The Eastchester Road Residence Complex, HP Pavilion dv7-2019ca Battery a 634-apartment complex comprising three 28 story apartment buildings, provides housing to all MD and PhD students (including some post-doctoral fellows) and their families.
Photons and energy quanta
Main articles: Photon and QuantumHP Pavilion dv7-1212ea Battery
In a 1905 paper, Einstein postulated that light itself consists of localized particles (quanta). Einstein’s light quanta were nearly universally rejected by all physicists, including Max Planck and Niels Bohr. This idea only became universally accepted in 1919, with Robert Millikan’s detailed experiments on the photoelectric effect, HP Pavilion dv7-1212tx Battery and with the measurement of Compton scattering.
Einstein concluded that each wave of frequency f is associated with a collection of photons with energy hf each, where h is Planck’s constant. He does not say much more, because he is not sure how the particles are related to the wave. But he does suggest that this idea would explain certain experimental results, HP Pavilion dv7-1213ea Batterynotably the photoelectric effect.
Quantized atomic vibrations
Main article: Einstein solid
In 1907 Einstein proposed a model of matter where each atom in a lattice structure is an independent harmonic oscillator. HP Pavilion dv7-1213tx Battery In the Einstein model, each atom oscillates independently – a series of equally spaced quantized states for each oscillator. Einstein was aware that getting the frequency of the actual oscillations would be different, but he nevertheless proposed this theory because it was a particularly clear demonstration that quantum mechanics could solve the specific heat problem in classical mechanics. HP Pavilion dv7-1214ea Battery Peter Debye refined this model.
Adiabatic principle and action-angle variables
Main article: Old quantum theory
Throughout the 1910s, quantum mechanics expanded in scope to cover many different systems. HP Pavilion dv7-1214tx BatteryAfter Ernest Rutherford discovered the nucleus and proposed that electrons orbit like planets, Niels Bohr was able to show that the same quantum mechanical postulates introduced by Planck and developed by Einstein would explain the discrete motion of electrons in atoms, and the periodic table of the elements. HP Pavilion dv7-1215ef Battery