how fast does light travel?
371210
3 * 10^8 m/s (approx.- this is used for the purpose of calculations)\nthe exact value is hard to calculate but the closest approximation is 299,792,458 m/s
64217
to answer your question it is possible to go faster the the speed of light. The speed of light is 186,000 miles per second.\n\nIf zooming beyond the local speed limit is punishable by law, then some scientists may have a gargantuan speeding ticket to pay. \n\nIn a controversial experiment reported in this weeks journal Nature, scientists at the NEC Research Institute in Princeton, New Jersey claim to have broken the ultimate speed limit -- the speed of light. Though hotly contested, some say this achievement could dramatically increase the speeds at which we can send and receive information. \n\nTaught in physics classes the world over, Albert Einsteins theory of special relativity holds that no object or information can move faster than the speed of light in a vacuum, or 186,000 miles (300,000 kilometers) per second. But NECs Lijun Wang says he created an experiment in which a light beam raced through a gas-filled chamber so quickly, it exceeded the speed of light by a factor of 300. Whats more, the light pulse appears to have left the confines of the chamber before it even entered a seemingly impossible occurrence according to theories of causality, which predict that causes must always precede their effects. \n\n"It sounds crazy, but this can actually occur," said Raymond Chiao, a physicist at the University of California at Berkeley. Chiao, one of a group of researchers who have been working to break the speed-of-light limit, explained that although a common object such as a baseball could never be flung faster than the speed of light, pulses of energy with certain complex properties have been known to bend the rules. \n\n\n\n"It sounds crazy, but it actually can occur." \n\n\n\n\nIn fact, several recent experiments, including one done by Chiao earlier this year, have pointed to energy pulses zooming faster than light speed. Yet each of these experiments has been encumbered by severe limitations on measurement or observation of the energy pulses. In contrast, this latest experiment is being touted by some as the most dramatic example yet of light breaking its own speed barrier. \n\n"The effects are much larger and more spectacular" than previous observations, said Chiao. \n\nIn Wangs experiment, a pulse of light passed through a small chamber filled with atoms of elemental cesium. A light beam traveling through such a medium has two different velocities a velocity for the individual light waves in the beam and a group velocity for the entire beam. Oddly, some light waves in the beam can actually travel backward for miniscule amounts of time, creating a sort of "tail" behind forward-moving waves. As such, a light wave and its tail can leave the gas cavity at different times, creating the effect that the light beam has left the cavity before its even entered. \n\nConfused? Youre not alone. In fact, even scientists who are familiar with this area of study are unsure about the details of Wangs experiment. And many scientists said the experiments results are still open to interpretation. \n\nWilliam Happer, a physicist at Princeton University argued that several specific problems exist with the experiment, including the fact that pulses get distorted when passed through any media other than a vacuum, or empty space. In addition, he said Wang and his colleagues performed the experiment in a way that doesnt tell the whole story, and that it can be interpreted incorrectly. "This is anything but dramatic," said Happer. "If you look at the data, theres essentially no evidence that [the beam] is going faster than the speed of light." \n\nWhats more, most scientists agree that even if such a beam can be proved speedier than light, it would probably not be able to carry any information. Such a feat could conceivably allow data to be sent back in time, thus violating laws of causality and sending quantum physics into disrepair. \n\nOthers are more optimistic as to the possible
54308
As you travel faster and faster, time for you slows down, and length contracts. From your point of view, when you measure the speed of light, it will always be the same. An observer standing still with respect to you and the beam of light could measure your speed at 185000 mps and the speed of light as 186000 mps, and say the difference in speed is 1000 mps. But that is relative to them. The speed of light will always be the same for whoever measures it, no matter how fast they are moving.\n\nSee the website below for more about relativity.
37094
well, its absolutely impossible to travel at the speed of light, but lets pretend you can so i can actually give you an answer to the question. The speed of light is actually the ultimate speed limit to the universe, nothing can travel faster than light, so although you would expect the light to be going at twice the speed of light (you plus the speed of light, because of einsteins theory of relativity)it can't because it is physically impossible for even light to travel faster than the speed of light so it would be going at the same speed of you and not reach any path in front of you. Of course, if you turned on your headlights before you started moving, the light would always be one step ahead of you.\n\nbut again, this situation couldn't happen anyway since you can't get to the speed of light, it would make the denomonator in the lorentz factor 0, and you cant have a 0 in the denomonator of a fraction.
204272
Light travels faster than sound.
435346
10% of the speed of light is roughly 1,116,000 mph (186,000 mp/sec * .1 and then mult by 60).\nIt is roughly 1,796,000 kph.
11469
the speed of light = 299 792 458 m / s
1148279
light travels at 3 x 10^8 m/s\n\nsound travels at 330 mph \n\nso it takes lot of time for sound to reach us, than light..even though both are produced at the same time...
697266
In a vacuum, the speed of light is 299,792,458meters per second and sound is 344meters per second at sea level and 70deg Fahrenheit.\n\nHowever, these speeds are dependent on various outside factors--namely the material they are passing through.
383249
The Hubble Space Telescope can see out to a distance of several billions of light-years. A light-year is the distance that light travels in 1 year. Since light has a speed of 186,000 miles per second (light can travel about 7 times around the entire earth in 1 second!), light travels about 5,865,696,000,000 miles in just one year. You can attach 9 more zeros to the end of this to get 1 billion light-years and another one for 10 billion light-years. The farthest that Hubble has seen so far is about 10-15 billion light-years away. The farthest area looked at is called the Hubble Deep Field.
455984
Photons because light travels at 300000km/s, it would be called teleportation if an human was able to travel at such a speed.
68058
Two of these answers were correct (the speed of light in a vacuum is exactly 299792458 meters per second), although the appropriate reference is not wikipedia but the Bureau International des Poids et Mesures (BPIM).  This is the internationally recognized "official" source.\nhttp://www.bipm.fr/en/si/base_units/\n\nThe speed of light in a vacuum is exactly known because the meter is defined (by the BPIM) as being the distance that light in a vacuum travels in 1/299792458 of a second\n\nThe answer from Trsmd is not quite correct in stating that the speed of anything can be measured by determining the distance in travels in a given amount of time.  Since our units of distance are defined in terms of the speed of light, the correct statement would be that distance can be determined by measuring the amount of time that it takes light to travel that distance.\n\nAlso notice the qualifier "in a vacuum".  The speed of light travels more slowly when it travels through something like air, water, or glass.  How much more slowly depends on the properties of the material (density, composition, temperature, etc.)
265157
It takes an infinite amount of energy to reach the speed of light, so the quick answer is "You can't".\n\nIf you are traveling at CLOSE TO the speed of light and you turn on your lights they will appear (to you) to create cones of light that travel at light speed relative to you.  If you measure the speed of the light, you will get c (approx 300,000 k/sec).  To you, the light will appear to be traveling 300,000 k/sec faster than you are.\n\nAn observer who is not moving (one who see's you as traveing at nearly light speed) will also see the light as traveling at speed c, but he will see it as moving only a little faster than you are.\n\nHow can this be?  It happens because of something called "time dialation/compression" (see the Theory of Special Relativity).  The "seconds" measured by you (in the car) are MUCH longer than the seconds measured by the motionless observer.  That's the magic of special relativity.\n\nThis is confusing stuff.  If you want to really understand it, look up special relativity and read carefully.
168923
>>>>why can nothing excede the speed of light?\n\nLots of things can and do exceed the speed of light.\n \nNo information or mass can exceed the speed of light. Why? Because the speed of light is our one reference point. If anything exceeded the speed of light it would arrive at its destination BEFORE it was sent.\n\nIt's exactly like recieving a letter the day before it is written. It's impossible and  it makes no real sesne to ask why it can't happen. Cause has to preceed effect.\n\n>>>>if radio waves are slower than light\n\nRadio waves are just electromagnetic radiation. They travel at lightspeed just like all other EMR.\n\n>>>>>then wouldnt gama and X rays be faster?\n\nNo, they also travel at C. They just have higher freqencies.\n\n>>> or do all waves travel at the same speed and the light >>> part is just a term\n\nWaves have all sorts of speeds. \nOcean waves travel at variable speeds, often les than 10  kms.hr. \nSound waves travel at a bit over 1000km/hr. \nLight waves travel at the speed of light.\n\n_______________\nInfinity said:"By the way, the quote "Lots of things can and \n>>>>>>do exceed the speed of light" is entirely false.\n\nI really, really wish people would do some basic research before attempting to adress points they clearly don't understand.\n\nThe expansion of the universe itself is faster than the speed of light (see the link below).\n\nAnd as wd5gnr and Hound both said it is perfectly possible for non-information bearing events to propagate faster than lightspeed. We recently had an in depth discussion on the experiments which have managed to produce pahse vlocities hundreds of times faster than light.\n\nAnd of course there are many many other events that travel at speeds well in excess of C.\n\nReally Infinity, you should at least take the time to do some research before correcting others. It saves you embarassment of this kind. More importantly it prevents you misleading others and spreading your ignorance.
600967
No there is no 'summation' of speeds involved with light.  Light is Electro-Magnetic Energy, although light travels as particles as well as waves.  In this Universe the speed of light is a constant, roughly 186,000 miles-per-second, or 300,000 km/sec or 300 Mega-Metres / sec.  Unless some POWERFUL external force acts upon light, it cannot change speed.  This entails the gravity of black-holes and such. (Not even light can escape from them.)\n\nA vehicle might weigh somewhere in the neighbor-hood of 3,300 lbs. (Approximately 1,500 Kg, for those of you who have not learned to count properly, just yet ...)\nCheck out da' math ...\n\n60mph = 100 kmph = 27.77r mps. \n(1,500 Kg x 27.77r mps) / 9.81 mps = ~ 4,246 N\n\nI doubt, very seriously, that a little over 4,000 Newtons is enough force to even put a dent in the factor of light-speed.  For more info, look-up Einstein's Theory of Realtivity' (Although I believe 90% of it to be short-sighted ancient crap ...)  This subject is covered in it ...\n(umm covered in Einstein's Theory, not copvered in crap .. which err .. is the same thing at times ...
281399
1) Light is both a wave and a particle phenomenon. Experiments can be devised to demonstrate either the particle or wave properties of light, just not at the same time (see 'particle wave duality').\n2) About 1,000 seconds. An astronomer named Christian Huygens (I think... might've been Oersted) first observed a 1,000 second discrepancy in the observation of Jupiter's moons eclipsing when observed in the summer as opposed to in the winter. This led him to the first good approximation for the speed of light, i.e. the extra time it took the light to cross the diameter of Earth's orbit could be measured, and since the approximate diameter of Earth's orbit was already known: Speed = Distance/Time or 186,000,000 miles divided by 1,000 seconds = 186,000 miles per second.\n3) The light year is a unit of DISTANCE, not TIME!! It is the distance that light travels in one year, or about six TRILLION miles. However even at this staggering speed it takes light over four years to reach the nearest star to Earth (other than the sun).
252752
When the lightwave is traveling in a vacuum, there is no change regardless of the wavelength.  All light travels where there is no matter at roughly 300,000 km/sec.\n\nFor other materials, you would have to look at the dispersion relation for that material.  This will tell how the speed of light at different wavelengths is affected by the material.