To satisfy E=MC^2  an item would have infinite mass if travellind at the speed of light and therefore.....?
459968
Since photons according to relativity interpretation are massless ,they cannot exist as a mass. \n\nSince photons is a mathematical invention which no one really knows what it is.\nHence cannot follow gravity laws.\nFor an entity to follow the laws of gravity ,Be Einstein's or Newton's , it must exist as a mass structure.\n\nYou question is very logical. It contradicts the reasoning that if a mass made up of atoms and when we apply power to make it move at the speed of light ,it will soak mass just like a sponge from its surrounding. Since mass is Energy according to relativity it will soak all the energy around it. \nSince as you say,    E=M *gamma *C^2  is infinite ,it makes sense that Energy would have to come from an infinite source.\n\nThey say mass increases with velocity.This has to.\n magically come from the inside of the atoms or is it a rain of mass that comes from the outside.The atoms become very massive, and at the same time shrink in dimension it the direction of motion only as they approach the speed of light.\n\nThese interpretation of Relativity are very difficult to make real sense out of it.\n\nThat brings to question is the theory of relativity misinterpreted  by scientists?. They did not understand it then,and I have my doubts about the present.Let alone really Understanding What Energy exactly represents!
954813
Yeah, it's E=mc^2 and it relates energy and mass.  E is energy, m is mass, c is the speed of light (celeritas).  The equation could come useful in physics, like atomic physics.\n\nWhat did you wanted to know?
1033843
e=mc^2\n\ne (energy)=m (mass) times c (the speed of light) squared
292835
According to Einstein's Theory of Relativity, E=MC squared, where E is energy, M is mass, and C is the speed of light, in order for something to approach C, it must have very little mass and a hell of a lot of energy.  However, if something has enough energy to approach the speed of light, its mass would be infinite. This means that even if you weigh 0.00000001 grams, which is basically nothing, when you approach the speed of light, the infinite energy that you have will make your mass infinite also (if you don't already burn up, that is)...you'll weigh more than everything in this universe combined.  You'll rip a hole through this universe like a heavy piece of weight through a thin piece of paper, then you'll be like a black hole sucking everything in.  However, since the energy in this universe is limited (and not infinite), if you somehow can harness ALL the energy in this universe to use for travelling, you'll only move as fast as the speed of light...that is, there's simply not enough energy in this whole universe to allow you to go faster than light by even .00001%, so we're basically "trapped" in this universe, unless we can find an alternate "exotic" energy source from another universe to use, or somehow "bend" space so that we can go from one point to another instantaneously. Now, photons are "light particles" that travels AT the speed of light, so they are the fastest things in this universe, so you may be wondering, "Well, since they travel as fast as light shouldn't they be very heavy also?"....and the answer is NO !!!   because although photons have the exact amount of available energy to travel as fast as light  (because they ARE light), they have absolutely zero mass....That's why when you shine a flashlight at your friend's forehead while he sleeps or something, you won't punch a hole through his head....because photons weigh NOTHING.
667965
No, at the speed of light, the space the arrow would occupy is everything, therefore I'd only be hit by an infinite fraction of the arrow, ergo nothing would be felt, noticed nor seen. Furthermore, the arrow would take an infinite amount of time to get anywhere, although it would, from the arrows point of view, still move at the speed of light.\n\n[edit]: After having read all the other posts, I realize that I need to bring some proof of my statement since everyone are making a clueless guess. Thusly, I present to you a link to wikipedia, which fortunately validates my school/university teachings. If you search for the Lorentz Transformation (the factor of which an object stretches in relation to its velocity), you will find that at low speed this factor is very close to 1 (meaning no noticable change in stretch). Though, at a speed infinitely close to the speed of light, the factor also reaches infinity, meaning the object will have an infinite size (but not infinite mass), which means that the atoms of the arrow will hit everything at once, causing its finite momentum (movement energy) to be exerted upon every single atom in the entire universe. Not only does this mean that an arrow with the velocity of light cannot hit a single target, but it also means that nothing will notice anything other than the arrow suddenly disappearing. Furthermore, special relativity states that nothing can achieve the speed of light within a finite time-frame, making you question very theorical.\n\nI would also like to point out the sheer lunacy of the average 'answerer' here on Answers. If you take my answer as being truthful, which you should given the high support within modern physics (which I am also a student of), you would notice that only a small fraction of the members of Answers aren't guessing cluelessly. This is quite sad, and I advice you to regard every answer with suspicion, and use google/wikipedia for valification.
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.
81056
ja :), that's a good one. E=mc^2 talks about the equivalence between matter and energy; c is just the constant that joins them both ..you won't attain a c ¨velocity¨out of it ; you'll just have to use \n E=mc^2/(sqrt(1-(v/c)^2) ( Is it Lorenz transf?) and I think Xav was pretty clear with his explanation! :)
274522
The energy in matter is equal to its mass times the square of the speed of light.
915960
According to Einstein's relativity, for matter (..mass) to move AT the speed of light would require infinite energy to gain that speed, and the mass would increase to infinity, both things being impossible.
588727
The equation E=MC2 is the derivation from Einstein's relativity theory. this is not a case of the classic mechanics. this equation explains the value of energy of an atom. \n\nE-> Energy\nM-> mass of the atom\nC-> speed of the light.\n\nin this only speed of the light is constant. the mass differs by frame to frame in accordance to theory of relativity. so the energy of the atoms also differs with frame to frame. but this equation is not fully correct and Lorentz had made corrections to it. \n\nAnybody who can prove this equation as a total wrong thing with strong evidences will be announced as the greatest of the universe..
471151
another one of einstein's equations is as follows:\nrelative mass = original mass divided by the square-root of "1-(velocity squared/speed of light squared)"\n\nyou can better picture the equation by going here:\nhttp://en.wikipedia.org/wiki/Mass-energy#Relativistic_mass\n\nexplained:\nas the object's velocity squared approached the same value of the speed of light squared, the phrase "v2-c2" would approach '1'. causing the entire bottom mathematical phrase to approach '0' because 1-1=0 :) \nas the bottom phrase approaches '0' the relative mass becomes almost infinite because anything divided by something so close to zero would experience a massive increase in value. example: 1/.01=100.  as .01 becomes smaller (approaches zero), the '100'(our hypothetical relative mass) goes -way- up (approaches infinity). \n\nremember that mathematics does not allow division by zero therefore anything having mass cannot attain the speed of light. because the energy required to accelerate near-infinite mass would itself be near infinite.
694183
First of all, since E = mc^2, you cannot have two massive, energyless bodies.  Secondly, by definition, they have a potential energy of \n.. R\n ∫(-GM1M2/R^2)dR, or GM1M2/R\n. 0\nwith respect to each other, so, again, they cannot be energyless.
624084
tut_einstein has the right idea here. A photon is an element that has no rest mass, and rest mass is what we speak of when talking about mass. But while traveling around at the speed of light it contributes to objects as if it does have mass. This is the relativistic mass that people are talking off. A photon though by definition and experiment is a massless entity. That doesnt mean it can't contribute to momentum and other forces. \n\nE=mc^2 is an equation that comes out of study of Einstein's theory of special relativity. This is meant to determine the conversion of energy into mass and vice versa. \n\nTaken from wikipedia:\nConversely, a single photon travelling in empty space cannot be considered to have an effective mass, m, according to the above equation. The reason is that such a photon cannot be measured in any way to be at "rest" and the formula above applies only to single particles when they are at rest. Photons are generally considered to be "massless," (i.e., they have no rest mass or invariant mass) even though they have varying amounts of energy.\n\nPhoton's cannot have mass because they cannot be at rest. The equation E=MC^2 as I have stated only applys to objects at rest. The total energy of a moving body is different it is calculated using the formula:\nE=(mc^2)/sqrt(1-v^2/c^2). If you solve for relative mass you can get the equation that E=m(realtice)c^2 and this equation is good for all particles moving or non moving. \n\nSo to sum it all up. A photon has no rest mass although it certainly has a relativistic mass when it is zipping through space at the speed of light.\n\nI hope that made sense
185055
The equations imply that it is impossible for any object with >0 rest mass to accelerate from below the speed of light up to exactly the speed of light. This is because, as has been mentioned, that would take an infinite amount of energy.\n\nThe equations don't prohibit an object traveling faster than the speed of light from the outset though. Photons have zero rest mass, and the instant they are created they are traveling at exactly c. If it were possible for a particle to exist that was traveling faster than c from the instant it was created, this would not be a problem for relativity. I'm not sure what it would imply about it's mass though. The name for such a particle is a tachyon (although there is no evidence these actually exist as far as I'm aware).
143269
As you approach the speed of light, your mass approached infinity... As your mass approaches infinity, it takes more force for you to accelerate... Therefore, I don't think it is possible for you to acchieve the speed of light...
28019
no. and light does not have mass. light is made up of little packets of energy called photons which are massless.\nthis is why it can't: lightspeed is the ultimate speed limit of the universe. 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) 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.
249306
Ask Einstein, the famous E=mc2 formula directly relates to your question.