Is Einstein's Theory of Relativity correct? If so, why is it a Theory, not a Law?
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Theories come in two forms. A theory in the scientific sense doesn't have anything to do with whether or not it is supported by evidence, contradicted by the evidence,or even if the theory is well liked. It only has to do with the way the theory is structured and the way it functions. Just because a theory is a scientific theory does not mean that the scientific community currently accepts it. There are many theories that are scientific, but have been rejected by the scientific community because the evidence is strongly against it. Phenomenological theories are observational generalizations of data. These theories only describe the processes that nature keeps repeating but do not explain their causes or mechanisms. Phenomenological theories are also called scientific laws, physical laws, and natural laws. Newton’s third law is one example of a phenomenological theory. It states that every action has an equal and opposite reaction. Explanatory theories attempt to explain the observations rather than generalize them. Whereas laws are descriptions of observational regularities, explanatory theories are conceptual constructions to explain why the data exist. For example, the atomic theory explains why we see certain observations. The same could be said with DNA and relativity. Explanatory theories are particularly helpful in such cases where the entities (like atoms, DNA, and so forth) cannot be directly observed.\n\nScientists at Massachusetts Institute of Technology and the National Institute of Standards and Technology (NIST) reported in Dec. 22, 2005 of the journal Nature that Albert Einstein's formula, E=mc2, was correct. \n\nThe researchers used an instrument developed by NIST (Gaithersburg, Md.) called GAMS4 (click link below for image) to again confirm that energy and matter are related: energy (E) equals mass (m) times the square of the speed of light (c2). Full article at  http://www.eetimes.com/news/latest/showArticle.jhtml;jsessionid=PK0GDDIIC0P4EQSNDBESKHA?articleID=175007386\n\nImage at\nhttp://i.cmpnet.com/eet/news/online/2005/12/image1_122005.jpg
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To answer your question literally - Yes! I'm quite sure\nsomeone knows what the theory of relativity is.
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First of all, it is fundementally impossible to go at the speed of light. Therefore, the question as stated is invalid.\n\nHowever, it may or may not surprise you that, indeed, it is THAT VERY QUESTION that Albert Einstein surmised in 1896.  Here is his quote:\n"If I pursue a beam of light with the velocity c (velocity of light in a vacuum), I should observe such a beam of light as a spatially oscillatory electromagnetic field at rest.  However, there seems to be no such thing, whether on the basis of experience or according to Maxwell's equations.  From the very beginning it appeared to me intuitively clear that, judged from the standpoint of such an observer, everything would have to happen according to the same laws as for an observer who, relative to the earth, was at rest.  For how, otherwise, should the first observer know, i.e., be able to determine, that he is in a state of fast uniform motion?  One sees that in this paradox the germ of the special relativity theory is already contained.  Today everyone knows, of course, that all attempts to clarify this paradox satisfactorily were condemned to failure as long as the axiom of the absolute character of time, viz., of a simultaneous, unrecognizedly was anchored in the unconscious.  Clearly to recognize this axiom and its arbitrary character really implies already the solution to the problem."\n\nTherefore, In 1905 he realised how it could be that light always goes at the same speed no matter how fast you go.  Events that are simultaneous in one reference frame will happen at different times in another that has a velocity relative to the first.  Space and time cannot be taken as absolute.  On this basis Einstein constructed the theory of special relativity, which has since been well confirmed by experiment.\n\nNow, I can't explain any more than that.  So there :P
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Well I would use examples and predictions. \n\nFirst I would say, there are TWO theories of relativity: the special theory, and the general theory. \n\nSpecial Theory\n--------------\n\nRather than go into an explanation of the why the speed of light is constant in all inertial frames, I would mention the predictions of the special theory. \n\n1. Nothing can go faster than the speed of light, which is like a speed limit for the universe. I think most children have seen speed limits, so this might seem familiar to them.  \n\n2. If you are in a space ship going very fast, close to the speed of light, time will slow down and you will age more slowly.\n\n3. If you are in a space ship going very fast, close to the speed of light, you will get shorter from front to back. You will become flattened like a pancake.\n\n4. If you are in a space ship going very fast, close to the speed of light, your mass will increase, so that if you were weighed you would be heavier. \n\nGeneral Theory\n---------------\n\nRather than talking about the curvature of space-time, I would again use the predictions of the general theory. \n\n1. When something is very heavy, it has a lot of gravity, and it can even pull on light. In this way, light can be bent. \n\n2. If the object is very heavy, the light is unable to get away at all, so we call the object a black hole. \n\nThis is good enough to start and whet their appetites. If they want more detail, there is a HUGE amount of material out there.
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Einstein postulated that the speed of light would remain the same regardless of the inertial frame in which it is measured.  This contradicts classical physics, since if an object is moving at a velocity v, as measured in an inertial frame, and that inertial frame is moving with a velocity v2 with respect to a second inertial frame, then you should take the vector sum of the two velocities to determine the velocity of that object with respect to the second inertial frame.\n\nEinstein postulated that within an inertial frame the laws of classical physics held.  So, to make things work out Einstein calculated that time and space are distorted with velocity.  It is as though you and your brother are of different heights, but you both want to be the same height, so you take a rubber ruler and stretch it so you get the same measurement for the two of you.\n\nIn this way you always measure the speed of light as the same value, no matter how fast the source of the light is moving with respect to you.  You adjust the rubber ruler so that what you want to believe remains true.
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Laws are accepted a-priori as the way nature works.  There is no way to prove a law, but some things must be accepted as fundamental upon which theories can be built.  There are few laws but many theories.  Laws are usually simple expressions such as conservation of mass/energy, conservation of momentum, but some (such as the second law of thermodynamics) are complicated.\n\nTheories are more complex constructs intended to explain why certain things happen the way they do, and the best theories allow the prediction of the outcome of experiments. They usually involve mathematical expressions,  A concept reaches the status of theory after much experimental verification along with general acceptance in the scientific community.\n\nBy the way, laws do change.  Before the 20th century  there was a conservation of mass law and a conservation of energy law.  After relativity showed mass-energy equivalence, that law had to be changed.
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That version of Einsteins theory of general relativity is only for particles with 0 momentum.  for ones that do wave momentum but no mas it is\nE= pc (p=momentum, c= speed of light)\n\nbut yes, it is only applicable for at the speed of light hence it only has c, the speed of light, and not v, another speed.
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Oh for Pete's sake people, please don't answer if you don't know what you are talking about.\n\n\nNewton certainly did have a theory of relativity, as you would have discovered if you had bothered with even the most basic web search.\n\nNewtonian relativity in simple terms, hmmm.\n\nIn simple terms Newtonian relativity simply says that all motion is relative to the observer, and not absolute. As a result we can and must choose which object is moving and which is at rest, it isn't chosen for us.\n\nFor example, if I throw a ball at your head at 10km/hr it will have EXACTLY the same effect as if I tied the ball to a string and you ran it to it at 10 km/hr. It will hurt you just as much, and the ball will bounce just as far off your head. \n\nWe normally assume that when I throw the ball it is moving, and when you run into a ball it is stationary. Netwonian relativity simply says there is no reason to assume that, and no way to prove it. For all we can prove mathematically you and I might be moving when I throw the ball, and the ball might stand still.\n\nSo why do we all KNOW the thrown ball moved? Because we refer to things that happen outside of our little world of ball, you and me. Only by referring to something else not involved, like the ground, can we say who moves and who stands still.  \n\nAnd that is essentially where we get the term Relativitivity from. All movement has to be described relative to a point outside of the actions we are describing. It can't be described bythe actual actions. Only by saying that the ground stands still and the ball moves relative to the ground cn we say that the ball moved. And only by saying that the ground stands still and you and I don't move relative to the ground can we say that you and I are stationary.\n\nWhere it gets interesting in practial terms is when our reference point is also moving. What happens if we are in a moving train doing 100km/hr and I throw a ball at your head? For you and me exactly the same thing as if we were standing on the ground, because we are making all our claculations relative to the floor of the train. The floor of the trainis our reference point. Since you and I don't move relative to the floor, and the ball does move relative to the floor there is no  difefrence t standing in the ground. \n\nBut if you were standing on the ground and I was in the train and threw the ball at you the efect would be very different for you. The ball would now hit you at the speed of the train + the 10km/hr I threw it at you. It would hit you doing 110km/hr and possibly kill you. Because our only common reference point is the ground that you stand on we have t do all our claculations form that point. W eignore the floor of the trian I am standing on an measure the speed of the ball relative to the ground only.\n\nAnd that's Newtonian relativity in a nutshell. There are all sorts of mathemetical descriptions and qualifiers, but you said you wanted it in simple terms.
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Relativity says no such thing.  Where do you get taht from?
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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?
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That is exactly the question Einstein asked himself that led to the special theory of relativity in 1905.\n\nEssentially, "the-dude"'s answer above is right.  \n\nHe wrote an excellent little book explaning how it (and general relativity) works.  It was written for college kids who don't know much about Physics, so if you have some basic math you can understand it pretty easily.\n\nI highly suggest reading it...\n\nHey...I found it below...enjoy the read.
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There are actually two parts to the "theory of relativity".\n\nThe General and the Special Relativity.\nGeneral relativity was developed by Einstein in the years 1911 - 1915. General relativity is a geometrical theory which postulates that the presence of matter "curves" spacetime, and this curvature affects the path of free particles (and even the path of light). It uses the mathematics of differential geometry and tensors in order to describe gravitation without the use of the force of gravity. This theory considers all observers to be equivalent, not only those moving with uniform speed.\n\nAlbert Einstein's 1905 paper "On the Electrodynamics of Moving Bodies" introduced the special theory of relativity. Special relativity considers that observers in inertial reference frames, which are in uniform motion relative to one another, cannot perform any experiment to determine which one of them is "stationary". This is known as the principle of relativity. While this principle was not new to Albert Einstein's work, he found that including electromagnetism in this principle required a new formalism with many surprising consequences. In particular, it required the speed of light in a vacuum to be the same for all these observers, regardless of their motion or the motion of the source of the light.\n\nOne of the strengths of special relativity is that it can be derived from only two premises:\n\n    * The laws of physics are the same in any inertial frame of reference. This means that the laws of physics observed by a hypothetical observer traveling with a relativistic particle must be the same as those observed by an observer who is stationary in the laboratory.\n    * The speed of light in a vacuum is constant (specifically, 299,792,458 meters per second).
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Your understanding of relativity is wrong.\n\nYou cannot even accelerate to the speed of light, let alone beyond it. Relativity predicts that infinite enrgy would be required to accelerate a mass to the speed of light. IT makes no predictions that would make travel backwards in time possible.
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Actually, the way modern physicists think of it, the question doesn’t quite make sense.  The problem is the “traveling at the speed of light” part, because one of the conclusions of Einstein’s Special Theory of Relativity is that nothing can travel that fast.\n\nInterestingly, though, its was consideration of a similar question that started Einstein down the path toward relativity… Light is best described by Maxwell’s Equations, which predict that any experiement will measure same speed for light in a vacuum.  When Einstein thought about traveling at the speed of light, he realized that there must be a problem.  In fact, Maxwell’s Equations don’t allow for a “standing wave” solution, which is what a light wave would look like if you were traveling at the speed of light. \n\nSo Einsten took things back to basics, which is what he was good at.  Let’s start with what he actually said… His Special Theory of Relativity started with two postulates (or assumptions): 1) that the laws of physics are observed to be the same in any non-accelerated “reference frame” and 2) that the speed of light (c) is observed to be the same for all observers.\n\nThe first assumption basically says that as long as you’re traveling at a constant speed, all your experiments will give the same results.  That seems reasonable.  But the thing about the speed of light always being the same sounds a little odd: the Michelson-Morley experiment (and others) had detected no change in the speed of light when measured from a moving frame of reference, however, and as I already mentioned, Maxwell’s Equations yield a specific value for the velocity of light.\n\nStarting from there, Einstein worked out how to add velocities together, and it comes out to be not simple addition, but a fraction that never gets larger than c. Basically, what happens is that the measurement of time and distance changes, so a physical object (e.g., a spaceship) can never achieve lightspeed.\n\nSo”  That’s a long-winded way of saying that your headlights themselves can’t travel at the speed of light.  If we want to think about them traveling very, very close to the speed of light, however, we realize that the light they emit still travels at lightspeed (as measured by the fast-moving headlights themselves), so they stil work the same way headlights would work on a car traveling much slower.\n\n\nRyan Wyatt\nRose Center for Earth & Space\nNew York, New York
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In brief: in Newton's physics, space and time are taught of as frameworks independent from the observer, and the gravity is a force. This means that, whoever observes a certain phenomenon, it has a given and fixed duration and a given and fixed size in space.\n\nIn Einstein's physics, space and time are entangled into the so-called spacetime and their measurements depend on the observer; moreover, the gravity is a distortion of the spacetime. Different observers will report different spacetime measurements for the same phenomenon and different geometrical properties of the same objects in different gravity fields.\n\nEinstein's physics, in principle, replaces Newton's physics completely, as it gives more accurate predictions with respect to experiments. However, the difference between the two is negligible at ordinary speed and gravity forces. Being Newton's physics mathematically much simpler, people prefer using it as long as they can, reserving the application of Relativity mainly to astrophysics and particle physics, where the differences are significant.
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The theory of relativity is being used in Fermi lab, U.S. to "create" either energy or new matter from energy.  Newton's laws only define motion, but they do not explain why some of the mysteries of the solar sytem or the universe occur.  With Einstein's theory, however, these mysteries become clearer.  We understand more why they occur this way and can predict how much energy is being "created" by calculating for how much matter is "lost."  Fermi lab is working to create anti-matter, combine it with matter to create energy, and utilizing the energy into more matter -- it's one of their big projects.  I'm sure they're testing for more than that, but it's the overview of what they are doing.
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There are plenty of good websites that answer this question, for any knowledge level. The concept is complex enough that you won’t get a meaningful answer here.\n\nIn horribly oversimplified terms Relativity simply states two things.\n\nOne that there is no universal ‘at rest point’, it all depends on how you choose to define it. You sit in a car doing 100mph and I stand beside the road. Normally we assume that you are in motion and I am at rest. Relativity states that we can just as accurately say that you and the car are at rest and I am moving at 100mph. Alternatively, we normally believe that the Earth orbits the sun and the Moon orbits the Earth. Relativity states that it is just as accurate to say that the Earth orbits the moon and the sun orbits the Earth, or we could say that we all orbit some imaginary point in between all three. It is all a matter of choice what we define as being the fixed point.\n\nThe second is that the speed of light is constant regardless of whether you are at rest or moving, and regardless of how fast you move. If you are sitting in a car doing 9/10 of lightspeed and are going past me standing still beside the road and we both look at exactly the same light beam shining down the road we will both see that light beam travelling away from us at exactly the speed of light relative to both of us. You don’t see it slowed down just because you are travelling almost as fast as it is. It will move away form me just as fast as it moves away form you.\n\nThose are the basics, and they aren’t all that hard to understand, even if they don’t seem to make much sense. What Einstein did was sit down and think really hard about the logical consequences of those two points.\n\n\n>>>>>>also is it true gravity on sun is greater than earth?\n\nYes.\n\n>>>>>if it is so ,sun would have had sucken all planets\n>>>> in it!!\n\n\nNo. Just as the Earth doesn't suck the moon in despite having much higher gravity.\n\nThe planets orbitthe Sun. In simple terms that means they are constantly falling around the sun in a ciruclar pattern.\n\nThe best way I have heard this described for the layman  is to imagine yourself throwing a heavy weight like a shotput. You could only throw it a few metres. Now imagine standingon the roof of a house and throwing that same shotput. This time it will go much further before it hits the gorund. Now go to the top of a rally high cliff and throw it. This time the shotput will travel for 20 or 30 metres before it hits the ground.\n\nThe higher you go the further somehting thrown will travel before it hits the ground. And if you go high enough the object will travel right around the world and back to where it starts before it hits the ground. It will continue falling forever. \n\nThe planets are doing exactly that WRT the sun. We are constantly flaling aorund the sun, but we can't be sucked in because we are falling from such a great height.