Black Body spectrum and Emission-Absorption spectrum are "explained"
Stern-Gerlach Experiment
- Discover of the spin: another quantum property is demonstrated for the athom.
Compton Effect
- Arthur Compton demonstrates light behavior is like particles' behavior: the concept of photon is confirmed
Kinds of complementarity:
- Position and momentum
- Energy and duration
- Spin on different axes
- Wave and particle
- Value of a field and its change (at a certain position)
- Entanglement and coherence
1935
Flavia Marcacci
Chair History of Scientific Thought
Quantum Mechanics History
Before Planck
- 1893: Wien's displacement (empirical) Law: for various temperatures, wavelength and maximum spectral radiance
- 1900: Rayleigh-Jeans (Lord Rayleigh and James Jeans) Law: approximation to the spectral radiance of electromagnetic radiation of a black-body by classical approach. As a consequence, empirical data disapproved the theoretic predictions (ultraviolet catastrophe)
Max Planck Hypothesis: Nature is discrete
Wolfgang Ernst Pauli (1900 – 1958), Nobel 1945
Exclusion principle: two or more identical fermions (particles with half-integer spin) cannot occupy the same quantum state within a quantum system simultaneously
Planck's Law for Black Body
- B = Black body spectral radiation
Paul Dirac (1902-84)
Erwin Schrödinger (1887 – 1961) and Werner Heisenberg (1901–1976): two formal theories for the same physical theory
- QM and SR
- hypotheses of the anti-matter
- Schrödinger and the temporal equation for QM
Rutherford's athom
James Chadwick (Hughes Medal 1932, Nobel 1935)
Neutron Discovery
Niels Bohr and the atomic model
Paradox and laws
Q.E.D.: QM and elementary particles
1935 Schrödinger's cat
1935 EPR paradox
QM applies to elementary particles (what happens inside a particle accelerator)
- a new atomic model, based on the quantum hypotheses
- Emission and absorption spectrum are explained
- 1915: Sommerfeld modifies Bohr's model by the introduction of elliptic orbits
Thermodynamics
De Broglie dual hypotheses
for matter
- Louis-Victor De Broglie (1892-1987, Nobel Physics 1929) suggests that particles of matter have properties wavelike. The wavelength is:
- The particle's energy E is related to the frequency of its associated wave by the Planck relation:
Richard Feyman (1918-88), Sin-Itiro Tomonaga (1906-79), Julian Schwinger (1918-94)
(Nobel Physics 1965)
Solvay Congress 1927 (Leyden)
Volta Conference (Como, 11-27 Sept.)
Radioactivity and discovery of a subatomic world
Only Einstein believes in quantum hypothese
Copenaghen QM
- Interpretation of the Wave Equation (De Broglie, Heisenberg, Schrödinger)
- Complementarity Principle (Bohr: objects have complementary properties which cannot all be observed or measured simultaneously)
1905: Photoelectric effect (Nobel 1921)
C - cathode assembly; the cathode itself is hot, and glows orange. It emits electrons which pass through the metal mesh grid (G) and are collected as an electric current by the anode (A) (from Wiki-source)
Complementary properties
Position and momentum
Energy and duration
Spin on different axes
Wave and particle
Value of a field and its change (at a certain position)
Entanglement and coherence[
Franck-Hertz experiment (1914, Nobel 1925)
First electrical measurement to clearly show the quantum nature of atoms (Bohr's model)
- Emission of electrons (or other free carriers) when light is shone onto a material.
- Photons like particles: light like discrete and localized quanta of energy
1926, principle of correspondence of Bohr
1925, principle of exclusion of Pauli: two electrons can never occupy the same quantum state.
1927, Heisenberg's principle of uncertainty.
1928, principle of Bohr's complementarity: the corpuscular and wavelike aspect of matter is never contradictory, because these aspects never come together.
Heisenberg Principle
Davisson and Germer
Heat capacity of solid (Eistein solid)
Experiment (1921 to 1925) to confirm De Broglie's hypotheses that particles' behaviour is wavelike.
Each atom is a quantum harmonic oscillator + same frequency for all the atoms
Heat capacity: amount of heat necessary to raise, or decrease, the temperature of a unit of mass of 1 K.