Photon
hideIn physics, a photon is an elementary particle, the quantum of the electromagnetic field and the basic "unit" of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force. The effects of this force are easily observable at both the microscopic and macroscopic level, because the photon has no rest mass; this allows for interactions at long distances. Like all elementary particles, photons are governed by quantum mechanics and will exhibit wave-particle duality – they exhibit properties of both waves and particles. For example, a single photon may be refracted by a lens or exhibit wave interference, but also act as a particle giving a definite result when its location is measured.
The modern concept of the photon was developed gradually by Albert Einstein to explain experimental observations that did not fit the classical wave model of light. In particular, the photon model accounted for the frequency dependence of light's energy, and explained the ability of matter and radiation to be in thermal equilibrium. It also accounted for anomalous observations, including the properties of black body radiation, that other physicists, most notably Max Planck, had sought to explain using semiclassical models, in which light is still described by Maxwell's equations, but the material objects that emit and absorb light are quantized. Although these semiclassical models contributed to the development of quantum mechanics, further experiments proved Einstein's hypothesis that light itself is quantized; the quanta of light are photons.
In the modern Standard Model of particle physics, photons are described as a necessary consequence of physical laws having a certain symmetry at every point in spacetime. The intrinsic properties of photons, such as charge, mass and spin, are determined by the properties of this gauge symmetry.
The photon concept has led to momentous advances in experimental and theoretical physics, such as lasers, Bose–Einstein condensation, quantum field theory, and the probabilistic interpretation of quantum mechanics. It has been applied to photochemistry, high-resolution microscopy, and measurements of molecular distances. Recently, photons have been studied as elements of quantum computers and for sophisticated applications in optical communication such as quantum cryptography.
For more information about Photon, read the full article at
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News tagged with photons
JQI researchers create entangled photons from quantum dots
Nov 18, 2009 |
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To exploit the quantum world to the fullest, a key commodity is entanglement—the spooky, distance-defying link that can form between objects such as atoms even when they are completely shielded from one another. Now, physicists ...
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Creating a six-qubit cluster state
Nov 02, 2009 |
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(PhysOrg.com) -- Many scientists believe that quantum entanglement is required in order for effective quantum computing. Entanglement takes place when there is a connection that exists between two objects - even when they ...
Fermi Telescope Peers Deep into Microquasar (w/ Video)
Nov 27, 2009 |
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(PhysOrg.com) -- NASA's Fermi Gamma-ray Space Telescope has made the first unambiguous detection of high-energy gamma-rays from an enigmatic binary system known as Cygnus X-3. The system pairs a hot, massive ...
Science Begins at the World's Most Powerful X-ray Laser (w/ Video)
Nov 02, 2009 |
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(PhysOrg.com) -- The first experiments are now underway using the world's most powerful X-ray laser, the Linac Coherent Light Source, located at the Department of Energy's SLAC National Accelerator Laboratory. ...
Tapering a Free-Electron Laser to Extract More Juice
Nov 20, 2009 |
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(PhysOrg.com) -- Researchers from the NSLS and Science Applications International Corporation (SAIC) have demonstrated a technique that could be used to significantly improve the quantity and quality of light ...
Planetary Society plans new 'solar sail'
Space & Earth / Space Exploration
Nov 09, 2009 |
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(AP) -- Four years after its first solar sail ended up in the ocean instead of orbit, The Planetary Society announced Monday that by the end of 2010 it will try again to launch a spacecraft that will be propelled by the ...
A quantum leap forward?
Nov 23, 2009 |
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The dusty boxes that line the walls of Jeff Barrett's UC Irvine office mark a high point in his academic career. Their contents: pages and pages of notes, most more than 50 years old, penned by late quantum ...
Proton therapy is well-tolerated in prostate cancer patients
Nov 02, 2009 |
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Proton beam therapy can be safely delivered to men with prostate cancer and has minimal urinary and rectal side effects, according to a study presented November 2, 2009, at the American Society for Radiation Oncology's 51st ...
Starburst galaxy sheds light on longstanding cosmic mystery
Nov 02, 2009 |
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(PhysOrg.com) -- An international collaboration that includes scientists from the University of Delaware's Bartol Research Institute in the Department of Physics and Astronomy has discovered very-high-energy ...
'Dropouts' pinpoint earliest galaxies
Nov 06, 2009 |
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Astronomers, conducting the broadest survey to date of galaxies from about 800 million years after the Big Bang, have found 22 early galaxies and confirmed the age of one by its characteristic hydrogen signature ...
Argonne 'homegrown' hybrid solar cell aims for low-cost power
Nanotechnology / Nanomaterials
Nov 10, 2009 |
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(PhysOrg.com) -- Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have refined a technique to manufacture solar cells by creating tubes of semiconducting material and then "growing" ...
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