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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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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First results from RENO: Observation of the weakest neutrino transformation
The Reactor Experiment for Neutrino Oscillations (RENO) research team announced the first result of the search for the remaining, most elusive puzzle of the neutrino transformation. They have found disappearance of neutrinos ...
Apr 09, 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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Italian physicist behind 'faster-than-light' test resigns
An Italian physicist at the head of a team that made a cautious but hugely controversial claim that neutrinos may travel faster than the speed of light resigned on Friday following calls for his dismissal.
Mar 30, 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 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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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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New picture of atomic nucleus emerges
(PhysOrg.com) -- When most of us think of an atom, we think of tiny electrons whizzing around a stationary, dense nucleus composed of protons and neutrons, collectively known as nucleons. A collaboration between ...
Mar 02, 2012 |
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In the early universe, rapid expansion or something very weird
(PhysOrg.com) -- The widely-accepted theory of cosmic inflation states that our universe expanded rapidly in the moments after its birth, resulting in the immense expanse we see today.
Feb 27, 2012 |
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Hitches emerge as culprit in 'faster-than-light' particle (Update)
Scientists who last year found particles that appeared to break the Universe's speed limit are looking at two technical issues that could have skewed the controversial finding, CERN said Thursday.
Feb 23, 2012 |
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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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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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Physicists develop theoretical framework for interpreting results of subatomic-particle collisions
Accelerating subatomic particles to almost the speed of light and then crashing them together reveals much about the nature of the matter. Nuclear physicists need to fully understand these complex collisions ...
Feb 17, 2012 |
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Through hardship to the stars
"Humanity's adventurous, stubborn, mad and glorious aspiration to reach the stars" is the subject of Physics World's lead feature in January.
Space & Earth / Space Exploration
Jan 04, 2012 |
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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.
