Is the theory of realtivity appicable on at the speeds of light? If not, what are the examples in daily life?
405952
Ask around if any of your friends have a GPS system.  There is your example of a daily-life example of the theory of relativity.  The Global Positioning System would not be able to give you very accurate locations if it did not take the corrections to time and distance from both special, and general reletivity into account.  I am pretty sure that it is the first piece of public consumer-grade equiptment that relies on our understanding of General Relativity.
13401
It's true that the speed of light is constant no matter what speed at which you or the source is moving.  This is a fundamental postulate of relativity, and there is no explination.  It's just accepted because our experiments indicate that it is true.  You used the formula "lights speed + X = actual speed"  this type of velocity addition is called "Galilean".  It turns out that speeds don't actually add that way.  Far out.\n\nWhere is the rest of the energy? Good question.  The frequency of the light you observe from the sun DOES depend on how fast you and it are moving.  The energy of each photon is given by E = hf, where f is the frequency of light.
144613
light rays do not move faster or slower than the speed of light.  the speed of light is the speed of light, period.\n\nthat said, light often travels *slower* than c, which is a constant defined as the speed of light IN A VACUUM, approximately 3x10^8 m/s.  here is a way you can actually observe some honest-to-god light traveling slower than c:\n\nstep 1.  find a window.\nstep 2.  look at it.\n\ncongratulations, you have observed light traveling slower than c.  in ANY medium (air, glass, water - you name it) the speed of light is slower than the speed of light in a vacuum.  \n\nin fact, the so-called index of refraction (n, which equals 1.4 for glass) is defined as the ratio of c to the speed of light in that material.  generally, denser materials have a higher index of refraction, and people have been able to make light go REALLY slow by making some very dense materials.  all of this is perfectly consistent with general relativity.\n\nas for FASTER than c:  under certain conditions, it is possible to make photons with a "phase velocity" that is greater than c.  however, when people speak of the speed of light, they usually refer to the "group velocity".  the distinction between phase velocity and group velocity is kind of technical; but phase velocity refers to the speed at which the individual phase fronts propagate through space.  \n\nit is possible to make these phase fronts go faster than c; but because the energy or information or whatever carried by the light travels at the group velocity, the actual speed (as far as stuff like general relativity is concerned) is still less than c.\n\nanyway, all of these results are entirely consistent with general relativity.  in fact, i don't know of any published results of a scientific experiment which are not consistent with GR.  \n\nthe fact that einstein's theory, largely concocted out of the blue from basic principles and logical reasoning, has stood the test of time for so many years is a testament to the genius of the man's work.\n\nhere are some links to learn about phase velocity, group velocity and the speed of light:\nhttp://en.wikipedia.org/wiki/Group_velocity\nhttp://physicsweb.org/articles/news/4/7/8/1
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No.\n\nIt seems like it ought to be different, doesn't it?  But the genius of Einstein's discovery was that the speed of light is a constant, and that it is the limiting speed of the universe.  Literally everything else--even time itself--will change in order to keep the speed of light constant (approximately 186,000 miles per second).  \n\nIt is a difficult concept to get your mind around, but it's been more than 90 years since Einstein did this work, and every experiment done since then has confirmed it.\n\nGood luck!!
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Einstein’s Special Theory of Relativity started with two postulates: 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 isn’t too worrisome, but the second seems trickier.  It’s certaonly not intuitively obvious, but it makes sense from both a theoretical and an observational perspective.  Observational because the Michelson-Morley experiment (and others) detected no change in the velocity of light when measured from a moving frame of reference; theoretical because Maxwell’s Equations yield a specific value for the velocity of light.\n\nWhen Einstein considered Maxwell’s Equations, he realized that they don’t allow for a “standing wave” solution, which is what a light wave would look like if you were travelling at the speed of light.  So he already sensed there would be a problem with travelling at very high speeds.  Indeed, when you re-work the addition of velocities, it comes out to be not simple addition, but a fraction that never gets larger than c.  \n\nThus, in the photon-photon collision you describe, each photon would “see” the other one travelling toward it with a velocity c.  (Although measuring velocities from a photon’s perspective is a little non-intuitive; you have to take the limit of the aforementioned addition formula, which causes some trepidation.)\n\nOh, and the ten-dimensional idea is just one among many…  No way yet to prove (or disprove) that one.\n\n\nRyan Wyatt\nRose Center for Earth & Space\nNew York, New York
1017047
I'm agreeing with chopperchopster.You won't loose anytime.As Eistein's Theory of Realitivity states:,in a revamped version \nSpecial 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 relative to the observer).
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http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/fast_light.html\n\nhave a look at this website
452909
Believe it or not, we already have it and use it everyday. I want to answer this in detail, but I cant disclose the true nature of how light travels until I publish.\nI will say that light that is propagated within a closed system can and does move at superluminal speeds relative to a location outside the closed system.\n\nI know-Everybody has a theory, but I can also explain why light bends at every instance without once referring to the fabric of space/time.\n\nWhat if Einstein was WRONG...errr...ok... (just so I dont offend anyone) not completely correct? What if light actually didnt travel by propelling itself into the electromagnetic field created by....itself? What if there was no such thing as a pure vacuum with zero atomic content? (by the way, there is no such vacuum.)\nResearch it, its true, there are always atoms left over to fill the space left by the vacated ones.\nDon't you find that at least a little interesting?  No such thing as a pure vacuum?
347791
Your example is actually a good one for how we know no one can travel faster than the speed of light.  The people on the boat would measure the same speed for the beam of light as those standing on the shore.\n\nEinstein's theory of special relativity states that, regardless of your motion, light's speed remains constant.  Space and time warp in order to make light's speed constant from all perspectives.  As matter gets closer and closer to the speed of light, space stretches and time contracts, requiring infinite energy to reach the speed of light.  Only things with no mass (i. e. energy only) can travel at the speed of light, and nothing we know of can go faster.\n\nHowever, Einstein's theories do suggest that we could bend space and time to allow us to get around the speed of light.  We can't travel a trillion miles per second, but, with enough energy, we could shift some spot a trillion miles away to right next to us.
380806
Well, there are believed to be a class of unverified particles that surpass the speed of light called Tachyons.  If they move toward the object that created it then perhaps it could be true.  That's about the only way I could think to prove it since actually getting any object of study to surpass the speed of light would likely cause the big collapse and pull the entire universe on to one spot right were the object reached that speed and gain infinite mass as Einstein also theorized.\n\nOn the other hand, claiming anything as entirely impossible is foolish.  Science lives in absolutes and when thy get proven wrong, there always tons of frumpy old men in lab coats ready to restate that it was a theory though they called it a fact the day before.
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There is a big difference between predictions that the speed of sound could not be broken and that the speed of light cannot. It was always known that *some* things can go faster than sound. Bullets for example. The question was whether we would have the technology to get people to that speed.\n\nThe speed of light is very different since we haven't seen *anything* go faster than light in a vacuum. Nothing. Ever. Furthermore, the predictions of special relativity have been verified in particle accelerators when the particles are going to within a hundred thousandth of the speed of light.\n\nAs an example, at Fermilab protons are accelerated to energies of 2TeV. This is over 2000 times the rest mass of those protons. To accelerate something the mass of a *gram* to an equivalent speed would take about the energy of the largest hydrogen bomb ever exploded. This amount of energy would be needed for each gram to get to that speed, so multiply it by 75000 for a medium sized human. And that doesn't count the spaceship they would have to travel in!\n\nNow, this is how much energy is needed to get to speed we *know* about. To go faster would require even more. Unfortunately, we have never seen a wormhole of any type. But the predictions are that the energy requirements would be even more prohibitive than what I just described.
122048
Peple I know you want the points, but can you please not just make up answers out of whole cloth like that?\n\n>>>>>Massive objects cannot go the speed of light.\n\nYeah, they can. They can't accellarate to the speed of light but they can be created at lightspeed and continue on.\n\n>>>>>> However if they could, no you could not see, becuase the light could not go furthur then the builbs at the front of your car\n\nNonsense. The speed of light is constant for all frames of reference. From the FOR of the bulbs the light would be seen travelling away from it at lightspeed. \n\n>>>> You'd be seeing the light go by your side.\n\nNo, you would not be seeing the light by your side. You would still be seeing all light in the universe travelling away form you or towards you at the speed of light, just as you do at your current velocity\n>>>>>The light would not shine out in front of you because you are going the same speed.\n\nIncorrect. Light always sines out in front at lightspeed in the observers FOR. It makes no difference if that FOR is stationary or lightspeed itself.\n\nYou quite obviously made that answer up.\n\nws, this question seems to get asked here every couple of days. You can go back and have a look and see it answered quite well several times.\n\nIn brief,\n\nLight is funny stuff. Light always travels at the same speed relative to you, it doens't matter how fast you travel. \n\nIf you are sitting still and a person is going past you at light speed you can both look at exactly the same light beam, and it will be travelling at lightspeed compared to both of you.\n\nIf you are going at lightspeed and turn on the headlights the light will move away fomr you at lightspeed. If it strikes something it will be refelected back at lightspeed. If someone is sitting completely still beside you he will also see that light move away form him at lightspeed, and get reflected back at lightspeed.\n\nIt's weird stuff light, it doesn't behave like anything else. The answer to any question that asks how fast light is moving towards you or away from you is always "lightspeed". It doesn’t matter what else we add to the question, the answer is always 'lightspeed".\n\nSo if the light leaves the bulbs at lightspeed and gets reflected back at lightspeed does that mean you could see?\n\nProbably not. \n\nAlthough light doesn't change speed relative to the observer it does change wavelength. The faster you travel towards a light source the bluer it will look. \n\nAny object that your headlights strike will reflect the light back to you at lightspeed, that's OK. But because you are travelling towards the object at lightspeed the light will be shifted way, way towards the blue end of the spectrum. It would all be ultraviolet an X-rays. The human eye simply can't see those wavelengths. So plenty of light would be reflected back, but it wouldn't be visible to you. As a result it would all look dark.\n\n\n>>>>> if the interior light inside your car was on at\n>>>>> the time would you see that?\n\nYes. Because both you and it are travelling at the same speed it woulnd't be red shifted at all. Similarly because you and the interior of the car are travelling at the same speed you would be able to see the light reflected off that just fine as well.\n\nEverything in the universe that is travelling as fast as you will look normal.Everything outside will appear black.
77099
it would be called superluminal.\n\nyou can read more about it here - \nhttp://en.wikipedia.org/wiki/Faster_than_light
970195
This is one of the oldest questions in the world, after Einstein came out with his special relativity.  The answer is that no matter how fast you are going, your headlight beam is STILL shining ahead at the speed of light. This is exactly what the equations say, and it works.  If it wasn't true, then all the giant particle smashers in the world costing billions of dollars wouldn't even work.
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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!
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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.
547699
Its a myth that thought is particularly fast- We can measure the speed that signals travel along nerves, in the spinal cord, brain, etc, and it's around 20-60 meters/second.  Not nearly as fast as light (186,000 miles/second).  Photons don't "accelerate" to the speed of light-that speed is a stable property of photons, thus they are going that speed at the instant they are created-they dont start from motionlessness and speed up.\n*edit* Mich is right-light can be slowed and accelerated, but again, a photon upon creation does not accelerate to it's maximum speed (whatever that is given the medium that it's in)-it starts life going at that speed.  All light does *not* travel at 186,000 miles/sec- that is the speed of light in a vacuum-the speed varies with the medium that light is traveling through.  The speed of light through normal clear glass, for example, is around 120,000 miles/sec.