Quantum Mechanics and the BohrEinstein Debate

1
Quantum Mechanics and the Bohr-Einstein Debate
2
Heroes of Quantum Mechanics
3
Heisenbergs Breakthrough, 1925 Matrix Mechanics

• Theory built on observables, e.g., transition
  probabilities of quantum jumps
• Motions were described by terms represented not
  by straightforward numbers, but by matrices
• Three-man-paper Heisenberg, Max Born, and
  Pascual Jordan
• pq-qph/2pi

4
De Broglie-Schrödingers Wave Mechanics

• Louis de Broglie If light can behave like
  particles, why cant matter (e.g., electrons)
  behave like waves?
• Schrödinger, 1925-1926 applied electron-as-wave
  concept to atomic theory
• Wave mechanics quantization came about because
  only in certain orbit could electron wave have
  integral number of vibrations.

5
Reactions to Two Rival Theories

• Bohr supported Heisenbergs while Einstein and
  Planck backed Schrödingers
• 1926 discovery of mathematical equivalence of
  the two theories
• Borns probability interpretation electron wave
  was not real wave, but only wave of probability
• Philosophical differences Matrix Mechanics
  emphasized particle aspect, denied visualization,
  threatened determinism wave mechanics gave a
  familiar, continuous, and causal world view

6
Bohr-Heisenberg Debate

• Heisenberg denied completely the wave aspect of
  quantum mechanics but Bohr thought that there was
  a particle-wave duality
• Heisenberg uncertainty principle ?p ?q h/2p
• Bohr complementarity particle-wave duality is a
  fundamental fact of nature
• Copenhagen Interpretation Uncertainty
  Complementarity

7
Bohr-Einstein Debate

• Bohr advocated Copenhagen interpretation
• Einstein admitted that quantum mechanics worked,
  but thought it was not completenot the final
  word
• Different philosophies Bohr was more empiricist
  believing that the goal of science as to organize
  our experience
• Einstein believed in fundamental unity and
  rationality of nature and the universe