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Quantum Mechanics from the Tombs

Quantum Mechanics from the Tombs. Peter Leung Feb. 16, 2011. Pre-20 th Century. Specific heat of diatomic gases: Discrete spectra: Angstrom (~ 1860). Max Planck (1858-1947). Planck: The Quantum Revolution. Planck U October 19, 1900 December 14, 1900

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Quantum Mechanics from the Tombs

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  1. Quantum Mechanics from the Tombs Peter Leung Feb. 16, 2011

  2. Pre-20th Century • Specific heat of diatomic gases: • Discrete spectra: Angstrom (~ 1860)

  3. Max Planck (1858-1947)

  4. Planck: The Quantum Revolution • Planck U October 19, 1900 December 14, 1900 E = N ε = N h f Ref.: Thomas Kuhn:“Black-Body Theory and the Quantum Discontinuity, 1894-1912 ”

  5. How did Planck discover the “quantum”? • To calculate cavity radiation intensity, need the energy density ~ U(T) • Now we have and • To calculate W, need to assume Then use combinatorics => W:

  6. Planck’s tomb

  7. Niels Bohr (1885-1962)The “Godfather” of Quantum Mechanics “If you are not shocked by quantum mechanics, you have not understood it!”

  8. Quantum Structure of Matter (1913) • m v r = n h /(2π) ( h has a dimension of angular momentum!) Derivation of Rydberg constant: R = 1.0973731 x 10E7 /m

  9. Other significant contributions • Correspondence Principle (1918): h → 0 or n →∞ : Quantum → Classical • Principle of Complementarity (1928): Two contradictory pictures (wave/particle) of reality complement each other • Copenhagen Interpretation of QM (1928)

  10. Here lies Niels Bohr - now in the ground state.--- John Hubisz

  11. Prince Louis-Victor de Broglie (1892-1987)

  12. Discovery of matter wave • Recherches sur la théorie des quanta (Researches on the quantum theory), Thesis Paris, 1924. (Advisor : Paul Langevin) • Einstein’s endorsement (any impact on the Bose-Einstein condensation?) For light: E = hf p = E/c = hf/c = h/λ Radiation-matter equivalence: E = mc^2 → For matter: f = E/h λ = h/p

  13. Werner Heisenberg (1901-1976)

  14. Discovery of Matrix Mechanics • Professors: Sommerfeld, Wien • Main ideas: theory should only contain observable (measurable) quantities -- frequency of electron in atom : ω → ω(mn) -- position of electron in atom : x → x(mn) -- momentum of electron in atom : p→ p(mn) → noncommuting x, p: x p – p x = ih/2  0

  15. Uncertainty principle (1927) • Heisenberg: thought experiment with gamma ray microscope (qualitative statement: x p  h ) • Kennard (1927): x p  h/4 • Robertion (1929): x p  <[x,p]>/2i

  16. Epitaph for Heisenberg He lies here, somewhere.

  17. Erwin Schrodinger (1887-1961)

  18. A Christmas Romance (1925) From Leon Lederman: “The God Particle” “Matter Waves and the Lady in the Villa” … Leaving his wife at home, Schrodinger booked a villa in the Swiss Alps… taking with him his notebooks,… and an old Viennese girlfriend …Then he placed the girlfriend in bed for inspiration…

  19. The Celebrated Equation(1926) • For Light: wave equation → ray (eikonal) equation as wavelength → 0 • For matter (e.g. an electron): particle (“ray) equation: F = ma →

  20. Entanglement (1935) • The poor pet…

  21. Epitaph by John Hubisz • Here lies Erwin Schrodinger - but without opening the casket, we can't besure he's dead.

  22. His Later Regrets… • Erwin Schrodinger : If we are going to stick to this damned quantum-jumping, then I regret that I ever had anything to do with quantum theory. ... • never like duality, probability,… till the end

  23. Max Born (1882-1970)

  24. Formulation of Quantum Mechanics • First published using the term: “Quantum Mechanics” --- (1924) • Completed matrix mechanics with Heisenberg and Jordan (1926): • Engraving:

  25. Tomb Inscription

  26. Probability: an indeterministic universe from a foot note! • Study of scattering problem: switch to wave mechanics (1926) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

  27. Paul Dirac (1902-1984) • Bohr: ‘ Of all Physicists, Dirac has the purest soul…’ (Graham Farmelo: “The Strangest Man”)

  28. Discovery of the “Quantum Possion Bracket” (1925) • Heisenberg → Fowler → Dirac Classical Possion BracketQuantum commutator

  29. The Dirac Equation (1928) • Relativistic wave equation for the electron: spin and antiparticle Westminster Plaque

  30. Other Contributions • Dirac delta function (1927) • Transformation theory (1927) • Theory of holes (1930) • Magnetic monopoles (1931) • Lagrangian in quantum mechanics (1932) • Large number hypothesis (1938) • Bra and ket (1939)

  31. Other Significant Contributors • Einstein • Pauli • Jordan • Eckart • Von Neumann • Feynman • Bell

  32. More References

  33. One of the Latest (and very good one!)

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