Interference, constructive and destructive; application to Young's double-slit experiment; phase change upon reflection; interference in thin films, nonreflective coatings; diffraction from narrow slits; resolution of apertures; difraction grating; x-ray diffraction by crystals; modes of polarization, effect of polarizers, Malus' law, polarization by reflection, Brewster's law; Galilean relativity, relativity of simultaneity, Einstein's special theory of relativity, time dilation, length contraction, twin paradox, Lorentz transformation (relativistic "mixing" of space and time coordinates), velocity transformation equation, relativistic energy and momentum, equivalence of mass and energy, relativistic "mixing" of electric and magnetic fields; general theory of relativity, principle of equivalence; blackbody radiation, Rayleigh-Jeans law vs. Planck's law; photons, photoelectric effect, work function, Einstein's formula; Compton effect; atomic spectra, Bohr's model of the hydrogen atom; Bohr's correspondence principle, wave-particle duality; de Broglie wavelength, importance of interference in the double-slit experiment for electrons; Heisenberg uncertainty principle; wave function and probability density; particle in a box, zero point energy, tunneling through a barrier, Schroedinger equation.