Upload
fergal
View
51
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Assessing the Decision to Build and Use the Atomic Bomb. Col. Paul W. Tibbets, Jr., pilot of the Enola Gay , the plane that dropped the atomic bomb on Hiroshima, waves from his cockpit before takeoff. Albert Einstein. Whether to Build an Atomic Bomb. - PowerPoint PPT Presentation
Citation preview
Assessing the Decision to Build and Use the Atomic Bomb
Col. Paul W. Tibbets, Jr., pilot of the Enola Gay, the plane that dropped the atomic bomb on Hiroshima, waves from his cockpit before takeoff.
Albert Einstein
Whether to Build an Atomic BombIn August 1939, FDR received a letter from Albert Einstein. He alerted FDR
that Germany might be building an atomic bomb. When Einstein wrote
this letter to Roosevelt, the US was not yet at war with Germany. However,
FDR took interest in the developments described in the letter. The bomb
would not only be the most powerful weapon on earth, it would transform warfare by making it possible to kill
more people with less effort.
In the 18 months following Einstein’s letter, members of the Roosevelt administration debated what action should be taken to
counter the German threat. Some officials wondered how serious the threat really
was. In addition, not all scientists agreed with Einstein. In fact, two Nobel Prize-
winning nuclear physicists, Enrico Fermi and Niels Bohr, believed that the
construction of an atomic bomb was a practical improbability.
Critical Thinking Question 1
You are an advisor to President Roosevelt. Which of the
following do you advise the president to do? Explain why.
A: Ignore scientific developments and do not
build an atomic bomb; concentrate U.S. efforts on
building conventional weapons, such as faster
planes and more powerful tanks.
B: Vigorously pursue the construction of an atomic bomb because the United
States is in a race against the Germans.
C: Postpone the development of an atomic bomb and send
spies into Germany to determine the accuracy of
Einstein’s letter.
D: Do not develop the bomb. Instead, monitor the
construction of new German weapon facilities and then send American bombers to
destroy them.
E: Denounce the development of atomic bombs as immoral.
Only evil could come from their development.
Question 1: Actual Decision• 1939 – FDR supported bomb research;
discovered a bomb could be built in two years
• Manhattan Project – code name for top secret project – Led by Robert Oppenheimer – 100,000 people involved – cost $2 billion – Fermi and Bohr major players in development
• No formal agreement; just understood that any weapon developed would be used to end war quickly
J. Robert Oppenheimer
How the Bomb WorkedA sphere of U-235 is made around the neutron
generator and a small bullet of U-235 is removed. The bullet is placed at the one end of a long tube with
explosives behind it, while the sphere is placed at the other end. A barometric-pressure sensor determines
the appropriate altitude for detonation and triggers the following sequence of events:
1.The explosives fire and propel the bullet down the barrel.
2.The bullet strikes the sphere and generator, initiating the fission reaction.
3.The fission reaction begins. 4.The bomb explodes.
Simulation: How the “Little Boy” bomb workedhttp://people.howstuffworks.com/nuclear-bomb5.htm
How the Bomb Worked, Con’t.Scientists recognized that compressing the
subcritical masses together into a sphere might be a good way to make a supercritical mass. There were problems with this idea. But the
Manhattan Project team solved the problems. When the bomb was detonated, this is what
happened: 1. The explosives fired, creating a shock wave. 2. The shock wave compressed the core. 3. The fission reaction began. 4. The bomb exploded.
Simulation: How the “Fat Man” bomb workedhttp://people.howstuffworks.com/nuclear-bomb6.htm
Workers with the Manhattan Engineer District gently carry the plutonium core for the world's first atomic bomb into the
McDonald Ranch house for assembly, July 12, 1945
A member of the Manhattan Project's Special Engineering
Detachment holds the assembled plutonium core for the world's
first atomic bomb in a special shock-
absorbing case on July 12, 1945. The core was
about the size of an orange and weighed
13.5 pounds.
Physicists Norris Bradbury and Boyce McDaniel stand at the top of a 100 foot tower after helping to assemble the world's first atomic bomb on July 15, 1945, one day before the Trinity test.
The device was nicknamed the "Gadget."
Photo of Trinity test site - Ten seconds after detonation
Oppenheimer and Leslie Groves inspect the tower.
Facts about the Bomb’s Test• Before dawn – July 16, 1945 – “gadget”
tested• Fireball so bright – blind girl saw flash• Cloud rose eight miles into the sky• Force so strong windows shattered in
buildings 125 miles away• Crater left in Earth was 1,200-foot-wide• People were told an ammunition dump
exploded• The sand directly under the tower got so
hot that it turned to glass
More Facts about the Bomb’s Test• The explosion was equal to 20,000 tons of
TNT• Half mile from the blast: everything was either
vaporized or burned beyond recognition• One Mile from the blast: all buildings above
ground were destroyed• Two miles: structures collapsed and rivers
flowed the wrong way • Three miles away: buildings sustained severe
fire and wind damage, people would have suffered second and third degree burns, if they were lucky
Revelation 6:12
And I beheld when he had opened the sixth seal, and, lo, there was a
great earthquake; and the sun became black as sackcloth of hair, and the moon became as
blood.
Harry S. Truman
Vice-president Harry S. Truman taking the oath of office after the death of FDR. Not until nearly two weeks after he was sworn in was he told about
the existence of the atomic bomb.
Whether to Drop an Atomic BombVice President Harry S. Truman became
president after Roosevelt unexpectedly died in April 1945. While attending an Allied
conference in Potsdam, Germany, three months later, Truman received a telegram
stating that the test of the atomic bomb had been successful. By this time in the war,
Germany had been utterly defeated. However, Japan had vowed to fight on, despite the Allies’
demand at Potsdam for an unconditional surrender. The Japanese felt that an
unconditional surrender would jeopardize the position of their emperor, whom they
considered divine (Godlike).
In addition, the Japanese viewed surrender as dishonorable. They fought with fanatic
resistance and believed it was more honorable to commit suicide than to surrender to enemy forces. In this vein, Japanese kamikaze pilots strapped themselves into planes loaded with explosives and crashed them into American naval vessels. They managed to destroy 53 ships and damage 158 others. The US had
hoped to end the Pacific War by invading the home islands of Japan. However, in the face of
Japanese fanaticism, Truman was deeply concerned that such an invasion would cost
tens of thousands of American lives.
In light of this concern, some of Truman’s advisors recommended that he end the war quickly by dropping a bomb without warning
on a large Japanese city. The undersecretary of the navy, Ralph Bard, disagreed and told Truman that dropping the bomb without a
specific warning would jeopardize “the position of the US as a great humanitarian
nation.” A group of scientists from the bomb project suggested that the US drop the bomb in a remote, unpopulated location to show the
bomb’s power and convince Japan to surrender.
Critical Thinking Question 2
You are a close advisor to President Truman. Which of the
following do you advise the president to do? Explain why.
A: Without warning, drop an atomic bomb on a Japanese
city as soon as possible.
B: Drop the bomb on an unpopulated area to
demonstrate its destructive capabilities.
C: Warn the Japanese that the United States possesses
atomic weapons and is willing to use them if they don’t
surrender in a specified time. If they don’t surrender, then
drop the bomb.
D: Reject the use of atomic weapons, and continue the
naval blockade and conventional bombing. If the measures do not produce a Japanese surrender, invade
Japan.
E: Reject the use of atomic weapons and negotiate an
end to World War II, allowing the Japanese to surrender
with their emperor as a part of the postwar government.
Question 2: Actual Decision• August 6, 1945 – Enola Gay dropped bomb
on Hiroshima; 100,000 people killed
• August 9, 1945 – bomb dropped on Nagasaki; 70,000 people killed
• Japan surrendered 5 days later
• Truman defended his decision by saying it saved the lives of thousands of American soldiers
Leaflets dropped on cities in Japan - c. August 6, 1945TO THE JAPANESE PEOPLE:America asks that you take immediate heed of what we say on this
leaflet.We are in possession of the most destructive explosive ever devised
by man. A single one of our newly developed atomic bombs is actually the equivalent in explosive power to what 2000 of our giant B-29s can carry on a single mission. This awful fact is one for you to ponder and we solemnly assure you it is grimly accurate.
We have just begun to use this weapon against your homeland. If you still have any doubt, make inquiry as to what happened to Hiroshima when just one atomic bomb fell on that city.
Before using this bomb to destroy every resource of the military by which they are prolonging this useless war, we ask that you now petition the Emperor to end the war. Our president has outlined for you the thirteen consequences of an honorable surrender. We urge that you accept these consequences and begin the work of building a new, better and peace-loving Japan.
You should take steps now to cease military resistance. Otherwise, we shall resolutely employ this bomb and all our other superior weapons to promptly and forcefully end the war.
EVACUATE YOUR CITIES.
ATTENTION JAPANESE PEOPLE. EVACUATE YOUR CITIES.Because your military leaders have rejected the thirteen part surrender
declaration, two momentous events have occurred in the last few days. The Soviet Union, because of this rejection on the part of the military has
notified your Ambassador Sato that it has declared war on your nation. Thus, all powerful countries of the world are now at war with you.
Also, because of your leaders' refusal to accept the surrender declaration that would enable Japan to honorably end this useless war, we have employed our atomic bomb.
A single one of our newly developed atomic bombs is actually the equivalent in explosive power to what 2000 of our giant B-29s could have carried on a single mission. Radio Tokyo has told you that with the first use of this weapon of total destruction, Hiroshima was virtually destroyed.
Before we use this bomb again and again to destroy every resource of the military by which they are prolonging this useless war, petition the emperor now to end the war. Our president has outlined for you the thirteen consequences of an honorable surrender. We urge that you accept these consequences and begin the work of building a new, better, and peace-loving Japan.
Act at once or we shall resolutely employ this bomb and all our other superior weapons to promptly and forcefully end the war.
EVACUATE YOUR CITIES.
Hiroshima, August 6, 1945
Nagasaki, August 9, 1945
Facts about the Bomb in Japan• Temperature at the center of blast – 100
million degrees
• People at the center vaporized – remains left shadows on pavement and walls
• Skin was seen peeling and hanging off of bodies
• Many died of radiation poisoning – lost their hair, vomited blood, then died
Whether Truman Made the Right DecisionImmediately following the dropping of the two atomic bombs on Japan, the majority of Americans felt the right
decision had been made. Surveys conducted by Fortune magazine in the fall of 1945 revealed that over 50% of Americans believed that the US “should have used the two bombs on cities just as we did.” Another
22.7% felt the US “should have quickly used many more before Japan had the chance to surrender.” American soldiers also supported Truman’s decision. One young
soldier stated: “When the bombs were dropped and news began to circulate that the invasion would not take place after all, that we would not be obliged to run up the beaches near Tokyo assault-firing while being mortared
and shelled…we cried with relief and joy. We were going to live. We were going to grow up to adulthood
after all.”
Many officials in the top ranks of the military and government supported Truman’s decision to
drop the atomic bombs. However, others expressed doubts. Admiral William D. Leahy
stated: “It is my opinion that the use of the barbarous weapon was of no material
assistance in our war against Japan. The Japanese were all ready defeated and ready to
surrender because of the effective sea blockade and the successful bombing with
conventional weapons. My own feeling was that being the first to use the bomb, we adopted an ethical standard common to the barbarians
of the Dark Ages.”
Dwight D. Eisenhower, a general with enormous prestige, expressed the hope that the US would
never have to use such a weapon against an enemy again because he disliked seeing the
country “initiate the use of anything so horrible and destructive.” Some historians have severely criticized Truman’s decision. They argue that the
Japanese were all ready defeated in August 1945, and that the atomic bombs were used primarily as a warning to the Soviet Union.
Although they were allies during WWII, the US and the USSR had very different visions for the
postwar world.
Historians critical of Truman’s decision argue that he authorized the use of the atomic bombs mainly to scare the Soviets out of Eastern
Europe and to keep them from gaining more territory in Asia. To these historians, the citizens of Hiroshima and Nagasaki were
sacrificed in a high-stakes poker game between two superpowers. They also argue that the
postwar nuclear arms race can be traced back to the fear and mistrust created by Truman’s decision. Other historians counter that the
military pressures Truman was under at the end of WWII played a much more important role in
his decision than the threat of Soviet aggression.
Critical Thinking Question 3
Truman’s decision to use atomic weapons against Japan is one of
the most controversial in history. In retrospect, do you think Truman
made the right decision in authorizing the use of atomic
weapons? Explain why.
A: Truman did not make the right decision when he
authorized the use of atomic weapons.
B: Truman made the right decision when he authorized the use of atomic weapons.
Question 3: The Debate Continues
• Truman defended his decision to his death.
• J. Robert Oppenheimer, the lead scientist of the Manhattan Project, said: “I am death, the destroyer of worlds.”
• Albert Einstein regretted ever writing FDR.
• By 1990 – approximately 100,000 nuclear weapons in existence
“Fat Man” and “Little Boy”
Located just under the hypocenter, only the dome-shaped framework and part of the outer wall remained. It
has come to be called "the A-bomb Dome."
August 6. 1945. This is one of six photographs recording the disaster of Hiroshima.
The cause of keloids is not clear yet, but it is considered to be caused by a combination of
powerful heat rays and radiation.
The dark portion of the pattern of the clothing was imprinted on the skin by the powerful heat rays.
A person sat down on the steps facing the direction of the hypocenter, possibly waiting for the bank to open. By a flash of
the heat rays, that person was incinerated on the stone steps.
A woman who was exposed to the A-bomb less than 2 kilometers from the hypocenter, judging by the
extent of the burns on her entire back.
Close to the hypocenter, victims were burned to death in their last gesture grasping at the air or trying
to escape.
This boy had thermal burns on more than one-third of his body. He miraculously recovered.
A child crying from the pain of having a gauze dressing changed. He suffered third-degree burns that exposed
the bone.
A view of Nagasaki after the explosion
A shadow made by the heat rays. This place is about 800 meters from the hypocenter. The unshielded asphalt surface was scorched, and the surface shielded by the handrail is a
whitish shadow.
This boy was burned to death with his hands placed on his chest, leaving an impression of agony.
Critical Thinking Question 3
Truman’s decision to use atomic weapons against Japan is one of
the most controversial in history. In retrospect, do you think Truman
made the right decision in authorizing the use of atomic
weapons? Explain why.
A: Truman did not make the right decision when he
authorized the use of atomic weapons.
B: Truman made the right decision when he authorized the use of atomic weapons.
Nuclear Testing After WWII