On 2nd
August, 1939, three Jewish scientists who
had fled to the United States from Europe, Albert
Einstein, Leo
Szilard
and Eugene Wigner, wrote a joint letter
to President Franklin D. Roosevelt,
about the developments that had been taking place in nuclear physics.
They warned Roosevelt that scientists in Nazi
Germany were working on the possibility of using uranium to produce
nuclear weapons. Roosevelt
responded by setting up a scientific advisory committee to investigate
the matter. He also had talks with the British government about ways
of sabotaging the German efforts to produce nuclear weapons.
In May,
1940, the German
Army invaded
Denmark, the home of Niels
Bohr, the world's leading expert on atomic research. It was feared
that he would be forced to work for Nazi
Germany. With the help of the British Secret Service he escaped
to Sweden before being moving to the United
States.
In 1942
the Manhattan Engineer Project was set up in the United States under
the command of Brigadier General Leslie Groves.
Scientists recruited to produce an atom bomb
included Robert
Oppenheimer (USA),
David Bohm (USA), Leo
Szilard
(Hungary), Eugene Wigner (Hungary), Rudolf
Peierls
(Germany), Otto
Frisch
(Germany), Niels Bohr (Denmark), Felix
Bloch
(Switzerland), James Franck (Germany),
James Chadwick
(Britain), Emilio
Segre
(Italy), Enrico Fermi (Italy), Klaus
Fuchs (Germany) and Edward
Teller (Hungary).
Winston
Churchill and Franklin D. Roosevelt
were deeply concerned about the possibility that Germany would produce
the atom bomb before the allies. At a conference held in Quebec in
August, 1943, it was decided to try and disrupt the German nuclear
programme.
In February
1943, SOE saboteurs successfully planted
a bomb in the Rjukan nitrates factory in Norway.
As soon as it was rebuilt it was destroyed by 150 US bombers in November,
1943. Two months later the Norwegian resistance managed to sink a
German boat carrying vital supplies for its nuclear programme.
Meanwhile
the scientists working on the Manhattan Project were developing atom
bombs using uranium and plutonium. The first three completed bombs
were successfully tested at Alamogordo, New Mexico on 16th July, 1945.
By the
time the atom bomb was ready to be used Germany
had surrendered. Leo
Szilard
and James
Franck
drafted a petition signed by just under 70 scientists opposed to the
use of the bomb on moral grounds. However, the advice was ignored
by Harry S. Truman,
the USA's new president, and he decided to use the bomb on Japan.
On 6th
August 1945, a B29 bomber dropped an atom bomb on Hiroshima.
It has been estimated that over the years around 200,000 people have
died as a result of this bomb being dropped. Japan did not surrender
immediately and a second bomb was dropped on Nagasaki
three days later. On 10th August the Japanese surrendered. The Second
World War was over.
(1)
Lise Meitner and Otto
Frisch, Uranium Fission (1938)
From chemical evidence, Hahn and Strassmann conclude that radioactive
barium nuclei (atom number Z = 56) are produced when uranium (Z =
92) is bombarded by neutrons. It has been pointed out that this might
be explained as a result of a "fission" of the uranium nucleus,
similar to the division of a droplet into two. The energy liberated
in such processes was estimated to be about 200 Mev, both from mass
defect considerations and from the repulsion of the two nuclei resulting
from the "fission" process.
If this
picture is correct, one would expect fast-moving nuclei of atomic
number 40 to 50 and atomic weight 100 to 150, and up to 100 Mev energy,
to emerge from a layer of uranium bombarded with neutrons. In spite
of their high energy, these nuclei should have a range in air of a
few millimeters only, on account of their high effective charge (estimated
to be about 20), which implies very dense ionization. Each such particle
should produce a total of about 3 million ion pairs.
By means
of a uranium-lined ionization chamber, connected to a linear amplifier,
I have succeeded in demonstrating the occurrence of such bursts of
ionization. The amplifier was connected to a thyratron which was biased
so as to count only pulses corresponding to at least 5 x 105 ion pairs.
About 15 particles per minute were recorded when 300 milligram of
radium, mixed with beryllium, was placed one centimeter from the uranium
lining. No pulses at all were recorded during repeated check runs
of several hours total duration when either the neutron source or
the uranium lining was removed. With the neutron source at a distance
of four centimeters from the uranium lining, surrounding the source
with paraffin wax enhanced the effect by a factor of two.
It was
checked that the number of pulses depended linearly on the strength
of the neutron source; this was done in order to exclude the possibility
that the pulses are produced by accidental summation of smaller pulses.
When the amplifier was connected to an oscillograph, the large pulses
could be seen very distinctly on the background of much smaller pulses
due to the alpha particles of uranium.
By varying
the bias of the thyratron, the maximum size of pulses was found to
correspond to at least 2 million ion pairs, or an energy loss of 70
Mev of the particle within the chamber. Since the longest path of
a particle in the chamber was 3 centimeters, and the chamber was filled
with hydrogen at atmospheric pressure, the particles must ionize so
heavily that they can make 2 million ion pairs on a path equivalent
to 0.8 cm of air or less. From this it can be estimated that the ionizing
particles must have an atomic weight of at least about seventy, assuming
a reasonable connection between atomic weight and effective charge.
This seems to be conclusive physical evidence for the breaking up
of uranium nuclei into parts of comparable size, as indicated by the
experiments of Hahn and Strassmann.
Experiments
with thorium instead of uranium gave quite similar results, except
that surrounding the neutron source with paraffin did not enhance,
but slightly diminished the effect. This gives evidence in favor of
the suggestion that also in the case of thorium some, if not all of
the activities produced by neutron bombardment, should be ascribed
to light elements. It should be remembered that no enhancement by
paraffin has been found for the activities produced in thorium, except
for one which is isotopic with thorium and is almost certainly produced
by simple capture of the neutron.
Meitner
has suggested another interesting experiment. If a metal plate is
placed close to a uranium layer bombarded with neutrons, one would
expect an active deposit of the light atoms emitted in the "fission"
of the uranium to form on the plate. We hope to carry out such experiments,
using the powerful source of neutrons which our high-tension apparatus
will soon be able to provide.
(2)
On 2nd August, 1939, three Jewish scientist, Albert
Einstein, Leo Szilard and Eugene
Wigner, who had fled Nazi persecution in Europe, wrote a joint
letter to President Franklin D. Roosevelt,
about the developments that had been taking place in nuclear physics.
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 radium-like 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 or exploded in a port, might well destroy the whole
port together with some of the surrounding territory. However, such
bombs might well prove to be too heavy for transportation by air.
(3)
Niels Bohr, letter to President Franklin
D. Roosevelt (3rd July, 1944)
A weapon of an unparalleled power is being created which will
completely change all future conditions of warfare. Unless some agreement
about the control of the use of the new active materials can be obtained
in due time, any temporary advantage, however great, may be outweighed
by a perpetual menace to human security. An initiative, aiming at
forestalling a fateful competition, should serve to uproot any cause
of distrust between the powers of whose harmonious collaboration the
fate of coming generations will depend.
(4)
Robert Oppenheimer, interviewed for
a BBC television documentary, The Building of the Bomb, in
1965.
We
were a true community of people working toward a common goal. I think
that irrespective of what was done with it, irrespective of what was
to come of it, it was clear that this was a very major change in the
human situation, and the people were playing a part in history. We
started out by thinking that it might make the difference between
defeat and victory, and ended by thinking that it might make a difference
between a world periodically convulsed by increasingly ferocious global
wars and a world in which there will be none.
(5)
Jim Tuck, a physical chemist at Manchester University joined the Manhattan
Project. He was interviewed for a BBC television documentary, The
Building of the Bomb, in 1965.
It had all the
greatest scientists of the Western World, and something
I'd never known before: they didn't care who you were, or what
you were. All they cared-about was what you could contribute
and what you had in the way of ideas. This was new to me.
I met scientists I would never have expected to have seen in my
whole life before.
(6)
Philip Morrison, a scientist, worked on the Manhattan
Project
at Alamogordo, New Mexico.
Studs Terkel interviewed Morrison
about his experiences during the Second World War
for his book, The Good War (1985)
We spent a lot of time
and risked a lot of lives to do so. Of my little group of eight, two
were killed. We were using high explosives and radioactive material
in large quantities for the first time. There was a series of events
that rocked us. We were working hard, day and night, to do something
that had never been done before. It might not work at all. I
remember working late one night with my friend Louis Slotin. He was
killed by a radiation accident. We shared the job. It could
have been I. But it was he, who was there that day.
James Franck, a truly wonderful
man, produced the Franck Report: Don't drop the bomb on a city. Drop
it as a demonstration and offer a warning. This was about a month
before Hiroshima. The movement against the bomb was beginning among
the physicists, but with little hope. It was strong at Chicago, but
it didn't affect Los Alamos.
We heard the news of Hiroshima
from the airplane itself, a coded message. When they returned, we
didn't see them. The generals had them. But then the people came back
with photographs. I remember looking at them with awe and terror.
We knew a terrible thing had been unleashed. The men had a great party
that night to celebrate, but we didn't go. Almost no physicists went
to it. We obviously killed a hundred thousand people and that was
nothing to have a party about.
The reality confronts you with things you could never anticipate.
Before I went to Wendover,
an English physicist. Bill Penney, held a seminar five days after
the test at Los Alamos. He applied his calculations. He predicted
that this would reduce a city of three or four hundred thousand people
to nothing but a sink for disaster relief, bandages, and hospitals.
He made it absolutely clear in numbers. It was reality. We knew it,
but we didn't see it. As soon as the bombs were dropped, the scientists,
with few exceptions, felt the time had come to end all wars.
(7)
Robert Wilson, a member of the Manhattan Project team, suggested that
the Allies should demonstrate the power of the atom bomb to a group
of Japanese observers. He explained his views in a letter to R. W.
Reid, the author of Tongues of Conscience (1970)
I made the suggestion
fully aware-of the difference between a first use of a new weapon
in which the blood of hundreds of thousands of men, women, and children
would be on our hands, and of the dreadful precedent that would thereby
be set - and that of illegally retaining, even executing, if you will,
a few men. I realised by the dramatic character of the statement how
far I had departed from the gentle pacifist of my student days. My
regret in retrospect is not for the savagery of the remark, but rather
that I did not use more forceful arguments with Oppenheimer in order
to influence him to take
more seriously my suggestion that some kind of a demonstration be
made instead of the actual use.
(8)
James
Franck
was
against dropping the atom bomb on Japan. He sent his views to President
Harry
S. Truman
on
11th June, 1945.
The military advantages
and the saving of American lives achieved
by the sudden use of atomic bombs against Japan may be
outweighed by the ensuing loss of confidence and by a wave of horror
and repulsion sweeping over the rest of the world and perhaps
even dividing public opinion at home.
From this point of view,
a demonstration of the new weapon might best be made, before the yes
of representatives of all the United Nations, on the desert or a barren
island. The best possible atmosphere for the achievement of an international
agreement could be achieved if America could say to the world, "You
see what sort of a weapon we
had but did not use. We are ready to renounce its use in the future
if other nations join us-in this renunciation and agree to the establishment
of an efficient international control.
(9)
Henry
L. Stimson, The
Decision to Use the Atom Bomb, Harper's
Magazine
(February, 1947)
The opinions of our scientific
colleagues on the initial use of these weapons
are not unanimous: they range from the proposal of a purely
technical demonstration to that of the military application best
designed to induce surrender. Those who advocate a purely technical
demonstration would wish to outlaw the use of atomic weapons,
and have feared that if we use the weapons now our position
in future negotiations will be prejudiced. Others emphasise
the opportunity of saving American lives by immediate military
use, and believe that such use will improve the international
prospects, in that they are more concerned with the prevention
of war than with the elimination of this special weapon. We
find ourselves closer to these latter views; we can propose no technical
demonstration likely to bring an end to the war; we see no acceptable
alternative to direct military use.
With regard to these general
aspects of the use of atomic energy, it
is clear that we, as scientific men, have no proprietary rights. It
is true that we are among the few citizens who have had occasion to
give thoughtful consideration to the problems during the past few
years. We have, however, no claim to special competence in solving
the political, social, and military problems which are presented
by the advent of atomic power.
(10)
Harry
S. Truman,
Year of Decisions (1955)
The task of creating the atomic bomb had been entrusted to a
special unit of the Army Corps of Engineers, the so-called Manhattan
District, headed by Major General Leslie R. Groves. The primary effort,
however, had come from British and American scientists, working in
laboratories and offices scattered throughout the nation.
Dr. J. Robert Oppenheimer,
the distinguished physicist from the University of California, had
set up the key establishment in the whole process at Los Alamos, New
Mexico. More than any other one man, Oppenheimer is to be credited
with the achievement of the completed bomb.
My own knowledge of these
developments had come about only after I became President, when Secretary
Stimson had given me the full story. He had told me at that time that
the project was nearing completion and that a bomb could be expected
within another four months. It was at his suggestion, too, that I
had then set up a committee of top men and had asked them to study
with great care the implications the new weapon might have for us.
At
Potsdam, as elsewhere, the secret of the atomic bomb was kept closely
guarded. We did not extend the very small circle of Americans who
knew about it. Churchill naturally knew about the atomic bomb project
from its very beginning, because it had involved the pooling of British
and American technical skill.
On July 24th I casually
mentioned to Stalin that we had a new weapon of special destructive
force. The Russian Premier showed no unusual interest. All he said
was that he was glad to hear it and hoped we would make "good
use of it against the Japanese".
The final decision of
where and when to use the atomic bomb was up
to me. Let there be no mistake about it. I regarded the bomb as
a military weapon and never had any doubt that it should be used.
(11)
General Dwight Eisenhower, the Supreme
Allied Commander, told President Harry S.
Truman that he was opposed to the dropping of the atom bomb on
Japan.
I voiced to him my grave misgivings, first on the basis of my
belief that Japan was already defeated and that dropping the bomb
was completely unnecessary, and secondly because I thought that our
country should avoid shocking world opinion by the use of a weapon
whose employment was, I thought, no longer mandatory as a measure
to save American lives. It was my belief that Japan was, at that very
moment, seeking some way to surrender with a minimum loss of "face".
(12)
William
Leahy, chief of staff to the commander in chief of
the United States, was opposed to the dropping of the atom bomb on
Japan. He wrote about this in his
autobiography, I Was There (1950)
Once it
had been tested, President Truman faced the decision as to whether
to use it. He did not like the idea, but was persuaded that it would
shorten the war against Japan and save American lives. It is my opinion
that the use of this barbarous weapon at Hiroshima and Nagasaki was
of no material assistance in our war against Japan. The Japanese were
already defeated and ready to surrender because of the effective sea
blockade and the successful bombing with conventional weapons.
It was
my reaction that the scientists and others wanted to make this test
because of the vast sums that had been spent on the project. Truman
knew that, and so did the other people involved. However, the Chief
Executive made a decision to use the bomb on two cities in Japan.
We had only produced two bombs at that time. We did not know which
cities would be the targets, but the President specified that the
bombs should be used against military facilities.
The lethal
possibilities of atomic warfare in the future are frightening. My
own feeling was that, in being the first to use it, we had adopted
an ethical standard common to the barbarians of the Dark Ages. I was
not taught to make war in that fashion, and wars cannot be won by
destroying women and children. We were the first to have this weapon
in our possession, and the first to use it. There is a practical certainty
that potential enemies will develop it in the future and that atomic
bombs will some time be used against us.
(13)
Edward
Teller was
interviewed for a BBC television documentary, The Building of the
Bomb, in 1965.
If we had made
a demonstration and that had failed, then I think dropping the bomb
would have been justified in order to end the war. To drop it without
warning was wrong. It was wrong on moral grounds - it killed; it was
wrong, although I could not see that at the time, on practical grounds
because the dropping of the bomb has distorted our views, has changed
our whole outlook. We are not now looking on the accomplishment of
atomic explosions as progress which can, and should, be used in the
right way. We had started at that time to look at it as something
horrible, something that should not be continued.
(14)
Harold Agnew was a physicist working on the Manhattan Project. He
was interviewed for a BBC television documentary, The Building
of the Bomb, in 1965.
I think it was
right to drop the bombs because I believe that the dropping of these
bombs brought the war to a close much quicker than would have been
possible otherwise. I think if people who now debate this question
had seen the preparations which we were making for evacuating the
wounded, the hospital preparations and everything, anticipating an
actual landing, that they would have realised that we actually saved
lives: not only our own soldiers' lives, but the lives of the Japanese,
because had we been forced to actually attempt to occupy the island
I think the death
toll would have been tremendous.
(15)
Henry Stimson, Secretary of War, letter
to President Harry S. Truman
(11th September, 1945)
The chief lesson I have learned in a long life is that the only way
you can make a man trustworthy is to trust him; and the surest way
to make him untrustworthy is to distrust him. If the atomic bomb were
merely another, though more devastating, military weapon to be assimilated
into our pattern of international relations, it would be one thing.
We would then follow the old custom of secrecy and nationalistic military
superiority relying on international caution to prescribe the future
use of the weapon as we did with gas. But I think the bomb instead
constitutes merely a first step in a new control by man over the forces
of nature too revolutionary and dangerous to fit into old concepts.
My idea of an approach to the Soviets would be a direct proposal after
discussion with the British that we would be prepared in effect to
enter an agreement with the Russians, the general purpose of which
would be to control and limit the use of the atomic bomb as an instrument
of war.
(16)
Freda Kirchwey, The
Nation (18th August, 1945)
The bomb that hurried Russia into Far Eastern war a week ahead of
schedule and drove Japan to surrender has accomplished the specific
job for which it was created. From the point of view of military strategy,
$2,000,000,000 (the cost of the bomb and the cost of nine days of
war) was never better spent. The suffering, the wholesale slaughter
it entailed, have been outweighed by its spectacular success; Allied
leaders can rightly claim that the loss of life on both sides would
have been many times greater if the atomic bomb had not been used
and Japan had gone on fighting. There is no answer to this argument.
The danger is that it will encourage those in power to assume that,
once accepted as valid, the argument can be applied equally well in
the future. If that assumption should be permitted, the chance of
saving civilization - perhaps the world itself - from destruction
is a remote one.
Last
updated: 4th September, 2002
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