News tagged with speed of light
Science nugget: Catching solar particles infiltrating Earth's atmosphere
(Phys.org) -- On May 17, 2012 an M-class flare exploded from the sun. The eruption also shot out a burst of solar particles traveling at nearly the speed of light that reached Earth about 20 minutes after ...
Space & Earth / Space Exploration
May 31, 2012 |
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Study finds single photons cannot exceed the speed of light
(PhysOrg.com) -- The rule that nothing can travel faster than the speed of light, c, is one of the most fundamental laws of nature. But since this speed limit has only been experimentally demonstrated for ...
Jun 24, 2011 |
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Hall effect at the speed of light: How can you demonstrate relativistic effects with your mobile phone?
The relativistic Hall effect describing objects rotating at speeds comparable with the speed of light has been reported.
May 21, 2012 |
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Computer simulations suggest graphynes may be even more useful than graphene
(PhysOrg.com) -- The past several years have seen a virtual explosion in the amount of research dedicated to graphene and as a result there has been a nearly constant stream of news pertaining to new discoveries ...
Nanotechnology / Nanomaterials
Mar 05, 2012 |
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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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First, fast, and faster
(Phys.org) -- Scientists in PML's Quantum Measurement Division have produced the first superluminal light pulses made by using a technique called four-wave mixing, creating two separate pulses whose peaks ...
Apr 06, 2012 |
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Researchers analyze the future of transistor-less magnonic logic circuits
(PhysOrg.com) -- As one of the newest research areas today, the field of magnonics is attracting researchers for many reasons, not the least being its possible role in the development of transistor-less logic ...
Jun 28, 2010 |
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Chandra finds fastest wind from stellar-mass black hole
Astronomers using NASA's Chandra X-ray Observatory have clocked the fastest wind yet discovered blowing off a disk around a stellar-mass black hole. This result has important implications for understanding ...
Feb 21, 2012 |
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First results from Daya Bay find new kind of neutrino transformation
The Daya Bay Reactor Neutrino Experiment, a multinational collaboration operating in the south of China, today reported the first results of its search for the last, most elusive piece of a long-standing puzzle: ...
Mar 08, 2012 |
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Scientists drag light by slowing it to speed of sound
(PhysOrg.com) -- Scientists at the University of Glasgow have, for the first time, been able to drag light by slowing it down to the speed of sound and sending it through a rotating crystal.
Jul 06, 2011 |
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Physicist creates scale model of LHC ATLAS experiment of out LEGO blocks
(PhysOrg.com) -- The Large Hadron Collider at the European Organization for Nuclear Research (CERN) in Switzerland has generated a lot of news of late, e.g. the announcement that a team had found what it believes ...
Dec 30, 2011 |
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Scientists take fresh look at 'faster-than-light' experiment
Scientists who threw down the gauntlet to physics by reporting particles that broke the Universe's speed limit said on Friday they were revisiting their contested experiment.
Oct 28, 2011 |
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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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Post-Quantum Correlations: Exploring the Limits of Quantum Nonlocality
(PhysOrg.com) -- When it comes to nonlocal correlations, some correlations are more nonlocal than others. As the subject of study for several decades, nonlocal correlations (for example, quantum entanglement) ...
May 07, 2009 |
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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.
