is momemtum  the speed of light  ?
115093
Momentum is the tendency of an object in motion to stay in motion. The speed of light is an actual speed.
811109
You misunderstand Einstein's Theory of Special Relativity. It doesn't say that you can't have something move faster than the speed of light. Only "information" can NOT move faster than the speed of light. By information, I mean any "signal", like electromagnetic waves (which includes light, radio waves, etc. etc.). Any material object within the Universe are also restricted by Special Relativity, since material objects also carry "information".\n\nFor the Universe or the fabric of spacetime to be expanding faster than the speed of light is NOT a violation of Special Relativity, and the Universe will not be moving backwards in time.\n\n--------------------------------------------------------\n\nEdit - Ok, here let me clarify why I said that Special Relativity (SR) does NOT apply to the expansion of the Universe:\n\nVelocity of something depends on which definition of distance we use. So, if we assume that the distance of an object at time t is the distance from our position at time t to the object's position at time t measured by a set of observers moving with the expansion of the Universe, and all making their observations when they see the Universe as having age t, then the velocity (change in D per change in t) can definitely be larger than the speed of light. This is not a contradiction of special relativity because this "distance" is not the same as the spatial distance used in SR, and the age of the Universe is not the same as the time used in SR.\n\nIn the special case of the "empty Universe", where one can show the model in both special relativistic and cosmological coordinates, the velocity defined by change in cosmological distance per unit cosmic time is given by v = c ln(1+z), where z is the redshift, which clearly goes to infinity as the redshift goes to infinity, and is larger than c for z > 1.718.\n\nFor the "critical density Universe", this velocity is given by v = 2c[1-(1/sqrt(1+z))], which is larger than c for z > 3. \n\nFor the "concordance model" based on CMB data and the acceleration of the expansion measured using supernovae, a flat Universe with Omega = 0.27 (this would be our Universe), the velocity is greater than c for z > 1.407\n\nAll this just means that for any expanding universe, there will be a value of z (i.e., redshift or cosmological distance) that will give the appearance of galaxies moving at velocities greater than c.
855043
It's all theory, we don't know if (something) can exceed the speed of light. I would argue that time would be void at that moment, but again it's my theory. Interesting thought though.
13401
It's true that the speed of light is constant no matter what speed at which you or the source is moving.  This is a fundamental postulate of relativity, and there is no explination.  It's just accepted because our experiments indicate that it is true.  You used the formula "lights speed + X = actual speed"  this type of velocity addition is called "Galilean".  It turns out that speeds don't actually add that way.  Far out.\n\nWhere is the rest of the energy? Good question.  The frequency of the light you observe from the sun DOES depend on how fast you and it are moving.  The energy of each photon is given by E = hf, where f is the frequency of light.
219832
The speed of light is indeed a constant.  What's important is that it is a constant to every observer.  If you are traveling toward a light source at 1000 m/s, you will measure the light's velocity at 300,000 m/s.  If you are traveling AWAY from the light source, it will still measure 300,000 m/s.\n\nLight IS the absolute speed limit. (Of this universe anyway)
337266
Um, well it depend on how you consider light. If you consider it as a stream of photons, then you might say that if you measure the positions of each of those photons it doesn't have velocity.\nIf you say it is a wave and always in motion then it is not relative to your velocity, exactly. Even if you were travelling at 30000000mph the light would still appear to be travelling at 3x10to the power of 8 m/s away from you. Light is the fixed speed limit for the universe. But at the far reaches where the material of space itself is expanding into nothing, it is expanding at a speed greater than the speed of light because that speed limit only applies to objects moving within the universe.
226867
The speed of light. 186,000 miles per second.
1029096
There are two types of particle in the universe. Those with a rest mass (ie a mass when they are stationary) and those with no rest mass. Only zero rest mass particles can travel at the speed of light.\n\nMeasurements have shown that the speed of light is the same however fast you are moving. This couterintuitive result is the basis for special relativity. It is fairly straightforward to show from this measurement that accelerating a particle with non zero rest mass close to the speed of light does not simply add to its energy but increases its mass. An infinite amount of energy would be needed to accelerate a particle with non-zero rest mass to the speed of light. This effect too can be measured in a lab.\n\nThe red shift does not have its origins in changes in the speed of light at all - in fact it relies on the speed of light being the same for all wavelengths of light. It is in effect the doppler effect for light - the same thing that makes the frequency of a passing car drop as it recedes.\n\nAnd it is perfectly possible - not even that difficult - to do measurements on the speed of light accurate to 8 or 9 decimal places.
49096
You can't go the speed of light, but even if you were going 99.9999999% the speed of light, yes, you could shine the beam forward, backwards, or sideways, and it would look normal in every direction.  That's the central idea behind relativty.\n\nAnd NO, the light would NOT be going twice the speed of light.  Anyone who says that is BSing you.
567624
yes light can be Speed manipulated.\n\nRead below...\n\n(poor bastard up above - yes education is the answer! however, do you think we have received it? we haven't even scratched the surface of how the universe works. there are exotic functions that will blow your mind away. things that defy physics as we know it)
426222
The speed of light is the same no matter where it is. It is 299,792,458 meters per second.
523357
*\nThe time-honored phrase "faster than the speed of light" might have to be reworked, thanks to the work of a Danish physicist.\n\nBy shooting a laser beam of light through a super-cooled glob of a kind of optical molasses, Lene Vestergaard Hau and her team at the Rowland Institute for Science in Cambridge, Massachusetts, were able to slow the speed of light down to just 38 miles per hour -- not even fast enough for the slow lane of a freeway.\n\nBy contrast, the normal speed of light in a vacuum is about 186,000 miles per second -- 20 million times as fast.\n\n"I would probably not call it God-like, but I would probably say ... we are tampering with nature in a very peculiar, very bizarre way," Hau says.\nlight maze\nHau points to an intricate maze of mirrors, part of the slowing process  \n\nThe research, conducted at the Rowland Institute and Harvard University, was reported in Thursday's issue of the journal Nature.\n\nThe substance that slows the light, called Bose-Einstein condensate, is a microscopic glob of atoms slowed to almost absolute zero -- 459.67 degrees below zero Fahrenheit, the lowest temperature theoretically possible.\n\nResearchers believe that it may be possible to slow the speed of light even further, by a factor of 1,000.\n\n"A human could move faster than that" says Stanford University's Steve Harris, who participated in the project. "But a human couldn't move through a Bose-Einstein condensate, I'll tell you that."\n\nResearchers believe learning how to slow light could eventually have a number of practical applications -- improving computers and communications devices, making television displays and laser light shows more vivid and creating better night-vision goggles.
1187636
Light always travels at the same speed in a vacuum, the speed changes ever so slightly when it has to go through a different medium (water e.g.) but its so fast to begin with you wouldn't really notice it. 300,000 kilometers per second is beyond human comprehension, I mean you can only imagine how fast that is, you can't experience it or 'know' it.
148002
It's technically impossible for something with mass (like a spacecraft) to go the speed of light in our universe under the laws of physics.  As something approaches the speed of light, it gains mass.  In theory, if something were to actually go the speed of light, it would have infinite mass, which is impossible.  \n\nOf course, no one can say for sure.  Science fiction on television and in books have gotten around these rules by using wormholes, subspace, etc., none of which are known to actually exist.
974250
This page gives a very nice table listing who, when, how, how accurately the speed of light has been measured including the first time when Olaus Roemer did it in a really neat way 330 years ago!\n\nhttp://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/measure_c.html
842139
No.\n\nIt seems like it ought to be different, doesn't it?  But the genius of Einstein's discovery was that the speed of light is a constant, and that it is the limiting speed of the universe.  Literally everything else--even time itself--will change in order to keep the speed of light constant (approximately 186,000 miles per second).  \n\nIt is a difficult concept to get your mind around, but it's been more than 90 years since Einstein did this work, and every experiment done since then has confirmed it.\n\nGood luck!!
11469
the speed of light = 299 792 458 m / s