The Development, Decision, and Reaction

Albert Einstein writes letter to FDR Telling him about the possibility of an atomic bomb AND That Germany might be working on one Special Theory of Relativity (E=mc²) Mass can be converted to Energy where “c” is the speed of light A small amount of mass can create a huge amount of energy

Code name for the project to develop the Atomic Bomb Code name for the project to develop the Atomic Bomb Named for site of Columbia University where much of early research done Named for site of Columbia University where much of early research done 125,000 workers 125,000 workers 2.2 Billion dollars 2.2 Billion dollars Complete secrecy Complete secrecy Most did not know the ultimate purpose of their work until news of Hiroshima bombing Most did not know the ultimate purpose of their work until news of Hiroshima bombing

Leo Szilard Leo Szilard Fled Germany in 1933 Fled Germany in 1933 Conducted 1 st controlled nuclear reaction Conducted 1 st controlled nuclear reaction Created 1 st Nuclear Reactor w/ Enrico Fermi Created 1 st Nuclear Reactor w/ Enrico Fermi J. Robert Oppenheimer J. Robert Oppenheimer Headed Los Alamos Laboratory Headed Los Alamos Laboratory Helped to direct 1 st test of atomic bomb Helped to direct 1 st test of atomic bomb Maj. Gen. Leslie Groves Maj. Gen. Leslie Groves Director of Manhattan Project Director of Manhattan Project Credited with success of it Credited with success of it

Fission – the splitting of an atomic nucleus resulting in the release of large amounts of energy Fission – the splitting of an atomic nucleus resulting in the release of large amounts of energy Energy Released from Each Fission Energy Released from Each Fission 200 MeV 200 MeV ( million electron volts) ( million electron volts) Includes gamma radiation (deadly) Includes gamma radiation (deadly)

Chain Reaction – Process in which neutrons released in fission produce an additional fission Chain Reaction – Process in which neutrons released in fission produce an additional fission

Time of Reaction – Time of Reaction – Released neutron travels at speed of 10 million meters per second Released neutron travels at speed of 10 million meters per second Complete Process of a bomb explosion is a microsecond (1 millionth of a second) Complete Process of a bomb explosion is a microsecond (1 millionth of a second) Critical Mass Critical Mass The point at which the chain reaction becomes self sustaining. The point at which the chain reaction becomes self sustaining.

Problems Problems Manufacturing & Separating Isotopes Necessary Manufacturing & Separating Isotopes Necessary U235 – only 0.7% of uranium U235 – only 0.7% of uranium P239 – not naturally occurring, had to be made P239 – not naturally occurring, had to be made Creating & Controlling Chain Reaction Creating & Controlling Chain Reaction How do you set it off without blowing yourself up? How do you set it off without blowing yourself up? Bomb Designs Bomb Designs The will work but are they safe? The will work but are they safe?

Uranium Bomb Uranium Bomb 220 lbs 220 lbs Simpler – More Fissionable Simpler – More Fissionable 900lbs total 900lbs total Gun - Type Gun - Type

Plutonium Bomb Plutonium Bomb More Complicated Process More Complicated Process Implosion started chain reaction Implosion started chain reaction Stronger of the two bombs Stronger of the two bombs

Alamogordo, NM Alamogordo, NM Plutonium Bomb Plutonium Bomb July 16, 1945 – 1 st Successful Test of Atomic Bomb July 16, 1945 – 1 st Successful Test of Atomic Bomb Explosion larger than expected Explosion larger than expected Equivalent to 20,000 tons of TNT Equivalent to 20,000 tons of TNT Shock felt 160 miles away Shock felt 160 miles away broke windows 120 miles away broke windows 120 miles away

Vaporization point Vaporization point (1/2 mile – 98% fatalities, 3000   C) (1/2 mile – 98% fatalities, 3000   C) Total destruction zone Total destruction zone (1 mile – 90% fatalities, all buildings destroyed) (1 mile – 90% fatalities, all buildings destroyed) Severe blast damage area Severe blast damage area (1.75 miles – 65% fatalities, 35% injuries – larger structures collapsed, bridges & roads damaged) (1.75 miles – 65% fatalities, 35% injuries – larger structures collapsed, bridges & roads damaged) Severe heat damage Severe heat damage (2.5 miles – 50% fatalities, 45% injuries – everything some kind of burn, people killed from suffocation – Oxygen used by fire) (2.5 miles – 50% fatalities, 45% injuries – everything some kind of burn, people killed from suffocation – Oxygen used by fire) Severe fire and wind damage Severe fire and wind damage (3 miles – 15% fatalities, 50% injuries – home & buildings damaged, people blown around, 2nd degree burns, if they survived) (3 miles – 15% fatalities, 50% injuries – home & buildings damaged, people blown around, 2nd degree burns, if they survived)

Ground Zero (hypocenter) Ground Zero (hypocenter) Point on earth directly under point of detonation Point on earth directly under point of detonation Thermal Effects Thermal Effects Radiation = Heat Radiation = Heat Travels at speed of light Travels at speed of light Visible Light – Visible Light – “flash blindness” – lasts several minutes “flash blindness” – lasts several minutes Skin Burns (2 nd & 3 rd Degree) Skin Burns (2 nd & 3 rd Degree) 10,000 severe burn cases 10,000 severe burn cases Can cause fires in homes & buildings Can cause fires in homes & buildings Thermal Pulse Thermal Pulse

Blast Effects Blast Effects Causes most damage Causes most damage Shockwave of air can crush & knockdown objects Shockwave of air can crush & knockdown objects Large buildings destroyed by change in air pressure Large buildings destroyed by change in air pressure People & Objects destroyed by wind People & Objects destroyed by wind Destruction can lead to fires Destruction can lead to fires

Nuclear Radiation Nuclear Radiation Initial – radiation that arrives during 1 st minute Initial – radiation that arrives during 1 st minute Strongest near ground zero – few die from it Strongest near ground zero – few die from it Why? Why? Residual – From radioactive fallout Residual – From radioactive fallout Fallout Fallout Radiation received from radioactive particles that are distributed at varying distances Radiation received from radioactive particles that are distributed at varying distances Carried by wind and rain Carried by wind and rain

Radiation Effects on Humans Radiation Effects on Humans Hair Loss Hair Loss Brain – seizures, immediate death Brain – seizures, immediate death Increased susceptibility to infection Increased susceptibility to infection Increased risk for leukemia & lymphoma Increased risk for leukemia & lymphoma Heart failure & death Heart failure & death Bloody vomiting, diarrhea Bloody vomiting, diarrhea Sometimes sterility Sometimes sterility Long Term Effects Long Term Effects Blood Disorders Blood Disorders Cataracts Cataracts Malignant Tumors (Cancers) Malignant Tumors (Cancers) Keloids

FDR died on April 12, 1945 Truman becomes President Knew nothing about Manhattan Project Favors use of bomb to end war quickly Interim Committee Interim Committee Gov’t leaders, officials, & scientists discuss usage Gov’t leaders, officials, & scientists discuss usage Recommend usage Recommend usage Many of scientists who had worked on project oppose usage Many of scientists who had worked on project oppose usage German threat defeated German threat defeated

B-29 Bomber B-29 Bomber Dropped “Little Boy” on Hiroshima Dropped “Little Boy” on Hiroshima Piloted by Colonel Paul Tibbets Piloted by Colonel Paul Tibbets

Why Chosen? Why Chosen? Major port, military HQ, war industries Major port, military HQ, war industries Untouched by previous bombing raids Untouched by previous bombing raids Urban area – hoped to break will of Japanese Urban area – hoped to break will of Japanese Population Population Military – 43,000 Military – 43,000 Civilian – 285,000 Civilian – 285,000

August 6 th – 8:15AM Little Boy Explodes Results Thousands Killed Instantly 70,000 Killed 20 US POWs 70,000 Injured By end of ,000 Dead (20,000 military) In 5 years time 200,000 dead

No Japanese Surrender No Japanese Surrender Why Chosen? Why Chosen? Large Seaport in Southern Japan Large Seaport in Southern Japan Wartime Industries Wartime Industries Manufactured torpedoes used at Pearl Harbor Manufactured torpedoes used at Pearl Harbor Actually secondary target Actually secondary target Weather poor at primary Weather poor at primary

August 9 th – 11:01AM August 9 th – 11:01AM Fat Man Explodes Fat Man Explodes Results Results Thousands Killed Instantly Thousands Killed Instantly 40,000 Killed 40,000 Killed 60,000 Injured 60,000 Injured Less Damage than Hiroshima – due to geography Less Damage than Hiroshima – due to geography By end of 1945 By end of ,000 Dead 70,000 Dead Final Total Dead = 140,000 Final Total Dead = 140,000

VJ Day – August 14 th 1945 Japanese Surrender

September 2, 1945 September 2, 1945 Official signing of surrender Official signing of surrender USS Missouri USS Missouri One of ships attacked at Pearl Harbor One of ships attacked at Pearl Harbor

Arms Race / Cold War Arms Race / Cold War Health of Japanese Health of Japanese Others Want/Get the Bomb Others Want/Get the Bomb

After watching the reenactment of the bombing of Hiroshima and seeing the effects of the A-Bombs, do you still believe your decision about what to do with the bombs is correct? Why or Why not? After watching the reenactment of the bombing of Hiroshima and seeing the effects of the A-Bombs, do you still believe your decision about what to do with the bombs is correct? Why or Why not?