Niels Bohr

Niels Henrik David Bohr (October 7, 1885 – November 18, 1962) was a Danish physicist who made essential contributions to understanding atomic structure and quantum mechanics.

Bohr's contributions to physics

• Bohr's model of atomic structure.
• The electron's orbital angular momentum is quantized; L=nħ.
• The theory that electrons travel in discrete orbits around the atom's nucleus, with the chemical properties of the element being largely determined by the number of electrons in the outer orbits.
• The idea that an electron could drop from a higher-energy orbit to a lower one, emitting a photon (light quantum) of discrete energy (this became the basis for quantum theory).
• The Copenhagen interpretation of quantum mechanics.
• The principle of complementarity: that items could be separately analyzed as having several contradictory properties.

Relationship with Heisenberg

Werner Heisenberg claimed in an interview after the war, when the author Robert Jungk was working on the book Brighter Than a Thousand Suns, that he had tried to establish a pact with Bohr such that scientists on neither side should help develop the atomic bomb. He also said that the German attempts were entirely focused on energy production, and that his circle of colleagues tried to keep it that way. Heisenberg nuanced his claims, though, and avoided implication that he and his colleagues had purposely sabotaged the bomb effort. However, this nuance was lost in Jungk's original publication of the book, which strongly implied that the German atomic bomb project was rendered purposely stillborn by Heisenberg.

When Bohr saw this depiction in the Danish translation of Jungk's book, he disagreed wholeheartedly. He said that Heisenberg had indeed let him know in Copenhagen that he was working on an atomic bomb project, and that he thought that Germany would win the war. He dismissed the idea of any pact as an after-the-fact construction. He drafted several letters to inform Heisenberg about this but never sent any of them.[1] (http://www.nbi.dk/NBA/release.html)

Michael Frayn's play Copenhagen, which ran on Broadway for a time, explores what might have happened at the 1941 meeting between Heisenberg and Bohr. The truth of the historical event is still a matter of scholarly debate.

Books about Bohr

• Niels Bohr: The Man, His Science, and the World They Changed, by Ruth Moore ISBN 0262631016
• Niels Bohr's Times, In Physics, Philosophy and Polity, by Abraham Pais, ISBN 0-19-852049-2

See also

• Asteroid 3948 Bohr, named after the physicist.

External links

Wikiquote has a collection of quotations related to:

Niels Bohr

• Niels Bohr Archive (http://www.nba.nbi.dk/)
• Nobel Foundation: Niels Bohr (http://www.nobel.se/physics/laureates/1922/)
• About Niels Bohr (http://www.nobel-winners.com/Physics/niels_henrik_david_bohr.html)

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