in case of relativity what is the problem when we are continuesly changing  frame of reference in twinpardox??
920732
No because, while time may pass at different rates for different people, they are all still "in the present."  You don't have one person in the past and one in the future.
447950
1.  According to the Special Theory of Relativity you can't travel as fast as the speed of light.\n\n2.  The General Theory of Relativity has to do with gravity, not what happens when you approach the speed of light.\n\n3.  If you could travel at the speed of light, the light from the sun could not catch up with you, no more than a pulse of light can catch up with another pulse of light.  So, you couldn't see the sun again.
233087
this is where relativity comes into play. It depends from what viewpoint. speed is always relative to a "fixed" point (which might not be so "fixed" after all). get my drift?
289731
Special Relativity?\n1) Laws of physics do not depend on reference frame\n2) Speed of light is independent of reference frame\n\nGeneral Relativity?\nAs above, but also that uniform acceleration in free space cannot be distinguished from uniform free fall due to gravity.\n\nTo get anything else other than these basic precepts you need a lot of maths. (Especially to a high level! 4-vectors :-)
874570
NO!!  If people would stop (mis)quoting half-remembered precepts here, and do a spot of THINKING, instead, we might get somewhere.\n\n1.  If a moving spherical ball directly hits an identical free, stationary ball head on in an elastic collision, the moving ball STOPS, and the previously stationary one heads off with the original velocity of the other.  So ALL of the moving ball's K.E. has been transferred to the other ball.  \n\nHere are two ways to see this:\n\n1a.  The device known somewhat indelicately to British schoolboys as "Newton's balls" (but in squeamish America as "The Swinging Wonder") provides an excellent table-top demonstration of this.  Most undergraduate physics instructors must haul this out from time to time.\n\n1b.  You can easily solve it analytically, but a thought experiment will also demonstrate it.  In the originally stationary ball's frame, let the other ball approach with speed v.  Now shift (with an appropriately directed speed of v/2) to the frame in which the two equal balls are simply approaching each other, each with a speed in this frame of that same v/2 (oppositely directed, of course)!  Clearly, from the symmetry of the situation, they'll bounce off each other with the same (oppositely directed) speeds in this frame, still of v/2.  Now go back to the original frame: the previously moving ball is now completely stationary, while the originally stationary one is haring off with speed v.  (You may need to make little sketches of what is happening as viewed successively from each of these frames, to see this; I admit that that's what I did.)\n\n2a.  A similar approach can be used to solve the general case for an arbitrary ratio of masses, m (initially moving)/M (initially stationary).  Hint: have the balls approach one another in their center of mass frame with equal but opposite momenta of mv and  MV.  They'll clearly bounce off one another in such a frame, retaining the same values of their respective (but now oppositely directed) speeds.  Then you can do the other frame-jugglings from there. \n\nHowever, this analytical approach, done accurately, is a tedious mess.  So, to appreciate the general problem more physically, consider just the following:\n\n2b.  The case of m << M.\n\nConsider the "equal but opposite momentum" frame for these two balls, in which MV = mv.  This means that if ball M is VERY MASSIVE, the speed it will have in such a frame, V = (m/M)v; that is, it's VERY SMALL compared to little puny m's high speed.\n\nSo, transforming to the frame in which M itself (the big guy) is initially stationary takes only a speed shift of O(m/M)v.  (In fact identically so.)  This only affects the speed of puny m minutely, so m's initial K.E. is still of order O(m v^2).  (There's no need to do picky constant book-keeping for these purposes.)  \n\nNow after the collision: In the original frame, Big M is now moving (and in fact at 2V if you think about it.)  But, being loose about the constants, M's K.E is only O(MV^2).  \n\nSo, the ratio (m's K.E.)/(M's K.E.) ~ (mv^2)/(MV^2)\n\n= (m/M)(M/m)^2 (since mv = MV)\n\n= M/m.\n\nBINGO!  The little bugger still carries by far the larger amount of the kinetic energy.  The massive ball (i) moves sluggishly, and (ii) because  K.E. involves both mass but also the SQUARE of the speed, the TWO POWERS of (small) speed more than cancel out the effect of its (large) mass.\n\nThis is a well-known fact in particle collision theory, that little particles basically bounce off big ones.  \n\nYou could also say that it's well-known in "space billiards": when spacecraft head close to Jupiter to receive a "gravitational sling-shot effect" that sends them off to the outermost planets.  \n\nIt's more complicated because of 3-D effects there, but analogous frame-shifting methods can be used to show that the spacecraft can pick up considerable speed AND change
890719
Why shouldn't they be the same?  The distance between the Earth and the Sun doesn't change much in one day.  And even if you argue that the rotation of the Earth gives is a relative speed that should be added to (or substracted from) the speed of light, you're forgetting that the speed of light is a constant.  You can't add or remove anything to it.  If you're on a train going at the speed of light and you turn on a flashlight, the "total relative speed" of that light won't be twice the speed of light.\n\nAs for how can this speed me mesured, there's an experiment that uses mirrors and a laser.  Those flat mirrors are glued around a cylinder and they rotate.  (It could also be a rotating screen with holes in it.) When the mirror is positionned right, the light comes back to the laser.  Knowing the distance between the mirror and knowing the frequency of the rotation, we can calculate the speed of light by mesuring how much times it takes for the light to go to the mirror and come back.  TRY FIZEAU OR FOUCAULT ON GOOGLE.  He's the guy who did that.
103856
Newton' and Einstein's on relativity
641394
As weird as it sounds, the theory of relativity says that if you are in a car traveling at 200,000,000 m/s with the headlights on, then the light from those headlights will pass a person standing still at 299,792,458 m/s and not 499,792,458 m/s. And if that stationary person shines a light at your car, you will see his light approaching you at 299,792,458 m/s and not 499,792,458 m/s.\n\nThe theory is so weird that numerous scientists have done numerous experiments to test it. The most famous of these experiments is the Michelson-Morley Experiment. All experiments have confirmed that this strange prediction of relativity is true.\n\nBelieve it or not!
385849
i was gonna suggest my physics book. it dedicates one chapter to relativity and Lorentz transformation equations are there.\nIt's University Physics by Young and Freedman.
306574
The important principle in this theory is:\n\nThe speed of light is not affected by the speed of the source emitting this light.\n \nThat is: “Once light is emitted from a source it moves in vacuum with a constant speed.\n\nSpeed of a matter and the speed of light are measured by measuring length and time.   But light is energy; whereas the source is a matter.\n\nIf both observers; one at rest and another moving; says that light’s speed is same for both, there are only two possibilities; 1. Both must be at rest or 2. Time and length must be different for the two observers. \n\nBut one observer sees that the other is moving with a speed relative to him. Therefore, time and length must be different for the two observers.\nThe other consequence is that mass is also affected by its speed. \n\nThe one at rest will observe that time and the length are shortened for a moving object such that the speed of light is the same for both frames of reference. \n\nSince the moving observer observes that the other one is moving and he is at rest he will say in the other man’s reference frame time and length are shortened such that the speed of light is the same for both frames of reference. \n\nThis is the theory of relativity.
876226
Visit this link for a good explanation:\n\nhttp://en.wikipedia.org/wiki/Theory_of_relativity
929095
Yes it is consistent with Special Relativity. K is not advocating time travel or travelling faster than the speed of light, nor any other Relativity flaunting theory. He is merely stating you can not live in the past, nor understand life by predicting the future.
378252
Frame of reference is essentially the frame of the observer. Say you are watching a train moving on the tracks from the outside..then for you the frame of reference is the outside of the train, but say an armadillo is watching the same train but is also simultaneously hitching a ride on it, then its frame of reference is inside the train. To make this clearer, frame of reference is the position of the observation post. \n\nA good example to make frame of reference clearer follows:\n\nSay there are two trains running side by side with the same speed. A person who is inside one of the trains looks out the window and sees the other train at rest, because from where he's watching or his frame of reference, the train isn't moving (concept of relative velocity), but for an observer outside, the train is obviously moving with some speed, because HIS frame of reference is at rest with respect to the train.\n\nI hope I have made myself clear.\nAyerhs
178453
Ignore the other retards who answered this.  This is actually a very intelligent question.  If you look into Einstein's theory of special relativity, you will see that no matter how fast you go (including light speed itself) light will always appear to be traveling at the same rate to you.  That means that you would still observe your headlights the same as usual.  They would still be ahead of you.  That also means that your time is slowing down greatly.  If there were a video camera on you while you were traveling this fast and someone were watching you on a monitor from the comfort of their own home, it would appear to them that you are almost frozen in time because your time reference would be so slow.  To you, your time would seem to go by at a normal pace.
118693
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.
687103
GPS is affected by General Relativity.  If it did not take into account gravitational time dilation, it would be giving people lots of wrong answers!  This is one area where if all we had was Newtonian mechanics, we would not have succeeded.  Even Special Relativity would not be enough to get the right answers.\n\nThis also confirms that, even if General Relativity is not the final answer, it is close enough to be useful!
24853
There are many ways to approach this problem. First, a quick and easy way:\n\nLet's agree that Alice is in frame A and Bob is in frame B.\n\nIf they both go on a trip and come back at the same time, as measured by Chuck who stayed home, then based on special relativity we can all agree that whomever was traveling closer to the speed of light on their trip will have a clock that's behind everyone else's (ignore accelerations for simplicity). So, if Alice traveled faster then her clock would be behind even Bob's clock. Based on this you must logically conclude that Alice would have observed Bob's clock ticking FASTER, not slower THAN HER OWN if she somehow viewed him in transit. Of course, Chuck would have seen both their clocks running slowly, but Alice's more slowly than Bob's.\n\nSome things are relative but you have some invariants, namely spacetime and the speed of light. Even if observers don't agree when things happened, the events are still fixed, in one position in spacetime. Einstein said that individually space and time are relative but you still have an absolute from which to measure, and that's spacetime. All entities are moving through spacetime at the speed of light (c). That's right, even you, but most of that velocity is directed through time. If an object were to have a zero velocity in space then its speed through time (the 4th dimension) is c. As you increase your speed through space some of your speed through time is diverted (but the vector total is always c) and thus time appears to slow down for you as observed by someone at rest in space.\nThe point being that there IS an absolute from which to measure so if Bob were traveling slower than Alice then Alice would see Bob's clock ticking faster than hers but slower than the stationary clock.\n\nI didn't quote any sources but most of my current conception of relativity came from an excellent book: "The Fabric of the Cosmos" by Brian Greene.