EquisDeXD Posted October 3, 2012 Share Posted October 3, 2012 As I understand it, as an object approaches the speed of light, time relative to the near-luminal object is said to slow down, but at a speed near the speed of light, the speed of light must still be the speed of light to any observer! As I understand it, somehow for some random reason, the relative distance between two objects increases the more you travel near the speed of light as to cause light to always be measures as traveling at the speed of light. What exactly causes this distance increase? The kinetic energy to accelerate something to near the speed of light has relative mass and therefore distorts the local fabric of space in such a way that 4 dimensional model light travels more distance before getting to the observer? Is there a more illustrated view of this? Link to comment Share on other sites More sharing options...
swansont Posted October 3, 2012 Share Posted October 3, 2012 As I understand it, as an object approaches the speed of light, time relative to the near-luminal object is said to slow down, but at a speed near the speed of light, the speed of light must still be the speed of light to any observer! As I understand it, somehow for some random reason, the relative distance between two objects increases the more you travel near the speed of light as to cause light to always be measures as traveling at the speed of light. What exactly causes this distance increase? The kinetic energy to accelerate something to near the speed of light has relative mass and therefore distorts the local fabric of space in such a way that 4 dimensional model light travels more distance before getting to the observer? Is there a more illustrated view of this? The length contracts, and the amount of that contraction matches the amount of the time dilation. It's all a consequence of the speed of light remaining the same. Link to comment Share on other sites More sharing options...
EquisDeXD Posted October 3, 2012 Author Share Posted October 3, 2012 The length contracts, and the amount of that contraction matches the amount of the time dilation. It's all a consequence of the speed of light remaining the same. So the length between any two objects "decreases" while the frame rate of events slows down the match that? Wouldn't that have no effect if they cancel out? And how does the speed of light being constant "make" that happen? Isn't it hte other way around? Doesn't the speed of light have to be constant becasuse of the length and dilation effect? Link to comment Share on other sites More sharing options...
swansont Posted October 3, 2012 Share Posted October 3, 2012 So the length between any two objects "decreases" while the frame rate of events slows down the match that? Wouldn't that have no effect if they cancel out? And how does the speed of light being constant "make" that happen? Isn't it hte other way around? Doesn't the speed of light have to be constant becasuse of the length and dilation effect? The effects are seen in the other frame, and you always get to say you are at rest. In your frame, time stays the same, and objects that are moving length contract, and you see their time as dilated. Link to comment Share on other sites More sharing options...
EquisDeXD Posted October 3, 2012 Author Share Posted October 3, 2012 The effects are seen in the other frame, and you always get to say you are at rest. In your frame, time stays the same, and objects that are moving length contract, and you see their time as dilated. So as an object approaches the speed of light going away from you ask you are going away from it, the distance between them somehow decreases (which wouldn't that make them seem to speed up to each other more?) but the frame rate decreases, what's the point of the length decreasing? Why isn't it purely the time dilation? And why isn't the length "increasing"? Link to comment Share on other sites More sharing options...
swansont Posted October 3, 2012 Share Posted October 3, 2012 So as an object approaches the speed of light going away from you ask you are going away from it, the distance between them somehow decreases (which wouldn't that make them seem to speed up to each other more?) but the frame rate decreases, what's the point of the length decreasing? Why isn't it purely the time dilation? And why isn't the length "increasing"? If the ship were trailing a cable with periodic markings, the cable, and those increments, would be shorter. The distance to the ship as measured by that cable would be shorter, but still increasing. Link to comment Share on other sites More sharing options...
ElasticCollision Posted October 3, 2012 Share Posted October 3, 2012 If the ship were trailing a cable with periodic markings, the cable, and those increments, would be shorter. The distance to the ship as measured by that cable would be shorter, but still increasing. I also have trouble with this whole subject. Here's what confuses me: If I were riding a photon from the sun to the earth (light-speed) then it takes me 8 minutes to get to earth. At the same time, if someone were observing me riding this photon from the sun to the earth, they would observe me take 8 minutes too. Now if instead I ran the distance, I would take hundreds of years and the observer would also see me take hundreds of years. Time doesn't change for me or the observer. I take the same amount of time from my own frame and from the observers frame. So as far as I can see, time isn't changing for either of us, I am simply changing my speed. Link to comment Share on other sites More sharing options...
ACG52 Posted October 3, 2012 Share Posted October 3, 2012 If I were riding a photon from the sun to the earth (light-speed) then it takes me 8 minutes to get to earth. Only as measured by a observer on earth. You, on the photon, would measure no time at all. Link to comment Share on other sites More sharing options...
ElasticCollision Posted October 3, 2012 Share Posted October 3, 2012 Only as measured by a observer on earth. You, on the photon, would measure no time at all. I don't understand how I would be measuring no time at all though. If I checked a watch on my wrist, the time for me to get from the sun to the Earth would be 8 minutes. The person observing me would also see me take 8 minutes. I know I'm wrong here, I just don't see why I'm wrong. That's what's frustrating me. Link to comment Share on other sites More sharing options...
EquisDeXD Posted October 3, 2012 Author Share Posted October 3, 2012 (edited) If the ship were trailing a cable with periodic markings, the cable, and those increments, would be shorter. The distance to the ship as measured by that cable would be shorter, but still increasing. Well, regardless of either case of stretching or shrinking, why does it happen just because I happen to travel near the speed of light? I travel near the speed of light, time slows down, and then for some reason increments of length decrease in some direction. Why? "because you always have to measure the speed of light as c" doesn't answer the question. Why do I always have to measure it at c? What is speeding up doing that's causing this length dilation? Edited October 3, 2012 by EquisDeXD Link to comment Share on other sites More sharing options...
ACG52 Posted October 3, 2012 Share Posted October 3, 2012 I don't understand how I would be measuring no time at all though. If I checked a watch on my wrist, the time for me to get from the sun to the Earth would be 8 minutes. The person observing me would also see me take 8 minutes. I know I'm wrong here, I just don't see why I'm wrong. That's what's frustrating me. Because you are ignoring relativistic time dilation. At the speed of light, time dilates to a stand still (of course, nothing with mass can achieve lightspeed). http://en.wikipedia.org/wiki/Time_dilation Link to comment Share on other sites More sharing options...
ElasticCollision Posted October 3, 2012 Share Posted October 3, 2012 I travel near the speed of light, time slows down, and then for some reason increments of length decrease in some direction. Why? "because you always have to measure the speed of light as c" doesn't answer the question. Why do I always have to measure it at c? What is speeding up doing that's causing this length dilation? I think this video will help you. It explains the length contraction as well as time dilation. Link to comment Share on other sites More sharing options...
ACG52 Posted October 3, 2012 Share Posted October 3, 2012 Why do I always have to measure it at c? You don't really have a choice. Light travels at the same velocity in all frames of reference, regardless of the relative motion of those frames. In order for this to be so, and it is, both space and time are not absolute, but relative. You keep asking why, and the answer is that's the way the universe works. Link to comment Share on other sites More sharing options...
ElasticCollision Posted October 3, 2012 Share Posted October 3, 2012 Because you are ignoring relativistic time dilation. At the speed of light, time dilates to a stand still (of course, nothing with mass can achieve lightspeed). http://en.wikipedia....i/Time_dilation I feel like I'm hijacking this thread with my own question, so I will end it here. I'm not ignoring time dilation though, I simply don't understand it. Link to comment Share on other sites More sharing options...
EquisDeXD Posted October 3, 2012 Author Share Posted October 3, 2012 (edited) It answers time dilation (though not very well in my opinion, I already know time dilation and I still had trouble understanding him), but I still don't see how it explains length dilation. It I guess explains "that" length dilation happens, but I still don't see "why" it happens, he just keeps using the example "because the speed of light is constant", like even in the speedometer he put c as the limit, but never explained why it always has to be c, why length mysteriously contracts just because you want to approach c. You travel slower...so the rate at which you measure increments of length of an object approaching the speed of light contract? I guess it would be easier if it was more visual, like the fabric of space got "pinched" inward the more an object travels at the speed of light which changed the distance light would have to travel to reach an object or also the length between intervals. Actually, I still don't completely understand why time dilation occurs in the traditional sense. The way I had always thought of it is that time flows at the speed of light, and the closer you approach light, the smaller the relative speed between time and the object is decreasing, like one car moving at 12 miles per hour and one car moving at 14 miles per hour to an outside observer. The car going 12 should measure the other one going at 2 miles per hour while the outside world flies by at 12 miles per our while to an outside observer both go at 12 and 14, but this doesn't seem to match up with the analogies in other sources. Edited October 4, 2012 by EquisDeXD Link to comment Share on other sites More sharing options...
Janus Posted October 3, 2012 Share Posted October 3, 2012 I don't understand how I would be measuring no time at all though. If I checked a watch on my wrist, the time for me to get from the sun to the Earth would be 8 minutes. The person observing me would also see me take 8 minutes. I know I'm wrong here, I just don't see why I'm wrong. That's what's frustrating me. For you, The distance between Earth and Sun would have contracted to zero, which is why you deem it to take no time. For someone watching you from the Earth, it takes 8 mins by their watch, but your watch remains frozen at 0 for the entire trip. Now, it is also true, that for you, no time would would pass on the Earth clock either. However there is a third effect in Relativity, known as the Relativity of Simultaneity. To explain this, imagine that there is a clock at the Sun also, and that according to the Earth observer, this clock reads the same time as his own. According to you, this clock will read 8 min behind the clock at Earth. So when you leave the Sun, according to you it is already 8 min later at the Earth. One thing should be said here. You really can't talk about what would be seen while traveling "at" the speed of light, only about traveling at near the speed of light. The speed of light itself is not a valid reference frame from which you can make observations. Link to comment Share on other sites More sharing options...
ACG52 Posted October 4, 2012 Share Posted October 4, 2012 You must also always keep in mind that all velocities (except light) are relative to some other reference frame. You might be in a spaceship traveling at .9c relative to earth, but relative to the ship keeping pace with you, you're not moving at all. Link to comment Share on other sites More sharing options...
EquisDeXD Posted October 4, 2012 Author Share Posted October 4, 2012 (edited) For you, The distance between Earth and Sun would have contracted to zero, which is why you deem it to take no time. For someone watching you from the Earth, it takes 8 mins by their watch, but your watch remains frozen at 0 for the entire trip. But if time is stopped, how can you be traveling distance over time? Wouldn't that be x/0? To explain this, imagine that there is a clock at the Sun also, and that according to the Earth observer, this clock reads the same time as his own. According to you, this clock will read 8 min behind the clock at Earth. So when you leave the Sun, according to you it is already 8 min later at the Earth. So if I traveled near the speed of light from the sun, my clock would count normally, but everyone else's clock would appear slower, while to everyone else, my clock would seem slower...how does that decrease the length between any two objects if one is traveling near the speed of light? I still don't see why traveling that speed makes time dilation in the graphical sense. I guess, as you approach the speed of light, you'd have to be gaining kinetic energy to travel at a greater speed, which in tern gives an object more relative mass which distorts the fabric of space a greater amount, I could see how this would work with length contraction, but how would it explain time dilation if its an accurate reason? Or, why do different gravitational masses slow time differently relative to other observer? Edited October 4, 2012 by EquisDeXD Link to comment Share on other sites More sharing options...
zapatos Posted October 4, 2012 Share Posted October 4, 2012 But if time is stopped, how can you be traveling distance over time? Wouldn't that be x/0? I'm happy to have anyone correct any errors I make here, but... I think the point Janus was trying to make was that a photon does not experience time. Since you cannot actually travel at c this is not an issue. So if I traveled near the speed of light from the sun, my clock would count normally, but everyone else's clock would appear slower, while to everyone else, my clock would seem slower...how does that decrease the length between any two objects if one is traveling near the speed of light? I still don't see why traveling that speed makes time dilation in the graphical sense. I guess, as you approach the speed of light, you'd have to be gaining kinetic energy to travel at a greater speed, which in tern gives an object more relative mass which distorts the fabric of space a greater amount, I could see how this would work with length contraction, but how would it explain time dilation if its an accurate reason? Or, why do different gravitational masses slow time differently relative to other observer? I think the issue is that it is not really a cause and effect situation. Going faster does not actually change distance and time, it changes the way you measure distance and time. An object travelling at near c relative to us measures our clock to be slower than does an object travelling at a velocity of 0 relative to us. Our clock is not actually doing two different things simultaneously. It is just viewed differently depending on relative velocity. The realization that light travels at c to all observers led to the realization that time and distance must not be constant as was assumed. There is no reason 'why' this is so, it just is. No one can answer why gravity has the force it does either. But experiments have verified that time, space, and gravity act as they do. 1 Link to comment Share on other sites More sharing options...
EquisDeXD Posted October 4, 2012 Author Share Posted October 4, 2012 (edited) I'm happy to have anyone correct any errors I make here, but... I think the point Janus was trying to make was that a photon does not experience time. Since you cannot actually travel at c this is not an issue. Well if to the reference of light time is stopped, how does light actually get from point a to point b? It instantaneously gets to all points because of infinite length contraction? There is no reason 'why' this is so, it just is. No one can answer why gravity has the force it does either. But experiments have verified that time, space, and gravity act as they do. No, there's answers I just don't understand them. There was some kind of answer on a graph, like the x axis is time, and y axis is space, and as you travel through more space, you travel through less time since the slope increases as you go a greater amount of space per second, using triangulation. Edited October 4, 2012 by EquisDeXD Link to comment Share on other sites More sharing options...
zapatos Posted October 4, 2012 Share Posted October 4, 2012 No, there's answers I just don't understand them. There was some kind of answer on a graph, like the x axis is time, and y axis is space, and as you travel through more space, you travel through less time since the slope increases as you go a greater amount of space per second, using triangulation. Well, best of luck finding out 'why' space and time act as they do, but perhaps an explanation of 'how' the speed of light is observed to be independent of reference frame would be of interest if you are not already familiar with it. In physics, the Lorentz transformation or Lorentz-Fitzgerald transformation describes how, according to the theory of special relativity, different measurements of space and time by two observers can be converted into the measurements observed in either frame of reference. It is named after the Dutch physicist Hendrik Lorentz. It reflects the fact that observers moving at different velocities may measure different distances, elapsed times, and even different orderings of events. The Lorentz transformation was originally the result of attempts by Lorentz and others to explain how the speed of light was observed to be independent of the reference frame, and to understand the symmetries of the laws of electromagnetism. Albert Einstein later re-derived the transformation from his postulates of special relativity. The Lorentz transformation supersedes the Galilean transformation of Newtonian physics, which assumes an absolute space and time (see Galilean relativity). According to special relativity, the Galilean transformation is a good approximation only at relative speeds much smaller than the speed of light. http://en.wikipedia.org/wiki/Lorentz_transformation Link to comment Share on other sites More sharing options...
ACG52 Posted October 4, 2012 Share Posted October 4, 2012 It instantaneously gets to all points because of infinite length contraction? From light's frame of reference, yes. Link to comment Share on other sites More sharing options...
EquisDeXD Posted October 4, 2012 Author Share Posted October 4, 2012 (edited) From light's frame of reference, yes. So if it get's to all points instantaneously, isn't it in a superposition of all points it would be determined to be in, in future time coordinates? If it get's to a location in literally 0 time with literally 0 distance to travel from its frame of reference, then that means it also get's to the next place its suppose to get to at the same time because it also takes 0 time to get to the next place, which means all light should be in every single location all the time...if that's actually true. But perhaps it works differently for light because it doesn't have mass. Edited October 4, 2012 by EquisDeXD Link to comment Share on other sites More sharing options...
ACG52 Posted October 4, 2012 Share Posted October 4, 2012 which means all light should be in every single location all the time From the photon's point of view, yes. It takes zero time IN THE PHOTON'S FRAME OF REFERENCE Link to comment Share on other sites More sharing options...
StringJunky Posted October 4, 2012 Share Posted October 4, 2012 Quoting DH: A rest frame of some object is a reference frame in which the object's velocity is zero. One of the key axioms of special relativity is that light moves at c in all reference frames. The rest frame of a photon would require the photon to be at rest (velocity=0) and moving at c (velocity=299792458 m/s). That of course is contradictory. In other words, the concept doesn't make sense. Forget about looking at things from the frame of a photon. 2 Link to comment Share on other sites More sharing options...
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