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Thread: Constancy of speed of light - I don't believe it.

  1. #1 Constancy of speed of light - I don't believe it. 
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    The speed of light being independent on the velocity of the observer is a thing I find hard to accept.
    So I've created a theory for myself that I find much more plausible than the relativity theory.

    I say: light sources cast light rays at lots of different speeds. But the only light rays we are able to see and measure are those that meet us at approximately 299 792 458 m / s. If we move towards the light source, the slower light rays will hit us at that speed, if we move away we get to see the faster light rays. Only being able to see the light that meets us at a certain speed is what causes the illusion of light having a constant speed, independent of the velocity of the observer.

    Why do slower and faster light rays become invisible? I believe it's a frequency thing. Resonance and all that. Maybe light at 299 792 458 m / s has exactly the frequency to make protons, neutrons, quarks, leptons whatever resonate, so that the massless photons can get noticed at all.

    Unfortunately, I know too little about physics to even know if i just made a complete fool out of myself.
    Anyway, it would be great to get any feedback on this theory.


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  3. #2 Re: Constancy of speed of light - I don't believe it. 
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    Quote Originally Posted by igor
    The speed of light being independent on the velocity of the observer is a thing I find hard to accept.
    So I've created a theory for myself that I find much more plausible than the relativity theory.

    I say: light sources cast light rays at lots of different speeds. But the only light rays we are able to see and measure are those that meet us at approximately 299 792 458 m / s. If we move towards the light source, the slower light rays will hit us at that speed, if we move away we get to see the faster light rays. Only being able to see the light that meets us at a certain speed is what causes the illusion of light having a constant speed, independent of the velocity of the observer.

    Why do slower and faster light rays become invisible? I believe it's a frequency thing. Resonance and all that. Maybe light at 299 792 458 m / s has exactly the frequency to make protons, neutrons, quarks, leptons whatever resonate, so that the massless photons can get noticed at all.

    Unfortunately, I know too little about physics to even know if i just made a complete fool out of myself.
    Anyway, it would be great to get any feedback on this theory.
    It's certainly not a frequency thing, seeing as light at lots of different frequencoes travels at c. Besides that, I really don't see where this is going.


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  4. #3  
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    Interesting theory, and it's great that you're thinking outside the box. But, given all the great minds over the past century that have tackled this concept, I doubt that the commonly held theories will be overturned.

    Ron
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    Quote Originally Posted by Ron
    Interesting theory, and it's great that you're thinking outside the box. But, given all the great minds over the past century that have tackled this concept, I doubt that the commonly held theories will be overturned.

    Ron
    True. Just trying to keep my sanity. All that space time continuum stuff is twisting my brain.
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    Quote Originally Posted by Ron
    Interesting theory, and it's great that you're thinking outside the box. But, given all the great minds over the past century that have tackled this concept, I doubt that the commonly held theories will be overturned.
    Look at this. Some of the "commonly held theories" aren't what Einstein worked out years back.

    "In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position. Now we might think that as a consequence of this, the special theory of relativity and with it the whole theory of relativity would be laid in the dust. But in reality this is not the case. We can only conclude that the special theory of relativity cannot claim an unlimited domain of validity ; its results hold only so long as we are able to disregard the influences of gravitational fields on the phenomena (e.g. of light)." Albert Einstein (The General Theory of Relativity: Chapter 22 - A Few Inferences from the General Principle of Relativity)"

    Igor, light always travels at c in vacuo. We always measure it as 300,000 km/s. However gravitational time dilation means our seconds change measurably and demonstrably (look up GPS). So whilst we never measure anything other than 300,000km/s, c obviously and actually varies. That's all gravity is. A gradient in c. I'll be getting a "prize" for this eventually, but at present people tend to say I must be wrong because that's not what all the great minds of the previous century thought. And they're wrong about that too. Shrug.
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  7. #6  
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    What do I know. I'm just a caveman.

    Ron
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  8. #7 Re: Constancy of speed of light - I don't believe it. 
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    Quote Originally Posted by billiards
    Quote Originally Posted by igor
    The speed of light being independent on the velocity of the observer is a thing I find hard to accept.
    So I've created a theory for myself that I find much more plausible than the relativity theory.

    I say: light sources cast light rays at lots of different speeds. But the only light rays we are able to see and measure are those that meet us at approximately 299 792 458 m / s. If we move towards the light source, the slower light rays will hit us at that speed, if we move away we get to see the faster light rays. Only being able to see the light that meets us at a certain speed is what causes the illusion of light having a constant speed, independent of the velocity of the observer.

    Why do slower and faster light rays become invisible? I believe it's a frequency thing. Resonance and all that. Maybe light at 299 792 458 m / s has exactly the frequency to make protons, neutrons, quarks, leptons whatever resonate, so that the massless photons can get noticed at all.

    Unfortunately, I know too little about physics to even know if i just made a complete fool out of myself.
    Anyway, it would be great to get any feedback on this theory.
    It's certainly not a frequency thing, seeing as light at lots of different frequencoes travels at c. Besides that, I really don't see where this is going.
    If lightspeed wasn't constant, GPS wouldn't work, and a Policemans Speed Radar wouldn't work. More dangerously, Air Traffic Controll Radar wouldn't work.

    If light could only travel at one frequency, then Radio Transmitting Communications systems are pretty well down the drain too. Never mind the ILS Landing system which the entire principal is based on 2 radio beams of 2 different frequencys entering a phase interference relationship.


    Explain the ILS system using your theory:
    Here's a video about how such a thing works:

    http://www.youtube.com/watch?v=qTy0U3UVjGE


    GPS by the way works on timing how long a signal (light/EM radiation) takes to get from a satellite in orbit to an object on earth (or just above it) X 7. with a correction for small time dialation due to the satellite being further away from Earth (remember the satelite is in geostationary orbit, so isn't going "Faster" than the ground.)
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    if the speed of perceived light is constant (like I suggest) then GPS, speed radar and all that will still work. Unless you travel at 90.000 miles per second rather than somewhere between 50 to 900 miles per hour.
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  10. #9 Re: Constancy of speed of light - I don't believe it. 
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    Quote Originally Posted by musicalaviator
    If lightspeed wasn't constant, GPS wouldn't work, and a Policemans Speed Radar wouldn't work. More dangerously, Air Traffic Controll Radar wouldn't work.
    Actually there would be no space/time existing for anything to work or not work. The physical properties of mass and energy wouldn't allow for the universe as we know it.
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    Quote Originally Posted by Farsight
    That's all gravity is. A gradient in c.
    Oh people, beware! This is utter, utter gibberish. So much so, I can't even think how to refute it. Farsight, do you know what the strict definition of a gradient is? Looks like you don't. How can there be a "gradient in c"? It doesn't parse, in any language.
    I'll be getting a "prize" for this eventually,
    You hugely over-estimate your abilities, you arrogant fool. You may get a prize for the most consistent forum moron, but that's all.
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    I guess my post was gibberish too, but I just have a problem understanding one thing. Maybe I should elaborate and somebody might be able to explain this to me.

    From what I read, c is always the same speed relative to whatever.
    Now, in the world we know a car driving on the highway has it's speed relative to its starting point, relative to the road, but not relative to other cars driving on the highway. A car overtaking me at 100mph while I drive 80mph has a speed of 20mph relative to me.
    With light it's different, scientists seem to be saying (if I understood them right). If I move away from a light source at c*0.8, the photon won't overtake me at a relative speed of c*0.2 (the photons speed c minus my speed of c*0.8 ), but still at c.
    How is this possible?
    An explanation I read said that time flows differently for things in motion. Noticeably only at speeds we haven't yet achieved. So let's say I travel at c*0.8 and I see things in timelapse, so that the photon's speed of c*0.2 appears to be c again. That would mean that a photon coming from the opposite direction would meet me at c (the photons speed) + c*0.8 (my speed) * 5 (the time lapse factor) = c*8, wouldn't it?
    I don't understand. Can somebody help me with this?
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    Quote Originally Posted by igor
    I guess my post was gibberish too, but I just have a problem understanding one thing. Maybe I should elaborate and somebody might be able to explain this to me.

    From what I read, c is always the same speed relative to whatever.
    Now, in the world we know a car driving on the highway has it's speed relative to its starting point, relative to the road, but not relative to other cars driving on the highway. A car overtaking me at 100mph while I drive 80mph has a speed of 20mph relative to me.
    With light it's different, scientists seem to be saying (if I understood them right). If I move away from a light source at c*0.8, the photon won't overtake me at a relative speed of c*0.2 (the photons speed c minus my speed of c*0.8 ), but still at c.
    How is this possible?
    An explanation I read said that time flows differently for things in motion. Noticeably only at speeds we haven't yet achieved. So let's say I travel at c*0.8 and I see things in timelapse, so that the photon's speed of c*0.2 appears to be c again. That would mean that a photon coming from the opposite direction would meet me at c (the photons speed) + c*0.8 (my speed) * 5 (the time lapse factor) = c*8, wouldn't it?
    I don't understand. Can somebody help me with this?
    Not sure I understand your maths, that doesn't necessarily mean it's wrong, it might just be that I'm bad at maths! The principle of relativity is basically that any experiment conducted in an inertial frame of reference will have the same result as an otherwise identical experiment conducted in another inertial frame, the two frames might be moving relative to one another, yet the results of two experiments (say for example trying to find the speed of light) will theoretically be exactly the same.

    This means that when dealing with relative velocities, rather than using the more intuitive galilean velocity transformation (which it looks like you were trying to do), we should really use a Lorentz transformation. At velocities << c, the results of applying these different transformations are almost exactly the same, but they are quite different at higher velocities.
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    This was my understanding, although it may be wrong.

    A photon has 0 mass. Therefore it will travel as fast as possible. For some reason, which I don't know, it is bounded by c, 300 000m/s. Because of time dialation, when you go fast, your second slows down. but light does not experience time and still travells at 300 000m/s. The only difference is now your seeing it based on your longer second.

    This could be wrong but it was my understanding based on a thread I started on this topic, I'll try to dig it up and post the link.

    edit: Here it is:
    http://www.thescienceforum.com/viewt...asc&highlight=

    maybe you'll make something out of it.

    By the way, does this have anything to do with the uncertainty principle? Because if you see light going c based on your speed, and someone else sees the same light going c based on their speed, is the light not in 2 different places at the same time?
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    Quote Originally Posted by shawngoldw
    but light does not experience time and still travells at 300 000m/s.
    Now this really confuses me. Without time there is no m/s, is there? I mean, a second is a time period. Without time, light would either not move at all, or at an infinite speed.

    I'm giving up for now. I realize I have to read so much more before I can even grasp what this is all about.
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    If what I said was right then you got it! It would be an infinite speed but c is the upper boundary. So it goes at c relative to the observer.
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    To my understanding (which is based upon little more than a few pop science books), if you were travelling at the speed of light in some massless laboratory, and you tried to measure the speed of light in a vacuum, the answer would be c, but because of time dilation you would never complete the experiment.

    I'm always reluctant to post in the physics forum (especially regarding modern physics) because i am not a physicist, i'm sure if i'm wrong someone more qualified will correct me!
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    gradient in the speed of light!!! yeh it is giberish. maybe he meant curviture in its path in an assumed uncurved spacetime. then he would have it the wrong way around, the curviture in the path of light is caused by gravity (which is distortion in the fabric of spacetime caused by mass). there is nothing to suggest that light is the medium for this curviture, ie that light in fact causes acceleration of bodies.
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    well igore, your theory is either very wrong (Depending on what you mean by "percieve") or incapable of being proven wrong (depending on what you mean by "percieve") - which is even worst than being wrong because your theory would then exist outside the realm of science and in the realm of religion.

    In addition, time dilation which is a consequence of the special theory of relativity and the constant speed of light has been shown to occur. Special thoery is therefore more than just about our perception of light, but also about what that means for our conception of time and space.
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    Quote Originally Posted by shawngoldw
    If what I said was right then you got it! It would be an infinite speed but c is the upper boundary. So it goes at c relative to the observer.
    An upper boundary to infinity? Please stop confusing me, this is driving me mad!
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    Quote Originally Posted by shawngoldw
    Because of time dialation, when you go fast, your second slows down. but light does not experience time and still travells at 300 000m/s. The only difference is now your seeing it based on your longer second.
    Also, when my second is "longer", that means that light coming from the opposite direction would also speed up from my point of view and become faster than c. This is what I described in my problem:

    Quote Originally Posted by igor
    So let's say I travel at c*0.8 and I see things in timelapse, so that the photon's speed of c*0.2 appears to be c again. That would mean that a photon coming from the opposite direction would meet me at c (the photons speed) + c*0.8 (my speed) * 5 (the time lapse factor) = c*8, wouldn't it?
    And yet another thing:
    if my second becomes "longer" that means that I'd perceive my own speed as being faster. Like, if I travel at c/2 and my second is twice as long as it would be without time dilation, that would mean that I would get the impression of moving at c.
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    yeh, i never quite understood the twin paradox. the only explanation which people have is that special relativity does not apply in non-inertial frames of reference.

    I suspect that something happens at the point the person who is in the spaceship slow down, stops then accelerates towards the earth. If i remember correctly, under general relativity, gravity is said to cause time dilation, and since gravity and acceleration are the same thing, then this accelation of the spaceship causes the time dilation to occur that leads to the person in the spaceship being younger on his or her return to earth. ofcourse i could be way off the mark.
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    After all, I found an article that might make sense:
    http://www.peterallport.com/
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    Quote Originally Posted by igor
    Quote Originally Posted by shawngoldw
    Because of time dialation, when you go fast, your second slows down. but light does not experience time and still travells at 300 000m/s. The only difference is now your seeing it based on your longer second.
    Also, when my second is "longer", that means that light coming from the opposite direction would also speed up from my point of view and become faster than c. This is what I described in my problem:

    Quote Originally Posted by igor
    So let's say I travel at c*0.8 and I see things in timelapse, so that the photon's speed of c*0.2 appears to be c again. That would mean that a photon coming from the opposite direction would meet me at c (the photons speed) + c*0.8 (my speed) * 5 (the time lapse factor) = c*8, wouldn't it?
    And yet another thing:
    if my second becomes "longer" that means that I'd perceive my own speed as being faster. Like, if I travel at c/2 and my second is twice as long as it would be without time dilation, that would mean that I would get the impression of moving at c.
    no. It is all based on YOUR second.
    Remember the line " Time is relative to the observer"
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  25. #24 Re: Constancy of speed of light - I don't believe it. 
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    Quote Originally Posted by igor
    The speed of light being independent on the velocity of the observer is a thing I find hard to accept.
    Why?

    Greets,
    Steve
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    Quote Originally Posted by Sohy
    yeh, i never quite understood the twin paradox. the only explanation which people have is that special relativity does not apply in non-inertial frames of reference.

    I suspect that something happens at the point the person who is in the spaceship slow down, stops then accelerates towards the earth. If i remember correctly, under general relativity, gravity is said to cause time dilation, and since gravity and acceleration are the same thing, then this accelation of the spaceship causes the time dilation to occur that leads to the person in the spaceship being younger on his or her return to earth. ofcourse i could be way off the mark.
    Not really, it's as simple as: travelling fast makes time dilate. The person in the space ship travels really fast, so time dilates, when they get back to earth after what only seems like a few years, they find that because time didn't dilate in the same way on earth, that the earth has aged maybe a few decades.
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    Quote Originally Posted by shawngoldw
    Quote Originally Posted by igor
    Quote Originally Posted by shawngoldw
    Because of time dialation, when you go fast, your second slows down. but light does not experience time and still travells at 300 000m/s. The only difference is now your seeing it based on your longer second.
    Also, when my second is "longer", that means that light coming from the opposite direction would also speed up from my point of view and become faster than c. This is what I described in my problem:

    Quote Originally Posted by igor
    So let's say I travel at c*0.8 and I see things in timelapse, so that the photon's speed of c*0.2 appears to be c again. That would mean that a photon coming from the opposite direction would meet me at c (the photons speed) + c*0.8 (my speed) * 5 (the time lapse factor) = c*8, wouldn't it?
    And yet another thing:
    if my second becomes "longer" that means that I'd perceive my own speed as being faster. Like, if I travel at c/2 and my second is twice as long as it would be without time dilation, that would mean that I would get the impression of moving at c.
    no. It is all based on YOUR second.
    Remember the line " Time is relative to the observer"
    Not sure what you meant by that.
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  28. #27 Re: Constancy of speed of light - I don't believe it. 
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    Quote Originally Posted by Steve Miller
    Quote Originally Posted by igor
    The speed of light being independent on the velocity of the observer is a thing I find hard to accept.
    Why?

    Greets,
    Steve
    Because it doesn't seem logical. Mathematically you run into the problems I've described, even when you take all that time dilation stuff into consideration.
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    An alternating position of an observer can not effect light on basic physical characteristics.
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    It's about the speed being relative to mine.

    The difference between two speeds is always speed2-speed1. Can we agree on that? This is logical, this makes sense. So: the difference in speeds does depend on my own speed.

    The difference between my speed and light is always c though. That contradicts what I've just said. That's why scientists have invented all those time dilation theories. To explain their paradox observations concerning the speed of light. At least, that's how I got it.
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    I don't wanna get into a verbal fight here and I don't know if you do,
    but seemingly you're talking about at least two different issues here,
    like two different persons.

    Your are right stating about the mathematical issue. What but if
    there was one train having a speed somewhere in China and an other
    one somewhere in the U.S..

    You subtract their speeds and will receive a mathematical correct
    result. But the physical issue was as put above. That's how I got it.

    Steve
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    Quote Originally Posted by igor
    It's about the speed being relative to mine.

    The difference between two speeds is always speed2-speed1. Can we agree on that? This is logical, this makes sense. So: the difference in speeds does depend on my own speed.

    The difference between my speed and light is always c though. That contradicts what I've just said. That's why scientists have invented all those time dilation theories. To explain their paradox observations concerning the speed of light. At least, that's how I got it.
    I thought the difference would be c - your speed.

    As to what I said before about this...
    Quote Originally Posted by igor
    And yet another thing:
    if my second becomes "longer" that means that I'd perceive my own speed as being faster. Like, if I travel at c/2 and my second is twice as long as it would be without time dilation, that would mean that I would get the impression of moving at c.
    I haven't heard any objections to the way I understood this so I'm just gonna assume I had it pretty much right and go on.

    If you travel at c/2(I'll call it 0.5c) You would not think you were going c. You would think your going 0.5c because you are travelling 150 000m/s that is how you would perceive it. You are no longer referencing everyone elses time, you are referencing your own NEW second.
    Everyone else would also see you going 150 000m/s but in THEIR second. You would still start in the same place and end in the same place from both perspectives.

    This could be a bad analogy but I'll go for it anyway...
    Imagine your on a beach. Your standing still and you see someone running by the water. They are 200m away. (I have no idea how fast a person runs so pardon me if this is way off) They are running 10m/s and that is what they percieve but from your far distance it looks like they are only going 5m/s.
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    Quote Originally Posted by shawngoldw
    Quote Originally Posted by igor
    It's about the speed being relative to mine.

    The difference between two speeds is always speed2-speed1. Can we agree on that? This is logical, this makes sense. So: the difference in speeds does depend on my own speed.

    The difference between my speed and light is always c though. That contradicts what I've just said. That's why scientists have invented all those time dilation theories. To explain their paradox observations concerning the speed of light. At least, that's how I got it.
    I thought the difference would be c - your speed.

    As to what I said before about this...
    Quote Originally Posted by igor
    And yet another thing:
    if my second becomes "longer" that means that I'd perceive my own speed as being faster. Like, if I travel at c/2 and my second is twice as long as it would be without time dilation, that would mean that I would get the impression of moving at c.
    I haven't heard any objections to the way I understood this so I'm just gonna assume I had it pretty much right and go on.

    If you travel at c/2(I'll call it 0.5c) You would not think you were going c. You would think your going 0.5c because you are travelling 150 000m/s that is how you would perceive it. You are no longer referencing everyone elses time, you are referencing your own NEW second.
    Everyone else would also see you going 150 000m/s but in THEIR second. You would still start in the same place and end in the same place from both perspectives.
    I meant if I was going at 0.5c BEFORE taking my "NEW second" into consideration. And then considering that my new second lasts longer, those 150 000 m/s (old seconds) would be like 300 000 m/s to me because my NEW second is twice as long. So if I went really fast I could travel to end of the solar system and only age one day, while the rest of the universe has aged a few years.
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    I thought the difference would be c - your speed.
    Exactly, so would I. That's what all my fuss is about. Scientists say, I wouldn't experience it that way.

    Watch this:
    http://video.stumbleupon.com/#p=s127a5gsjt

    What it doesn't explain is: why does he see alberts light at "the speed of light" when he flies back? They've just explained that, when at half the speed of light, he sees the light beam twice as fast as expected because of time dilation. So when returning you'd expect him to see the second light beam twice as fast too, which in this case would not be c (the light beam) - c/2 (his speed) * 2 (time dilation) , but would be c (the light beam) + c/2 (his speed in the opposite direction) * 2 (time dilation). In this case the expected result would be c*3.
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    no. there is currently a thread going on about this very topic

    http://www.thescienceforum.com/time-...ling-6447t.php

    stay tuned there for a bit
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    Not really, it's as simple as: travelling fast makes time dilate. The person in the space ship travels really fast, so time dilates, when they get back to earth after what only seems like a few years, they find that because time didn't dilate in the same way on earth, that the earth has aged maybe a few decades.
    No no no. Remember velocity is relative. There is no such thing as absolute notion of time dilation (ie one not in reference to an observer) when we talk about relative velocity. the person in the spaceship has as much right saying that time moves slower for the person on earth as the person on earth does for the dude in the spaceship. Thus the paradox.

    The only reason that when the dude in the spaceship comes back to earth, he is in fact younger is that because he has accelerated, and acceleration being an absolute concept, ie the resisting of the influence of gravity on the space-time fabric, we would then have one person being younger than another because of this acceleration (or space-time curviture).
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    igor wrote:
    It's about the speed being relative to mine.

    The difference between two speeds is always speed2-speed1. Can we agree on that? This is logical, this makes sense. So: the difference in speeds does depend on my own speed.

    The difference between my speed and light is always c though. That contradicts what I've just said. That's why scientists have invented all those time dilation theories. To explain their paradox observations concerning the speed of light. At least, that's how I got it.


    I thought the difference would be c - your speed.

    As to what I said before about this...
    igor wrote:
    And yet another thing:
    if my second becomes "longer" that means that I'd perceive my own speed as being faster. Like, if I travel at c/2 and my second is twice as long as it would be without time dilation, that would mean that I would get the impression of moving at c.


    I haven't heard any objections to the way I understood this so I'm just gonna assume I had it pretty much right and go on.

    If you travel at c/2(I'll call it 0.5c) You would not think you were going c. You would think your going 0.5c because you are travelling 150 000m/s that is how you would perceive it. You are no longer referencing everyone elses time, you are referencing your own NEW second.
    Everyone else would also see you going 150 000m/s but in THEIR second. You would still start in the same place and end in the same place from both perspectives.

    nonono. I cant claim that i have quite grasped special relativity (which is kinda sad as it is suppose to be not too hard) but i can point out a few flows to your thought on the matter.

    you are relying on your classical conceptions of space time, and to some extent, even preclassical notions of speed (what i mean by that is a notion of absolute velocity).

    remember in special relativity, when you discuss anything, you MUST make reference to a point of view or a frame of reference. That is after all what the whole thing is based on.

    therefore, there is no such thing as if you are moving at c/2. it is if you are moving at c/2 relative to X. (now here is where i gotto do a little thinking or reading, would that mean that x would see the velocity of a certain beam of light relative to you to be between c/2 and 3c/2 depending on your direction of motion and can we even talk about it this way).

    anyway, this is not important. issue is, X will see you going c/2 velocity of light, you will X going c/2 velocity of light. you will not see time slowing down for yourself. rather for X. but from your point of view, 1 second is 1 second and that is how you measure X's velocity. and as the speed of light is a constant c. then X will according to you still be travelling at c/2.
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    Quote Originally Posted by Sohy
    Not really, it's as simple as: travelling fast makes time dilate. The person in the space ship travels really fast, so time dilates, when they get back to earth after what only seems like a few years, they find that because time didn't dilate in the same way on earth, that the earth has aged maybe a few decades.
    No no no. Remember velocity is relative. There is no such thing as absolute notion of time dilation (ie one not in reference to an observer) when we talk about relative velocity. the person in the spaceship has as much right saying that time moves slower for the person on earth as the person on earth does for the dude in the spaceship. Thus the paradox.

    The only reason that when the dude in the spaceship comes back to earth, he is in fact younger is that because he has accelerated, and acceleration being an absolute concept, ie the resisting of the influence of gravity on the space-time fabric, we would then have one person being younger than another because of this acceleration (or space-time curviture).
    :? it has been shown by highly accurate radiometric clocks that time dilation is real. Like for example that experiment where they set up two clocks, one on the ground and the other on a jet plane, the jet plane flew around the world and when it came back its clock was a little bit behind the one on the ground, in accordance with the time dilation predicted by (special?) relativity.

    Also, I don't wish to sound rude, but almost everything written on this thread is complete garbage. This may sound rich coming from me, but much of what has been written is highly dubious, and I am educated enough to see some of the major flaws. One major thing: investigate the Lorentz transformation.
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    Quote Originally Posted by "billiards
    Also, I don't wish to sound rude, but almost everything written on this thread is complete garbage. This may sound rich coming from me, but much of what has been written is highly dubious, and I am educated enough to see some of the major flaws. One major thing: investigate the Lorentz transformation.
    ermm thats probably me. :wink: I didn't hear any objections so I figured I was on the right track... next time someone warn me!
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    "it has been shown by highly accurate radiometric clocks that time dilation is real. Like for example that experiment where they set up two clocks, one on the ground and the other on a jet plane, the jet plane flew around the world and when it came back its clock was a little bit behind the one on the ground, in accordance with the time dilation predicted by (special?) relativity.

    Also, I don't wish to sound rude, but almost everything written on this thread is complete garbage. This may sound rich coming from me, but much of what has been written is highly dubious, and I am educated enough to see some of the major flaws. One major thing: investigate the Lorentz transformation."
    Please before you tup that kinda response, actually read what i have written, then if you disagree, then post a reply that actually contradicts what i am saying. You yourself actually gave an example of a accelerated motion leading to a non-inertial frame of reference. In that case, there would be an absolute notion of time dilation.

    the entire point of the twin paradox is that only in non inertial frames of reference can we say that time actually has slowed down for individual than the other. Otherwise, the person in the spaceship while he is moving at a constant speed away from earth has as much right as the person on earth in claiming that time has slowed down for the other.

    Only once the person in the spaceship decelerates to turn around to we have something which has in a sense absolutely (ie relative to the fabric of spacetime) occured differently for the person in the spaceship and the person on earth. the person on earth is more distant from the "spacetime curviture??" caused by the spaceship slowing down and turning around (roughly speaking) which means that as a result its time will move more rapidly relatively to the person in the spaceship.

    Now i am sure there is a special relativity solution to this problem, but as i have said, i am yet to run into one palatable by my limited intelectual ability.
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    Quote Originally Posted by Sohy
    "it has been shown by highly accurate radiometric clocks that time dilation is real. Like for example that experiment where they set up two clocks, one on the ground and the other on a jet plane, the jet plane flew around the world and when it came back its clock was a little bit behind the one on the ground, in accordance with the time dilation predicted by (special?) relativity.

    Also, I don't wish to sound rude, but almost everything written on this thread is complete garbage. This may sound rich coming from me, but much of what has been written is highly dubious, and I am educated enough to see some of the major flaws. One major thing: investigate the Lorentz transformation."
    Please before you tup that kinda response, actually read what i have written, then if you disagree, then post a reply that actually contradicts what i am saying. You yourself actually gave an example of a accelerated motion leading to a non-inertial frame of reference. In that case, there would be an absolute notion of time dilation.

    the entire point of the twin paradox is that only in non inertial frames of reference can we say that time actually has slowed down for individual than the other. Otherwise, the person in the spaceship while he is moving at a constant speed away from earth has as much right as the person on earth in claiming that time has slowed down for the other.

    Only once the person in the spaceship decelerates to turn around to we have something which has in a sense absolutely (ie relative to the fabric of spacetime) occured differently for the person in the spaceship and the person on earth. the person on earth is more distant from the "spacetime curviture??" caused by the spaceship slowing down and turning around (roughly speaking) which means that as a result its time will move more rapidly relatively to the person in the spaceship.

    Now i am sure there is a special relativity solution to this problem, but as i have said, i am yet to run into one palatable by my limited intelectual ability.
    I have the impression that you're talking about the rate at which we see the clocks ticking in the twin paradox. This is not at all what I'm talking about though.
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    I have the impression that you're talking about the rate at which we see the clocks ticking in the twin paradox. This is not at all what I'm talking about though.
    well i am talking about more than that but either way, my point remains valid. When you talk about your old second and your new second, you are taking a completely wrong approach to the whole thing. You cannot talk about time and velocity WITHOUT EXPLICITLY MENTIONING A POINT OF REFERENCE.

    once you start doing that, things start falling into place.
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    Quote Originally Posted by Sohy
    You cannot talk about time and velocity WITHOUT EXPLICITLY MENTIONING A POINT OF REFERENCE.
    I thought I had.
    In most cases my point of reference was the pilot. His speed, his timeframe and things moving relative to him.

    For some reason we are missing each other at some point, so maybe we should brake it up into little pieces to see where we get each other wrong or where we disagree (if we disagree at all - maybe there's just some misunderstanding).

    Let's start like this:
    If I move away from earth at 500mph (relative to earth) in a space shuttle and another space shuttle overtakes me with a speed of 505mph (relative to earth), what will I see when I look out the window?
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    Let's start like this:
    If I move away from earth at 500mph (relative to earth) in a space shuttle and another space shuttle overtakes me with a speed of 505mph (relative to earth), what will I see when I look out the window?
    this should be fun, it might help me get my head around this thing ....

    well the dude looking out the window will see the earth moving away from at 500 mph, and the other shuttle overtaking him at:

    5/(1-(500*505)/c^2) miles per hour. i dont know what the speed of light is in miles per hour so you gonna have to do the math.

    but clearly the relative velocity will be greater than 5.
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    Ah, there I have it.
    That formula makes sense, because I always thought that any speed relative to mine would change in the same way.

    Like: I understood that the relative speed to the other pilot would increase (just like you said), but thought that in conclusion the relative speed of things coming from the opposite direction would increase too.
    Meaning, that a spaceship coming towards me at 500 mph would have a relative speed greater than 1000mph. That's what I thought. But according to the formula it would be less. And that makes sense.

    So as I approach the speed of light, things moving in one direction will appear faster and things moving in the opposite direction will appear slower. Crazy. Now I got it. Thanks for clearing things up. My bad.
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    yeh, pretty much, not that i fully understand it yet. but as i said you should be careful with how you frame it, it can put you off track:

    Meaning, that a spaceship coming towards me at 500 mph would have a relative speed greater than 1000mph. That's what I thought. But according to the formula it would be less. And that makes sense.
    x isnt coming at you at 500 mph, it is moving in the opposite direction to you relative to the earth from the point of view of the earth at 500 mph.
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    True. That's what I meant. 500mph relative to earth in the opposite direction.
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    *cough* from the point of view of the earth *cough*

    dont mean to be pedantic, but since frame of reference is the key thing, i think it should be pointed out explicitly. Because i think in the example you gave, "relative to earth in the opposite direction" from the point of view of the first spaceship it will actually be less than 500 mph.
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    "c" is a constant because its the measure of the speed of light in a vacuum but the speed of light is not always constant. It actually slows down depending on the medium its going through. The changes are so small that no adjustment is needed to correct your end approx. result except when dealing with the exertion of intense gravitational or electromatic forces over large distances or measurements dealing on the nano and pico scale of time.
    Man casts a long shadow only at morning and sunset. He stands in his own shadow at the height of his noon.
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    "c" is a constant because its the measure of the speed of light in a vacuum but the speed of light is not always constant. It actually slows down depending on the medium its going through. The changes are so small that no adjustment is needed to correct your end approx. result except when dealing with the exertion of intense gravitational or electromatic forces over large distances or measurements dealing on the nano and pico scale of time.
    That is true, if c were always a constant then such phenomena as diffraction could not physically occur.

    ~~~ On the question of why is c 300,000m/s I would guess that it is probably because this is the result of a photon possessing the maximum energy it can have before possessing a mass. Any more energy and the photon would probably spontaneously condense into matter* and from there you enter the curious world of particle physics! This is just me guessing though really as it raises the question as to how one can possess enough energy to form matter... I'll stop before I start confusing myself which is not good 2 weeks before a physics exam featuring both the EM spectrum and particle physics!
    *I believe this event is called pair production when a particle and it's anti-particle are produced form seemingly nothing.
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    well actually c is constant, the speed of light is not.
    however that is beside the point, we are discussing special relativity and not refraction. it has nothing to do with the other. it just confuses the issue. (and btw, changes in speed of light in different medium is not negligable, i have heard of light being slowed down to something like 20 m/s in certain substances. and it also slows down quite significantly in water)
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    Wrong. Sorry.

    Here's how it works. Let's look at GPS:

    http://en.wikipedia.org/wiki/Global_Positioning_System

    According to the theory of relativity, due to their constant movement and height relative to the Earth-centered inertial reference frame, the clocks on the satellites are affected by their speed (special relativity) as well as their gravitational potential (general relativity). For the GPS satellites, general relativity predicts that the atomic clocks at GPS orbital altitudes will tick more rapidly, by about 45,900 nanoseconds (ns) per day, because they are in a weaker gravitational field than atomic clocks on Earth's surface. Special relativity predicts that atomic clocks moving at GPS orbital speeds will tick more slowly than stationary ground clocks by about 7,200 ns per day. When combined, the discrepancy is 38 microseconds per day; a difference of 4.465 parts in 1010. To account for this, the frequency standard onboard each satellite is given a rate offset prior to launch, making it run slightly slower than the desired frequency on Earth; specifically, at 10.22999999543 MHz instead of 10.23 MHz.

    The time "runs" a little slower down here on earth, so the GPS satellites are set to run a little slower than standard. It isn't much, but it's real. So you can get a metre ruler, and measure how long it takes for a beam of light to get from one side to the other. You get the same result in seconds wherever you do it, be it on the surface of the earth or in orbit. But that "same result" down here on earth is different to the value you'd get in orbit by 4.465 parts in 1010.

    We could do something similar if you were travelling at a relativistic speed compared to me. Remember that length contraction only applies to the direction of travel, so we hold our rulers in a transverse fashion. It's the same metre, but the seconds are different, so c is different too.

    Wherever there's time dilation, it's because c is different. You can't measure it to be different, because the speed of light defines how you count time. It's a "scale change", and we're totally immersed in it. people normally call this "curved spacetime" without actually understanding what it is.

    It's just all so incredibly simple. Once you see it you'll be amazed that other people can't.
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  54. #53 Re: Constancy of speed of light - I don't believe it. 
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    Quote Originally Posted by igor
    I say: light sources cast light rays at lots of different speeds. But the only light rays we are able to see and measure are those that meet us at approximately 299 792 458 m / s. If we move towards the light source, the slower light rays will hit us at that speed, if we move away we get to see the faster light rays. Only being able to see the light that meets us at a certain speed is what causes the illusion of light having a constant speed, independent of the velocity of the observer.

    Why do slower and faster light rays become invisible? I believe it's a frequency thing. Resonance and all that. Maybe light at 299 792 458 m / s has exactly the frequency to make protons, neutrons, quarks, leptons whatever resonate, so that the massless photons can get noticed at all.
    Nah.

    Without the obvious suggestion to spend more time studying Einstein's theory of relativity, some more time studying light would make things clearer as well. EM wavelengths are a different matter as well.

    Not to shoot you down, that's a decent argument. Keep at it.
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    farsight, we are talking about the change in the speed of light through different mediums here, not discussing the effect of mass on space time curviture and the light beam.
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