Directional Momentum Assigned to Light Quanta
Einstein's radiation arguments associated localized quanta with directed momentum as well as energy, moving the light-quantum concept closer to the later photon picture.
Albert Einstein · Year
1909
Albert Einstein records dated 1909, drawn directly from the World History Database source collection.
Particle Contribution Identified in Radiation Fluctuations
A second term in Einstein's fluctuation analysis had the form associated with independently moving energy quanta, strengthening his argument that radiation also possesses particle-like properties.
Radiation Fluctuation Formula Separates Two Terms
Einstein derived a thermal-radiation fluctuation expression containing two distinct contributions, one with wave-like behaviour and another with the statistical form expected from independent quanta.
Radiation Pressure Fluctuations Analyzed
Einstein studied statistical fluctuations in radiation pressure and used them to expose both continuous-wave and discrete-quantum aspects of thermal radiation.
Salzburg Address Defends Dual Radiation Structure
At the Salzburg meeting Einstein presented radiation as a problem requiring both electromagnetic waves and quantum-like localized events, highlighting a central unresolved issue of early quantum theory.
Salzburg Quantum Lecture
Presents a major lecture arguing that radiation displays both wave-like and particle-like properties.
Thermal Radiation Statistics Support Quantum Picture
Einstein used the statistical behaviour of black-body radiation to argue that purely classical wave theory could not account for all observed fluctuations in radiant energy.
University of Zurich Appointment
Becomes associate professor of theoretical physics at the University of Zurich.
Wave Contribution Identified in Radiation Fluctuations
Einstein interpreted one part of the radiation fluctuation formula as the signature of interference and wave structure within the electromagnetic field.
Wave-Particle Duality Proposed for Radiation
Einstein argued that a future theory of light would need to combine wave structure with localized quantum structure instead of choosing only one classical description.
University of Geneva Honorary Doctorate
Receives his first honorary doctorate, awarded by the University of Geneva.
Zurich Physical Society Membership
Becomes a member of the Physical Society of Zurich.