Niels Bohr

Niels Bohr was a Danish physicist who proposed a quantum model of the atom in 1913, received the Nobel Prize in Physics in 1922, and directed the institute for theoretical physics in Copenhagen. He developed the principle of complementarity and is the central figure of the Copenhagen interpretation of quantum mechanics. His long debate with Einstein over the completeness of quantum theory remains a touchstone in the philosophy of physics.

Key ideas

• Complementarity: wave and particle descriptions are mutually exclusive yet both needed for a complete account of quantum phenomena.
• Quantum phenomena must be described together with the experimental arrangement that produces them.
• Experimental results must be communicated in the concepts of classical physics.
• Against Einstein, quantum mechanics is a complete description within the limits of what can be observed.

Major works

• On the Constitution of Atoms and Molecules (1913)
• Atomic Theory and the Description of Nature (1934)
• Can Quantum-Mechanical Description of Physical Reality Be Considered Complete? (1935)
• Discussion with Einstein on Epistemological Problems in Atomic Physics (1949)

In the conversation

• Question What did Bell’s theorem actually prove? I keep hearing three different answers Ethan Mercer · 4 replies
• Question QBism says the wavefunction is my degrees of belief. What exactly is it claiming? Wanjiru Njenga · 3 replies