Atomic bomb
   The atomic bomb was a weapon made using enriched uranium, which on detonation caused a chain nuclear reaction involving the fission of atomic particles. Development of the atomic bomb in the United States began after Albert Einstein wrote to Franklin D. Roosevelt in August 1939 informing him of the early discoveries in atomic science and the potential to create a powerful bomb based on nuclear fission and warning of the need to develop such weaponry before Nazi Germany. In 1942, the government established the Manhattan Project under the leadership of General Leslie R. Groves, and on 16 July 1945 the first bomb was tested in Alamogordo, New Mexico. The first bomb was used during World War II when it was dropped on Hiroshima, Japan, on 6 August 1945. A second bomb was dropped on 9 August on Nagasaki. Both bombs had devastating effects, and shortly afterward proposals were drawn up in an effort to prevent the proliferation of atomic weapons.
   These proposals were put to the United Nations in the Baruch Plan but were rejected by the Soviet Union. With the onset of the Cold War and the testing of an A-bomb by the Soviet Union in 1949, the threat of nuclear war became a real possibility. In 1952, the atomic bomb was superseded by the hydrogen bomb, a more powerful weapon based on nuclear fusion rather than fission.
   See also Atomic Energy Act.

Historical Dictionary of the Roosevelt–Truman Era . . 2015.

Look at other dictionaries:

  • Atomic bomb — Atomic A*tom ic, Atomical A*tom ic*al, a. [Cf. F. atomique.] 1. Of or pertaining to atoms. [1913 Webster] 2. Extremely minute; tiny. [1913 Webster] {Atomic bomb}, see {atom bomb} in the vocabulary. {Atomic philosophy}, or {Doctrine of atoms}, a… …   The Collaborative International Dictionary of English

  • atomic bomb — atomic bombs N COUNT (The form atom bomb is also used, mainly in British English.) An atomic bomb or an atom bomb is a bomb that causes an explosion by a sudden release of energy that results from splitting atoms …   English dictionary

  • atomic bomb — ☆ atomic bomb n. an extremely destructive type of bomb, the power of which results from the immense quantity of energy suddenly released when a very rapid chain reaction of nuclear fission is set off by neutron bombardment in the atoms of a… …   English World dictionary

  • atomic bomb — 1. a bomb whose potency is derived from nuclear fission of atoms of fissionable material with the consequent conversion of part of their mass into energy. 2. a bomb whose explosive force comes from a chain reaction based on nuclear fission in U… …   Universalium

  • atomic bomb — noun a nuclear weapon in which enormous energy is released by nuclear fission (splitting the nuclei of a heavy element like uranium 235 or plutonium 239) (Freq. 2) • Syn: ↑atom bomb, ↑A bomb, ↑fission bomb, ↑plutonium bomb • Hypernyms: ↑nuclear… …   Useful english dictionary

  • atomic bomb — atom bomb UK / US or atomic bomb UK / US noun [countable] Word forms atom bomb : singular atom bomb plural atom bombs Word forms atomic bomb : singular atomic bomb plural atomic bombs a bomb that causes a very large nuclear explosion from the… …   English dictionary

  • Atomic bomb — Atom bomb At om bomb , Atomic bomb A*tom ic bomb . a bomb of great power in which the explosive energy is derived from the nuclear fission of a fissionable material, such as plutonium or uranium 235. It is a type of nuclear weapon. The strength… …   The Collaborative International Dictionary of English

  • atomic bomb — Nuclear weapon Nu cle*ar wea pon, n. A weapon of great explosive power, such as an {atomic bomb} or a {hydrogen bomb}, which depends for most of its explosive power on the release of energy from within atomic nuclei by a nuclear reaction. A… …   The Collaborative International Dictionary of English

  • atomic bomb — atominė bomba statusas T sritis apsauga nuo naikinimo priemonių apibrėžtis Aviacinė bomba su atominiu užtaisu, branduolinio šaudmens rūšis. Į taikinį neša naikintuvai, taktiniai naikintuvai, bombonešiai. Pagrindinės atominės bombos dalys:… …   Apsaugos nuo naikinimo priemonių enciklopedinis žodynas

  • atomic bomb — atominė bomba statusas T sritis fizika atitikmenys: angl. atomic bomb vok. Atombombe, f rus. атомная бомба, f pranc. bombe atomique, f …   Fizikos terminų žodynas

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