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In 1905, Einstein proposed a theory of the photoelectric effect using a concept that light consists of tiny packets of energy known as photons or light quanta. Each packet carries energy h ν {\displaystyle h\nu } that is proportional to the frequency ν {\displaystyle \nu } of the corresponding electromagnetic wave.
Perhaps the most famous conference was the fifth Solvay Conference on Physics, which was held from 24 to 29 October 1927. The subject was Electrons and Photons and the world's most notable physicists met to discuss the newly formulated quantum theory. The leading figures were Albert Einstein and Niels Bohr.
Photons are massless particles of definite energy, definite momentum, and definite spin. To explain the photoelectric effect , Albert Einstein assumed heuristically in 1905 that an electromagnetic field consists of particles of energy of amount hν , where h is the Planck constant and ν is the wave frequency .
A spectrum of many such photons will show an emission spike at the wavelength associated with these photons. An absorption line is formed when an atom or molecule makes a transition from a lower, E 1, to a higher discrete energy state, E 2, with a photon being absorbed in the process. These absorbed photons generally come from background ...
In that theory, the mass of electrons (or, more generally, leptons) is modified by including the mass contributions of virtual photons, in a technique known as renormalization. Such " radiative corrections " contribute to a number of predictions of QED, such as the magnetic dipole moment of leptons , the Lamb shift , and the hyperfine structure ...
Stimulated emission was a theoretical discovery by Albert Einstein within the framework of the old quantum theory, wherein the emission is described in terms of photons that are the quanta of the EM field. [5] [6] Stimulated emission can also occur in classical models, without reference to photons or quantum-mechanics.
The first person to correctly predict the phenomenon of spontaneous emission was Albert Einstein in a series of papers starting in 1916, culminating in what is now called the Einstein A Coefficient. [1] [2] Einstein's quantum theory of radiation anticipated ideas later expressed in quantum electrodynamics and quantum optics by several decades. [3]
The Einsteinhaus on the Kramgasse in Bern, Einstein's residence at the time. Most of the papers were written in his apartment on the first floor above the street level. At the time the papers were written, Einstein did not have easy access to a complete set of scientific reference materials, although he did regularly read and contribute reviews to Annalen der Physik.