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A photon (from Ancient Greek φῶς, φωτός (phôs, phōtós) 'light') is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force.
Electron discovered by J. J. Thomson [4] 1899 Alpha particle discovered by Ernest Rutherford in uranium radiation [5] 1900 Gamma ray (a high-energy photon) discovered by Paul Villard in uranium decay [6] 1911 Atomic nucleus identified by Ernest Rutherford, based on scattering observed by Hans Geiger and Ernest Marsden [7] 1919
In physical cosmology, the photon epoch was the period in the evolution of the early universe in which photons dominated the energy of the universe. The photon epoch started after most leptons and anti-leptons were annihilated at the end of the lepton epoch , about 10 seconds after the Big Bang . [ 1 ]
In the letter, he proposed a photon being a structural element, not energy. He insisted on the need for a new variable, the number of photons . Although his theory differed from the quantum theory of light introduced by Albert Einstein in 1905, his name was adopted for what Einstein had called a light quantum (Lichtquant in German).
Conversely, an electron that absorbs a photon gains energy, hence it jumps to an orbit that is farther from the nucleus. Each photon from glowing atomic hydrogen is due to an electron moving from a higher orbit, with radius r n, to a lower orbit, r m. The energy E γ of this photon is the difference in the energies E n and E m of the electron:
Under the proper circumstances, the photon's magnetic fields effect is as strong as their electric field – as e.g. in solar cells. The discovery is a surprise, because it is not straightforward to derive the strong magnetic effect from the physical equations, and thereby indicate that this quantum mechanical effect would be interesting enough.
A photon emitted by the laser hits the first beam splitter and is then in a superposition between the two possible paths. In the second beam splitter these paths interfere, causing the photon to hit the photodetector on the right with probability one, and the photodetector on the bottom with probability zero. [ 46 ]
Specifically, when the photon hits electrons, it releases loosely bound electrons from the outer valence shells of atoms or molecules. The effect was discovered in 1923 by Arthur Holly Compton while researching the scattering of X-rays by light elements, and earned him the Nobel Prize for Physics in 1927.