anything and everything can and is moving faster than c

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danhezee

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Why do people belief that the speed of light is a barrier that matter cannot pass? I think everything moves faster than light<br /><br />I have a thought experiment for everyone to consider. First of all, everything that I am gonna say is based on the idea that speed is relative; meaning for speed to be measured it has to have a point of reference. Let’s say, that the universe is expanding at speeds close to the speed of light, for instance 0.7 c to 0.9 c, and someone on the north pole observes a galaxy A moving at 0.7c directly away from the earth; then later someone at the south pole observe a galaxy B moving at 0.8c directly from earth which so happens to be exactly 180 degrees from galaxy A. From our perspective neither galaxy is moving faster than light but if you measure the speed at which B moves from A; B is achieving 1.5c speeds. <br /><br />That being said isn’t safe to assume that our galaxy is moving away from a reference point we can not detect at a superluminal speed. Also, if you agree with what I am saying it would mean the whole universe is larger than currently thought. Think about it for a bit and lets debate it.<br /><br />Also, I have another question about light speed with another thought experiment. I am in a space ship and it accelerated to 0.9999999999999999c (because that is the limit:(:(), and I am sitting outside the ship in my space suit playing with a baseball and I throw in a forward direction at 0.0000000000000002c faster than the ship. Now why doesn’t physics allow for the ball to go 1.000000000000001c when referenced to the earth? What do the current models say about that scenario?<br /> <div class="Discussion_UserSignature"> </div>
 
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larper

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Because that is the way the universe works. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>
 
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SpeedFreek

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<font color="yellow">Let’s say, that the universe is expanding at speeds close to the speed of light</font><br /><br />Expanding at speeds close to the speed of light <b>over what distance?</b> Over certain distances it is <i>apparently</i> expanding at an almost infinitesimally small rate. At another distance it is <i>apparently</i> expanding at the speed of light. At yet another distance it is <i>apparently</i> expanding superluminally.<br /><br />Do you understand the concept of the metric expansion of space?<br /><br />It is indeed possible for an observer in a galaxy to see another galaxy receding at speeds faster than light, over a certain distance (the Hubble limit). This is not due to either galaxy actually moving faster than light, but due to the space in between them expanding metrically, where the metric that defines distance changes over time.<br /><br />Superluminal speeds due to metric expansion do not violate general relativity, as neither galaxy is moving through inertia.<br /><br />As for your other question - a little more complicated. As described by relativity, if you are travelling at 0.99999~c and shine a light in front of you, <i>you see the light moving away at the speed of light!</i> You see it move away from you at 186,000 miles per second faster than yourself!<br /><br />Whatever speed you travel at, you always measure the speed of light as 186,000 miles per second faster than yourself. It is what everybody else sees that differs, and that's where relativity comes in. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>
 
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yevaud

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And there are your relative Frames of Motion for you. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>
 
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danhezee

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so what you are saying is there is no magical barrier preventing the ball i throw from accelerating pass the speed of light?<br /><br />I have always heard that nothing can go faster than light. yet i have always been confused because speed is based on a reference point.<br /><br />since metric expansion is being used to destroy my thought experiment, lol. how about when a star blows up, it sends matter in all direction at close to c speeds. well the same is true for particles 180 degrees from each other as my galaxy thought experiment. <br /> <div class="Discussion_UserSignature"> </div>
 
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larper

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Nope. You keep changing frames of reference on yourself. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>
 
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SpeedFreek

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I am saying there is a magic barrier that stops you moving faster than light, or even <b>at</b> light speed. Nothing can <i>move</i> at the speed of light except light itself, due to the infinite amount of energy required to accelerate <i>any</i> mass to that velocity.<br /><br />If we were looking at 2 spaceships, one travelling at 0.9c and one travelling at 0.2c, and both shone a light out in front of them, we would measure both ships lights as travelling at 299,792,458 m/s and each ship would measure their own light as travelling at 299,792,458 m/s faster than themselves. How can this be possible?<br /><br />Well it seems that the way the universe works is that the speed of light is the constant, and it is time that changes to compensate!<br /><br />One of the effects described by special relativity is time-dilation, where the faster the speed you accelerate to, the slower you experience time. So your measurement of the speed of light will be, unbeknownst to you, different from someone elses measurement who didnt accelerate.<br /><br />As a grossly simplified example, if we see a ship travel at 90% of c, then we see it's front light travel 10% faster than itself, so we see its light travel at c. But on that ship time is slowed, and their seconds pass ten times slower than ours (but they cannot tell as their watches seem to tick as normal, to them), so when they measure that light, they see it travelling at c too! <img src="/images/icons/wink.gif" /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>
 
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vogon13

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Hey, I'll be on your side with this idea if you can explain the 17/23 correlation.<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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R1

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theres a short video of Einstein and Bertrand in spaceships trying to demonstrate this<br />in youtube.com under a 'time dilation' search. <div class="Discussion_UserSignature"> </div>
 
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dragon04

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<font color="yellow">so what you are saying is there is no magical barrier preventing the ball i throw from accelerating pass the speed of light?</font><br /><br />There most certainly is a barrier. E=mc^2 clearly states that no mass can be accelerated beyond <i>c</i> because there is not enough energy in the Universe to make it happen.<br /><br />This is exactly why we still can't explain why entire galaxies at the most extreme distances are receding from each other at apparent superluminal velocities.<br /><br />Physics as we know it does not allow for it.<br /><br />The problem is that as you try to <b>accelerate</b> your ball to light speed, it takes increasing amounts of energy to do so. That's because as your ball accelerates, its relative mass increases. Which means it takes more and more energy to keep accelerating it.<br /><br />Even light (photons) cannot travel faster than light. Were that the case, then we could see light that was actually emitted from distances many times farther than we could observe it. IOW, we could see that the Universe was much bigger than it observably is.<br /><br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>
 
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danhezee

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why does inertia break down at light speed?? my ship isnt accelerating it has reached its maximum velocity so that means everything is moving at close to c, like 10 mph under. i know can i throw a baseball 40 mph. so why cant i throw the baseball past 30 mph over c?<br /><br />why is it that when i ride in a car at any speed i can throw a ball straight up and down and not have to compensate for the speed, except for when the car is accelerating, but you are telling me that close to c i would need generate a tremendous amount of energy to throw my ball at 40 mph?<br /><br />the earth spins at 1000 mph and and revolves at 66,660 mph and hell our galaxy is moving at an incredibly fast speed yet i dont feel like i have to overcome those speeds to throw my ball. <br /><br /> <div class="Discussion_UserSignature"> </div>
 
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larper

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You keep changing frames of references. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>
 
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heyscottie

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The problem is that, contrary to what you might think, you CANNOT add speeds like you are trying to do. And this effect is not only when we are moving close to light speed, but all the time. It only becomes large enough to be measurable when we get to such high velocities.<br /><br />Because of time dilation and length contraction, 0.9c + 0.2 c does not equal 1.1 c like you might want it to.<br /><br />Just look up relativistic velocity addition, and you will have the equations that fell out of special relativity to give you the right answer. A short examination of the equations will show you that for any two numbers less than c you add together, you always get a number less than c back out.<br /><br />Sorry, but the universe conspires against us at this point.
 
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danhezee

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well i guess i am gonna have to try to understand why time dilation breaks the laws of inertia and basic addition because that seems to be everyone's answer. <div class="Discussion_UserSignature"> </div>
 
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lukman

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<blockquote><font class="small">In reply to:</font><hr /><p> As for your other question - a little more complicated. As described by relativity, if you are travelling at 0.99999~c and shine a light in front of you, you see the light moving away at the speed of light! You see it move away from you at 186,000 miles per second faster than yourself! <p><hr /></p></p></blockquote><br /><br />But for outside observer, the light is moving very slowly away from the source. Due to time dilation, the person become very slow. Say if the speed is C less 1m/s, we can be sure that the person will be extreme slow, surely cant walk faster than 1m/s. How if there is a stand still enemy intercept the person with a rocket misslie, at the speed and position, the impact was calculated at 1 sec. Means that the person at C less 1m/s will be a stting duck and unable to react due to time dilation? <div class="Discussion_UserSignature"> </div>
 
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xmo1

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I've asked, and no one has corrected me yet so...<br /><br />I think the bonding evaporates at the speed of light with the result being entropy. In other words, you can't travel faster than the thing holding you together. <div class="Discussion_UserSignature"> <p>DenniSys.com</p> </div>
 
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vandivx

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<blockquote><font class="small">In reply to:</font><hr /><p>As a grossly simplified example, if we see a ship travel at 90% of c, then we see it's front light travel 10% faster than itself, so we see its light travel at c. But on that ship time is slowed, and their seconds pass ten times slower than ours (but they cannot tell as their watches seem to tick as normal, to them), so when they measure that light, they see it travelling at c too! <p><hr /></p></p></blockquote><br /><br />suppose they also happen to have a rear light <img src="/images/icons/wink.gif" /><br /><br />vanDivX <div class="Discussion_UserSignature"> </div>
 
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jgreimer

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While it is true trying to accelerate a massive object to the speed of light would take an infinite amount of energy, that is not the reason objects cannot be accelerated to c. The real reason is the dilation of time and the contraction of length at relativistic speeds according to the formula sqrt(1 – v^2) where v is expressed as a fraction of c. Objects accelerated by gravity such as the ones falling into a blackhole do not gain mass yet they too cannot reach c.<br /><br />So what about two spaceships approaching each other, each traveling at 0.9 c, how fast will one see the other approaching? In Newtonian physics the two velocities are simply added but not in relativity. In relativity the two velocities are added using the formula v=(a + b)/(1 + ab/c^2). One spaceship sees the other approaching at (0.9 + 0.9)/(1+.81) or about 0.994475 c.<br />
 
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vandivx

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<blockquote><font class="small">In reply to:</font><hr /><p>suppose they also happen to have a rear light <p><hr /></p></p></blockquote><br /><br />speedfreek, anybody? <br /><br />that was a challenge, a glove thrown you know<br /><br />vanDivX<br /><br /> <div class="Discussion_UserSignature"> </div>
 
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Anonymous

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Case 1:<br />And, that is why, we are travelling in time.<br />Time, is going on.....and it proves that we travel in time.<br /><br />Case 2:<br />If we are travelling so, the question that arises is that can we travel in time faster than we are actually doing. <div class="Discussion_UserSignature"> <strong><font size="2"><p align="center"><br /><img id="a9529085-d63d-481e-9277-832ea5d58917" src="http://sitelife.space.com/ver1.0/Content/images/store/9/2/a9529085-d63d-481e-9277-832ea5d58917.Large.gif" alt="blog post photo" /><br /><font color="#339966">Oops! this is my alien friend.</font></p><p align="center"><font color="#ff6600">╬→Ť╠╣є ’ M€ ’<br />╬→ Ðôŵņ2Ëãřŧĥ ๑<br />╬→ ЙДm€ :Varsha<br /></font></p></font></strong> </div>
 
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Anonymous

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But if we are moving at c speed then our mass should be constantly changing, is it happening? <div class="Discussion_UserSignature"> <strong><font size="2"><p align="center"><br /><img id="a9529085-d63d-481e-9277-832ea5d58917" src="http://sitelife.space.com/ver1.0/Content/images/store/9/2/a9529085-d63d-481e-9277-832ea5d58917.Large.gif" alt="blog post photo" /><br /><font color="#339966">Oops! this is my alien friend.</font></p><p align="center"><font color="#ff6600">╬→Ť╠╣є ’ M€ ’<br />╬→ Ðôŵņ2Ëãřŧĥ ๑<br />╬→ ЙДm€ :Varsha<br /></font></p></font></strong> </div>
 
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Saiph

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the main reason <i>why</i> there's a light speed barrier rests upon an observational fact:<br /><br />Light, in all frames of reference (i.e. no matter how the observer is moving) is <i>always</i> measured to be C (in a vacuum of course). If you take the reason for this being that space and time are not absolute (and are malleable in scale), as opposed to another reason (such as aether theory) the light speed barrier is a direct consequence of this observation.<br /><br />If you want to understand why and how this is, I highly suggest reading up on special relativity, as any text on the subject will directly address your questions.<br /><br />Also note that a particle with mass <i>can</i> go at the speed of light, or faster than the speed of light. However they <i>cannot</i> make a transition between these speeds. I.e. a < C particle cannot be made to move > C or = C, and same with all the other cases.<br /><br />Throw in the fact that we observe no particles with mass moving at C, or faster than C (theorized tachyons) we aren't really incorrect in saying that matter can't move faster than C, we're just being over general.<br /><br /><br />And some breif answers to your "throwing a ball" question: You're going at .9c, and launch an object at .2c. You will measure the ball's speed to be .2c, especially once I point out that you don't have to consider yourself moving at all, and can say you're stationary (not at 0.9c) while everyone else is moving. However, outside observers, who see you at 0.9c, and themselves stationary, will see you launch the ball not at 0.2c, but at a slower speed, that does not add with 0.9c to exceed C (I don't feel like doing the simple relativisitc velocity addtion, I've got a cold). Instead it'll be something like 0.95c.<br /><br />So, now we have a problem right? You say the ball is at 0.2c, they say it's only going 0.95c with your velocity added on, who's right? You both are, because speed is relative, and you're in different referen <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
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SpeedFreek

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Sorry vanDivX, we just got a puppy a couple of days ago, so I have not had much time recently!<br /><br /><font color="yellow"><i>"suppose they also happen to have a rear light?"</i></font><br /><br />Well, we would measure <i>that</i> light as travelling at c, too.<br /><br /><i>If you throw a ball forward from a moving car then that ball goes faster relative to the ground than if you throw it from a car that is not moving. If you throw the ball backward from a moving car, then it goes slower relative to the ground than if you throw it from a stationary car. <b>This effect does not hold for light.</b> Whether you shine a light forward or backward from a moving car, the light always goes equally fast relative to the ground (and also relative to you in the car!). You cannot tell how fast the sender moves from the speed at which light reaches you. If distance and time were independent and absolute, then you would be able to tell something about the speed of the sender from the speed of the received signal, so distance and time are apparently not universal.</i><br /><br />From here.<br /><br />I made a small mistake in my previous example, in that I said the ship would see the light at the front recede from it at 300,000 km/s due to time-dilation affecting its measurements, when I should have said that time-dilation combined with <b>length contraction</b> was the actual reason for that. But the ship travelling at 90% of c <i>would</i> measure its front light receding at 300,000 km/s, and the same would apply for that ships measurements of the light travelling away behind it - it would measure it receding at 300,000 km/s.<br /><br />The observer measures those lights travelling at 300,000 km/s, in both directions, 10% of c faster than the ship for the light in front as the ship is already travelling at 90% of c. To the observer the light <i>behind</i> would propagate at c f <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>
 
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vandivx

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<blockquote><font class="small">In reply to:</font><hr /><p>But that does not, of course, mean that the ship sees the light behind it recede at 190% of c! No, the ship has length contraction and time dilation affecting its calculations. Space seems shortened in front of it and lengthened behind it, and that ships seconds tick away at a slower rate. So the ship has less seconds in which to measure the light in front of it, compared to the observer. That, and the fact that distance is shorter in front of it, means that the ship calculates the light as travelling away from it at 300,000 km/s in front (because distance is shortened) and 300,000 km/s behind (because distance is lengthened). Both measurements would also be affected by the same amount of time-dilation.<br /><br />You knew I had forgotten about length contraction, didn't you! Thanks for asking the question that would help me see my omission. <p><hr /></p></p></blockquote><br /><br />as it happens I didn't harp at the length contraction as we are talking in rough terms anyway but yes you need both time dilation and length contraction to have everything work out right<br /><br />reason I asked about rear lights is because everybody is always concerned with something traveling FTL and so is always talking about forward motion (vitness the guy throwing a ball forward, it never came to him to ask about the ball thrown backwards and I don't know about anybody who ever asked)<br /><br />I assumed you were giving standard official explanation here but you talk about 'length dilation' ("distance is lengthened"), I thought SR knows only length contraction<br /><br />but even then, allowing your length lengthening <img src="/images/icons/smile.gif" /> you still don't have time speeding up (opposite of time dilation - which again is the only effect regarding time that SR knows, I suppose such effect could be called time contraction, i.e., seconds would tick faster) and to explain the rear light question I posed you would need precisely the op <div class="Discussion_UserSignature"> </div>
 
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dsir

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In response to the apparent confoundedness expressed above in several posts by <b>danhezee</b>, I'll offer this.<br /><br />The answers to your two concerns are easy. I think some of your confusion is based on thinking of motion as being relative to space, proper. Your first analogy is good though, because it refers to Earth as the base station. One galaxy is receding at .7c due Northward, while another is receding at .8c due Southward. So you'd think that galaxy A is travelling at 1.5c relative to galaxy B but no, it isn't. According to your thesis, no radio signal could emit from galaxy A and reach B, but you're wrong, as it definitely would reach B. From the perspective of galaxy A (eg. per the reckoning of its sapient inhabitants), they are stock still, Earth is receding away at .7c; but galaxy B is receding at .96c. The observers stationed on A cannot take unqualified the word of any Earthling about how fast galaxy B is moving, because Earth is in relative motion (at near lightspeed), and so the Lorentz Transform adjustments need to be applied to Earthlings' measures to correct them to the Galaxy A perspective. <br /><br />As for your other quandary, about tossing the baseball, there you must first rid any notion of the initial .9999999c velocity being an "absolute", or being relative to "space, proper". Let's just say it's relative to Earth again. So, to the spaceship crew, they are utterly unmoving -- it's Earth that is receding so fast. When you toss the baseball at 40 MPH, it goes just that, 40 MPH away from you, UNIMPEDED. The fact that Earth happens to be scooting away in the opposite direction obviously can't have any bearing on how that plays out. So, you ask, how fast is the baseball moving as gauged by Earthlings? You must use the Addition of Velocities formula, which is simply a derivative of the plain Lorentz Transformation. The sum of two velocities u and v (when expressed as fractions of lightspeed) is (u+v)/(1+uv).<br /><br />
 
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