News tagged with speed of light
Model describes universe with no big bang, no beginning, and no end
(PhysOrg.com) -- By suggesting that mass, time, and length can be converted into one another as the universe evolves, Wun-Yi Shu has proposed a new class of cosmological models that may fit observations of the universe better ...
Jul 29, 2010 |
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Discovery that quasars don't show time dilation mystifies astronomers
(PhysOrg.com) -- The phenomenon of time dilation is a strange yet experimentally confirmed effect of relativity theory. One of its implications is that events occurring in distant parts of the universe should ...
Apr 09, 2010 |
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Atom smasher achieves 'Big Bang' collisions (Update)
Scientists at the world's biggest atom smasher on Tuesday started colliding particles at record energy levels, opening a new era in the quest for the universe's deepest secrets.
Mar 30, 2010 |
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Researchers create light from 'almost nothing'
(PhysOrg.com) -- A group of physicists working out of Chalmers University of Technology in Gothenburg, Sweden, have succeeded in proving what was until now, just theory; and that is, that visible photons could ...
Jun 06, 2011 |
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Gamma-ray photon race ends in dead heat; Einstein wins this round
Racing across the universe for the last 7.3 billion years, two gamma-ray photons arrived at NASA's orbiting Fermi Gamma-ray Space Telescope within nine-tenths of a second of one another. The dead-heat finish ...
Oct 28, 2009 |
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A hint of Higgs: An update from the LHC
The physics world was abuzz with some tantalizing news a couple of weeks ago. At a meeting of the European Physical Society in Grenoble, France, physicists -- including some from Caltech -- announced that ...
Aug 16, 2011 |
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Large Hadron Collider gains pace: CERN
The world's biggest atom smasher is swiftly gaining pace as scientists seek to unravel the secrets of the universe, the European Organisation for Nuclear Research (CERN) said on Monday.
Jun 28, 2010 |
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Faster than light neutrinos? More like faulty wiring
You can shelf your designs for a warp drive engine (for now) and put the DeLorean back in the garage; it turns out neutrinos may not have broken any cosmic speed limits after all.
Feb 22, 2012 |
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New theories emerge to disprove OPERA faster-than-light neutrinos claim
(PhysOrg.com) -- It's been just two weeks since the Oscillation Project with Emulsion-tRacking Apparatus (OPERA) team released its announcement claiming that they have been measuring muon neutrinos moving faster t ...
Oct 06, 2011 |
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'Faster-than-light' particles fade after cross-check
Neutrinos do not go faster than light, according to fresh measurements of a test last year that had suggested the particles broke the Universe's speed limit, CERN said on Friday.
Mar 16, 2012 |
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How does the proton get its spin?
(PhysOrg.com) -- At a meeting this week of the American Physical Society in Washington, MIT Associate Professor of Physics Bernd Surrow reported on new results from the STAR experiment at the Relativistic ...
Feb 17, 2010 |
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'Faster-than-light' particles spark science drama
Oh Albert. Did you get it wrong? In 2011, physics was shaken by an experiment which said the Universe's speed limit, enshrined by Einstein in his 1905 theory of special relativity, could be broken.
Dec 09, 2011 |
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'Neutrino oscillation': Particle chameleon caught in the act of changing
(PhysOrg.com) -- Researchers on the OPERA experiment at the INFN's Gran Sasso laboratory in Italy today announced the first direct observation of a tau particle in a muon neutrino beam sent through the Earth ...
May 31, 2010 |
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New look at relativity: Electrons can't exceed the speed of light -- thanks to light itself, says biologist
When resolving why electrons can never beat the speed limit set by light, it might be best to forget about time. Thanks to insight from studying movement inside a biological cell, it seems that light itself -- not the relativity ...
Nov 19, 2010 |
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Large Hadron Collider smashes another record
The world's biggest particle collider set a new record early Monday, a feat that should accelerate the quest to pinpoint the elusive particle known as the Higgs Boson, a senior physicist said.
May 23, 2011 |
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Speed of light
The term speed of light generally refers to a fundamental physical constant of spacetime that limits the rate of transfer of matter or information. The speed of light is the speed of not just visible light, but of all electromagnetic radiation in vacuum (also called free space), and usually is denoted by the symbol c. Speeds faster than that of light are encountered in physics but, in all such cases, no matter or information is transmitted faster than c. The speed of light also plays a role in general relativity, and is believed to be the speed of gravitational waves.
In SI units, the magnitude of the speed of light in vacuum is exactly 299,792,458 metres per second (m/s) because of the way the metre is defined. More about this topic is found below in Speed of light set by definition.
For many practical purposes, the speed of light is so great that it can be regarded to travel instantaneously. An exception is where long distances or precise time measurements are involved. For example, in the Global Positioning System (GPS), a GPS receiver measures its distance to satellites based on how long it takes for a radio signal to arrive from the satellite. In astronomy, distances are often measured in light-years, the distance light travels in a year.
The speed of light when it passes through a transparent or translucent material medium, like glass or air, is less than its speed in vacuum. The speed is inversely proportional to the refractive index of the medium. In specially-prepared media, the speed can be tiny, or even zero.
For many years the speed of light was the subject of speculation, some believing it to be infinite. The first effective measurements of the speed of light were made in the seventeenth century, and these were progressively refined until, in 1983, the speed of light in vacuum was fixed by definition.
For more information about Speed of light, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
