former Czechoslovakia. while the
most important source of uranium is Belgian Congo……. I understand that
Germany has actually stopped the sale of uranium from the Czechoslovakian
mines which she has taken over. That she should have taken such early action
might perhaps be understood on the ground that the son of the German UnderSecretary of State, von Weizsäcker, is attached to the Kaiser-Wilhelm-Institut in
Berlin where some of the American work on uranium is now being repeated.
Ernst Freiherr von Weizsäcker (B.1882 – D.1951) was a German
diplomat and politician. He served as Secretary of State at the Foreign
Office from 1938 to 1943, and as German Ambassador to the Holy See
from 1943 to 1945. He was a member of the prominent Weizsäcker
family, and the father of German President Richard von Weizsäcker
and physicist and philosopher Carl Friedrich von Weizsäcker.
29
Carl Friedrich Freiherr von Weizsäcker
Carl Friedrich Freiherr von Weizsäcker (B. 1912 – D.
2007) was a German physicist and philosopher. He was the
longest-living member of the research team which
performed nuclear research in Germany during the Second
World War, under Werner Heisenberg's leadership. During
the Second World War, Weizsäcker joined the German
nuclear energy project, participating in efforts to construct
an atomic bomb. He was present at a crucial meeting at the
Army Ordnance headquarters in Berlin on 17 September
1939, at which the German atomic weapons program was
launched. In July 1940 he was co-author of a report to the
Army on the possibility of "energy production" from refined
uranium, and which also predicted the possibility of using
plutonium for the same purpose including the production of
a new type of explosives.
30
Debate about Weizsäcker
There is ongoing debate as to whether he, and the other members of the
team, actually willingly pursued the development of a nuclear bomb for
Germany during this time. Historians have been divided as to whether
Heisenberg and his team were sincerely trying to construct a nuclear
weapon, or whether their failure reflected a desire not to succeed
because they did not want the Nazi regime to have such a weapon. In a
recent report based on additional documents from Russian archives,
historian Mark Walker concludes that "in comparison with Diebner [and]
Gerlach ... Heisenberg and finally Weizsäcker did obviously not use all
power they commanded to provide the National Socialists with nuclear
weapons
31
Weizsäcker, Bohr and Heisenberg
Ivan Supek
(B. 1915 –
D. 2007)
was a
Croatian
physicist
According to Ivan Supek (one of Heisenberg's
students and friends), he was informed in confidence
by Bohr's wife Margrethe about the meeting. In his
interview claimed that Weizsäcker was the main
figure of the famous and controversial in
Copenhagen in September 1941. Allegedly, he tried
to persuade Bohr to mediate for peace between
Germany and Great Britain. According to
Weizsäcker's own account, he had persuaded
Heisenberg to meet Bohr in order to broker an accord
of the international nuclear physicist "community" not
to build the bomb.
Niels Bohr and Margrethe Bohr
32
World War II began
World War II began with the German invasion of
Poland on September 1, 1939, the Einstein–
Szilárd letter was signed by Einstein on August 2,
and it was hand-delivered to Roosevelt by the
economist Alexander Sachs on October 11, 1939.
The letter advised Roosevelt of the existence of
the German nuclear energy project and warned
that it was likely the Germans were working on an
atomic bomb using uranium, and that the U.S.
should be concerned about locating sources of
uranium and researching nuclear weapon
technology. At this time the U.S. policy was neutral
in the war.
33
Reply from Roosevelt
THE WHITE HOUSE
WASHINGTON
October 19, 1939
My dear Professor:
I want to thank you for your recent letter and the most interesting and important
enclosure.
I found this data of such import that I have convened a Board consisting of the
head of the Bureau of Standards and a chosen representative of the Army and
Navy to thoroughly investigate the possibilities of your suggestion regarding the
element of uranium.
I am glad to say that Dr. Sachs will cooperate and work with this Committee and I
feel this is the most practical and effective method of dealing with the subject.
Please accept my sincere thanks.
34
Uranium Committee (1939–1941)
As a result of the letter Roosevelt asked Lyman James Briggs,
director of the National Bureau of Standards, secretly to organize
the Briggs Advisory Committee on Uranium. The committee's first
meeting was on October 21, 1939, in Washington, D.C.; $6,000
was budgeted for conducting neutron experiments conducted by
Fermi and Szilárd at Columbia.
Four aspects of uranium seem to be critical from the start:
Finding reliable sources of uranium ore in places where the supply
cannot be interfered by other countries.
Developing mass production methods of extracting uranium-235
from ore and/or creating plutonium.
Making uranium (fission) chain-reaction bombs.
Using controlled fission to power machines and synthesize
isotopes.
35
Frisch–Peierls memorandum
Otto Robert Frisch
(B. 1904, Vienna – D.1979),
The Frisch–Peierls memorandum was written by Otto Frisch
and Rudolf Peierls while they were both working at the
University of Birmingham, England. The memorandum
contained new calculations about the size of the critical mass
needed for an atomic bomb. The memorandum contradicted
the common thinking of the time that many tons of uranium235 would be needed to make a bomb, requiring delivery by
ship. The calculation in the memorandum showed that a bomb
might be possible using as little as one pound of uranium-235,
and could be quite practical for aircraft to carry. The
memorandum is dated March 1940.
Sir Rudolf Ernst Peierls,
(B.1907, Berlin – D. 1995, Oxford),
The opening paragraph of the
Frisch–Peierls memorandum
36
Who is Peierls ?
Sir Rudolf Ernst Peierls, (B.1907 – D. 1995), was a Germanborn British physicist. Rudolf Peierls had a major role in
Britain's nuclear program, but he also had a role in many
modern sciences. His impact on physics can probably be best
described by his obituary in Physics Today: "Rudolph
Peierls...a major player in the drama of the irruption of nuclear
physics into world affairs...". In 1929, he studied solid-state
physics in Zurich under the tutelage of Werner Heisenberg and
Wolfgang Pauli. His early work on quantum physics led to the
theory of positive carriers to explain the thermal and electrical
conductivity behaviors of semiconductors. He was a pioneer of
the concept of "holes" in semiconductors. The ironic truth is
that both Peierls and Frisch were excluded from working on
radar (then known as RDF) as it was considered too secret for
scientists with foreign backgrounds.
37
MAUD committee
Sir Henry Thomas Tizard
(B. 1885 - D.1959 ) was an
English chemist and inventor.
Marcus Oliphant passed the
document on to Henry Tizard,
chairman of the Committee on the
Scientific Survey of Air Defence
who, as a result, requested the
setting-up of what was to become
the secret MAUD Committee. The
Maud Committee (Military
Application of Uranium
Detonation) was the beginning of
the British atomic bomb project.
Maud Committee first met on 10
April 1940 to consider Britain's
actions regarding the "uranium
problem“. On the other hand,
situation deteriorated very fast.
Sir Marcus 'Mark'
Laurence Elwin Oliphant,
(B.1901 – D. 2000) was
an Australian physicist and
humanitarian who played
a fundamental role in the
first experimental
demonstration of nuclear
fusion and also the
development of the atomic
bomb.
38
Nazi was marching! (1940)
Germany invaded France, invaded Belgium,
invaded the Netherlands, and invaded
Luxembourg on 10 May 1940, the same day
Neville Chamberlain resigned as British
Prime Minister. The Netherlands and
Belgium were overrun using blitzkrieg tactics
in a few days and weeks, respectively.
British troops were forced to evacuate the
continent at Dunkirk, abandoning their heavy
equipment by the end of the month. On 10
June, Italy invaded France, declaring war on
both France and the United Kingdom;twelve
days later France surrendered and was
soon divided into German and Italian
occupation zones,and an unoccupied rump
state under the Vichy Regime.
39
London was burning! (1940)
The Blitz was the sustained
bombing of Britain by Nazi
Germany between
6 September 1940 and
10 May 1941, during the
Second World War. The Blitz
hit many towns and cities
across the country, but it
began with the bombing of
London for 76 consecutive
nights. By the end of May
1941, over 43,000 civilians,
half of them in London, had
been killed by bombing and
more than a million houses
were destroyed or damaged
in London alone.
40
MAUD committee
The biggest problem faced by the MAUD Committee was to find a way to
separate the 0.7% of uranium-235 from the 99.3% of uranium-238. This is
difficult because the two types of uranium are chemically identical. However,
Franz Simon had been commissioned by MAUD to investigate methods. Simon
reported in December 1940 that gaseous diffusion was feasible, calculating the
size and cost of the industrial plant needed. The MAUD Committee realized that
an atomic bomb was "not just feasible; it was inevitable". Dr Philip Baxter at ICI
made the first small batch of gaseous uranium hexafluoride for Professor James
Chadwick in 1940. ICI received a formal contract later in 1940 to make 3 kg of
this vital material for the future work.
Sir Francis Simon, (B. 1893 – D.1956), was a German and later British
physical chemist and physicist who devised the method, and confirmed
its feasibility, of separating the isotope Uranium-235 and thus made a
major contribution to the creation of the atomic bomb.
41
MAUD Committee
The breakthrough with plutonium was at the Cavendish
Laboratory by Egon Bretscher and Norman Feather. They
realized that a slow neutron reactor fuelled with uranium would
theoretically produce substantial amounts of plutonium-239 as
a by-product. This is because U-238 absorbs slow neutrons
and forms a new isotope U-239. The new isotope's nucleus
rapidly emits an electron through beta decay producing a new
element with a mass of 239 and an atomic number of 93. This
element's nucleus then also emits an electron and becomes a
new element of mass 239 but with an atomic number 94 and a
much greater half-life.
Bretscher and Feather showed theoretically feasible grounds that element 94 would
be readily 'fissionable' by both slow and fast neutrons, and had the added advantage
of being chemically different from uranium, and could easily be separated from it.
This new development was also confirmed in independent work at Berkeley
Radiation Laboratory also in 1940 by Seaborg.
42
Who is Bretscher?
Egon Brestcher
(right)
Egon Bretscher (B.1901-D.1973) Born near Zurich, Switzerland in
1901 and educated at the ETH there, Bretscher gained a PhD
degree in organic chemistry at Edinburgh in 1926. He returned to
Zurich as privatdocent to Peter Debye, later moving in 1936 to
work in Rutherford’s laboratory at the Cavendish in Cambridge as a
Rockefeller Scholar. Here he switched to research in nuclear
physics, proposing with Norman Feather in 1940 that the 239
isotope of element 94 could be produced from the common isotope
of uranium-238 by neutron capture and that, like U-235, this should
be able to sustain a nuclear chain reaction. In addition, he devised
theoretical chemical procedures for purifying this unknown element
away from the parent uranium; this element was named Plutonium
by Nicholas Kemmer. In 1944 he became a part of the British
Mission to the Manhattan Project in Los Alamos, New Mexico led
by James Chadwick, where he made the first measurements on
the energy released in fusion processes.
43
What Feather remembered…
Norman Feather
(B.1904 – D.1978),
was an English physicist.
Feather:
Oh, it was before that. Because it was in December, 1940,
that Bretscher and I put in a minority report, or shall we say
were allowed to put in an appendix, to a feasibility document
for the Directorate. We said that we believed that if uranium235 had the characteristics which were suitable for this job of
a bomb, if 235 uranium had it, then we believed 239
plutonium would have it. Although no one had any at that time.
And that probably technically the chemical process of
separating plutonium 239 from a reactor might be less difficult
than separating isotope-wise 235 uranium, in the isotope
separation plant. That was in December ‘40.
Interview with Norman Feather
By Charles Weiner
In Edinburgh, Scotland
(James Clerk Maxwell Physics Building)
February 25, 1971
44
MAUD committee
On 15 July 1941 the Maud Committee
approved its two final reports and
disbanded. Their report concluded
that a bomb was feasible, describing it
in technical detail, providing specific
proposals for developing a bomb and
including cost estimates and so it
recommended that the work should be
continued with high priority in
cooperation with the Americans.
45
Creation of OSRD
Sir Marcus 'Mark' Laurence Elwin
Oliphant (B. 1901 – D. 2000)
Vannevar Bush
(B. 1890 – D.1974)
Their reports were sent to Briggs, but were ignored.
One of the members of the MAUD Committee, Mark
Oliphant, flew to the United States in late August 1941
to find out why the U.S. was ignoring the MAUD
Committee's findings. He reported that "this inarticulate
and unimpressive man (Briggs) had put the reports in
his safe and had not shown them to members of his
committee."
Oliphant then met with the whole Uranium Committee
and other physicists to galvanize the USA into action.
As a result, in December 1941 Vannevar Bush created
the larger and more powerful Office of Scientific
Research and Development—which was empowered to
engage in large engineering projects in addition to
research—and became its director.
46
Pearl Harbor, Dec 7th 1941
December 6: Vannevar Bush holds a
meeting to organize an accelerated
research project, still managed by Arthur
Compton. Harold Urey is assigned to
develop research into gaseous diffusion as
a uranium enrichment method, while
Ernest O. Lawrence is assigned to
investigate electromagnetic separation
methods.
December 7: The Japanese attack Pearl
Harbor. The United States issues a formal
declaration of war against Japan the next
day. Four days later, Nazi Germany
declares war on the United States.
December 18: First meeting of the OSRD
sponsored S-1 project, dedicated to
developing fission weapons
47
U.S. effort quickly caught up
James Bryant Conant
(B.1893 – D. 1978) was
a chemist, educational
administrator, and
government official. As
the President of Harvard
University he reformed it
as a research institution.
As a result of the MAUD Report, the British had started a
uranium bomb program referred to by the codename Tube
Alloys. Perceived slowness on the part of the United States
had become a contentious issue between American and
British scientists. Upon entry into the war, the U.S. placed
increasing importance on working cooperatively with the
British program. British realized that their pioneering effort
would have no value if it were not quickly capitalized.
On June 17, 1942, Roosevelt approved a proposal by Bush
to dissolve the original S-1 Section and created the S-1
Executive Committee, chaired by James B. Conant, with
the membership of Briggs, Compton, Urey, Lawrence, and
Edgar Murphee. The program entered into increased
cooperation between the OSRD and the U.S. Army.
48
S-1 Executive Committee (1942)
The Advisory Committee on Uranium, now called the S-1 section, meets to establish the
first timetables for bomb production. The first large scale contracts for research into
isotope separation are also let. From Left: Harold Urey, Ernest Lawrence, James B.
Conant, Lyman Briggs, Eger Murphree, Arthur Compton.
49
Who is Urey?
Harold Clayton Urey (B. 1893 – D. 1981) was an American
physical chemist whose pioneering work on isotopes earned him
the Nobel Prize in Chemistry in 1934. He played a significant role
in the development of the atom bomb. Urey became interested in
nuclear systematics. This led to his discovery of deuterium.
During this time, Urey isolated deuterium by repeatedly distilling a
sample of liquid hydrogen. In 1931, he and his associates went on
to demonstrate the existence of heavy water. Urey was awarded
the Nobel Prize in Chemistry in 1934 for this work. During World
War II, Urey's team at Columbia worked on a number of research
programs that contributed towards the Manhattan Project to
develop an atomic bomb for the United States. Most importantly,
they developed the gaseous diffusion method to separate uranium235 from uranium-238. In autumn 1941, Urey, with G. B. Pegram,
led a diplomatic mission to England to establish co-operation on
development of the atomic bomb.
50
Who is Lawrence?
Ernest Orlando Lawrence (B. 1901 – D.1958) was an
American physicist .In 1939, Lawrence was awarded the Nobel
Prize in Physics for his work in inventing the cyclotron and
developing its applications. During World War II, Lawrence
eagerly helped to ramp up the American investigation of the
possibility of a weapon utilizing nuclear fission. His Radiation
Laboratory, became one of the major centers for wartime
nuclear research, and it was Lawrence who first introduced J.
Robert Oppenheimer into what would soon become the
Manhattan Project. An early champion of the electromagnetic
separation method to enrich uranium and increase its
percentage of fissile U-235. After the war, Lawrence
campaigned extensively for government sponsorship of large
scientific programs. Lawrence was a forceful advocate of "Big
Science" with its requirements for big machines and big money.
51
Uranium enrichment
During the first half of 1942, at Columbia
University, Harold Urey worked on the
gaseous diffusion and centrifuge systems for
isotope separation. At Berkeley, Ernest
Lawrence continued his investigations on
electromagnetic separation using the
"calutron" he had converted from his thirtyseven-inch cyclotron. Phillip Abelson at the
National Bureau of Standards to the Naval
Research Laboratory, continued his work on
liquid thermal diffusion but with few
positive results, and he had lost all contact
with the S-1 Section of the Office of Scientific
Research and Development.
52
Uranium enrichment
Meanwhile Eger Murphree’s group hurriedly studied
ways to move from laboratory experiments to
production facilities. Despite the difficulties
encountered with the centrifuge and gaseous
diffusion methods, and even with Lawrence's
successes at Berkeley, no clear-cut victor had yet
emerged. The question of which method of uranium
enrichment would prove most effective remained wide
open.
Eger Vaughan Murphree (B.1898 – D.1962) was an American chemist,
best known for his co-invention of the process of fluid catalytic cracking. He
worked at Exxon, and served from 1947 to 1962 as its VP of research and
engineering. He was also briefly involved in the Manhattan Project.
53
Manhattan Project
The Manhattan Project was the codename for a
project conducted during World War II to develop the
first atomic bomb. The project was led by the United
States, and included participation from the United
Kingdom and Canada. Formally designated as the
Manhattan Engineer District (MED), it refers
specifically to the period of the project from 1942–
1946 under the control of the U.S. Army Corps of
Engineers, under the administration of General Leslie
R. Groves. The scientific research was directed by
American physicist J. Robert Oppenheimer.
Leslie Richard Groves
(August 17, 1896 – July 13, 1970)
54
Who is Oppenheimer?
J. Robert Oppenheimer
(B1904 –D1967) was an American theoretical physicist and
professor of physics at the University of California, Berkeley. He is
best known for his role as the scientific director of the Manhattan
Project, the World War II effort to develop the first nuclear
weapons at the secret Los Alamos National Laboratory in New
Mexico. For this reason he is remembered as "The Father of the
Atomic Bomb". In reference to the Trinity test in New Mexico,
where his Los Alamos team first tested the bomb, Oppenheimer
famously recalled the Bhagavad Gita: "If the radiance of a
thousand suns were to burst at once into the sky, that would be
like the splendor of the mighty one." and "Now I am become
Death, the destroyer of worlds."
55
Manhattan project in 1942
September 17: Col. Leslie Groves is assigned command of
the Manhattan Engineering District. Six days later he is
appointed to Brigadier General.
September 24: After a visit to Tennessee, Groves purchases
52,000 acres (210 km²) of land in Tennessee for "Site X",
which will become the Oak Ridge, Tennessee laboratory
and production site.
September 26: The Manhattan Project is given permission
to use the highest wartime priority rating by the War
Production Board.
October 15: Groves appoints Robert Oppenheimer to
coordinate the scientific research of the project at the "Site
Y" laboratory.
November 16: Groves and Oppenheimer visit Los Alamos,
New Mexico and designate it as the location for "Site Y".
56
Decision on enrichment
Walter S. Carpenter
Jr.(1888-1976) served
DuPont for eight decades.
DuPont supplied explosives
and a host of other products
to the war effort. He also
guided DuPont’s heavy
involvement in perhaps the
most ambitious research and
development undertaking in
history, the Manhattan
Project
The Military Policy Committee met on November 12, 1942,
and its decisions were ratified by the S-1 Executive
Committee two days later. The Military Policy Committee,
acting on Groves's and James Conant's recommendations,
cancelled the centrifuge project. Gaseous diffusion, the pile,
and the electromagnetic method were to proceed directly to
full-scale, eliminating the pilot plant stage. The S-1
Executive Committee approved these recommendations
and agreed that the gaseous diffusion facility was of lower
priority than either the pile or the electromagnetic plant but
ahead of a second pile. The scientific committee also asked
DuPont to look into methods for increasing American
supplies of heavy water in case it was needed to serve as a
moderator for one of the new piles. Now that the various
committees had finally chosen which horses to back, the
only things left to do were to get final presidential approval
and to run the race.
57
Italian navigator has landed
The first controlled nuclear reaction
occurred at CP-1 (Chicago Pile 1),
on an old squash court under the
University of Chicago's Stagg Field.
The 1942 feat marked the start of the
Atomic Age.
The first major scientific hurdle of the project
was solved on December 2, 1942, beneath the
bleachers of Stagg Field at the University of
Chicago, where a team led by Enrico Fermi,
initiated the first artificial self sustaining nuclear
chain reaction in an experimental nuclear
reactor named Chicago Pile-1. A coded phone
call from Compton saying, "The Italian
navigator [referring to Fermi] has landed in the
new world, the natives are friendly" to Conant
in Washington, D.C., brought news of the
experiment's success.
58
Mass production of plutonium
Glenn Theodore Seaborg
(B. 1912 – D. 1999) was an
American scientist who won
the 1951 Nobel Prize in
Chemistry for "discoveries in
the chemistry of the
transuranium elements.
Using lanthanum fluoride as a carrier, Seaborg isolated a
weighable sample of plutonium in August 1942. Seaborg's
discovery and subsequent isolation of plutonium were major
events in the history of chemistry, but it remained to be seen
whether they could be translated into a production process
useful to the bomb effort. The laboratory process created
by Seaborg would have to be scaled-up a billion-fold to be
implemented in an industrial separation plant. By the end
of January 1945, the highly purified plutonium underwent
further concentration in the completed chemical isolation
building, where remaining impurities were removed
successfully. Los Alamos received its first plutonium from
Hanford on February 2. While it was still by no means clear
that enough plutonium could be produced for use in bombs
by the war's end, Hanford was by early 1945 in operation.
59
Little Boy
The Hiroshima bomb, Little Boy, was made from uranium235, a rare isotope of uranium that has to be physically
separated from the more plentiful uranium-238 isotope,
which is not suitable for use in an explosive device. Since
U-235 makes up only 0.7% of raw uranium and is
chemically identical to the 99.3% of U-238, various
physical methods were considered for separation. During
the Manhattan Project enriched uranium was given the
codename oralloy, a shortened version of Oak Ridge alloy,
after the location of the plants where the uranium was
enriched. The term oralloy is still occasionally used to refer
to enriched uranium. There are about 2,000 tonnes (t, Mg)
of highly enriched uranium in the world, produced mostly
for nuclear weapons, naval propulsion, and smaller
quantities for research reactors.
60
Little Boy
The uranium bomb was a gun-type fission
weapon. One mass of U-235, the "bullet," is fired
down a more or less conventional gun barrel into
another mass of U-235, rapidly creating the critical
mass of U-235, resulting in an explosion. The
method was so certain to work that no test was
carried out before the bomb was dropped over
Hiroshima, Also, the bomb that was dropped used
all the existing extremely highly purified U-235
(and even most of the less highly purified material)
so there was no U-235 available for such a test
anyway.
61
62
Thin Man
"Thin Man" plutonium
gun test casings.
Emilio Gino Segrè
(B.1905 – D. 1989)
was an Italian
physicist and
Nobel laureate in
physics.
In 1943–1944, development efforts were directed to a
gun-type fission weapon with plutonium, called "Thin
Man". The chain reaction of U-235 was slow enough
that gun-type assembly would work. But In April 1944,
experiments by Emilio G. Segrè on the newly reactorproduced plutonium from Hanford showed that it
contained impurities in the form of the element
plutonium-240. "early" neutrons from spontaneously
fissioning Pu-240 would start the chain reaction more
quickly during detonation. This would release enough
energy to disperse the critical mass with only a
minimal amount of plutonium reacted, reducing the
resulting yield of the weapon. In July 1944, based on
the measurements of spontaneous fission for Hanford
plutonium, the decision was made to cease work on a
gun-type assembly for plutonium. There would be no
"Thin Man."
63
Implosion
Ideas for alternative detonation schemes
had existed for some time at Los Alamos.
One of the more innovative was the idea
of "implosion". Using chemical explosives,
a sub-critical sphere of fissile material
could be squeezed into a smaller and
denser form. When the fissile atoms were
packed closer together, the rate of neutron
capture would increase, and the mass
would become a critical mass. The metal
needed to travel only very short distances,
so the critical mass would be assembled
in much less time than it would take to
assemble a mass by a bullet impacting a
target.
64
Nuclear Test “Trinity”
Because of the complexity of an implosion-style weapon, it was decided that,
despite the waste of fissile material, an initial test would be required. The first
nuclear test took place on July 16, 1945, near Alamogordo, New Mexico, under the
supervision of Groves's deputy Brig. Gen. Thomas Farrell. Oppenheimer gave the
test the code name "Trinity". It was conducted by the United States on July 16,
1945, at a location 35 miles (56 km) southeast of Socorro, New Mexico on the
White Sands Proving Ground, headquartered near Alamogordo.
65
Now I am become Death
Oppenheimer later recalled that, while witnessing the explosion, he thought of a
verse from the Hindu holy book, the Bhagavad Gita:
If the radiance of a thousand suns were to burst at once into the sky, that would
be like the splendor of the mighty one...
Years later he would explain that another verse had also entered his head at that
time: namely, the famous verse; "Kalo Asmi Loka-ksaya-krit Pravardho, Lokan
Samartum iha Pravattah" and was quoted by Oppenheimer after the successful
detonation of the first nuclear weapon. He translated it as "Now I am become
Death, the destroyer of worlds."
66
What is Gita ?
The Bhagavad Gītā also more simply known as Gita, is a sacred Hindu scripture,
considered among the most important texts in the history of literature and philosophy.
The Bhagavad Gita comprises roughly 700 verses, and is a part of the Mahabharata.
The teacher of the Bhagavad Gita is Lord Krishna, who is revered by Hindus as a
manifestation of God (Parabrahman) himself, and is referred to within as Bhagavan,
the Divine One.The content of the Gita is the conversation between Lord Krishna
and Arjuna taking place on the battlefield before the start of the Kurukshetra war.
Responding to Arjuna's confusion and moral dilemma about fighting his own cousins,
Lord Krishna explains to Arjuna his duties as a warrior and prince and elaborates on
different Yogic and Vedantic philosophies, with examples and analogies. This has led to
the Gita often being described as a concise guide to Hindu theology and also as a
practical, self-contained guide to life. During the discourse, Lord Krishna reveals His
identity as the Supreme Being Himself, blessing Arjuna with an awe-inspiring
vision of His divine universal form.
67
Germany Surrender (May, 1945)
By late 1944, the Red Army had driven the Germans back
into Central Europe and the Western Allies were advancing
into Germany. Hitler realized that Germany had lost the war,
but allowed no retreats. In April 1945, Soviet forces
attacked the outskirts of Berlin. Hitler's followers urged him
to flee to the mountains of Bavaria to make a last stand in
the National Redoubt. But Hitler was determined to either
live or die in the capital. On 29 April, Hitler dictated his will
and political statement On 30 April 1945,, when Soviet
troops were within a block or two of the Reich Chancellery,
Hitler committed suicide, shooting himself in the temple
while simultaneously biting into a cyanide capsule. On 2
May, Berlin surrendered.
68
War was not over…
The Battle of Iwo Jima (February 19 – March 26, 1945), or
Operation Detachment, was a battle in which the United
States fought for and captured Iwo Jima from Japan. The
U.S. invasion was charged with the mission of capturing the
three airfields on Iwo Jima. The battle produced some of the
bloodiest and fiercest fighting in the Pacific Campaign of
World War II. Of the more than 18,000 Japanese soldiers
present at the beginning of the battle, only 34 were taken
prisoner. The rest were killed or were missing and assumed
dead. The lessons learned on Iwo Jima served as guidelines
for the following Battle of Okinawa and the planned invasion
of the Japanese homeland.
69
And become bitter and bitter…
The Battle of Okinawa, codenamed Operation
Iceberg,[was fought on the Ryukyu Islands of Okinawa
and was the largest amphibious assault in the Pacific War.
The 82-day-long battle lasted from early April until midJune, 1945. The battle resulted in one of the highest
number of casualties of any World War II engagement.
Japan lost over 100,000 troops, and the Allies suffered
more than 50,000 casualties. Simultaneously, more than
100,000 civilians (12,000 in action) were killed, wounded,
or committed suicide. Approximately one-quarter of the
civilian population died due to the invasion. Some military
historians believe that Okinawa led directly to the atomic
bombings of Hiroshima and Nagasaki, as a means of
avoiding the planned ground invasion of the Japanese
mainland.
70
Frank Report
The Franck Report of June 1945 was a document signed by several prominent
nuclear physicists recommending that the United States not use the atomic bomb
as a weapon to prompt the surrender of Japan in World War II. The report was
named for James Franck, the head of the committee that produced it. The
committee was appointed by Arthur Compton and met in secret, in all-night
sessions in a highly secure. The report recommended that the nuclear bomb not be
used, and proposed that either a demonstration of the "new weapon" be made
before the eyes of representatives of all of the United Nations, on a barren island or
desert, or to try to keep the existence of the nuclear bomb secret for as long as
possible. The Franck Report was signed by James Franck (Chairman), Donald J.
Hughes, J. J. Nickson, Eugene Rabinowitch, Glenn T. Seaborg, and Leo Szilard.
Franck took the report to Washington June 12,and a separate committee,
appointed by the President, met on June 21 to reexamine the use of the atomic
bomb. However this committee reaffirmed that there was no alternative to the use
of the bomb.
71
Who is James Franck?
James Franck
(B. 1882 – D. 1964) was a German physicist and Nobel
laureate . In 1920, Franck became ordinarius professor
of experimental physics and Director of the Second
Institute for Experimental Physics at the University of
Göttingen. While there he worked on quantum physics
with Max Born, who was Director of the Institute of
Theoretical Physics. In 1925, Franck received the
Nobel Prize in Physics, mostly for his work in 19121914, which included the Franck-Hertz experiment, an
important confirmation of the Bohr model of the atom.
72
A man of courage
Mention should be made of Professor Franck's courage in
following what was morally right. He was one of the first who
openly demonstrated against the issue of racial laws in Germany,
and he resigned from the University of Göttingen in 1933 as a
personal protest against the Nazi regime under Adolf Hitler.
Later, in his second homeland, his moral courage was again
evident when in 1945 (two months before Hiroshima) he joined
with a group of atomic scientists in preparing the so-called
"Franck Report" to the War Department, urging an open
demonstration of the atomic bomb in some uninhabited locality
as an alternative to the military decision to use the weapon
without warning in the war against Japan. This report, although
failing to attain its main objective, still stands as a monument to
the rejection by scientists of the use of science in works of
destruction.
73
Frank’s Medal
George Charles de Hevesy,
(B 1885 – D1966)
was a Hungarian radiochemist and Nobel
laureate, recognized in 1943 for his key role
in the development of radioactive tracers to
study chemical processes such as in the
metabolism of animals.
When Nazi Germany invaded
Denmark in World War II, the
Hungarian chemist George de
Hevesy dissolved the gold Nobel
Prizes of Max von Laue and James
Franck in aqua regia to prevent the
Nazis from stealing them. He placed
the resulting solution on a shelf in
his laboratory at the Niels Bohr
Institute. After the war, he returned
to find the solution undisturbed and
precipitated the gold out of the acid.
The Nobel Society then recast the
Nobel Prizes using the original gold.
74
Szilárd petition
The Szilárd petition, drafted by scientist Leó
Szilárd, was signed by 155 scientists working
on the Manhattan Project in Oak Ridge,
Tennessee, and the Metallurgical Lab in
Chicago, Illinois. It was circulated in July
1945 and asked President Harry S. Truman
to consider an observed demonstration of the
power of the atomic bomb first, before using it
against people. However, the petition never
made it through the chain of command to
President Truman. It also was not
declassified and made public until 1961.
75
Hiroshima, 1945.8.6
By executive order of President Harry S. Truman the
U.S. dropped the nuclear weapon "Little Boy" on the
city of Hiroshima on Monday, August 6, 1945
Before Bomb
After Bomb
76
After the bomb
According to most estimates, the immediate effects of the
blast killed approximately 70,000 people in Hiroshima.
Estimates of total deaths by the end of 1945 from burns,
radiation and related disease, the effects of which were
aggravated by lack of medical resources, range from 90,000
to 140,000. Emperor Hirohito, the government, presented a
letter of protest to the Government of the United States
through the Government of Switzerland on August 10, 1945
and the war council were considering four conditions for
surrender: the preservation of the kokutai (Imperial institution
and national polity), assumption by the Imperial Headquarters
of responsibility for disarmament and demobilization, no
occupation of the Japanese Home Islands, Korea, or
Formosa, and delegation of the punishment of war criminals
to the Japanese government.
77
Nagasaki,1945.8.9
On the morning of August 9,
1945, the U.S. B-29
Superfortress Bockscar, carried
the nuclear bomb code-named
"Fat Man", with Kokura as the
primary target and Nagasaki the
secondary target. By the time
they reached Kokura a half hour
later, a 70% cloud cover had
obscured the city, prohibiting the
visual attack required by orders.
At 11:01, the "Fat Man" weapon,
containing a core of ~6.4 kg
(14.1 lbs.) of plutonium-239, was
dropped over the city's industrial
valley.
78
Witness of Nagasaki bomb
彭明敏目睹了8月9日美軍對長崎投擲原子彈的歷史事件。
原子彈爆炸的後果，實在難以描寫。有些水泥建築物仍屹立著，但是，裡面所有木
料和其他易燃物都在頃刻間化為烏有。據說在學校教室內，從整齊排列的白灰燼所
在可以看出在死亡瞬間正坐在書桌旁的每一個學生。熱度竟有那樣強烈。大部分的
醫科學生都罹難，其中包括四位曾經慷慨輸血給我的台灣留學生。他們有用的生命
被消滅，我卻仍活著，這真是悲劇的命運。
79
Japan surrender (August,1945)
Hirohito recorded on August 14 his capitulation
announcement which was broadcast to the Japanese
nation the next day despite a short rebellion by militarists
opposed to the surrender.In his declaration, Hirohito
referred to the atomic bombings:
Moreover, the enemy now possesses a new and terrible
weapon with the power to destroy many innocent lives
and do incalculable damage. Should we continue to fight,
not only would it result in an ultimate collapse and
obliteration of the Japanese nation, but also it would lead
to the total extinction of human civilization.
Such being the case, how are We to save the millions of
Our subjects, or to atone Ourselves before the hallowed
spirits of Our Imperial Ancestors? This is the reason why
We have ordered the acceptance of the provisions of the
Joint Declaration of the Powers.
80
Regret of Einstein
The atomic bombings of Japan occurred three months after the surrender of
Germany, whose potential for creating a Nazi a-bomb had led Einstein to push for
the development of an a-bomb for the Allies. Einstein withheld public comment on
the atomic bombing of Japan until a year afterward. A short article on the front page
of the New York Times contained his view: "Prof. Albert Einstein... said that he was
sure that President Roosevelt would have forbidden the atomic bombing of
Hiroshima had he been alive and that it was probably carried out to end the Pacific
war before Russia could participate." Einstein later wrote, "I have always
condemned the use of the atomic bomb against Japan." In November 1954, five
months before his death, Einstein summarized his feelings about his role in the
creation of the atomic bomb: "I made one great mistake in my life... when I signed
the letter to President Roosevelt recommending that atom bombs be made; but
there was some justification - the danger that the Germans would make them."
81
Hydrogen Bomb
The idea of a thermonuclear fusion bomb ignited by a
smaller fission bomb was first proposed by Enrico Fermi
to his colleague Edward Teller in 1941 at the start of what
would become the Manhattan Project. Stanislaw Ulam, a
coworker of Teller's, made the first key conceptual leaps
towards a workable fusion design. Ulam's two innovations
were that compression of the thermonuclear fuel before
extreme heating was a practical path towards the
conditions needed for fusion, and the idea of staging or
placing a separate thermonuclear component outside a
fission primary component, and somehow using the
primary to compress the secondary. Teller then realized
that the gamma and X-ray radiation produced in the
primary could transfer enough energy into the secondary
to create a successful implosion and fusion burn.
82
Ivy Mike
The 10.4 Mt "Ivy Mike" shot of
1952 appeared to vindicate
Teller's long-time advocacy for
the hydrogen bomb.
Following the Soviet Union's first test
detonation of an atomic bomb in 1949,
President Truman announced a crash
development program for a hydrogen bomb.
On November 1, 1952, the Teller–Ulam
configuration was tested at full scale in the
"Ivy Mike" shot at an island in the Enewetak
Atoll, with a yield of 10.4 megatons (over
450 times more powerful than the bomb
dropped on Nagasaki during World War II).
The device, dubbed the Sausage, used an
extra-large fission bomb as a "trigger" and
liquid deuterium—kept in its liquid state by
20 short tons (18 metric tons) of cryogenic
equipment—as its fusion fuel, and weighed
around 80 short tons (70 metric tons)
altogether.
83
Who is Edward Teller
Edward Teller (B. 1908 – D. 2003) was a Hungarianborn American theoretical physicist, known colloquially
as "the father of the hydrogen bomb," In his later years
he became especially known for his advocacy of
controversial technological solutions to both military and
civilian problems, including a plan to excavate an
artificial harbor in Alaska using thermonuclear
explosives. He was a vigorous advocate of Ronald
Reagan's Strategic Defense Initiative, perhaps
overselling the feasibility of the program. Over the
course of his life, Teller was known both for his scientific
ability and his difficult interpersonal relations and volatile
personality, and is considered one of the inspirations for
the character Dr. Strangelove in the 1964 movie of the
same name.
84
Oppenheimer Controversy
December 1953, partly as the result of evidence
provided by the U.S. Army's Signals Intelligence
Service, Oppenheimer was accused of being a
security risk, and President Dwight D. Eisenhower
asked him to resign. Oppenheimer refused and
requested a hearing to assess his loyalty. The public
hearing that followed in April-May 1954 focused on
Oppenheimer's past Communist ties and his
association during the Manhattan Project with
suspected disloyal or Communist scientists.
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Oppenheimer Controversy
Teller detailed ways in which he felt that Oppenheimer
had hindered his efforts towards an active
thermonuclear development program, and at length
criticized Oppenheimer's decisions not to invest more
work onto the question at different points in his career,
saying:
If it is a question of wisdom and judgment, as
demonstrated by actions since 1945, then I would
say one would be wiser not to grant clearanc
After a public hearing, the authorities agreed with
Teller. Oppenheimer's security clearance was
eventually stripped. After the Oppenheimer
controversy, Teller became ostracized by much of
the scientific community, Nobel Prize winning
physicist Isidor I. Rabi once suggested that "It
would have been a better world without Teller”.
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War in the shadow of bombs
A photograph of Operation
Castle thermonuclear test,
Castle Romeo shot
The liquid deuterium fuel of Ivy Mike was
impractical for a deployable weapon, and the next
advance was to use a solid lithium deuteride
fusion fuel instead. In 1954 this was tested in the
"Castle Bravo" shot (the device was code-named
the Shrimp), which had a yield of 15 megatons
(2.5 times higher than expected) and is the
largest U.S. bomb ever tested. In the Soviet
Union, the design was known as Andrei
Sakharov's "Third Idea," first tested in 1955.
Similar devices were developed by the United
Kingdom, China, and France, though no specific
code names are known for their designs.
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Hahn as Peace Maker
Immediately after the Second World War, Hahn reacted to the dropping of the atomic
bombs on Hiroshima and Nagasaki by coming out strongly against the use of nuclear
energy for military purposes. He saw the application of his scientific discoveries to
such ends as a misuse, or even a crime. Consequently, he initiated the Mainau
Declaration of 1955, in which a large number of Nobel Prize-winners called attention
to the dangers of atomic weapons and warned the nations of the world urgently
against the use of "force as a final resort". He was also instrumental and one of the
authors of the Göttingen Manifesto of 1957, in which, together with 17 leading
German atomic scientists, he protested against a proposed nuclear arming of the
new West German armed forces . In January 1958, Otto Hahn signed the Pauling
Appeal to the United Nations for the "immediate conclusion of an international
agreement to stop the testing of nuclear weapons". Right up to his death, he never
tired of warning urgently of the dangers of the nuclear arms race between the great
powers and of the radioactive contamination of the planet. From 1957, Hahn was
repeatedly nominated for the Nobel Peace Prize by a number of organizations.
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