why is impossible to reach light speed?
411862
According to Einstein's theories, if you took a particle with a non-zero mass mi on the earth, and accelerated it to a speed v respect to the earth, then the mass would increase according to something like m = mi/(1-v^2/c^2), where c is the speed of light.  There may be a square root in there.  The point is that the mass becomes infinite as v approaches c, because the denominator goes to zero.  As the mass increases it takes more and more energy to accelerate it, so that the amount of energy required getting to the speed of light becomes infinite.  Clearly, there is not an infinite amount of energy available for this experiment.\n\nBut, if Einstein was wrong then it might be possible to do.
3887
It is impossible to actually go at the speed of light because in the formula for time dialation (That's right Velocity distorts time. The faster you go, the slower time goes for you. This effect is negligable unless you are going very close to the speed of light.) if v(velocity) were equal to c(the speed of light) you would have a zero in the denomonator.\nthe formula is:\nt'=t/sqrt(1-v^2/c^2)\n\nwhere t' is the time that has passed from a stationary observer, t is the time that has passed for you, sqrt means square root and ^2 means squared. As you can notice, when v is small, since c^2 is so huge, you get a miniscule decimal, and 1 minus that number is basically as small as 1.0000000000001 or something, and so time is not really affected. As v gets larger(it can never be the speed of light, then the denomonator would be zero) that fraction becomes closer to 1, so when you subtract it from one, the denomonator gets smaller and smaller, meaning t gets smaller(in order for t' to remain constant) this means that time actuall slows down for the object moving at such velocities. This formula is correct, it is part of Einstein's theory of relativity, and I have had to derive it myself from ordinary mechanics formulas. \n\nAlong with time, length contracts and mass expands by the same factor.  If you were to go close to the speed of light, your mass would increase and length would decrease. This means that the density of your body would increase more and more as you went faster and faster, and your blood eventually wouldn't be able to flow anymore and your cells would die of oxygen starvation.  Not that it really matters, because to even begin witnessing this effect, you would have to be going at least 90 or 95% or so the speed of light.  \n\nNow to answer your question in that is it actually physically possible to get close... considering they have particle accelerators stories high and miles long requiring tremendous amounts of energy in order to even get tiny protons and neutrons to move at such speeds, it doesn't seem like they're anywhere near accelerating something big anytime soon.  F=ma, meaning in order to get something that weighs one gram, like a paperclip to accelerate to the same degree as they do the protons, you would need about 2x10^24 times the force.  That notation just means a 2 with 24 zeros after it.  The reason for this is that that is how much more mass a paperclip has then a proton.  An actual human isn't going to get anywhere close for a very long time.
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.
177169
If it has rest mass, it can't travel faster than light, because as it gets closer to lightspeed, more of the energy you're using to increase its speed is converted into an increase in mass, which of course makes it harder to increase its speed.  Lorentz and Fitzgerald worked out the equations a century ago, and they've been confirmed in particle accelerators.  See the link.
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.
24020
Neglecting the lengthy derivation of why light speed travel is impossible, the first postulate of relativity is that light has the same velocity regardless of how fast you're moving.  So, at ANY speed you can achieve in your car, when you turn the lights on you'll see the waves moving away from you very very quickly.
1186042
That's the problem. You can't go beyond the speed of light. It is the cosmic speed limit. But if you could, then you'll be able to travel through time, past and future.
34913
It is not possible for any particle that has mass to travel faster than the speed of light. The reason has a lot to do with relativity. Because the faster you go, the slower time passes for you. So if you are at 80% of the speed of light, and launch a projectile in front of you at light speed, because of your slow passage through time, it will still appear to you to travel at light. Everything is relative, and because of that, certain constants like the speed of light never change.\n\nAlso, a particle with mass would achieve infinite weight at light speed. Since you can't obviously exceed infinite weight, you can't exceed light.\n\nThe ideas behind things like "warp speed" don't propose actually traveling faster than light. What they propose is taking shortcuts through space, kind of like skipping a stone across the surface of the water. Even "warp speed" is subject to the laws of relativity.
25993
No.  No terrestrial object can travel at the speed of light.  If you were traveling at the speed of light you would literally dissentigrate from the millions of pounds of air resistance pinning you down.
566668
No object that has mass can be accelerated to move at the speed of light. If you were somehow moving at 0.99c and then shown a flashlight, the velocity of the photons would not be 1.99c, it would just be c. The speed of light is invariant. The true formula at relativistic speeds is the following:\n\nV = (v+u) / (1 + vu/c²)\n\nWhen the velocites are not relativistic (i.e. throwing a ball out of a moving car) this approximates to V = v+u. So if you are moving toward something that is emitting photons at c, and you yourself are somehow also moving at c, the velocity you observe the photons to be moving is still just c. Try it in the formula: V = (c+c) / (1 + cc/c²) = c\n\nIt can be derived from special relativity or the Lorentz transformations.
3115
This is considered to be impossible.  As you APPROACH the speed of light, your energy and/or mass change.  If  you HIT the speed of light, your energy and mass approach zero and infinity.  So there would be nothing left of you to actually EXCEED the speed of light.\n\nBut I encourage you to try.  Write us and tell us how it goes!
644825
According to Special Relativity Theory, when you are transporting a mass at a speed near lightspeed, the energy needed to increase your speed rises to infinity. We can't provide the system with enough energy to reach the light of speed.\n\nEnergy, though, can travel at the speed of light because it has no mass. If we could transform a mass in energy (remember: E = m c^2) and re-create it at destination, travelling at lightspeed would be possible.\n\nBut, as Dark Helmet said, speed of light is too slow. We need ludicrous speed!
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.
1061558
Moving faster than light isn't really the real issue for space travel as traveling AT the speed of light solves all the distance problems(unless you are interested in time travel!). Of course that in itself is a big challenge. If one could demass the vehicle then surely one could achieve the speed of light!!! Afterall photons do travel at this speed.\nBut we would do very well even with speeds like .99999c because time dilation will reduce the time required drastically. Have the science, just need the technology!
117448
From our current undestanding of physics, we cannot. That does not mean in 500 more years or 5000 more years we will not have a better understanding of physics that includes methods for travelling faster than the speed of light in a vaccuum. However, at the moment it looks very doubtful. \n\nWe have substantial evidence that special relativity is true from years of operating particle accelerators. From special relativity, it appears that it would require an infinite amount of energy to accelerate to the speed of light. The glib manner people here are discussing an infinite amount of energy tells me that people do not understand what infinite means. \n\nAn infinite amount of energy is more energy than the sun produces. It is more than the energy produced by a billion suns. It is more than the energy produced by a billion galaxies full of hundreds of billions of stars. It is more energy than would be produced if every particle in the universe (about 10^70, the Eddington Number) was converted into a star like our sun. In fact, it is an INFINITELY greater amount of energy than 10^70 suns would produce. \n\nIf something is going at a speed greater than the speed of light in a vacuum (tachyonic speeds), then presumably the formulae we have for special relativity would not apply. There has been some occasional attempts to look for tachyons (particles going faster than the speed of light), but they have never been reliably discovered. \n\nThere are postulated entities called wormholes that might enable this kind of travel. Of course, we have no evidence for them at all.\n\nHowever, our understanding of physics is still very crude. We do not understand dark matter. Unifited field theory is still unproven. Even if it is proven, we do not understand the consequences of it (a lot of technology came from unifying electricity and magnetism). We do not understand what happens in black holes. We do not understand how the quantum world and gravity fit together. Even in quantum electrodynamics, which is viewed as settled and accepted, we end up performing illegal mathematical operations to get answers that agree with experiments. The role of the observer in quantum mechanics is not understood. We do not understand quantum teleportation very well. We do not understand BCS theory and its instantaneous coupling very well. We do not understand the apparent accelerating expansion of the universe (a sort of anti-gravity). There are immense holes in our understanding. Therefore, I would not be too confident that our current physics means very much here. \n\nThe only way to address this, is to continue to enhance our basic understanding of the way the physical universe operates. This might not be as romantic as it appears in the movies, but the hard work has to be done.
72735
No it is not possible to travel faster than light because the equipment you try to use will not work. The fastest thing to probably work may be a fast car. But there is still no way to travel fater than the speed of light. Speed of light travels at about 7 miles per second. I hope this helps.
53622
Well, its absolutely impossible to travel at or faster then 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 slower than 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 be one step ahead of you.\n\nOf course, still, nothing can go faster then the speed of light because in the formula for time dialation(time slows down for an object moving close to the speed of light) t'=t/sqrt(1-v^2/c^2) where t' is the time passing for an outside observer, t is the time that passes for the object going at the high velocity, v is velocity, speed is the speed of light and ^2 is squared. (note: this formula is definately correct, it's part of einstein's theory of relativity and I've had to derive it myself for class in the past) so if v was bigger than c, you would have a number greater than one and therefore a negative number under a square root, which is impossible.