Bohr–Einstein debates

A series of exchanges between Niels Bohr and Albert Einstein about quantum mechanics, especially whether its account of physical reality is complete.

Double-slit experiment: An experiment in which particles or waves pass through two openings, producing an interference pattern under suitable conditions. Einstein’s challenges and Bohr’s replies drew on how measurements alter interference.
Quantum measurement problem: The puzzle of how definite measurement outcomes arise from quantum states that allow multiple outcomes. The debates exposed disagreement over whether measurement has a special role in quantum theory.
Niels Bohr: A Danish physicist who developed the Bohr model of the atom and helped establish quantum theory. Bohr defended quantum mechanics through complementarity and replies to Einstein’s thought experiments.
Bell's theorem: A theorem showing that no theory satisfying Bell-locality can reproduce all quantum predictions. It converted a central implication of the EPR dispute into constraints testable by experiment.
Einstein's photon box: A thought experiment proposing a box that emits a photon at a precisely timed moment to challenge energy–time uncertainty. Bohr answered Einstein’s proposed way to measure a photon’s energy and emission time.
Quantum entanglement: A relation between quantum systems in which their joint state cannot be described as independent states of each system. Entanglement underlies Einstein’s concern about distant correlations and physical locality.
Albert Einstein: A German-born theoretical physicist whose work transformed modern physics, including relativity and quantum theory. Einstein accepted quantum mechanics’ successes but questioned whether it was a complete description.
Bell test: An experiment testing whether measured correlations violate a Bell inequality. Bell tests found correlations that rule out broad classes of local hidden-variable theories.
EPR paradox: A 1935 argument that quantum mechanics cannot be complete if distant measurements reveal definite correlated properties without disturbance. Einstein’s most influential published challenge to quantum completeness emerged from this argument.
Heisenberg uncertainty principle: A quantum principle limiting the precision with which certain pairs of observables can simultaneously have definite values. Einstein repeatedly devised measurement setups intended to challenge uncertainty relations.

Linked from 7 pages