Why can't anything travel faster than light?
928008
The short answer is all objects with an initial "rest" mass become infinitely massive as their velocity approaches the speed of light.\n\nMost of the energy expended to make an already fast mover go faster, as it approaches the speed of light, goes mostly into increasing its relativistic mass and increasingly less into increasing its velocity. The formula for this is (which I suggest you graph to see what's happening):\n\nM = m / SQRT (1 - v^2/c^2), where M is the relativistic mass, m is the initial "rest" mass, v is the relative velocity, and c is the velocity of light.\n\nAs v approaches c, the their ratio approaches unity, 1 minus the square of their ratio approaches zero, the square root approaches zero, and the relativistic mass approaches infinity.\n\nThis doesn't come about because of theory. This is observation. The Special Theory of Relativity tries to explain what is observed.\n\nThe web site cited has an interactive Java applet that will let you plug in velocity to see how much the relativistic mass increases as an object approaches the speed of light.\n\nNow, if somehow an object were already going faster than the speed of light, it presumably would shed mass if it went even faster and move backwards in time. Tachyons were proposed as particles that could do this, but no one has ever observed a tachyon.\n\nAs for fighter jets, they can and do go a LOT faster than the twice the speed of sound, but no where near light speed.
532772
nothing but light can travel at light speed.  the faster you go, the more energy it requires to accelerate.  at speeds that are close to the speed of light, you would need what is basically an infinite amount of power to accelate.  with current technology, it is impossible.  the only reason light can travel that fast, is because when it is created it is already traveling that fast.  it doesnt have to accelerate.
140231
This has been answered many times. Use the search function to find out more information. \n\nThere are two relativities:\n1. special theory\n2. general theory\n\nThe special theory makes many predictions about things that move very fast:\n\n1. They get shorter, front to back.\n2. They gain mass\n3. Time slows down for them\n\nInformation cannot be transferred at a speed greater than the speed of light. \n\nGeneral relativity describes gravity as a bending of space. So gravity can bend light. And it also predicts something called a black hole, which light cannot escape, and is a place where the equations of physics break down.
883877
Going faster than light speed violates the laws of special relativity.  You simply cannot start at rest or any velocity less than light, reach light speed, then get faster.  However, it does not violate special relativity if your starting velocity is faster than light.  This is how tachyons are hypothesized.  When a tachyon forms, it immediately starts which a velocity faster than light.  Therefore it can never slow down to the speed of light or less.  If tachyons exist, they'll give off a certain type of radiation so they won't be invisible. \n\nSo in other words, it will never be possible for us to make some spaceship or anything that can go faster than light, which means no "warp drives" or anything like that.
1063094
Being accelerated past the speed of light is impossible because of the nature of momentum.  It is not simply mass times velocity, but mass times velocity times gamma.  Gamma is a factor which adjusts for the fact that as an object's velocity increases, it has more kinetic energy, which, because E=mc^2, is mass.  Gamma is equal to 1/(1-v^2/c^2), where v = velocity and c is speed of light. As the velocity approaches C, v^2/c^2 becomes 1, and Gamma becomes 1/(1-1), or 1/0.  This means a massive particle traveling at the speed of light has infinite momentum.  It takes infinite force to accelerate to infinite momentum, so breaking the speed of light (for a macroscopic object with mass) is, according to current theory and law, impossible.\n\nHowever, other avenues for an artificial increase of speed are possible.  You mention a lot of them, and not much is really known about them, but it could be possible to warp space-time to let us effectively travel faster than light (like the warp drive in Star Trek).
521845
The question is irrelevant since nothing with a mass can travel at light speed.
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.
8700
no. 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)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, and if you want to know why, look at some of my answers to other questions about time travel (which involves velocity distorting time) and shining flashlights and such.
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.
452560
Yes, it is thought that neutrinos travel faster than the speed of light-In fact, it is thought that the speed of light is the *lower* speed limit for neutrinos.  Thought is not particularly fast,and is measurable at a few hundred miles/hour.  Einstein's theory says that nothing can be accelerated to the speed on light, and only refers to massive particles and objects.  The theoretical connection between particles created together (paired particles) seems to obey no speed limit, and react instantly regardeless of the distance, but we are not sure if this represents somethign traveling between the objects, or a connection that exists in a different plane or dimension.
109643
No you can not.\nNothing can travel faster than light. Not even light itself.\n\nIf you think that light is a wave (like a wave on the ocean) Imagine that you were riding one wave and were trying to make a new wave from your position (with equal frequenzy ofcours). The new wave would not have twize the speed as the one you were riding, it would have the same speed as the one you ride (try in the bathroom and you will see).\n\nMy point with this explanation is that the light from the back of your car will never reatch the mirror. I think your mirror would seem black, because no light would reatch it. The lightwave from the back of your car would be "flying" towards the mirror in the same speed that the mirror would fly from it. :)
334240
Well, completely aside from size, light-speed travel is currently impossible by our technology. When and if that technology is ever invented, I would say 'yes', because there is no such thing as wind resistance in space ^_^
1160139
theoretically nothing can travel faster than light which is 186,000 miles/sec, but i don't agree with that theory at all
612849
NO energy, matter, or information has EVER been observed to exceed the speed of light.\n\nTheoretically, there are particles known as "tachyons" ( see wikipedia ) that travel ALWAYS in excess of that of light but never AT or BELOW that speed. Although never observed, their theoretical existence has sent many physicists to look for them ( or their trails ! ) \n\nthere are many abstract entities that "travel" faster than light.  for example, the shadow of a large celestial object ( a planet say ) on another celestial object can be observed to move at great speeds.  a shadow however is not a real entity ( i.e. mass or energy ) and it cannot convey information.
37917
this is somewhat similar to a question I answered realative to time travel. The short answer is no, there was never a time, nor will there ever be a time when matter (massive fermions) travel faster than light (massless bosons). This is because massive objects need energy to accelerate and regaurdless of how much energy was released in the big bang, it could not have been infinite, and that is what is required to move a massive particle faster than light. Light speed is not a derived measurement, it is a fundemental constant that is the same in all reference frames. Here's the cool exception though.....and this is how a theoretical warp drive would work..... the actual expansion of space itself might have been faster than light. There has never been a limit imposed on the speed at which space expands although because gravity is a result of the deformation of space and gravitons are the theoretical force carrier, it has been assumed that the expansion of space would occur only as fast as gravitons can travel....which is most likely light speed. One of the many postulates asserted by string theory is that gravitons may not be bound to our spatial demensions, that they might radiate through extra demensions (which would account for gravity's lack of strenght compared to the other forces). If this is the case that the gravitons travel through other demensions it is quite possible that within a given reference time, a graviton could pop into a superior demension and back into our at some other point and essentially beat light to some defined location.\n\nI know thats a little confusing.....but its fun to think about.
711259
I have always been a fan of this discussion. I propose that ANYTHING can travel faster than the speed of light (SOL). I also believe that was the driving force behind Einstein's assumptions. When we start talking about time slowing down as we approach SOL, we are talking about time RELATIVE to something else...If two people are together on a SOL spacecraft, then the time they experience is the same as if they were standing still. \n\nBefore I ramble on too much, What stops light from going any faster? If we had a theoretical spacecraft that could travel at 1/2 SOL, and we shot a laser off the front of it, how fast would the light be travelling? To the observers on the SOL-craft, the light would be travelling at absolute SOL, but to someone standing next to the craft when the laser was activated, would the light NOT be travelling at 1.5 SOL?
828289
It is exactly that question that inspired Einstein to formulate his theory that nothing can ever travel faster than light. I am not saying the Einstein had a goal to make a theory saying nothing can travel faster than light. I am saying that the question made him think about how to explain what would happen in such a case and then the math lead him to a theory of motion in general which says nothing can travel faster than light.