Matches in DBpedia 2014 for { <http://dbpedia.org/resource/Speed_of_light> ?p ?o. }
- Speed_of_light abstract "The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its value is exactly 299,792,458 metres per second, a figure that is exact because the length of the metre is defined from this constant and the international standard for time. This is, to three significant figures, 186,000 miles per second, or about 671 million miles per hour. According to special relativity, c is the maximum speed at which all matter and information in the universe can travel. It is the speed at which all massless particles and changes of the associated fields (including electromagnetic radiation such as light and gravitational waves) travel in vacuum. Such particles and waves travel at c regardless of the motion of the source or the inertial frame of reference of the observer. In the theory of relativity, c interrelates space and time, and also appears in the famous equation of mass–energy equivalence E = mc2.The speed at which light propagates through transparent materials, such as glass or air, is less than c. The ratio between c and the speed v at which light travels in a material is called the refractive index n of the material (n = c / v). For example, for visible light the refractive index of glass is typically around 1.5, meaning that light in glass travels at c / 1.5 ≈ 200000 km/s; the refractive index of air for visible light is 1.000293, so the speed of light in air is 299705 km/s or about 88 km/s slower than c.In some cases, light and other electromagnetic waves can be thought to be moving "instantaneously", but for long distances and very sensitive measurements their finite speed has noticeable effects. In communicating with distant space probes, it can take minutes to hours for a message to get from Earth to the spacecraft, or vice versa. The light we see from stars left them many years ago, allowing us to study the history of the universe by looking at distant objects. The finite speed of light also limits the theoretical maximum speed of computers, since information must be sent within the computer from chip to chip. The speed of light can be used with time of flight measurements to measure large distances to high precision. Ole Rømer first demonstrated in 1676 that light travelled at a finite speed (as opposed to instantaneously) by studying the apparent motion of Jupiter's moon Io. In 1865, James Clerk Maxwell proposed that light was an electromagnetic wave, and therefore travelled at the speed c appearing in his theory of electromagnetism. In 1905, Albert Einstein postulated that the speed of light with respect to any inertial frame is independent of the motion of the light source, and explored the consequences of that postulate by deriving the special theory of relativity and showing that the parameter c had relevance outside of the context of light and electromagnetism. After centuries of increasingly precise measurements, in 1975 the speed of light was known to be 299792458 m/s with a measurement uncertainty of 4 parts per billion. In 1983, the metre was redefined in the International System of Units (SI) as the distance travelled by light in vacuum in 1/299,792,458 of a second. As a result, the numerical value of c in metres per second is now fixed exactly by the definition of the metre.".
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- Speed_of_light wikiPageID "28736".
- Speed_of_light wikiPageRevisionID "606755771".
- Speed_of_light caption "497.0".
- Speed_of_light data "1".
- Speed_of_light data "1.0".
- Speed_of_light data "1.3".
- Speed_of_light data "1.3254192E8".
- Speed_of_light data "1080000000".
- Speed_of_light data "119 ms".
- Speed_of_light data "134 ms".
- Speed_of_light data "173".
- Speed_of_light data "186000".
- Speed_of_light data "3.15576E12".
- Speed_of_light data "3.3".
- Speed_of_light data "300000".
- Speed_of_light data "498.00000000000006".
- Speed_of_light data "671000000".
- Speed_of_light data "7.8894E11".
- Speed_of_light data "7.8894E13".
- Speed_of_light data "Time".
- Speed_of_light expiry "2014-11-01".
- Speed_of_light hasPhotoCollection Speed_of_light.
- Speed_of_light header "Approximate light signal travel times".
- Speed_of_light header "Approximate values".
- Speed_of_light header "Exact values".
- Speed_of_light label Kilometres_per_hour.
- Speed_of_light label Metre_per_second.
- Speed_of_light label Miles_per_hour.
- Speed_of_light label "Distance".
- Speed_of_light label "Planck length per Planck time".
- Speed_of_light label "across the Milky Way".
- Speed_of_light label "astronomical units per day".
- Speed_of_light label "from Moon to Earth".
- Speed_of_light label "from Sun to Earth".
- Speed_of_light label "from geostationary orbit to Earth".
- Speed_of_light label "from nearest star to Sun".
- Speed_of_light label "from the Andromeda Galaxy to Earth".
- Speed_of_light label "from the nearest galaxy to Earth".
- Speed_of_light label "one foot".
- Speed_of_light label "one metre".
- Speed_of_light label "the length of Earth's equator".
- Speed_of_light labelstyle "font-weight:normal".
- Speed_of_light small "yes".
- Speed_of_light title "Speed of light".
- Speed_of_light subject Category:Concepts_in_physics.
- Speed_of_light subject Category:Fundamental_constants.
- Speed_of_light subject Category:Light.
- Speed_of_light subject Category:Special_relativity.
- Speed_of_light subject Category:Units_of_velocity.
- Speed_of_light comment "The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its value is exactly 299,792,458 metres per second, a figure that is exact because the length of the metre is defined from this constant and the international standard for time. This is, to three significant figures, 186,000 miles per second, or about 671 million miles per hour.".
- Speed_of_light label "Lichtgeschwindigkeit".
- Speed_of_light label "Lichtsnelheid".
- Speed_of_light label "Prędkość światła".
- Speed_of_light label "Speed of light".
- Speed_of_light label "Velocidad de la luz".
- Speed_of_light label "Velocidade da luz".
- Speed_of_light label "Velocità della luce".
- Speed_of_light label "Vitesse de la lumière".
- Speed_of_light label "Скорость света".
- Speed_of_light label "سرعة الضوء".
- Speed_of_light label "光速".
- Speed_of_light label "光速".
- Speed_of_light sameAs Rychlost_světla.
- Speed_of_light sameAs Lichtgeschwindigkeit.
- Speed_of_light sameAs Ταχύτητα_του_φωτός.
- Speed_of_light sameAs Velocidad_de_la_luz.
- Speed_of_light sameAs Argiaren_abiadura.
- Speed_of_light sameAs Vitesse_de_la_lumière.
- Speed_of_light sameAs Laju_cahaya.
- Speed_of_light sameAs Velocità_della_luce.
- Speed_of_light sameAs 光速.
- Speed_of_light sameAs 빛의_속력.
- Speed_of_light sameAs Lichtsnelheid.
- Speed_of_light sameAs Prędkość_światła.
- Speed_of_light sameAs Velocidade_da_luz.
- Speed_of_light sameAs m.073n8.
- Speed_of_light sameAs Mx4rvVi4E5wpEbGdrcN5Y29ycA.
- Speed_of_light sameAs Q2111.
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- Speed_of_light wasDerivedFrom Speed_of_light?oldid=606755771.
- Speed_of_light depiction Earth_to_Sun_-_en.png.