Introduction



Physicist J. Robert Oppenheimer, head of the Manhattan Project. Courtesy of the National Archives and Records Administration.

An explosive device that releases nuclear energy (energy that comes from an atom's core). All previous explosive devices were powered by rapid burning or decomposition of a chemical compound; they only released energy from the outermost electrons of an atom. Nuclear explosives are energized by splitting an atom, a process called fission. On July 16, 1945 the first atomic bomb was detonated at 5:30 a.m. The resulting implosion initiated a chain reaction of nearly 60 fission generations in about a micro-second. It produced an intense flash of light, followed by a fireball expanding to a diameter of about 600 meters in two seconds, and then it rose to a height of more than 12 kilometers, forming its ominous mushroom shape. Forty seconds later, an air blast hit the observer bunkers, followed by a sustained and awesome roar. In August 1945, the United States dropped atomic bombs on Japan over the cities of Hiroshima and Nagasaki. The Hiroshima bomb, using the code name "Little Boy," had a force of 13,000 tons (11,791 metric tons), or 13 kilotons, of TNT. Its element base was uranium-235. The Nagasaki bomb, using the code name "Fat Man," had a force of 22,000 tons (19,954 metric tons), or 22 kilotons, of TNT. Its element base was plutonium. In 1949 the Soviet Union tested its first atomic bomb, followed by Britain (1952), France (1960), China (1964), India (1974), and Pakistan (1998).

 

Recommended Resources

  1. Dawning of the Nuclear Age: Cold War Almanac
  2. J. Robert Oppenheimer Biography
  3. The Making of the Atomic Bomb Study Guide (eNotes)

All Resources

Display as: Categories, List
  1. "Letters from Los Alamos" - 1940's Government and Politics
  2. 1939 | Science: The People's Chronology
  3. 1942 | Science: The People's Chronology
  4. Aftermath Study Guide (eNotes)
  5. Albert Einstein
  6. America at War: The War at Home - 1940's Government and Politics
  7. America at War: The War Ends in the Pacific - 1940's Government and Politics
  8. American Scientists Campaign Against Nuclear Testing
  9. Atomic Bombing of Japan
  10. Atomic Bombs Destroy Hiroshima and Nagasaki
  11. Atomic Energy Act (Salem on History)
  12. Atoms and More: Physics - 1930's Science and Technology
  13. Chemistry - 1930's Science and Technology
  14. China Conducts Atmospheric Nuclear Test (Salem on History)
  15. China Explodes Its First Nuclear Bomb: Salem on History
  16. Cold War: The Bomb - 1950's Government and Politics
  17. Dawning of the Nuclear Age: Cold War Almanac
  18. Dr. Strangelove Or How I Learned to Stop Worrying and Love the Bomb
  19. Dr. Strangelove Or How I Learned to Stop Worrying and Love the Bomb Movie Learning Guide
  20. Draft Letter from Niels Bohr to Werner Heisenberg, ca. 1957 ...
  21. Dwight D. Eisenhower: "Chance for Peace" Address
  22. Dwight D. Eisenhower: UN Speech "Peaceful Uses of Atomic Energy"
  23. Enola Gay: The Men, the Mission, the Atomic Bomb
  24. Enrico Fermi - 1940's Science and Technology
  25. Fat Man and Little Boy (1989) Movie Learning Guides
  26. H-Bomb - 1950's Science and Technology
  27. Harry S. Truman: Excerpt of Comments on the Manhattan Project
  28. Harry S. Truman: Statements on the Surrender of Germany and the Surrender of Japan
  29. Hirohito: West's Encyclopedia of American Law
  30. Hiroshima Maiden Movie Learning Guides
  31. Hiroshima: Genocide and Crimes Against Humanity
  32. J. Robert Oppenheimer Biography
  33. J. Robert Oppenheimer Biography
  34. Julius and Ethel Rosenberg
  35. Mutual Assured Destruction: Cold War Almanac
  36. Oppenheimer and the Atomic Bomb
  37. Oppenheimer, J. Robert 1904-1967 - 1940's Science and Technology
  38. Origins of the Cold War: Cold War Almanac
  39. Overview - 1940's Science and Technology
  40. Radiation - 1950's Medicine and Health
  41. Radiation Injuries: Encyclopedia of Medicine
  42. Radiation Injuries: Encyclopedia of Nursing & Allied Health
  43. Spies and Scientists: World War II Almanac
  44. The Atomic Energy Commission Is Established: Salem on History
  45. The Defeat of Japan: World War II Almanac
  46. The First Atomic Bomb Is Successfully Detonated: Salem on History
  47. The H Bomb - 1950's Science and Technology
  48. The Holocaust and the Atomic Bomb: Fifty Years Later Criticism
  49. The Making of the Atomic Bomb Study Guide (eNotes)
  50. The Religious Response to the Atomic Bomb - 1940's Religion
  51. Victory Over Japan Study Guide (eNotes)
  52. Weapons of Mass Destruction: Genocide and Crimes Against Humanity
  53. What Was Enrico Fermi's Contribution To The Understanding Of Nuclear Power?
  54. What Was The Manhattan Project?
  55. Why Did Albert Einstein Want The United States To Develop The Atomic Bomb?
  56. Why Was J. Robert Oppenheimer Accused Of Being Disloyal To The United States?