Special relativity says that, speed of light is constant w.r.t any observer. i.e. two observers moving at constant speed relative to each other will observe the same speed of light.
I can't understand, why? Light has a definite speed. And two observers moving relative to each other should observe different light speeds.
Now I understand that experiments have been conducted that confirm the constancy of light; But I couldn't find the explanation as how or why does it happen.
Can anyone provide the explanation for this bizarre phenomenon.
Hi daljeet et al,
QUOTE (daljeet+)
Special relativity says that, speed of light is constant w.r.t any observer. i.e. two observers moving at constant speed relative to each other will observe the same speed of light.
I can't understand, why? Light has a definite speed. And two observers moving relative to each other should observe different light speeds.
Now I understand that experiments have been conducted that confirm the constancy of light; But I couldn't find the explanation as how or why does it happen.
Can anyone provide the explanation for this bizarre phenomenon.
I can't understand, why? Light has a definite speed. And two observers moving relative to each other should observe different light speeds.
Now I understand that experiments have been conducted that confirm the constancy of light; But I couldn't find the explanation as how or why does it happen.
Can anyone provide the explanation for this bizarre phenomenon.
It is a strange thing that this occurs when you begin to think about it. In one point of view who are we to question how the Universe works... it just does. We might discuss the effect of Relativity for quite a long while without ever understanding why things are the way they are. There is a simple reason for this phenomenon though. Unfortunately it is so "obvious" that it is hard to accept. We have a lot of learned prejudices.
Lets "ignore" for the sake of this discussion that we never actually "see" light moving anywhere. Light itself in free space is "invisible". It can only be seen when it interacts with matter. Lets "pretend" we can measure these effects in free space for the sake of the clarity of the argument.
When light is emitted by a source it obviously must have a speed relative to the source of C (the speed of light). This is not surprising for anyone. If I have a gun and I fire a bullet from the front and from the back of a moving train the bullet appears to me to always travel "at the speed of a bullet" away from the train regardless of the velocity of the train and regardless of which way the bullet is fired (ignoring the wind resistance). It can be fired in the direction in which the train is moving or can be fired out of the back of the train. It can be fired even inside the train and measurements relative to the train will always record a very typical velocity for the bullet regardless of the "external motion" of the train relative to the stationary Earth. So light "must" obey this rule for common sense sake as well. Light always appear to travel away from a source (from the source's perspective) always at the characteristic speed of light.
The conundrum comes when the bullet is observed from a position external to the train (perhaps a "relatively stationary" one alongside the track). How a bullet will be seen to "move" is, to a very great level of accuracy, the vector sum of the bullet's velocity and the velocity of the train. It is conceivable that if you boarded a "true bullet train" which actually traveled at exactly the speed of a bullet and fired the bullet horizontally from a gun out the back of the train, an external observer nearby (using a high speed slow motion cine camera) could record the fact that the bullet "fell" directly from the muzzle of the moving gun to the ground accelerated only by the same accelerations that any object dropped at the same time and the same place and at the same height from within the rest frame of the stationary observer. The "movement" of the two objects, the bullet and the equivalent object, could not be distinguished from that frame.
The same bullet fired from the front of the train will move at twice the horizontal velocity from the point of view of the stationary observer with the camera. Interestingly all bullets will still reach the ground at exactly the same time. This is what we expect. This is because we understand that the bullet is "carried" by the train and "already has" the velocity of the train even before it is fired from a gun. The gun just gives it an "extra boost" in velocity in the direction of motion of the train or against the direction of motion of the train. This is a vector "sum"... the direction of the velocity vector is in the same direction as the motion of the train in once case (doubling the bullets velocity relative to the stationary observer) and against the direction of motion of the train (subtracting equal vectors leading to a null vector) in the other case. This is pretty well understood and "works" for most velocities that are small relative to the speed of light. So what is the difference with light in this same situation? Why does the summation of these vectors not work now?
Here is the secret... The real difference is light can't get a "push" from a moving source (neither can a bullet because once the flash of light or a bullet is "released"... it is on it's own). It can't be encouraged to go faster or slower relative to the external observer (any external observer at any relative velocity). It simply has the velocity seen from the perspective of the marksman on the train. This is the true meaning of the "constancy of the speed of light". When light is emitted it is "constrained" on the surface of a constantly expanding sphere surrounding the source outwards centered on the original point where and when it was first emitted. The same happens for a bullet (...if bullets were able to maintain the velocity... which of course they cannot except in the vacuum of space). Naturally there is only one bullet here but several bullets emitted in several directions at the same time "in space" would maintain their relative positions on the surface of a expanding sphere (just like light). As the light is emitted (let's take it as a single flash of light from the source each second) the position it is seen to be emitted from is not dragged along with the train... the flash is seen where it was originally physically emitted in the observers frame and the recipient observer will receive that pulse a certain time later dependent on the distance and the speed of light. As long as we are only discussing the one frame of reference... the observer frame of reference... there is really no relativity to speak of... none whatsoever. While we are not comparing time or distances "between" reference frames then the timing is "exact"... the light takes s/C seconds to reach the observer (s is the distance from the source position of he observer when the flash was emitted in the observer's frame). This is simply the propagation delay time due to the fact that both light and bullets have a finite velocity.
By now you probably think I have made some mistake... I have not. Surely what I have said is wrong? You clearly understand that "light can't be pushed or pulled" after a flash has been emitted from a source. But surely this "motion" is subject to relativity. Not at all... I am concentrating only on one coordinate system... the frame of reference of the observer. In that frame the flash of light emanates from a particular point when the train is exactly in the place the observer sees the flash. That was a time s/C seconds ago in a particular direction (according to the observer) where s is the distance according to Pythagoris and the root of the sum of the square in the difference in the three coordinates (x,y,z). This is equal to the time of propagation to that "radius" times the speed of light (Ct) and we will not worry at this stage about some sign conventions right now and continue to explain it in simple terms. We have three coordinates since this is a sphere expanding in three dimensions (... plus a fourth time dimension in Einstein's Theory). This aspect is not surprising in itself ... it is exactly what you were hoping would be the case (but thought was wrong) because this is what happens for th bullet. What does the source motion actually do then? All that motion of the train does is move that point source along a vector to relocate the source at the next flash position one second later (observer time). This "distance" may be toward the observer or away from the observer (shortening the distance or lengthening it). So if each flash from the source were originally emitted at one second intervals "aboard the moving train" the signals will be emitted from a distance that is either shortening or lengthening from the point of view of the observer depending on whether the source is approaching or receding respectively. The time interval between these flashes will be either shortening or increasing respectively. If the rate (which is the number of flashes per second) is "higher" than one flash per second this due to the falling "propagation time" or time it takes for light to reach the observer from the source because the source is approaching the observer and the observer is getting closer to the source all the time. If the rate (which is the number of flashes per second) is "lower" than one flash per second, this due to the lengthening "propagation time" or time it takes for light to reach the observer from the source because the observer is getting further away from the source all the time. Thee differences are small since the time light takes to travel a short distance is exceedingly small compared with the velocity of a train. Still it is easily measured with accurate measuring instruments and leads to a change in "optic pitch" or frequency in the light (no matter what frequency).
Rather than any "pushing or pulling" of the light after it is emitted it is the measured "rate of flashing" or even the rate that the frequency of the light that is altered that is "observed"... this is Relativistic Doppler Shift similar to the effect of the same process with a moving source of sound in air leading to a rise in an approaching sound source and a fall in frequency pitch as the source passes into the distance (like the trains whistle). The "pitch" is altered but not the speed at which it is received in still air with the observer at "rest".
All of this has not diverged from any way we understand what might happen with light. Thus far it is identical to the same phenomenon that might be measured in air with sound. In "still air" the speed of sound can't be "pushed either" by the motion of the source (the motion of the train). The sound is always received by the observer at the speed of sound over ground (regardless of the speed of the train), only the frequency has been changed due to the motion of the source towards the observer or away from him. The exact same argument applies to light.
We now change one more thing... lets move relative to the ground (relative to the speed of the train or the still air). This "adds" a new vector velocity to the rate at which sound arrives at the observer since the speed of sound through the air is still constant but now we are moving relative to the air so the sound will be altered in pitch by this motion "added" to the speed of sound or subtracted from the speed of sound. The moving observer causes a change in pitch the same as a moving source. These two movements will add for sound. This is because we have motion relative to the "medium" in which sound is "moving" (the air). We find that motion relative to the medium "counts" with sound. It can also occur if there is a wind (which is motion of the medium relative to the stationary earth as well). The velocity of the observer relative to the ground is an additive effect and the velocity of the air (in bulk) relative to the ground is an additive effect. The two summed will then impose on the Doppler you considered before and also we have a factor in which the sound can actually approach at a speed greater or less than the local speed of sound due to the motion of the medium or the motion of the observer. These "modifications" will all be quite correct for sound.
What if we try and do the same for light? Earlier in the story of light it was thought that, like sound, light also needed a "medium" (like the air) to propagate. Therefore movement relative to this "aether" would influence light in exactly the same way as the movement of the observer relative to the surface of the earth or the "aether wind" that carried this "optical vibration" to the observer. A large number of experiments were performed to find this "material" that was thought to allow light to propagate. It was never detected regardless of the state of motion of the observer or the earth. Only the relative difference in speed between the source and the observer changed anything.
Translated into what this meant for the experiment is the stationary observer was always 'apparently stationary" relative to an aether regardless of the motion of that observer relative to the source (which is still in motion) or alternatively there was never any aether in the first place. So the idea of an observer "at rest" needed to be replaced by an observer in relative motion to the source that behaved just like the observer described above at rest relative to the surface of the earth (just remove the earth). The motion of the observer was still important but only in the context of the relative speed differential between the source and the observer and the concept of any idea of an absolute rest frame or an aether needed to be abandoned. The "aether" did not have an influence on the experiment at all.
As in the case of the stationary observer in still air always receives the sound from a train at the surface velocity of the speed of sound no matter where he was situated and no matter what velocity the train was moving... so too this was exactly the rule that worked for light with one qualification that there was no aether to move in relation to. All observers in all "relative moving frames" moving at a constant velocity in all directions relative to the source always received the signals from a light source at the same speed as if they were all at rest relative to an "aether" or to an "absolute rest frame". There were no preferred frames of motion, they were all equivalent. Experiment verified they all received light at the same speed.
Our minds are so accustomed to thinking about this "aether substance" that is at rest 'somewhere" that we find it hard to accept that it did not exist. If aether does not exist then there can be no detectable motion relative to it. That means it is "exactly" equivalent to the situation for sound where all observers are at rest relative to the earths surface and no wind. There is no "aether" at rest or in motion relative to that so called stationary surface. We now know all constantly moving frames in relative motion are equivalent to rest frames. All that differs is that all observers may have a different velocity relative to the "moving" source. What matters is only the relative velocity between the source and the observer.
All of this is absolutely positively not Special Relativity, it is simple kinematics under the conditions as outlined (no aether). Actually the problem is actually simpler than the problem posed with sound in the air. Now regarding relativity itself.... This is the conversion between measurements in one coordinate frame of reference to the coordinates in another relatively moving frame. This set of transformations compares "apples with oranges" (not the same). Relatively moving systems are more difficult to measure with yardsticks and clocks based in the observer rest frame when the moving frame is moving near the speed of light. What is found is our definition of simultaneity is flawed simply because Newton assumed that the speed of light is infinite... it is not. If the speed of light is finite (no matter how large a number it is) it will affect the measurement times and distance due to the propagation delays (as mentioned before). These effects can be accounted for and they lead to some rather bizarre optical phenomena. Still this is really not relativity either... this is "optics" near the speed of light. Like running in the rain when it is falling vertically water will strike you in he face. In a similar way (for a single point of view or perspective) light will approach us from different directions due to our relative motion and it is called "stellar aberration". Still most people think this is relativity... no... not really... it is only an optical effect equivalent to a sonic effect you would have with sound as well due to relative motion.
The "real" effect of Relativity (Special and General) is two fold due to only one effect... "Light falls down" .... along a geodesic called the Null Geodesic... this "path" is the perspective that a photon 'sees"... observers "see" light move along long paths through space and these sometimes take a lot of time. These "spacetime" path lengths are a result not of the "motion of light" but of the "motion of the observers" and they are constrained by the existence of mass. Light is not constrained by it's own "mass" but is "sees" the rest of the mass and "falls" under the influence of gravity. The length of this geodesic for photons of light is exactly "zero" in it's own frame of reference. Everywhere is the one place and all times are the same to photons. Photons "suffer" the most extreme case of time and space relativistic phenomena. The equations that govern this motion are really the same as those of Special Relativity since, as I said, light really can't be "pushed or pulled" in it's own frame of reference. There really are only two effects of being forced to move along this path that occur.
1. Time Dilation (for light ... the total loss of the passage of time for the photon)
2. Length Contraction (for light ... the total loss of the appreciation of separation between points in our extended space).
All other particle that try and approach this "shortest path" through time and space between points will fail because of the existence of the particles mass. As other particles "try" and make their path approach the one that light takes as it "falls under gravity" their properties will approach this "shortest path" (properties of photons) by experiencing incomplete time dilation and length contraction where their world line shortens such that the experience of time in comparison to time experienced by "slower observers" is relatively shorter and the distance between points is "contracted" (spatially rotated). These two effects complement each other such that vast journeys can be made in relatively short "ship's time" at the expense of the passage of much longer periods of time in the rest frames of the Earth. A journey of 100,000 light years "may" be shortened to a period of months for a traveler if sufficient energy were made available. The period that light takes to travel that same distance (100,000 "Earth years") as seen by external observers (who see the distance as 100,000 light years) is an absolute minimum of time to elapse "back home". Therefore world lines of a highly accelerated traveler and those left behind on Earth will not match after a round trip (bringing these world lines back together).
The object that underwent the greatest acceleration (according to General Relativity) will be the one that experiences the greatest relative time dilation. The means of acceleration is irrelevant to time dilation or length contraction... all acceleration is 100% equivalent (Equivalence Principle)... in that sense gravity and the forces felt in acceleration by a rocket is "identical". All the while a great "length contraction" (spatial rotation) will also be experienced but the optical effect is quite different to "simple linear contraction" of distances ... it actually appears as a spatial rotation where the field of view will be compressed forward as a contracted "patch" in a very intense "blue shift" while the aft perspective will be seen as an intense "red shift" .... possibly all the way to "blackness" in the extreme situation.. This is because the frequencies approaching from those respective directions are frequency shifted in the extreme while "time" is "nearly frozen" for travelers as observed by external unaccelerated onlookers along the way.
Hope that cuts it with you all... feel free to comment.
Cheers
Lets "ignore" for the sake of this discussion that we never actually "see" light moving anywhere. Light itself in free space is "invisible". It can only be seen when it interacts with matter. Lets "pretend" we can measure these effects in free space for the sake of the clarity of the argument.
When light is emitted by a source it obviously must have a speed relative to the source of C (the speed of light). This is not surprising for anyone. If I have a gun and I fire a bullet from the front and from the back of a moving train the bullet appears to me to always travel "at the speed of a bullet" away from the train regardless of the velocity of the train and regardless of which way the bullet is fired (ignoring the wind resistance). It can be fired in the direction in which the train is moving or can be fired out of the back of the train. It can be fired even inside the train and measurements relative to the train will always record a very typical velocity for the bullet regardless of the "external motion" of the train relative to the stationary Earth. So light "must" obey this rule for common sense sake as well. Light always appear to travel away from a source (from the source's perspective) always at the characteristic speed of light.
The conundrum comes when the bullet is observed from a position external to the train (perhaps a "relatively stationary" one alongside the track). How a bullet will be seen to "move" is, to a very great level of accuracy, the vector sum of the bullet's velocity and the velocity of the train. It is conceivable that if you boarded a "true bullet train" which actually traveled at exactly the speed of a bullet and fired the bullet horizontally from a gun out the back of the train, an external observer nearby (using a high speed slow motion cine camera) could record the fact that the bullet "fell" directly from the muzzle of the moving gun to the ground accelerated only by the same accelerations that any object dropped at the same time and the same place and at the same height from within the rest frame of the stationary observer. The "movement" of the two objects, the bullet and the equivalent object, could not be distinguished from that frame.
The same bullet fired from the front of the train will move at twice the horizontal velocity from the point of view of the stationary observer with the camera. Interestingly all bullets will still reach the ground at exactly the same time. This is what we expect. This is because we understand that the bullet is "carried" by the train and "already has" the velocity of the train even before it is fired from a gun. The gun just gives it an "extra boost" in velocity in the direction of motion of the train or against the direction of motion of the train. This is a vector "sum"... the direction of the velocity vector is in the same direction as the motion of the train in once case (doubling the bullets velocity relative to the stationary observer) and against the direction of motion of the train (subtracting equal vectors leading to a null vector) in the other case. This is pretty well understood and "works" for most velocities that are small relative to the speed of light. So what is the difference with light in this same situation? Why does the summation of these vectors not work now?
Here is the secret... The real difference is light can't get a "push" from a moving source (neither can a bullet because once the flash of light or a bullet is "released"... it is on it's own). It can't be encouraged to go faster or slower relative to the external observer (any external observer at any relative velocity). It simply has the velocity seen from the perspective of the marksman on the train. This is the true meaning of the "constancy of the speed of light". When light is emitted it is "constrained" on the surface of a constantly expanding sphere surrounding the source outwards centered on the original point where and when it was first emitted. The same happens for a bullet (...if bullets were able to maintain the velocity... which of course they cannot except in the vacuum of space). Naturally there is only one bullet here but several bullets emitted in several directions at the same time "in space" would maintain their relative positions on the surface of a expanding sphere (just like light). As the light is emitted (let's take it as a single flash of light from the source each second) the position it is seen to be emitted from is not dragged along with the train... the flash is seen where it was originally physically emitted in the observers frame and the recipient observer will receive that pulse a certain time later dependent on the distance and the speed of light. As long as we are only discussing the one frame of reference... the observer frame of reference... there is really no relativity to speak of... none whatsoever. While we are not comparing time or distances "between" reference frames then the timing is "exact"... the light takes s/C seconds to reach the observer (s is the distance from the source position of he observer when the flash was emitted in the observer's frame). This is simply the propagation delay time due to the fact that both light and bullets have a finite velocity.
By now you probably think I have made some mistake... I have not. Surely what I have said is wrong? You clearly understand that "light can't be pushed or pulled" after a flash has been emitted from a source. But surely this "motion" is subject to relativity. Not at all... I am concentrating only on one coordinate system... the frame of reference of the observer. In that frame the flash of light emanates from a particular point when the train is exactly in the place the observer sees the flash. That was a time s/C seconds ago in a particular direction (according to the observer) where s is the distance according to Pythagoris and the root of the sum of the square in the difference in the three coordinates (x,y,z). This is equal to the time of propagation to that "radius" times the speed of light (Ct) and we will not worry at this stage about some sign conventions right now and continue to explain it in simple terms. We have three coordinates since this is a sphere expanding in three dimensions (... plus a fourth time dimension in Einstein's Theory). This aspect is not surprising in itself ... it is exactly what you were hoping would be the case (but thought was wrong) because this is what happens for th bullet. What does the source motion actually do then? All that motion of the train does is move that point source along a vector to relocate the source at the next flash position one second later (observer time). This "distance" may be toward the observer or away from the observer (shortening the distance or lengthening it). So if each flash from the source were originally emitted at one second intervals "aboard the moving train" the signals will be emitted from a distance that is either shortening or lengthening from the point of view of the observer depending on whether the source is approaching or receding respectively. The time interval between these flashes will be either shortening or increasing respectively. If the rate (which is the number of flashes per second) is "higher" than one flash per second this due to the falling "propagation time" or time it takes for light to reach the observer from the source because the source is approaching the observer and the observer is getting closer to the source all the time. If the rate (which is the number of flashes per second) is "lower" than one flash per second, this due to the lengthening "propagation time" or time it takes for light to reach the observer from the source because the observer is getting further away from the source all the time. Thee differences are small since the time light takes to travel a short distance is exceedingly small compared with the velocity of a train. Still it is easily measured with accurate measuring instruments and leads to a change in "optic pitch" or frequency in the light (no matter what frequency).
Rather than any "pushing or pulling" of the light after it is emitted it is the measured "rate of flashing" or even the rate that the frequency of the light that is altered that is "observed"... this is Relativistic Doppler Shift similar to the effect of the same process with a moving source of sound in air leading to a rise in an approaching sound source and a fall in frequency pitch as the source passes into the distance (like the trains whistle). The "pitch" is altered but not the speed at which it is received in still air with the observer at "rest".
All of this has not diverged from any way we understand what might happen with light. Thus far it is identical to the same phenomenon that might be measured in air with sound. In "still air" the speed of sound can't be "pushed either" by the motion of the source (the motion of the train). The sound is always received by the observer at the speed of sound over ground (regardless of the speed of the train), only the frequency has been changed due to the motion of the source towards the observer or away from him. The exact same argument applies to light.
We now change one more thing... lets move relative to the ground (relative to the speed of the train or the still air). This "adds" a new vector velocity to the rate at which sound arrives at the observer since the speed of sound through the air is still constant but now we are moving relative to the air so the sound will be altered in pitch by this motion "added" to the speed of sound or subtracted from the speed of sound. The moving observer causes a change in pitch the same as a moving source. These two movements will add for sound. This is because we have motion relative to the "medium" in which sound is "moving" (the air). We find that motion relative to the medium "counts" with sound. It can also occur if there is a wind (which is motion of the medium relative to the stationary earth as well). The velocity of the observer relative to the ground is an additive effect and the velocity of the air (in bulk) relative to the ground is an additive effect. The two summed will then impose on the Doppler you considered before and also we have a factor in which the sound can actually approach at a speed greater or less than the local speed of sound due to the motion of the medium or the motion of the observer. These "modifications" will all be quite correct for sound.
What if we try and do the same for light? Earlier in the story of light it was thought that, like sound, light also needed a "medium" (like the air) to propagate. Therefore movement relative to this "aether" would influence light in exactly the same way as the movement of the observer relative to the surface of the earth or the "aether wind" that carried this "optical vibration" to the observer. A large number of experiments were performed to find this "material" that was thought to allow light to propagate. It was never detected regardless of the state of motion of the observer or the earth. Only the relative difference in speed between the source and the observer changed anything.
Translated into what this meant for the experiment is the stationary observer was always 'apparently stationary" relative to an aether regardless of the motion of that observer relative to the source (which is still in motion) or alternatively there was never any aether in the first place. So the idea of an observer "at rest" needed to be replaced by an observer in relative motion to the source that behaved just like the observer described above at rest relative to the surface of the earth (just remove the earth). The motion of the observer was still important but only in the context of the relative speed differential between the source and the observer and the concept of any idea of an absolute rest frame or an aether needed to be abandoned. The "aether" did not have an influence on the experiment at all.
As in the case of the stationary observer in still air always receives the sound from a train at the surface velocity of the speed of sound no matter where he was situated and no matter what velocity the train was moving... so too this was exactly the rule that worked for light with one qualification that there was no aether to move in relation to. All observers in all "relative moving frames" moving at a constant velocity in all directions relative to the source always received the signals from a light source at the same speed as if they were all at rest relative to an "aether" or to an "absolute rest frame". There were no preferred frames of motion, they were all equivalent. Experiment verified they all received light at the same speed.
Our minds are so accustomed to thinking about this "aether substance" that is at rest 'somewhere" that we find it hard to accept that it did not exist. If aether does not exist then there can be no detectable motion relative to it. That means it is "exactly" equivalent to the situation for sound where all observers are at rest relative to the earths surface and no wind. There is no "aether" at rest or in motion relative to that so called stationary surface. We now know all constantly moving frames in relative motion are equivalent to rest frames. All that differs is that all observers may have a different velocity relative to the "moving" source. What matters is only the relative velocity between the source and the observer.
All of this is absolutely positively not Special Relativity, it is simple kinematics under the conditions as outlined (no aether). Actually the problem is actually simpler than the problem posed with sound in the air. Now regarding relativity itself.... This is the conversion between measurements in one coordinate frame of reference to the coordinates in another relatively moving frame. This set of transformations compares "apples with oranges" (not the same). Relatively moving systems are more difficult to measure with yardsticks and clocks based in the observer rest frame when the moving frame is moving near the speed of light. What is found is our definition of simultaneity is flawed simply because Newton assumed that the speed of light is infinite... it is not. If the speed of light is finite (no matter how large a number it is) it will affect the measurement times and distance due to the propagation delays (as mentioned before). These effects can be accounted for and they lead to some rather bizarre optical phenomena. Still this is really not relativity either... this is "optics" near the speed of light. Like running in the rain when it is falling vertically water will strike you in he face. In a similar way (for a single point of view or perspective) light will approach us from different directions due to our relative motion and it is called "stellar aberration". Still most people think this is relativity... no... not really... it is only an optical effect equivalent to a sonic effect you would have with sound as well due to relative motion.
The "real" effect of Relativity (Special and General) is two fold due to only one effect... "Light falls down" .... along a geodesic called the Null Geodesic... this "path" is the perspective that a photon 'sees"... observers "see" light move along long paths through space and these sometimes take a lot of time. These "spacetime" path lengths are a result not of the "motion of light" but of the "motion of the observers" and they are constrained by the existence of mass. Light is not constrained by it's own "mass" but is "sees" the rest of the mass and "falls" under the influence of gravity. The length of this geodesic for photons of light is exactly "zero" in it's own frame of reference. Everywhere is the one place and all times are the same to photons. Photons "suffer" the most extreme case of time and space relativistic phenomena. The equations that govern this motion are really the same as those of Special Relativity since, as I said, light really can't be "pushed or pulled" in it's own frame of reference. There really are only two effects of being forced to move along this path that occur.
1. Time Dilation (for light ... the total loss of the passage of time for the photon)
2. Length Contraction (for light ... the total loss of the appreciation of separation between points in our extended space).
All other particle that try and approach this "shortest path" through time and space between points will fail because of the existence of the particles mass. As other particles "try" and make their path approach the one that light takes as it "falls under gravity" their properties will approach this "shortest path" (properties of photons) by experiencing incomplete time dilation and length contraction where their world line shortens such that the experience of time in comparison to time experienced by "slower observers" is relatively shorter and the distance between points is "contracted" (spatially rotated). These two effects complement each other such that vast journeys can be made in relatively short "ship's time" at the expense of the passage of much longer periods of time in the rest frames of the Earth. A journey of 100,000 light years "may" be shortened to a period of months for a traveler if sufficient energy were made available. The period that light takes to travel that same distance (100,000 "Earth years") as seen by external observers (who see the distance as 100,000 light years) is an absolute minimum of time to elapse "back home". Therefore world lines of a highly accelerated traveler and those left behind on Earth will not match after a round trip (bringing these world lines back together).
The object that underwent the greatest acceleration (according to General Relativity) will be the one that experiences the greatest relative time dilation. The means of acceleration is irrelevant to time dilation or length contraction... all acceleration is 100% equivalent (Equivalence Principle)... in that sense gravity and the forces felt in acceleration by a rocket is "identical". All the while a great "length contraction" (spatial rotation) will also be experienced but the optical effect is quite different to "simple linear contraction" of distances ... it actually appears as a spatial rotation where the field of view will be compressed forward as a contracted "patch" in a very intense "blue shift" while the aft perspective will be seen as an intense "red shift" .... possibly all the way to "blackness" in the extreme situation.. This is because the frequencies approaching from those respective directions are frequency shifted in the extreme while "time" is "nearly frozen" for travelers as observed by external unaccelerated onlookers along the way.
Hope that cuts it with you all... feel free to comment.
Cheers
QUOTE (daljeet+Jun 10 2008, 07:27 AM)
Special relativity says that, speed of light is constant w.r.t any observer. i.e. two observers moving at constant speed relative to each other will observe the same speed of light.
I can't understand, why? Light has a definite speed. And two observers moving relative to each other should observe different light speeds.
Now I understand that experiments have been conducted that confirm the constancy of light; But I couldn't find the explanation as how or why does it happen.
Can anyone provide the explanation for this bizarre phenomenon.
There is no explanation (this is why it is a postulate). There is ample experimental confirmation , though.
I can't understand, why? Light has a definite speed. And two observers moving relative to each other should observe different light speeds.
Now I understand that experiments have been conducted that confirm the constancy of light; But I couldn't find the explanation as how or why does it happen.
Can anyone provide the explanation for this bizarre phenomenon.
There is no explanation (this is why it is a postulate). There is ample experimental confirmation , though.
QUOTE (daljeet+Jun 10 2008, 07:27 AM)
Special relativity says that, speed of light is constant w.r.t any observer. i.e. two observers moving at constant speed relative to each other will observe the same speed of light.
I can't understand, why? Light has a definite speed. And two observers moving relative to each other should observe different light speeds.
Now I understand that experiments have been conducted that confirm the constancy of light; But I couldn't find the explanation as how or why does it happen.
Can anyone provide the explanation for this bizarre phenomenon.
I haven't read good elf's post. It's rather long and I've had quite a long day! Apologies if this is a repeat of what's already been said.
The original theoretical justification for the postulate of special relativity that states the speed of light is constant was given by Maxwell. He (re)derived what are now called Maxwell's equations and showed they predicted a wave that moves with a speed c.
Now, Maxwell's equations describe the electromagnetic field and the wave that moves at c is electromagnetic radiation (or simply light).
So physicists got thinking about light and it's speed. Naturally, you can ask what the speed is relative to. It doesn't take much imagination to see that the earth is moving with respect to the sun which is moving with respect to the galaxy etc etc. There is manifestly no unique standard of rest that the light could be said to move at c relative to.
So physicists proposed the existence of the ether, which is a fixed background that the light could move at c relative to. It was proved wrong by the Michelson Morley experiment which found the speed of light was the same no matter which direction it was measured in. (Have a look here for more info on this.)
So, the revolutionary proposal (at the time) was the speed of light moves at c with respect to any observer. As trout says, there have been many experiments that have shown c is constant. It is totally counter intuitive, but it seems to be the way nature is.
I can't understand, why? Light has a definite speed. And two observers moving relative to each other should observe different light speeds.
Now I understand that experiments have been conducted that confirm the constancy of light; But I couldn't find the explanation as how or why does it happen.
Can anyone provide the explanation for this bizarre phenomenon.
I haven't read good elf's post. It's rather long and I've had quite a long day! Apologies if this is a repeat of what's already been said.
The original theoretical justification for the postulate of special relativity that states the speed of light is constant was given by Maxwell. He (re)derived what are now called Maxwell's equations and showed they predicted a wave that moves with a speed c.
Now, Maxwell's equations describe the electromagnetic field and the wave that moves at c is electromagnetic radiation (or simply light).
So physicists got thinking about light and it's speed. Naturally, you can ask what the speed is relative to. It doesn't take much imagination to see that the earth is moving with respect to the sun which is moving with respect to the galaxy etc etc. There is manifestly no unique standard of rest that the light could be said to move at c relative to.
So physicists proposed the existence of the ether, which is a fixed background that the light could move at c relative to. It was proved wrong by the Michelson Morley experiment which found the speed of light was the same no matter which direction it was measured in. (Have a look here for more info on this.)
So, the revolutionary proposal (at the time) was the speed of light moves at c with respect to any observer. As trout says, there have been many experiments that have shown c is constant. It is totally counter intuitive, but it seems to be the way nature is.
H Trout, prometheus, daljeet et al,
The negative comments in feedback suggests that Trout has a better explanation. So the "better explanation" for "Why Light Has Constant Speed W.r.t Any Observer" is
A 'feature' of light is that it is made up of photons. If you get a photon then nobody else gets it .. the consequence is that you are only entitled to measure the speed of light for light that you actually receive. Someone else will get their own light and it will be 'at the speed of light' for them but there may be no direct connection between their 'speed of light' in their frame and your 'speed of light' in your frame .. it isn't the same light.
-C2.
The above statement is , of course, falsified by multiple experiments that describe the measurements of light speed from moving sources. Since , in relativity, motion is ....relative, the experiments are equivalent to measuring the light speed by...a set of moving observers. It pays of to learn mainstream science before making up posts.
I do not have a new theory .. this is also an area for discussion.
This is exactly what I was saying, you only have misinterpretations of existent theories. They could be remedied by your getting some education but you refuse to do that.
This part is for the people interested in physics, not for crackpots who keep questioning relativity (but, who knows, it might work on them as well).
I will modify an existent experiment, by Fizeau. In Fizeau's experiment the cog wheel (see the reference) has slits at regular angles "alpha". In order for light to bounce off the remote mirror and to be seen by the observer the wheel needs to rotate at the angular speed "omega" where:
omega=alpha*c/(2L) , where L is the distance between the light source and the mirror.
From the above, Fizeau determined the speed of light to be :
c=2L*omega/alpha
Now, I am going to show you how two (or more) observers can measure the speed of the SAME flux of photons by making a simple modification to the original Fizeau experiment:
A SECOND cog wheel is introduced between the first cog wheel and the mirror at distance l<L from the mirror. In order for light to pass through the inserted wheel, it needs to rotate at the angular speed :
Omega=alpha*c/(2l)
Obviously, Omega>omega.
An observer situated next to the inserted cog wheel measures light speed to be
c=2l*Omega/alpha
So, quite the contrary to your "beliefs", light speed can be measured by multiple observers using the SAME EXACT photons. Because, rather than blocking the photon flux, the clever experiment designed above relies on PASSING photon fluxes.
Historically Trout will claim this experiment shows I don't understand relativity .. so lets take that for granted.
Correct, you don't. The experiment (and its theory) goes back to the 1930's. It is the Ives-Stilwell experiment. Find another hobby.
Bob can observe and also has f,v and c to work from .. where does he make his marks? In particular .. what result for L does he get?
-C2.
Bob measures :
L'=L/gamma (relativistic length contraction)
f'=f/gamma (transverse Doppler effect)
where gamma=1/sqrt(1-(v/c)^2)
Any other basic thing that you don't understand and you want me to explain?
The negative comments in feedback suggests that Trout has a better explanation. So the "better explanation" for "Why Light Has Constant Speed W.r.t Any Observer" is
QUOTE (Trout+)
There is no explanation. (this is why it is a postulate).
Not answering a direct question is a mistake. People do not want an answer that says "just because it is so".
My answer was long and I apologize for that but you won't find this explanation in any of your wrote textbooks (... thats a challenge folks... go and find it). This detail is required so people understand the circumstances and also the motivation behind Relativity. If you do not analyze this concept then you will not understand why Relativity works and you begin to accept things "just because they are so" as Trout is saying. You can accept what Trout says on the basis of "authority"... what I offer is "understanding" on the basis of a real knowledge... your knowledge. The difference is this is harder at first but the "gain is worth the pain". You will truly "understand" a concept that other take on "authority" handed down by "the high priesthood of science".
I don't believe anything people tell me about anything in science unless I have first tried to understand it. It is far safer than "blind acceptance" and "blind acceptance" is not necessary in science since experiment can confirm the validity. Science has the "Scientific Method" where you can know for yourselves and not simply because someone tells you to believe and remain silent. It is "very important" for people to actually "know" why things are the way they are and not some other way. "Scientific Democracy" in the hands of "true believers" is a very dangerous thing, you end up with "mobs" of "collective foolishness". If you have gone all your lives "not truly knowing anything" then I am saddened because you have missed out on a "great joy". I am willing to accept the "flack" from those who will not try or can't make a sufficient effort to gain this tiny foothold on a deep wisdom. If only one of you succeed then I am very happy for you... honestly... you have done something of great personal achievement. Millions and even billions on this Earth "know" Relativity but only a handful "understand" Relativity. You could be one of those few rare individuals who one day will make a real difference. You need to choose...
I will try and put this "proof" a different way. Movement relative to a background is easy to explain... movement without a background is not so easy to explain and that is what this "essay" is all about. What it shows is a bullet, sound and light have a common methodology in their analysis. The difference is sound needs a medium for "transmission" while a bullet does not need a medium for "transmission" and this is analogous to light which does not need a medium for transmission either. However the "rub" is sound and light share a common basis... wave motion.
This explanation relies on the notions everybody uses to justify "phenomena" such as "absolute motion". The loss of this "absoluteness" means the loss of a medium or any way to view the light at any other speed than the speed of light. This assertion must be shown not simply "asserted" so that you can all understand. The velocity of a bullet, the velocity of sound, and the velocity of light have more facts in common than usually recognized. Sound will always propagate away from all sources at the speed of sound (in the medium) regardless of the motion of the source. If "air" is stationary sound will always be received by all stationary observers at the speed of sound regardless of the state of motion of that source. Movement of the source relative to the "air" does not change the velocity at which sound is "launched". Sound always expands away from the point in space at which it was "formed" at the speed of sound in the still air. This is because sound can't be "pushed or pulled" or made to go faster or slower in still air. This is exactly the same situation as for another kind of wave motion ... light. The speed of approach of sound in still air can be altered if the observer "moves with a velocity" relative to the still air in which the sound is moving as a wave. This can cause sound to "approach or recede" at a speed greater than or less than the nominal velocity of sound in still air. If a "wind" blows in your face the sound is "carried with the moving air" to you at a speed apparently faster than sound in the still air. This is simply because sound is a wave motion moving in a medium... the stationary air. The observer can move relative to "the stationary air"... the air is always stationary if you move along with it of if it is "still", thus air always has a preferred frame of reference... the still air. The argument now revolves around this point... why does this not happen for light? Why is there no "preferred frame of reference" for light?
Contrast this with a bullet which when fired out the back of a moving "bullet train"... if the speed of the bullet and the train have matching but opposing velocity ... even in the vacuum of space (lets say in free fall)... the bullet will go "nowhere".... it does not "propagate"... it does not need to propagate like a wave... it is a projectile. While the gun travels away from the bullet at the speed of a bullet (in the bullet train), the bullet itself is "motionless" relative to the observer in the still air (and would normally fall to the ground). On the other hand... Sound must always propagate in a medium regardless of the speed of the source. That is the difference. Sound "projected" out the back of a train moving at the speed of sound and does not cause sound to "stop its motion" like the bullet... it continues to propagate through the air at the speed of sound. It cannot pick up any speed from the train at all... it cannot be "pushed or pulled", it propagates at the speed of sound as if on the surface of an expanding sphere in the "still air".
So Sound (unlike a projectile) propagates through the medium at the speed of sound relative to all "stationary observers" (meaning observes whose state of motion has the air stationary with respect to them). Sound in such circumstances will always be "heard" at the speed of sound by all "stationary observers" but the pitch is altered depending on the velocity of the source. This is just the influence of lineal translation of the source "stretching our or compressing together" the successive wavefronts of the vibration of the sound source.
In the case of light it does not behave like the bullet since it is like sound ... it is a wave not a projectile. Light can never be "arrested" in motion like the bullet was. The single and only difference in the analysis is sound can move through a medium and the observers can be in motion relative to that medium too and thus the reception of sound can be at a velocity other than the speed of sound in still air (plus or minus the relative velocity of the observer "through" the still air). The still air is the absolute state of motion (rest frame or frame of reference) to which everything is referenced.
Light does not need a medium to propagate and in a vacuum is received by all observers in a constant state of motion in any direction as if they were entirely motionless in a "fictitious medium"... the aether. This observer velocity only appears to alter the relative velocity between the source and the observer but is totally ineffective at altering the velocity between the observer and the proposed aether.. So this motion is exactly equivalent to changing the velocity of the source while the observer considers itself always at rest... or visa versa.. it is absolutely identical.
If the observer can't move relative to the "aether medium" no matter how he moves at constant velocity, then the observer can't "observe" light arriving at a velocity of light "plus the relative velocity that the observer has relative to the medium". The subtlety is nothing the observer does can cause this differential "aether breeze" (motion through the stationary aether) to "blow on their faces" which would bring the light to them faster or retard the light from arriving "on time" depending on the observers direction of motion. The light always arrives at the exact speed of light.... a universal constant and an experimental fact.
It is as if all our experiments are in deep space far away from all external references and we do not know who is at rest and who is moving. Is the source moving towards us or are we moving towards the source? All we appear to know is the source-observer distance is shortening and all our experiments confirm this surprising fact. It is surprising because we expect that "aether wind in our face" and it appears not to "blow" no matter what. Furthermore it appears that it does not make any perceivable difference if we should propose that there is no aether at all. If the aether wind can't "blow" the light will always arrive at the same speed since we appear to always be "at rest" with respect to the expanding shells of the waves.
This "explains" the question... "Why Light Has Constant Speed W.r.t Any Observer". Every observer no matter what his or her motion is relative to the source "appears to remain at rest". It is demonstrating a "principle" regarding this aether (a material substance needed for the propagation of light in a similar way air is for sound). This hypothetical aether is always at rest relative to any constantly moving observer (or source) regardless of where we are or in what direction or relative velocity he should move with (up to but not including the speed of light). Using Occam's Razor there is no proof that any "substance" like an aether follows us all around to cause light to have no added motion relative to all observers. Not only that what could this "special mechanism" for the material aether be to hide this absolute motion from us? Neither light from a lightbulb in your room nor light from a distant star that is moving at a vast speed relative to us or even light from our own Sun around which our planet revolves.... no relative motion of an all pervading aether could be found. Now you can understand why the light always approaches at the speed of light and naturally is emitted at the speed of light as well. And more importantly why there is no absolute frame of reference or aether.
Now "postulate" why this is not true! No mere winging please... complaining that you simply don't like it. Think about this like a "true scientist" and find that deep level of satisfaction that comes to you when you really understand something in a way that only a scientist can feel.
Cheers
PS: Some background additional material...
PhysOrg: "Relativity" Speaking
My answer was long and I apologize for that but you won't find this explanation in any of your wrote textbooks (... thats a challenge folks... go and find it). This detail is required so people understand the circumstances and also the motivation behind Relativity. If you do not analyze this concept then you will not understand why Relativity works and you begin to accept things "just because they are so" as Trout is saying. You can accept what Trout says on the basis of "authority"... what I offer is "understanding" on the basis of a real knowledge... your knowledge. The difference is this is harder at first but the "gain is worth the pain". You will truly "understand" a concept that other take on "authority" handed down by "the high priesthood of science".
I don't believe anything people tell me about anything in science unless I have first tried to understand it. It is far safer than "blind acceptance" and "blind acceptance" is not necessary in science since experiment can confirm the validity. Science has the "Scientific Method" where you can know for yourselves and not simply because someone tells you to believe and remain silent. It is "very important" for people to actually "know" why things are the way they are and not some other way. "Scientific Democracy" in the hands of "true believers" is a very dangerous thing, you end up with "mobs" of "collective foolishness". If you have gone all your lives "not truly knowing anything" then I am saddened because you have missed out on a "great joy". I am willing to accept the "flack" from those who will not try or can't make a sufficient effort to gain this tiny foothold on a deep wisdom. If only one of you succeed then I am very happy for you... honestly... you have done something of great personal achievement. Millions and even billions on this Earth "know" Relativity but only a handful "understand" Relativity. You could be one of those few rare individuals who one day will make a real difference. You need to choose...
I will try and put this "proof" a different way. Movement relative to a background is easy to explain... movement without a background is not so easy to explain and that is what this "essay" is all about. What it shows is a bullet, sound and light have a common methodology in their analysis. The difference is sound needs a medium for "transmission" while a bullet does not need a medium for "transmission" and this is analogous to light which does not need a medium for transmission either. However the "rub" is sound and light share a common basis... wave motion.
This explanation relies on the notions everybody uses to justify "phenomena" such as "absolute motion". The loss of this "absoluteness" means the loss of a medium or any way to view the light at any other speed than the speed of light. This assertion must be shown not simply "asserted" so that you can all understand. The velocity of a bullet, the velocity of sound, and the velocity of light have more facts in common than usually recognized. Sound will always propagate away from all sources at the speed of sound (in the medium) regardless of the motion of the source. If "air" is stationary sound will always be received by all stationary observers at the speed of sound regardless of the state of motion of that source. Movement of the source relative to the "air" does not change the velocity at which sound is "launched". Sound always expands away from the point in space at which it was "formed" at the speed of sound in the still air. This is because sound can't be "pushed or pulled" or made to go faster or slower in still air. This is exactly the same situation as for another kind of wave motion ... light. The speed of approach of sound in still air can be altered if the observer "moves with a velocity" relative to the still air in which the sound is moving as a wave. This can cause sound to "approach or recede" at a speed greater than or less than the nominal velocity of sound in still air. If a "wind" blows in your face the sound is "carried with the moving air" to you at a speed apparently faster than sound in the still air. This is simply because sound is a wave motion moving in a medium... the stationary air. The observer can move relative to "the stationary air"... the air is always stationary if you move along with it of if it is "still", thus air always has a preferred frame of reference... the still air. The argument now revolves around this point... why does this not happen for light? Why is there no "preferred frame of reference" for light?
Contrast this with a bullet which when fired out the back of a moving "bullet train"... if the speed of the bullet and the train have matching but opposing velocity ... even in the vacuum of space (lets say in free fall)... the bullet will go "nowhere".... it does not "propagate"... it does not need to propagate like a wave... it is a projectile. While the gun travels away from the bullet at the speed of a bullet (in the bullet train), the bullet itself is "motionless" relative to the observer in the still air (and would normally fall to the ground). On the other hand... Sound must always propagate in a medium regardless of the speed of the source. That is the difference. Sound "projected" out the back of a train moving at the speed of sound and does not cause sound to "stop its motion" like the bullet... it continues to propagate through the air at the speed of sound. It cannot pick up any speed from the train at all... it cannot be "pushed or pulled", it propagates at the speed of sound as if on the surface of an expanding sphere in the "still air".
So Sound (unlike a projectile) propagates through the medium at the speed of sound relative to all "stationary observers" (meaning observes whose state of motion has the air stationary with respect to them). Sound in such circumstances will always be "heard" at the speed of sound by all "stationary observers" but the pitch is altered depending on the velocity of the source. This is just the influence of lineal translation of the source "stretching our or compressing together" the successive wavefronts of the vibration of the sound source.
In the case of light it does not behave like the bullet since it is like sound ... it is a wave not a projectile. Light can never be "arrested" in motion like the bullet was. The single and only difference in the analysis is sound can move through a medium and the observers can be in motion relative to that medium too and thus the reception of sound can be at a velocity other than the speed of sound in still air (plus or minus the relative velocity of the observer "through" the still air). The still air is the absolute state of motion (rest frame or frame of reference) to which everything is referenced.
Light does not need a medium to propagate and in a vacuum is received by all observers in a constant state of motion in any direction as if they were entirely motionless in a "fictitious medium"... the aether. This observer velocity only appears to alter the relative velocity between the source and the observer but is totally ineffective at altering the velocity between the observer and the proposed aether.. So this motion is exactly equivalent to changing the velocity of the source while the observer considers itself always at rest... or visa versa.. it is absolutely identical.
If the observer can't move relative to the "aether medium" no matter how he moves at constant velocity, then the observer can't "observe" light arriving at a velocity of light "plus the relative velocity that the observer has relative to the medium". The subtlety is nothing the observer does can cause this differential "aether breeze" (motion through the stationary aether) to "blow on their faces" which would bring the light to them faster or retard the light from arriving "on time" depending on the observers direction of motion. The light always arrives at the exact speed of light.... a universal constant and an experimental fact.
It is as if all our experiments are in deep space far away from all external references and we do not know who is at rest and who is moving. Is the source moving towards us or are we moving towards the source? All we appear to know is the source-observer distance is shortening and all our experiments confirm this surprising fact. It is surprising because we expect that "aether wind in our face" and it appears not to "blow" no matter what. Furthermore it appears that it does not make any perceivable difference if we should propose that there is no aether at all. If the aether wind can't "blow" the light will always arrive at the same speed since we appear to always be "at rest" with respect to the expanding shells of the waves.
This "explains" the question... "Why Light Has Constant Speed W.r.t Any Observer". Every observer no matter what his or her motion is relative to the source "appears to remain at rest". It is demonstrating a "principle" regarding this aether (a material substance needed for the propagation of light in a similar way air is for sound). This hypothetical aether is always at rest relative to any constantly moving observer (or source) regardless of where we are or in what direction or relative velocity he should move with (up to but not including the speed of light). Using Occam's Razor there is no proof that any "substance" like an aether follows us all around to cause light to have no added motion relative to all observers. Not only that what could this "special mechanism" for the material aether be to hide this absolute motion from us? Neither light from a lightbulb in your room nor light from a distant star that is moving at a vast speed relative to us or even light from our own Sun around which our planet revolves.... no relative motion of an all pervading aether could be found. Now you can understand why the light always approaches at the speed of light and naturally is emitted at the speed of light as well. And more importantly why there is no absolute frame of reference or aether.
Now "postulate" why this is not true! No mere winging please... complaining that you simply don't like it. Think about this like a "true scientist" and find that deep level of satisfaction that comes to you when you really understand something in a way that only a scientist can feel.
Cheers
PS: Some background additional material...
PhysOrg: "Relativity" Speaking
For the benefit of those not aware of the nature of this section.. (eg Trout)
YOU ARE READING AN ENTRY IN THE NEW THEORIES SECTION OF THE FORUM .. ANY TRUTH IT CONTAINS MAY BE PURE COINCIDENCE.
A 'feature' of light is that it is made up of photons. If you get a photon then nobody else gets it .. the consequence is that you are only entitled to measure the speed of light for light that you actually receive. Someone else will get their own light and it will be 'at the speed of light' for them but there may be no direct connection between their 'speed of light' in their frame and your 'speed of light' in your frame .. it isn't the same light.
-C2.
YOU ARE READING AN ENTRY IN THE NEW THEORIES SECTION OF THE FORUM .. ANY TRUTH IT CONTAINS MAY BE PURE COINCIDENCE.
A 'feature' of light is that it is made up of photons. If you get a photon then nobody else gets it .. the consequence is that you are only entitled to measure the speed of light for light that you actually receive. Someone else will get their own light and it will be 'at the speed of light' for them but there may be no direct connection between their 'speed of light' in their frame and your 'speed of light' in your frame .. it isn't the same light.
-C2.
QUOTE (Confused2+Jun 12 2008, 09:57 AM)
A 'feature' of light is that it is made up of photons. If you get a photon then nobody else gets it .. the consequence is that you are only entitled to measure the speed of light for light that you actually receive. Someone else will get their own light and it will be 'at the speed of light' for them but there may be no direct connection between their 'speed of light' in their frame and your 'speed of light' in your frame .. it isn't the same light.
-C2.
The above statement is , of course, falsified by multiple experiments that describe the measurements of light speed from moving sources. Since , in relativity, motion is ....relative, the experiments are equivalent to measuring the light speed by...a set of moving observers. It pays of to learn mainstream science before making up posts.
For the benefit of those not aware of the nature of this section.. (eg Trout)
YOU ARE READING AN ENTRY IN THE NEW THEORIES SECTION OF THE FORUM .. ANY TRUTH IT CONTAINS MAY BE PURE COINCIDENCE.
Hi Trout,
Are you happy with light being made up of photons?
If 'yes' then can two observers detect the same photon?
If 'no' then can you clarify how you measure the speed of light without actually detecting the light? My point was that that the speed of light between any two points is always (measured to be) the same .. are you disagreeing or agreeing?
-C2.
YOU ARE READING AN ENTRY IN THE NEW THEORIES SECTION OF THE FORUM .. ANY TRUTH IT CONTAINS MAY BE PURE COINCIDENCE.
Hi Trout,
Are you happy with light being made up of photons?
If 'yes' then can two observers detect the same photon?
If 'no' then can you clarify how you measure the speed of light without actually detecting the light? My point was that that the speed of light between any two points is always (measured to be) the same .. are you disagreeing or agreeing?
-C2.
QUOTE (Confused2+Jun 12 2008, 03:27 PM)
For the benefit of those not aware of the nature of this section.. (eg Trout)
YOU ARE READING AN ENTRY IN THE NEW THEORIES SECTION OF THE FORUM .. ANY TRUTH IT CONTAINS MAY BE PURE COINCIDENCE.
A new theory doesn't mean "your misunderstandings about existent theories passed as a new theory".
Hi Trout,
Are you happy with light being made up of photons?
If 'yes' then can two observers detect the same photon?
Simple,
The two observers don't have to detect the same photon in order to measure light speed. You didn't know that, right? How about if you read a few papers that I sourced in the link, you would learn something useful and you could stop now trying to pass your misunderstandings about physics as a new theory.
YOU ARE READING AN ENTRY IN THE NEW THEORIES SECTION OF THE FORUM .. ANY TRUTH IT CONTAINS MAY BE PURE COINCIDENCE.
A new theory doesn't mean "your misunderstandings about existent theories passed as a new theory".
QUOTE
Hi Trout,
Are you happy with light being made up of photons?
If 'yes' then can two observers detect the same photon?
Simple,
The two observers don't have to detect the same photon in order to measure light speed. You didn't know that, right? How about if you read a few papers that I sourced in the link, you would learn something useful and you could stop now trying to pass your misunderstandings about physics as a new theory.
For the benefit of those not aware of the nature of this section.. (eg Trout)
YOU ARE READING AN ENTRY IN THE NEW THEORIES SECTION OF THE FORUM .. ANY TRUTH IT CONTAINS MAY BE PURE COINCIDENCE.
I do not have a new theory .. this is also an area for discussion.
Please select an experiment that illustrates your point..
YOU ARE READING AN ENTRY IN THE NEW THEORIES SECTION OF THE FORUM .. ANY TRUTH IT CONTAINS MAY BE PURE COINCIDENCE.
I do not have a new theory .. this is also an area for discussion.
Please select an experiment that illustrates your point..
QUOTE (Confused2+Jun 12 2008, 04:04 PM)
I do not have a new theory .. this is also an area for discussion.
This is exactly what I was saying, you only have misinterpretations of existent theories. They could be remedied by your getting some education but you refuse to do that.
QUOTE
Please select an experiment that illustrates your point..
This part is for the people interested in physics, not for crackpots who keep questioning relativity (but, who knows, it might work on them as well).
I will modify an existent experiment, by Fizeau. In Fizeau's experiment the cog wheel (see the reference) has slits at regular angles "alpha". In order for light to bounce off the remote mirror and to be seen by the observer the wheel needs to rotate at the angular speed "omega" where:
omega=alpha*c/(2L) , where L is the distance between the light source and the mirror.
From the above, Fizeau determined the speed of light to be :
c=2L*omega/alpha
Now, I am going to show you how two (or more) observers can measure the speed of the SAME flux of photons by making a simple modification to the original Fizeau experiment:
A SECOND cog wheel is introduced between the first cog wheel and the mirror at distance l<L from the mirror. In order for light to pass through the inserted wheel, it needs to rotate at the angular speed :
Omega=alpha*c/(2l)
Obviously, Omega>omega.
An observer situated next to the inserted cog wheel measures light speed to be
c=2l*Omega/alpha
So, quite the contrary to your "beliefs", light speed can be measured by multiple observers using the SAME EXACT photons. Because, rather than blocking the photon flux, the clever experiment designed above relies on PASSING photon fluxes.
The constant nature of the speed of light appears to indicate there is also an absolute zero or absolute stationary reference. It is not a relative reference since relative reference has no impact on the speed of light. Relative reference only affects the aspect of energy implicit of wavelength and frequency. That allows light to exist in 0,C,V. Matter is in O,V. When energy is absorbed by matter there needs to be a 0 connection or C would vary.
Light appear to exist in more than one reference at the same time 0,C and V. One way to see this is to consider SR. As we approach C, we get distance contraction and time dilation approaching zero. Relative to energy at C and SR, we should only see quanta, due to time dilation and distance contraction, with the tiniest wavelength and faster frequency. But the reality is we can get distance and time affects implicit of V lower than C.
To put this in perspective, if we had a meter stick on a SR rocket to where it should look like 0.5 meters, in stationary reference, due to distance contraction, but we measured 1 meter, then we would assume there is something fishy going on or the velocity was 0. Light does this all the time. It travels it C where the meter stick should say zero but it can say 100 meters. It is not entirely part of SR or relative reference; only one aspect.
Light appear to exist in more than one reference at the same time 0,C and V. One way to see this is to consider SR. As we approach C, we get distance contraction and time dilation approaching zero. Relative to energy at C and SR, we should only see quanta, due to time dilation and distance contraction, with the tiniest wavelength and faster frequency. But the reality is we can get distance and time affects implicit of V lower than C.
To put this in perspective, if we had a meter stick on a SR rocket to where it should look like 0.5 meters, in stationary reference, due to distance contraction, but we measured 1 meter, then we would assume there is something fishy going on or the velocity was 0. Light does this all the time. It travels it C where the meter stick should say zero but it can say 100 meters. It is not entirely part of SR or relative reference; only one aspect.
QUOTE (Trout+Jun 12 2008, 05:37 PM)
This is exactly what I was saying, you only have misinterpretations of existent theories. They could be remedied by your getting some education but you refuse to do that.
This part is for the people interested in physics, not for crackpots who keep questioning relativity (but, who knows, it might work on them as well).
I will modify an existent experiment, by Fizeau. In Fizeau's experiment the cog wheel (see the reference) has slits at regular angles "alpha". In order for light to bounce off the remote mirror and to be seen by the observer the wheel needs to rotate at the angular speed "omega" where:
omega=alpha*c/(2L) , where L is the distance between the light source and the mirror.
From the above, Fizeau determined the speed of light to be :
c=2L*omega/alpha
Now, I am going to show you how two (or more) observers can measure the speed of the SAME flux of photons by making a simple modification to the original Fizeau experiment:
A SECOND cog wheel is introduced between the first cog wheel and the mirror at distance l<L from the mirror. In order for light to pass through the inserted wheel, it needs to rotate at the angular speed :
Omega=alpha*c/(2l)
Obviously, Omega>omega.
An observer situated next to the inserted cog wheel measures light speed to be
c=2l*Omega/alpha
So, quite the contrary to your "beliefs", light speed can be measured by multiple observers using the SAME EXACT photons. Because, rather than blocking the photon flux, the clever experiment designed above relies on PASSING photon fluxes.
Are you sure?
This part is for the people interested in physics, not for crackpots who keep questioning relativity (but, who knows, it might work on them as well).
I will modify an existent experiment, by Fizeau. In Fizeau's experiment the cog wheel (see the reference) has slits at regular angles "alpha". In order for light to bounce off the remote mirror and to be seen by the observer the wheel needs to rotate at the angular speed "omega" where:
omega=alpha*c/(2L) , where L is the distance between the light source and the mirror.
From the above, Fizeau determined the speed of light to be :
c=2L*omega/alpha
Now, I am going to show you how two (or more) observers can measure the speed of the SAME flux of photons by making a simple modification to the original Fizeau experiment:
A SECOND cog wheel is introduced between the first cog wheel and the mirror at distance l<L from the mirror. In order for light to pass through the inserted wheel, it needs to rotate at the angular speed :
Omega=alpha*c/(2l)
Obviously, Omega>omega.
An observer situated next to the inserted cog wheel measures light speed to be
c=2l*Omega/alpha
So, quite the contrary to your "beliefs", light speed can be measured by multiple observers using the SAME EXACT photons. Because, rather than blocking the photon flux, the clever experiment designed above relies on PASSING photon fluxes.
Are you sure?
Hi Trout,
Despite your imaginings I'm a pretty OK guy. The point (about relativity) is more interesting (to me) than many things. I invite you to propose a second experiment.
-C2.
Despite your imaginings I'm a pretty OK guy. The point (about relativity) is more interesting (to me) than many things. I invite you to propose a second experiment.
-C2.
Hey C2, check out the last line of my signature. 
Hi TheDoc,
Please explain how you think Trout's response clarifies the 'constant speed of light' postulate in the present context.
-C2.
Please explain how you think Trout's response clarifies the 'constant speed of light' postulate in the present context.
-C2.
DISCLAIMER: I am quite ignorant of the matter and have had almost zero training.
I have been told that if the speed of light isn't constant, then Maxwell's equations, etc, are not the same in all frames. Additionally, I have been told that if c isn't constant, than there are conservation law problems from one reference to the next.
Don't take my word for it though...
I have been told that if the speed of light isn't constant, then Maxwell's equations, etc, are not the same in all frames. Additionally, I have been told that if c isn't constant, than there are conservation law problems from one reference to the next.
Don't take my word for it though...
QUOTE (Confused2+Jun 12 2008, 11:06 PM)
Hi TheDoc,
Please explain how you think Trout's response clarifies the 'constant speed of light' postulate in the present context.
-C2.
You didn't get the point of my previous post, did you?
Please explain how you think Trout's response clarifies the 'constant speed of light' postulate in the present context.
-C2.
You didn't get the point of my previous post, did you?
And you clearly didn't get the point of mine..
QUOTE (Confused2+Jun 12 2008, 11:47 PM)
And you clearly didn't get the point of mine..
Clearly, we both face the same dilemma!
Clearly, we both face the same dilemma!
No, I am hoping Trout will come up with something good .. I have no idea what you are doing here/this thread/this forum.
QUOTE (Grasshopper+Jun 12 2008, 11:13 PM)
I have been told that if the speed of light isn't constant, then Maxwell's equations, etc, are not the same in all frames. Additionally, I have been told that if c isn't constant, than there are conservation law problems from one reference to the next.
Don't take my word for it though...
Who told you that? I sincerely hope it wasn't a physics instructor because it's completely wrong. The beauty of Maxwells equations is that they are not invariant in all reference frames but they are covariant. That is, if you are in the rest frame of a charge you see only electric field. If you transform to a frame that is not at rest wrt the charge you see a mixture of electric and magnetic field. The fields change in just the right way so that all the physics that we like holds, like conservation of energy etc.
c is a constant (until to get to quantum field theory in curved space, which is 1) on the bleeding edge of physics research and 2) one of the things an office mate at work is researching)
Don't take my word for it though...
Who told you that? I sincerely hope it wasn't a physics instructor because it's completely wrong. The beauty of Maxwells equations is that they are not invariant in all reference frames but they are covariant. That is, if you are in the rest frame of a charge you see only electric field. If you transform to a frame that is not at rest wrt the charge you see a mixture of electric and magnetic field. The fields change in just the right way so that all the physics that we like holds, like conservation of energy etc.
c is a constant (until to get to quantum field theory in curved space, which is 1) on the bleeding edge of physics research and 2) one of the things an office mate at work is researching)
QUOTE (prometheus+Jun 13 2008, 07:08 AM)
Who told you that? I sincerely hope it wasn't a physics instructor because it's completely wrong. The beauty of Maxwells equations is that they are not invariant in all reference frames but they are covariant.
You need to be careful about this. In the covariant formulation , "c" is the same in all the frames. Otherwise, the formulation doesn't work.
You need to be careful about this. In the covariant formulation , "c" is the same in all the frames. Otherwise, the formulation doesn't work.
QUOTE (Trout+Jun 13 2008, 05:36 PM)
You need to be careful about this. In the covariant formulation , "c" is the same in all the frames. Otherwise, the formulation doesn't work.
Yes. c is the same in all frames. E and B are not.
Yes. c is the same in all frames. E and B are not.
QUOTE (prometheus+Jun 13 2008, 07:16 PM)
Yes. c is the same in all frames. E and B are not.
The takeway from your discussion with Grashopper is that c HAS to be frame invariant in order for the relativistic form of the Maxwell equations to be covariant.
The takeway from your discussion with Grashopper is that c HAS to be frame invariant in order for the relativistic form of the Maxwell equations to be covariant.
Alice sets up a microwave cavity in her laboratory. The frequency is f, the number of peaks is N and the wavelength is c/f, the length of the cavity (L) is therefore Nc/(2f)
To detect the peaks Alice mounts a flourescent tube in the cavity .. it glows at the voltage peaks and is dark elsewhere.
Bob is invited to walk smartly through the laboratory at v (about 0.9c) ..
Bob is given a green felt tip pen to mark where he sees the bright bits on the tube as he passes and a red felt tip pen to mark what he predicts will be the distance between the bright bits. Bob is told the frequency of the source in the lab frame and a small amount is radiated so he can measure the frequency using his own frequency counter.
On a good day his observations and his predictions should be the same.
Historically Trout will claim this experiment shows I don't understand relativity .. so lets take that for granted.
Bob can observe and also has f,v and c to work from .. where does he make his marks? In particular .. what result for L does he get?
-C2.
To detect the peaks Alice mounts a flourescent tube in the cavity .. it glows at the voltage peaks and is dark elsewhere.
Bob is invited to walk smartly through the laboratory at v (about 0.9c) ..
Bob is given a green felt tip pen to mark where he sees the bright bits on the tube as he passes and a red felt tip pen to mark what he predicts will be the distance between the bright bits. Bob is told the frequency of the source in the lab frame and a small amount is radiated so he can measure the frequency using his own frequency counter.
On a good day his observations and his predictions should be the same.
Historically Trout will claim this experiment shows I don't understand relativity .. so lets take that for granted.
Bob can observe and also has f,v and c to work from .. where does he make his marks? In particular .. what result for L does he get?
-C2.
QUOTE (Confused2+Jun 13 2008, 11:28 PM)
Historically Trout will claim this experiment shows I don't understand relativity .. so lets take that for granted.
Correct, you don't. The experiment (and its theory) goes back to the 1930's. It is the Ives-Stilwell experiment. Find another hobby.
QUOTE (Confused2+Jun 12 2008, 09:32 PM)
I invite you to propose a second experiment.
-C2.
Ah, I see, you didn't understand the modified Fizeau experiment I explained to you so you introduced a second one (Ives-Stilwell) that you want me to explain to you , though you will not understand it either.
-C2.
Ah, I see, you didn't understand the modified Fizeau experiment I explained to you so you introduced a second one (Ives-Stilwell) that you want me to explain to you , though you will not understand it either.
QUOTE (Confused2+Jun 13 2008, 11:28 PM)
Bob can observe and also has f,v and c to work from .. where does he make his marks? In particular .. what result for L does he get?
-C2.
Bob measures :
L'=L/gamma (relativistic length contraction)
f'=f/gamma (transverse Doppler effect)
where gamma=1/sqrt(1-(v/c)^2)
Any other basic thing that you don't understand and you want me to explain?
QUOTE (Trout+)
Ah, I see, you didn't understand the modified Fizeau experiment I explained to you so you introduced a second one (Ives-Stilwell) that you want me to explain to you , though you will not understand it either.
You seemed to think the first cog is a source of light .. I assumed you had simply made a mistake .. apparently not. To get max light transmission at the second cog it needs to rotate at the same rate (say radians/sec) as the first cog (but not the same phase). With only one (implied) detector close to the source your experiment seemd to have no bearing on the original problem. Further clarification please.
-C2.
You seemed to think the first cog is a source of light .. I assumed you had simply made a mistake .. apparently not. To get max light transmission at the second cog it needs to rotate at the same rate (say radians/sec) as the first cog (but not the same phase). With only one (implied) detector close to the source your experiment seemd to have no bearing on the original problem. Further clarification please.
-C2.
The purpose of introducing a means whereby the speed of light could be constant in every frame without length contraction was to clarify the reality of 'length contraction'. Once clarified we could perhaps go back to the 'pole and barn' discussion and see whether length contraction is real (or not) on that thread.
Thank you for your time.
-C2.
Thank you for your time.
-C2.
QUOTE (Confused2+Jun 14 2008, 06:23 AM)
QUOTE (Trout+)
Ah, I see, you didn't understand the modified Fizeau experiment I explained to you so you introduced a second one (Ives-Stilwell) that you want me to explain to you , though you will not understand it either.
You seemed to think the first cog is a source of light .. I assumed you had simply made a mistake .. apparently not.
No, I didn't. It is just your standard misunderstanding. Like I said, the post was for people that understand physics.
No, it doesn't. If it did, light would get blocked. I gave you the exact formulas for "omega" and "Omega" right here. Another one of your inabilities to understand. Nothing new here. I suggest that you pick another hobby. have you considered lead ball table tennis?
Omega=alpha*c/(2l)
Obviously, Omega>omega.
I really can't follow your explanation .. can you help please?
-C2.
Omega=alpha*c/(2l)
Obviously, Omega>omega.
I really can't follow your explanation .. can you help please?
-C2.
It is really simple, during the same time t,
-the light travels to the mirror and back , so t=2l/c
-while the cog wheel advances by the angle alpha=Omega*t
From the above two equations it follows that 2l/c=alpha/Omega.
So: Omega=alpha*c/(2l)
For the wheel farther from the mirror (at distance =L)
omega=alpha*c/(2L)
Since L>l it follows that Omega>omega.
All you needed to know was some simple algebra and tenth class physics.
Omega=alpha*c/(2l)
Obviously, Omega>omega.
I really can't follow your explanation .. can you help please?
-C2.
This gitty twerp has real trouble following his own shadow.
Yep, that is how they would do it. They do it when they paint satellites with a laser. Leading a target is required when a projectile (photon) travels at a finite speed. The amount of lead is dependent on the distance to the target, the relative speed of the target, and the speed of the projectile.
No.. your satellites are in motion relative to the source. In my example the two spaceships had no relative motion .. they are in the same 'frame' .. the laser does not need to be pointed ahead/behind to allow for motion relative to anything else. The speed of light being (found to be) the same in every frame.
-C2.
You seemed to think the first cog is a source of light .. I assumed you had simply made a mistake .. apparently not.
No, I didn't. It is just your standard misunderstanding. Like I said, the post was for people that understand physics.
QUOTE
To get max light transmission at the second cog it needs to rotate at the same rate (say radians/sec) as the first cog .
No, it doesn't. If it did, light would get blocked. I gave you the exact formulas for "omega" and "Omega" right here. Another one of your inabilities to understand. Nothing new here. I suggest that you pick another hobby. have you considered lead ball table tennis?
Post deleted .. gone for a think !
QUOTE (Confused2+Jun 14 2008, 04:07 PM)
Post deleted .. gone for a think !
Could be gone for years; judging by past extreme inability to form coherent rational thought thus far (with any luck).
Seriously though, I reckon he's just gone shopping for some lead table-tennis balls - speaking of lead; poor, very dense C2 should utilize his head as radiation shielding for nuclear reactor cores, thus achieving something worthwhile for a change.
Could be gone for years; judging by past extreme inability to form coherent rational thought thus far (with any luck).
Seriously though, I reckon he's just gone shopping for some lead table-tennis balls - speaking of lead; poor, very dense C2 should utilize his head as radiation shielding for nuclear reactor cores, thus achieving something worthwhile for a change.
Hi Trout,Fivedoughnut,
Obviously if the second cog is close to the first then Omega=omega for best transmission. Obviously the same applies if the second cog is next to the mirror.. so the Trout solution looks incorrect .. yes .. you agree?
-C2.
On the Wiki discussion pages it seems there is someone trying to pass off 'own research' as standard theory. Would that be someone trying to discredit you ? .. it works (poetic or what?) .. the consequence is that anyone who blindly accepts your posts has rather missed the point of this section. I agree that 'new' doesn't necessarily mean 'wrong' .. but caution is appropriate. (TheDoc/5D please note)
Obviously if the second cog is close to the first then Omega=omega for best transmission. Obviously the same applies if the second cog is next to the mirror.. so the Trout solution looks incorrect .. yes .. you agree?
-C2.
On the Wiki discussion pages it seems there is someone trying to pass off 'own research' as standard theory. Would that be someone trying to discredit you ? .. it works (poetic or what?) .. the consequence is that anyone who blindly accepts your posts has rather missed the point of this section. I agree that 'new' doesn't necessarily mean 'wrong' .. but caution is appropriate. (TheDoc/5D please note)
QUOTE (Confused2+Jun 16 2008, 08:19 AM)
Hi Trout,Fivedoughnut,
Obviously if the second cog is close to the first then Omega=omega for best transmission. Obviously the same applies if the second cog is next to the mirror.. so the Trout solution looks incorrect .. yes .. you agree?
-C2.
I see, the explanation using two different angular speeds is too difficult for you to understand. Since you insist on using the same angular speed, I can modify Fizeau 's experiment in a different way. Note, what follows is for people that know physics, not for cranks.
Both wheels are now rotating at the same angular speed but they are offset as follows:
1. The first slit on the cog wheel closer to the mirror is offset behind the first slit of the wheel further away from the mirror by the angle:
delta=omega*(L-l)/c
This allows the second cog wheel to rotate in the appropriate postion in order to allow light to pass through.
2. The angle between two consecutive teeth of the wheel closer to the mirror is still:
beta=omega*2l/c
This alows light passing thru une cog in the direction light source-> mirror to pass through the following gog on the return pass from the mirror.
3. The second cog of the wheel farthest from the mirror is offset behind the second cog of the wheel closest to the mirror by the angle delta=omega*(L-l)/c.
In other words, the angle between two consecutive cogs of the wheel furthest from the mirror is still:
alpha=beta+2*delta=omega*2l/c+2*omega*(L-l)/c=omega*2L/c
This means that the SAME ray of light (flux of photons) passes thru consecutive cogs belonging to BOTH wheels, so, two observers sitting next to the two wheels in the modified Fizeau experiment will measure the same speed for light, c.
What are you rambling about?
Obviously if the second cog is close to the first then Omega=omega for best transmission. Obviously the same applies if the second cog is next to the mirror.. so the Trout solution looks incorrect .. yes .. you agree?
-C2.
I see, the explanation using two different angular speeds is too difficult for you to understand. Since you insist on using the same angular speed, I can modify Fizeau 's experiment in a different way. Note, what follows is for people that know physics, not for cranks.
Both wheels are now rotating at the same angular speed but they are offset as follows:
1. The first slit on the cog wheel closer to the mirror is offset behind the first slit of the wheel further away from the mirror by the angle:
delta=omega*(L-l)/c
This allows the second cog wheel to rotate in the appropriate postion in order to allow light to pass through.
2. The angle between two consecutive teeth of the wheel closer to the mirror is still:
beta=omega*2l/c
This alows light passing thru une cog in the direction light source-> mirror to pass through the following gog on the return pass from the mirror.
3. The second cog of the wheel farthest from the mirror is offset behind the second cog of the wheel closest to the mirror by the angle delta=omega*(L-l)/c.
In other words, the angle between two consecutive cogs of the wheel furthest from the mirror is still:
alpha=beta+2*delta=omega*2l/c+2*omega*(L-l)/c=omega*2L/c
This means that the SAME ray of light (flux of photons) passes thru consecutive cogs belonging to BOTH wheels, so, two observers sitting next to the two wheels in the modified Fizeau experiment will measure the same speed for light, c.
QUOTE
On the Wiki discussion pages it seems there is someone trying to pass off 'own research' as standard theory. Would that be someone trying to discredit you ? .. it works (poetic or what?) .. the consequence is that anyone who blindly accepts your posts has rather missed the point of this section. I agree that 'new' doesn't necessarily mean 'wrong' .. but caution is appropriate. (TheDoc/5D please note)
What are you rambling about?
Hello all
A device that uses a reflecting mirror, to measure "c", measures the average speed (time of flight) of light. Oneway measurements of "c" require a more elaborate measuring system. Things tend to move during the measuring of "c".
If one was "at rest with the universe" then the "time of flight" for the outgoing ray/photon would be the same as the incoming/reflected ray/photon.
A device that uses a reflecting mirror, to measure "c", measures the average speed (time of flight) of light. Oneway measurements of "c" require a more elaborate measuring system. Things tend to move during the measuring of "c".
If one was "at rest with the universe" then the "time of flight" for the outgoing ray/photon would be the same as the incoming/reflected ray/photon.
Hi Trout,
A splendid recovery from your mistake.
-C2.
A splendid recovery from your mistake.
-C2.
Hi Montec,
Imagine two spaceships travelling at the same velocity relative to Earth. Each ship points a laser at the other. If the effect you propose existed then eaxh ship would have to point the laser slightly ahead of the other ship so it would be in the right place when the light arrived .. it seems no such effect can be detected by this or any other experiment ever performed .. leading to the conclusion that the speed of light is the same in every frame.
-C2.
Imagine two spaceships travelling at the same velocity relative to Earth. Each ship points a laser at the other. If the effect you propose existed then eaxh ship would have to point the laser slightly ahead of the other ship so it would be in the right place when the light arrived .. it seems no such effect can be detected by this or any other experiment ever performed .. leading to the conclusion that the speed of light is the same in every frame.
-C2.
QUOTE (Confused2+Jun 16 2008, 04:30 PM)
Hi Trout,
A splendid recovery from your mistake.
-C2.
When you cannot follow an explanation, just say so, I will give you another one. This will give the people that know physics the opportunity of seeing new things. Too bad that you are not in that category.
A splendid recovery from your mistake.
-C2.
When you cannot follow an explanation, just say so, I will give you another one. This will give the people that know physics the opportunity of seeing new things. Too bad that you are not in that category.
QUOTE (Trout+)
Omega=alpha*c/(2l)
Obviously, Omega>omega.
I really can't follow your explanation .. can you help please?
-C2.
Hello Confused2
Yep, that is how they would do it. They do it when they paint satellites with a laser. Leading a target is required when a projectile (photon) travels at a finite speed. The amount of lead is dependent on the distance to the target, the relative speed of the target, and the speed of the projectile.
Remember there is a headlight effect for any emission source that is in motion.
QUOTE
If the effect you propose existed then each ship would have to point the laser slightly ahead of the other ship so it would be in the right place when the light arrived
Yep, that is how they would do it. They do it when they paint satellites with a laser. Leading a target is required when a projectile (photon) travels at a finite speed. The amount of lead is dependent on the distance to the target, the relative speed of the target, and the speed of the projectile.
Remember there is a headlight effect for any emission source that is in motion.
QUOTE (Confused2+Jun 16 2008, 05:14 PM)
QUOTE (Trout+)
Omega=alpha*c/(2l)
Obviously, Omega>omega.
I really can't follow your explanation .. can you help please?
-C2.
It is really simple, during the same time t,
-the light travels to the mirror and back , so t=2l/c
-while the cog wheel advances by the angle alpha=Omega*t
From the above two equations it follows that 2l/c=alpha/Omega.
So: Omega=alpha*c/(2l)
For the wheel farther from the mirror (at distance =L)
omega=alpha*c/(2L)
Since L>l it follows that Omega>omega.
All you needed to know was some simple algebra and tenth class physics.
QUOTE (Confused2+Jun 16 2008, 05:14 PM)
QUOTE (Trout+)
Omega=alpha*c/(2l)
Obviously, Omega>omega.
I really can't follow your explanation .. can you help please?
-C2.
This gitty twerp has real trouble following his own shadow.
Hi Trout,
Wasn't the essence of the Fizeau experiment that the light went out in one 'slot' and came back in the next .. a chopped beam. If you do anything that isn't synchronous with the original 'chop' .. surely you end up with nonsense .. or have I misunderstood fizeau's experiment?
-C2.
Edit see diagram
http://en.wikipedia.org/wiki/Image:Speed_o...28Fizeau%29.PNG
Wasn't the essence of the Fizeau experiment that the light went out in one 'slot' and came back in the next .. a chopped beam. If you do anything that isn't synchronous with the original 'chop' .. surely you end up with nonsense .. or have I misunderstood fizeau's experiment?
-C2.
Edit see diagram
http://en.wikipedia.org/wiki/Image:Speed_o...28Fizeau%29.PNG
QUOTE (Confused2+Jun 16 2008, 05:36 PM)
Hi Trout,
Wasn't the essence of the Fizeau experiment that the light went out in one 'slot' and came back in the next .. a chopped beam. If you do anything that isn't synchronous with the original 'chop' .. surely you end up with nonsense .. or have I misunderstood fizeau's experiment?
-C2.
Edit see diagram
http://en.wikipedia.org/wiki/Image:Speed_o...28Fizeau%29.PNG
I showed you two ways of achieving this , one by using different angles between the cogs while rotating at the same angular speed and the other one by using the same angle between the cogs while using different angular speeds. Either method can be used.
Wasn't the essence of the Fizeau experiment that the light went out in one 'slot' and came back in the next .. a chopped beam. If you do anything that isn't synchronous with the original 'chop' .. surely you end up with nonsense .. or have I misunderstood fizeau's experiment?
-C2.
Edit see diagram
http://en.wikipedia.org/wiki/Image:Speed_o...28Fizeau%29.PNG
I showed you two ways of achieving this , one by using different angles between the cogs while rotating at the same angular speed and the other one by using the same angle between the cogs while using different angular speeds. Either method can be used.
QUOTE (Montec+)
Yep, that is how they would do it. They do it when they paint satellites with a laser. Leading a target is required when a projectile (photon) travels at a finite speed. The amount of lead is dependent on the distance to the target, the relative speed of the target, and the speed of the projectile.
No.. your satellites are in motion relative to the source. In my example the two spaceships had no relative motion .. they are in the same 'frame' .. the laser does not need to be pointed ahead/behind to allow for motion relative to anything else. The speed of light being (found to be) the same in every frame.
-C2.
QUOTE (me+)
If you do anything that isn't synchronous with the original 'chop' .. surely you end up with nonsense .
QUOTE (Trout+)
.. using diferent the same angle ..
.. as predicted ..
-C2.
Edit .. a rotating cog with 2N teeth will chop at twice the rate of one with N teeth .. is that the result you wanted to demonstrate?
.. as predicted ..
-C2.
Edit .. a rotating cog with 2N teeth will chop at twice the rate of one with N teeth .. is that the result you wanted to demonstrate?
QUOTE (Confused2+Jun 16 2008, 06:09 PM)
QUOTE (me+)
If you do anything that isn't synchronous with the original 'chop' .. surely you end up with nonsense .
QUOTE (Trout+)
.. using diferent the same angle ..
.. as predicted ..
-C2.
I told you that the solutions were for people that comprehend physics
Not for the first time - I don't think we have been chasing the same rabbit.
Not for the first time - I don't think we have been chasing the same rabbit.
I agree, I'm not chasing any rabbits while rabbit-chasing seems to be one of your favorite hobbies (along with underwater stamp collection).
If you have two synced cogged wheels, A and B, that are separated by a distance, then can you guarantee that the TOF (for light) from A to B is the same as the TOF from B to A?
One way light speed is isotropic. See here
.. as predicted ..
-C2.
I told you that the solutions were for people that comprehend physics
You are using the Fizeau experiment to show that a rotating cog with 2N teeth will chop at twice the rate of one with N teeth .. yes?
QUOTE (Confused2+Jun 16 2008, 06:19 PM)
You are using the Fizeau experiment to show that a rotating cog with 2N teeth will chop at twice the rate of one with N teeth .. yes?
Nope. You have a fixation with chopping, eh? Could this become your new hobby?
Nope. You have a fixation with chopping, eh? Could this become your new hobby?
QUOTE (Trout+)
Nope.
Yes. A trivial result with no bearing on the original point. Sorry.
-C2.
Yes. A trivial result with no bearing on the original point. Sorry.
-C2.
My original point was that the constant speed of light in every frame could be a trick due to 'not the same light'.
Trout introduced the Fizeau experiment ..
http://en.wikipedia.org/wiki/Image:Speed_o...28Fizeau%29.PNG
and a modification which I can make no sense of.
A more drastic modification would be to place the slotted wheels (say) every ten yards .. or closer.. much closer.. creating a coarse pitched worm gear through which the light travels without interruption (the return beam is of no interest here). Viewed from 'anyframe' the distance travelled [Length] and rate of rotation [1/Time] are no longer free variables. This may have been what Trout intended from the start (I have no idea) .. but certainly Trout saw the way to deal with the problem so I must thank him and add him to my list of amazing people posting on the net.
-C2.
Trout introduced the Fizeau experiment ..
http://en.wikipedia.org/wiki/Image:Speed_o...28Fizeau%29.PNG
and a modification which I can make no sense of.
A more drastic modification would be to place the slotted wheels (say) every ten yards .. or closer.. much closer.. creating a coarse pitched worm gear through which the light travels without interruption (the return beam is of no interest here). Viewed from 'anyframe' the distance travelled [Length] and rate of rotation [1/Time] are no longer free variables. This may have been what Trout intended from the start (I have no idea) .. but certainly Trout saw the way to deal with the problem so I must thank him and add him to my list of amazing people posting on the net.
-C2.
QUOTE (Confused2+Jun 17 2008, 09:49 PM)
My original point was that the constant speed of light in every frame could be a trick due to 'not the same light'.
...so I showed you how multiple observers can measure the speed of the same flux of photos while arriving to the same value for the light speed. You still don't get this, eh?
Trout introduced the Fizeau experiment ..
http://en.wikipedia.org/wiki/Image:Speed_o...28Fizeau%29.PNG
and a modification which I can make no sense of.
A more drastic modification would be to place the slotted wheels (say) every ten yards .. or closer.. much closer.. creating a coarse pitched worm gear through which the light travels without interruption (the return beam is of no interest here). Viewed from 'anyframe' the distance travelled [Length] and rate of rotation [1/Time] are no longer free variables. This may have been what Trout intended from the start (I have no idea) .. but certainly Trout saw the way to deal with the problem so I must thank him and add him to my list of amazing people posting on the net.
-C2.
Find another hobby (the lead ball pingpong sounds a perfect fit for you), physics is too tough when you have no education and no willingness to learn.
...so I showed you how multiple observers can measure the speed of the same flux of photos while arriving to the same value for the light speed. You still don't get this, eh?
QUOTE
Trout introduced the Fizeau experiment ..
http://en.wikipedia.org/wiki/Image:Speed_o...28Fizeau%29.PNG
and a modification which I can make no sense of.
A more drastic modification would be to place the slotted wheels (say) every ten yards .. or closer.. much closer.. creating a coarse pitched worm gear through which the light travels without interruption (the return beam is of no interest here). Viewed from 'anyframe' the distance travelled [Length] and rate of rotation [1/Time] are no longer free variables. This may have been what Trout intended from the start (I have no idea) .. but certainly Trout saw the way to deal with the problem so I must thank him and add him to my list of amazing people posting on the net.
-C2.
Find another hobby (the lead ball pingpong sounds a perfect fit for you), physics is too tough when you have no education and no willingness to learn.
QUOTE
...so I showed you how multiple observers can measure the speed of the same flux of photos while arriving to the same value for the light speed. You still don't get this, eh?
Not for the first time - I don't think we have been chasing the same rabbit.
QUOTE (Confused2+Jun 18 2008, 06:06 AM)
Not for the first time - I don't think we have been chasing the same rabbit.
I agree, I'm not chasing any rabbits while rabbit-chasing seems to be one of your favorite hobbies (along with underwater stamp collection).
While you have been dreaming the C2 foundry has been producing Confusalizers .. available in any length. One side is painted white and the other side is painted black .. there are clear markings at 1m intervals. You can see exactly what the light inside is doing by examining the device from the outside. These things can be poked into black holes .. wherever you like really (let's try to miss out the obvious place shall we?)
-C2.
Edit .. you have to rotate them so the light passes without interuption .. in case that wasn't obvious from the start.
-C2.
Edit .. you have to rotate them so the light passes without interuption .. in case that wasn't obvious from the start.
QUOTE (Confused2+Jun 18 2008, 07:54 AM)
While you have been dreaming the C2 foundry has been producing Confusalizers ..
I have to agree with you but I thought they were called "crackpotties"
I have to agree with you but I thought they were called "crackpotties"
Trout and I seem to have been monopolizing the thread recently .. does anyone want to add anything sensible? If not would it be OK to play with the confusalizer on this thread?
-C2.
-C2.
Hello Confused2, Trout, et al.
The round trip communication lag to the moon is about 2.7 seconds. In a "mythical" frame the one-way time would be 1.35 seconds. When a receiver moves during the time of flight (TOF) of the signal then there is a measurable change in the TOF. The GPS system takes this effect into account. The receiver on the surface of the Earth is the moving/rotating change in the TOF equation.
So you have two spaceships, A and B, traveling through space at the same velocity with A in the lead. Make the separation between the ships 1AU. Do you expect that there will be a difference between the TOF from A to B versus B to A? Keep in mind that the ships move during the TOF of the signal. My answer is that there will be a change in the TOF in all but one case.
If you have two synced cogged wheels, A and B, that are separated by a distance, then can you guarantee that the TOF (for light) from A to B is the same as the TOF from B to A? Keep in mind that the synced cogged wheels may be moving through space.
The round trip communication lag to the moon is about 2.7 seconds. In a "mythical" frame the one-way time would be 1.35 seconds. When a receiver moves during the time of flight (TOF) of the signal then there is a measurable change in the TOF. The GPS system takes this effect into account. The receiver on the surface of the Earth is the moving/rotating change in the TOF equation.
So you have two spaceships, A and B, traveling through space at the same velocity with A in the lead. Make the separation between the ships 1AU. Do you expect that there will be a difference between the TOF from A to B versus B to A? Keep in mind that the ships move during the TOF of the signal. My answer is that there will be a change in the TOF in all but one case.
If you have two synced cogged wheels, A and B, that are separated by a distance, then can you guarantee that the TOF (for light) from A to B is the same as the TOF from B to A? Keep in mind that the synced cogged wheels may be moving through space.
QUOTE (Montec+Jun 18 2008, 05:50 PM)
If you have two synced cogged wheels, A and B, that are separated by a distance, then can you guarantee that the TOF (for light) from A to B is the same as the TOF from B to A?
One way light speed is isotropic. See here
Hello Trout, et al.
A quote from your link.
I agree the the speed of light is isotropic and as such the speed of light is independent from any moving frame of reference. This is equivalent to saying that light is isotropic only in a aether frame (if I understand the meaning in the above quote).
Do we agree that the speed of light is independent of any moving reference frame?
However the phrase "one-way" is defining a frame of reference. Since the speed of light is finite and is independent from any frame then a moving frame will measure differences in the one-way time of flight (TOF) of light. Notice I am saying that the speed of light remains the same but the distance traveled by the light changes in a "moving" reference frame.
A quote from your link.
QUOTE
Note that while these experiments clearly use a one-way light path and find isotropy, they are inherently unable to rule out a large class of theories in which the one-way speed of light is anisotropic. These theories share the property that the round-trip speed of light is isotropic in any inertial frame, but the one-way speed is isotropic only in an æther frame.
I agree the the speed of light is isotropic and as such the speed of light is independent from any moving frame of reference. This is equivalent to saying that light is isotropic only in a aether frame (if I understand the meaning in the above quote).
Do we agree that the speed of light is independent of any moving reference frame?
However the phrase "one-way" is defining a frame of reference. Since the speed of light is finite and is independent from any frame then a moving frame will measure differences in the one-way time of flight (TOF) of light. Notice I am saying that the speed of light remains the same but the distance traveled by the light changes in a "moving" reference frame.
QUOTE (Montec+Jun 18 2008, 08:12 PM)
Hello Trout, et al.
A quote from your link.
I agree the the speed of light is isotropic and as such the speed of light is independent from any moving frame of reference.
correct
Not quite. I have had quite a few exchanges with the person who posted that and I pointed out that there is a flaw in his statement. He stubbornly refuses to correct the website. The correct statement is :
"In SR , light speed is isotropic in ALL inertial reference frames"
The other theories that he's talking about are not experimentally indistinguishable from SR, but this is a very advanced subject.
Not quite. I have had quite a few exchanges with the person who posted that and I pointed out that there is a flaw in his statement. He stubbornly refuses to correct the website. The correct statement is :
"In SR , light speed is isotropic in ALL inertial reference frames"
The other theories that he's talking about are not experimentally indistinguishable from SR, but this is a very advanced subject.
Do we agree that the speed of light is independent of any moving reference frame?
...as shown by another class of experiments (that confuse Confused2)
However the phrase "one-way" is defining a frame of reference. Since the speed of light is finite and is independent from any frame then a moving frame will measure differences in the one-way time of flight (TOF) of light.
Irrelevant. TOF has nothing to do with measuring light speed. You keep trying to make a connection between the anisotropy of TOF and a presumable anisotropy of light speed. There isn't any.
Irrelevant. TOF has nothing to do with measuring light speed. You keep trying to make a connection between the anisotropy of TOF and a presumable anisotropy of light speed. There isn't any.
Notice I am saying that the speed of light remains the same but the distance traveled by the light changes in a "moving" reference frame.
Yes, so what? No bearing on light speed isotropy.
A quote from your link.
I agree the the speed of light is isotropic and as such the speed of light is independent from any moving frame of reference.
correct
QUOTE
This is equivalent to saying that light is isotropic only in a aether frame (if I understand the meaning in the above quote).
Not quite. I have had quite a few exchanges with the person who posted that and I pointed out that there is a flaw in his statement. He stubbornly refuses to correct the website. The correct statement is :
"In SR , light speed is isotropic in ALL inertial reference frames"
The other theories that he's talking about are not experimentally indistinguishable from SR, but this is a very advanced subject.
QUOTE (->
| QUOTE |
| This is equivalent to saying that light is isotropic only in a aether frame (if I understand the meaning in the above quote). |
Not quite. I have had quite a few exchanges with the person who posted that and I pointed out that there is a flaw in his statement. He stubbornly refuses to correct the website. The correct statement is :
"In SR , light speed is isotropic in ALL inertial reference frames"
The other theories that he's talking about are not experimentally indistinguishable from SR, but this is a very advanced subject.
Do we agree that the speed of light is independent of any moving reference frame?
...as shown by another class of experiments (that confuse Confused2)
QUOTE
However the phrase "one-way" is defining a frame of reference. Since the speed of light is finite and is independent from any frame then a moving frame will measure differences in the one-way time of flight (TOF) of light.
Irrelevant. TOF has nothing to do with measuring light speed. You keep trying to make a connection between the anisotropy of TOF and a presumable anisotropy of light speed. There isn't any.
QUOTE (->
| QUOTE |
However the phrase "one-way" is defining a frame of reference. Since the speed of light is finite and is independent from any frame then a moving frame will measure differences in the one-way time of flight (TOF) of light. |
Irrelevant. TOF has nothing to do with measuring light speed. You keep trying to make a connection between the anisotropy of TOF and a presumable anisotropy of light speed. There isn't any.
Notice I am saying that the speed of light remains the same but the distance traveled by the light changes in a "moving" reference frame.
Yes, so what? No bearing on light speed isotropy.
Hi Trout,
Do you know why light has a constant speed wrt any observer?
Yes or no will suffice.
-C2.
Do you know why light has a constant speed wrt any observer?
Yes or no will suffice.
-C2.
Hello Trout, et al.
True the above quote has no bearing on light speed isotropy, but it is applicable to the measuring the TOF of light using synced cogged wheels where the radial angle between the cog openings between the two wheels is a function of the TOF of light between the wheels.
Actually the above experiment would be interesting to do with the ability to change the radial angle between the cogs (or rotation speed). Any variation in the radial angle (or rotation speed) when measuring the TOF for each direction would correspond to the velocity of the moving reference frame of the cogs. The cogs could be synced with atomic clocks, so there would be no need of a direct physical link. Two units with atomic clocks, syncing cogs, photo detectors and lasers with different beam polarity would be needed.
True the above quote has no bearing on light speed isotropy, but it is applicable to the measuring the TOF of light using synced cogged wheels where the radial angle between the cog openings between the two wheels is a function of the TOF of light between the wheels.
I have already shown that TOF has no impact on measuring light speed in the modified Fizeau experiment.
QUOTE
QUOTE (->
| QUOTE |
Notice I am saying that the speed of light remains the same but the distance traveled by the light changes in a "moving" reference frame. Yes, so what? No bearing on light speed isotropy. |
True the above quote has no bearing on light speed isotropy, but it is applicable to the measuring the TOF of light using synced cogged wheels where the radial angle between the cog openings between the two wheels is a function of the TOF of light between the wheels.
Actually the above experiment would be interesting to do with the ability to change the radial angle between the cogs (or rotation speed). Any variation in the radial angle (or rotation speed) when measuring the TOF for each direction would correspond to the velocity of the moving reference frame of the cogs. The cogs could be synced with atomic clocks, so there would be no need of a direct physical link. Two units with atomic clocks, syncing cogs, photo detectors and lasers with different beam polarity would be needed.
QUOTE (Confused2+Jun 18 2008, 09:46 PM)
Hi Trout,
Do you know why light has a constant speed wrt any observer?
Yes or no will suffice.
-C2.
No one does. This is why it is a postulate in SR. I have written this several times already. Once at the very start of this thread.
When and if a new theory will be discovered that encompasses SR, the light speed frame invariance will become a theorem in the new theory.
Do you know why light has a constant speed wrt any observer?
Yes or no will suffice.
-C2.
No one does. This is why it is a postulate in SR. I have written this several times already. Once at the very start of this thread.
When and if a new theory will be discovered that encompasses SR, the light speed frame invariance will become a theorem in the new theory.
QUOTE
True the above quote has no bearing on light speed isotropy, but it is applicable to the measuring the TOF of light using synced cogged wheels where the radial angle between the cog openings between the two wheels is a function of the TOF of light between the wheels.
I have already shown that TOF has no impact on measuring light speed in the modified Fizeau experiment.
Hello Trout, et al.
Isn't (L-l)/c a measure of time? IE m/(m/s) = s So anywhere you use (L-l)/c you are using a time value.
The distance light travels per unit time is independent of any moving frame of reference, so this implies that you cant use the speed of light to define a time over a set distance within a moving frame of reference. As a corollary, the only accurate way to measure the speed of light is to remove "motion" from the measuring frame. When you take an average, a to and fro sum/2, you are removing the "motion" of a moving frame.
Have you really moved if you end up where you started?
Isn't (L-l)/c a measure of time? IE m/(m/s) = s So anywhere you use (L-l)/c you are using a time value.
The distance light travels per unit time is independent of any moving frame of reference, so this implies that you cant use the speed of light to define a time over a set distance within a moving frame of reference. As a corollary, the only accurate way to measure the speed of light is to remove "motion" from the measuring frame. When you take an average, a to and fro sum/2, you are removing the "motion" of a moving frame.
Have you really moved if you end up where you started?
QUOTE (Montec+Jun 18 2008, 11:21 PM)
Hello Trout, et al.
Isn't (L-l)/c a measure of time? IE m/(m/s) = s So anywhere you use (L-l)/c you are using a time value.
I just showed you that time does not intervene in the measurements made in the Fizeau experiment. Time is eliminated by the clever use of the rotating disk such that light transition time needs to match the rotation time between two consecutive slits.
The above is incomprehensible. One way light speed measurements are very easy to do (I can describe the method) , so you are not making any sense.
Isn't (L-l)/c a measure of time? IE m/(m/s) = s So anywhere you use (L-l)/c you are using a time value.
I just showed you that time does not intervene in the measurements made in the Fizeau experiment. Time is eliminated by the clever use of the rotating disk such that light transition time needs to match the rotation time between two consecutive slits.
QUOTE
The distance light travels per unit time is independent of any moving frame of reference, so this implies that you cant use the speed of light to define a time over a set distance within a moving frame of reference. As a corollary, the only accurate way to measure the speed of light is to remove "motion" from the measuring frame. When you take an average, a to and fro sum/2, you are removing the "motion" of a moving frame.
The above is incomprehensible. One way light speed measurements are very easy to do (I can describe the method) , so you are not making any sense.
Hello Trout, et al.
I guess the disagreement is over the "light transition time" being the same between the cogs for the light going towards the mirror and the light going away from the mirror for a moving reference frame.
I say they are different because the actual distance over which the light travels is different do to the movement of the cogs through space.
You say (correct me if I am wrong) that the distance the light travels or "light transition time" is the same for either direction even though the cogs may move through space.
I guess the disagreement is over the "light transition time" being the same between the cogs for the light going towards the mirror and the light going away from the mirror for a moving reference frame.
I say they are different because the actual distance over which the light travels is different do to the movement of the cogs through space.
You say (correct me if I am wrong) that the distance the light travels or "light transition time" is the same for either direction even though the cogs may move through space.
QUOTE (Montec+Jun 19 2008, 12:07 AM)
Hello Trout, et al.
I guess the disagreement is over the "light transition time" being the same between the cogs for the light going towards the mirror and the light going away from the mirror for a moving reference frame.
No, it isn't. You need to follow the simple math, it is L/c in both directions for the further wheel, l/c in both directions for the closer wheel and it is (L-l)/c in both directions between the wheels.
You say wrong.
You say wrong.
You say (correct me if I am wrong) that the distance the light travels or "light transition time" is the same for either direction even though the cogs may move through space.
The cog movement is perpendicular to the light movement (acts like a shutter), so it has nothing to do with the "light transition time"
Now I can appreciate the logic of the postulate that the velocity of the source has no bearing on the speed of light. But I can't understand the other one. How can you prove the constancy of light w.r.t. any observer based on the two postulates of SR?
Please help me understand?
Because , in SR, there is only one kind of motion, relative motion.
The complete formulation of the postulate of light constancy is :
"Light speed is invariant to the relative motion between source and observer".
So, SR postulates that one measures the same light speed independent of how many observers in relative motion at various speeds wrt the light source measure it.
I guess the disagreement is over the "light transition time" being the same between the cogs for the light going towards the mirror and the light going away from the mirror for a moving reference frame.
No, it isn't. You need to follow the simple math, it is L/c in both directions for the further wheel, l/c in both directions for the closer wheel and it is (L-l)/c in both directions between the wheels.
QUOTE
I say they are different because the actual distance over which the light travels is different do to the movement of the cogs through space.
You say wrong.
QUOTE (->
| QUOTE |
| I say they are different because the actual distance over which the light travels is different do to the movement of the cogs through space. |
You say wrong.
You say (correct me if I am wrong) that the distance the light travels or "light transition time" is the same for either direction even though the cogs may move through space.
The cog movement is perpendicular to the light movement (acts like a shutter), so it has nothing to do with the "light transition time"
Hello Trout, et al
For me rotation is different than movement. Sorry for the confusion.
For me rotation is different than movement. Sorry for the confusion.
QUOTE (Montec+Jun 19 2008, 02:52 AM)
Hello Trout, et al
For me rotation is different than movement. Sorry for the confusion.
The cog wheels rotate, the light travels in straight line. Didn't you get that?
For me rotation is different than movement. Sorry for the confusion.
The cog wheels rotate, the light travels in straight line. Didn't you get that?
Hi Trout,
I'm getting the distinct impression you think you will get an impulse* from your first cog. The apparatus shown here http://en.wikipedia.org/wiki/Image:Speed_o...28Fizeau%29.PNG looks like it produces a 50-50 mark/space ratio .. are your 'cogs' what others would call wheels with very narrow slits cut in them?
-C2.
Some technical terms:-
Impulse .. a very narrow pulse
mark space ration .. the ratio of 'on' time to 'off' time.
I'm getting the distinct impression you think you will get an impulse* from your first cog. The apparatus shown here http://en.wikipedia.org/wiki/Image:Speed_o...28Fizeau%29.PNG looks like it produces a 50-50 mark/space ratio .. are your 'cogs' what others would call wheels with very narrow slits cut in them?
-C2.
Some technical terms:-
Impulse .. a very narrow pulse
mark space ration .. the ratio of 'on' time to 'off' time.
QUOTE (Trout+Jun 18 2008, 10:09 PM)
No one does. This is why it is a postulate in SR. I have written this several times already. Once at the very start of this thread.
When and if a new theory will be discovered that encompasses SR, the light speed frame invariance will become a theorem in the new theory.
Historically speaking, Maxwell showed that light travels at a constant speed and Einstein developed relativity to have a theory of mechanics consistent with that.
When and if a new theory will be discovered that encompasses SR, the light speed frame invariance will become a theorem in the new theory.
Historically speaking, Maxwell showed that light travels at a constant speed and Einstein developed relativity to have a theory of mechanics consistent with that.
The reason this thread was created was to understand "WHY" light has a constant speed w.r.t. any observer, not "HOW"!!
I think we are putting our energies to discuss one odd experiment.
Now, we know constancy of the speed of light has been shown experimentally. The point is to understand WHY it happens.(I understand some of you have already mentioned that "no one knows why!!")
The post by Good elf tries to address that point. Although his posts were very long, he has put some very good argument. Moreover he has used simple logic rather than complex maths to explain his point. But I am still not convinced.
One of the points he has mentioned about the postulate of SR is
"the velocity at which a light source is moving has no bearing on the speed of the light that emanates from the source. The speed of light is constant, regardless of how fast or slow its source happens to be moving. Based on the two postulates of the SR, Einstein showed that Speed of light is constant w.r.t. any observer)
Now I can appreciate the logic of the postulate that the velocity of the source has no bearing on the speed of light. But I can't understand the other one. How can you prove the constancy of light w.r.t. any observer based on the two postulates of SR?
Please help me understand?
I think we are putting our energies to discuss one odd experiment.
Now, we know constancy of the speed of light has been shown experimentally. The point is to understand WHY it happens.(I understand some of you have already mentioned that "no one knows why!!")
The post by Good elf tries to address that point. Although his posts were very long, he has put some very good argument. Moreover he has used simple logic rather than complex maths to explain his point. But I am still not convinced.
One of the points he has mentioned about the postulate of SR is
"the velocity at which a light source is moving has no bearing on the speed of the light that emanates from the source. The speed of light is constant, regardless of how fast or slow its source happens to be moving. Based on the two postulates of the SR, Einstein showed that Speed of light is constant w.r.t. any observer)
Now I can appreciate the logic of the postulate that the velocity of the source has no bearing on the speed of light. But I can't understand the other one. How can you prove the constancy of light w.r.t. any observer based on the two postulates of SR?
Please help me understand?
Hi Daljeet,
I was hoping my pole with a beam of light inside it would clarify matters .. unfortunately it seems Trout is more interested in insulting me than in dealing with the problem .. if anyone else would like to take up the idea they are most welcome.
-C2.
I was hoping my pole with a beam of light inside it would clarify matters .. unfortunately it seems Trout is more interested in insulting me than in dealing with the problem .. if anyone else would like to take up the idea they are most welcome.
-C2.
QUOTE (Confused2+Jun 19 2008, 06:27 AM)
Hi Trout,
I'm getting the distinct impression you think you will get an impulse* from your first cog. The apparatus shown here http://en.wikipedia.org/wiki/Image:Speed_o...28Fizeau%29.PNG looks like it produces a 50-50 mark/space ratio .. are your 'cogs' what others would call wheels with very narrow slits cut in them?
Yes, you mean that all this time you were discussing the experiment you did not understand the fundamentals ?
I'm getting the distinct impression you think you will get an impulse* from your first cog. The apparatus shown here http://en.wikipedia.org/wiki/Image:Speed_o...28Fizeau%29.PNG looks like it produces a 50-50 mark/space ratio .. are your 'cogs' what others would call wheels with very narrow slits cut in them?
Yes, you mean that all this time you were discussing the experiment you did not understand the fundamentals ?
QUOTE (daljeet+Jun 19 2008, 12:30 PM)
Now I can appreciate the logic of the postulate that the velocity of the source has no bearing on the speed of light. But I can't understand the other one. How can you prove the constancy of light w.r.t. any observer based on the two postulates of SR?
Please help me understand?
Because , in SR, there is only one kind of motion, relative motion.
The complete formulation of the postulate of light constancy is :
"Light speed is invariant to the relative motion between source and observer".
So, SR postulates that one measures the same light speed independent of how many observers in relative motion at various speeds wrt the light source measure it.
You will never get the answer from SR itself because its purpose was to transform one perception to another, not explain how or why.
Try this.
Try this.
Hi daljeet , Confused2, Trout, prometheus, et al,
I am really sorry about being long winded... this comment below illustrates why I made it long winded and why it becomes confusing if an idea is not followed through "exactly"... forgive me for pointing this out but it illustrates just why we all need to be very careful what we all "mean" since "meaning" is everything in this "game". People are using the word 'postulate" (still using it)... we really need to understand what a postulate is as opposed to a Theory. I can propose that the speed of light is a constant as a holding postulate but if it is shown to be true it no longer is a postulate. If an asserted statement is required to be always true but never proven to be true by experiment it is not science and is a "religious tenant" required to be believed by "faith". Science (as opposed to everything else) makes progress by converting these unsubstantiated "postulates" into facts through experiment (... questions placed directly to the Universe "herself") and then proposing theories that explain only the facts. I am also "cautioning" all, as with the "Oracle of Delphi", that the right question is "everything"... The road to scientific "Hell" is paved with bad questions.
I am really sorry about being long winded... this comment below illustrates why I made it long winded and why it becomes confusing if an idea is not followed through "exactly"... forgive me for pointing this out but it illustrates just why we all need to be very careful what we all "mean" since "meaning" is everything in this "game". People are using the word 'postulate" (still using it)... we really need to understand what a postulate is as opposed to a Theory. I can propose that the speed of light is a constant as a holding postulate but if it is shown to be true it no longer is a postulate. If an asserted statement is required to be always true but never proven to be true by experiment it is not science and is a "religious tenant" required to be believed by "faith". Science (as opposed to everything else) makes progress by converting these unsubstantiated "postulates" into facts through experiment (... questions placed directly to the Universe "herself") and then proposing theories that explain only the facts. I am also "cautioning" all, as with the "Oracle of Delphi", that the right question is "everything"... The road to scientific "Hell" is paved with bad questions.
QUOTE (daljeet+)
The post by Good elf tries to address that point. Although his posts were very long, he has put some very good argument. Moreover he has used simple logic rather than complex maths to explain his point. But I am still not convinced.
One of the points he has mentioned about the postulate of SR is
"the velocity at which a light source is moving has no bearing on the speed of the light that emanates from the source. The speed of light is constant, regardless of how fast or slow its source happens to be moving. Based on the two postulates of the SR, Einstein showed that Speed of light is constant w.r.t. any observer)
Now I can appreciate the logic of the postulate that the velocity of the source has no bearing on the speed of light. But I can't understand the other one. How can you prove the constancy of light w.r.t. any observer based on the two postulates of SR?
Please help me understand?
One of the points he has mentioned about the postulate of SR is
"the velocity at which a light source is moving has no bearing on the speed of the light that emanates from the source. The speed of light is constant, regardless of how fast or slow its source happens to be moving. Based on the two postulates of the SR, Einstein showed that Speed of light is constant w.r.t. any observer)
Now I can appreciate the logic of the postulate that the velocity of the source has no bearing on the speed of light. But I can't understand the other one. How can you prove the constancy of light w.r.t. any observer based on the two postulates of SR?
Please help me understand?
No criticism here... Firstly this statement above is not a quote, it is your interpretation by way of paraphrasing of concepts I was trying to make... I do not know exactly what you mean by that statement (you are then commenting on the fact that you do not understand your own paraphrasing... he he he!). Two negatives do not make any positives, you are questioning something I never said. I need your comment on what I did say where I can place it in my own context then I can answer the question.
I now must try and think what it is you are getting at there. I never asked anyone to accept a postulate... that is a bad idea in this question of "why?"
I now must try and think what it is you are getting at there. I never asked anyone to accept a postulate... that is a bad idea in this question of "why?"
QUOTE (Dictionary definition of postulate+)
1. To make claim for; demand.
2. To assume or assert the truth, reality, or necessity of, especially as a basis of an argument.
3. To assume as a premise or axiom; take for granted. See synonyms at presume.
You cannot answer the question "why?" by proposing a list of "postulates". You either believe "postulates" or not... it will not tell you or anyone "why" you believed it or not or even "should" you believe it or not.... like the quantum postulates for instance which are just as unintelligible. All "postulates" are arbitrary and confusing and the obvious starting point for disagreement not agreement. What I asked for is to follow normal logic ... without any postulates.
No human can "follow" the progress of a beam of light in the vacuum... it is a quantum event in progress. It is not like a bullet... I can take a synchronized double snapshot of a bullet in flight and you can triangulate it's current position by parallax. You cannot do this with a flash of light. There are several methods of determination of the velocity of light. Some of these would not convince anyone that it is a transparent means of velocity determination. That does not mean that they are incorrect but a lot of Theory is required as a starting point in order to convince anyone of validity. They are certainly not postulates though. Check out Wikipedia reference on the "Speed of Light ... Measurement of the speed of light".
Wikipedia:"Speed of Light ... Measurement of the speed of light"
The "motion" of light can only be determined by timing the arrival of the disturbance caused by electromagnetic phenomena at two separate places in the rest frame or the arrival of the event or at two separate times for the same event in the rest frame of an observer. First point is all observations to be consistent must be made in the one frame of reference. The usual way is the use of a "flash" of light. A flash of light must contain more than one photon since at least two determinations are required to determine velocity, and all the photons must ideally be on the one expanding wavefront. A "flash" ideally will exist as a partial shell of expanding EM disturbance whose "center" relative to this expanding "shell" is fixed relative to the shell surface and is a half diameter away from any point at which it is intersected... that center is determinable through a "postulate" that the speed of light is constant and lies on the surface of a geometric sphere. This postulate has been shown to be experimentally true. The "shape" of this expanding shell cannot be altered by the motion of the person who measures it's arrival at position at any later point in time after it is launched... it always "looks" like an expanding spherical shell and is simple Pythagorean Mathematics to determine where the center is and where things are relative to the center. Note that successive flashes may originate from different relative positions to the observer. That "relative position" depends only on the relative velocity since we have discussed that all velocity relative to a hypothetical "aether" is not able to be experimentally measured (therefore the postulate that the "aether wind" can distort this shell is wrong). Simple reflection on these points will indicate this is 'obvious" but inevitably leads to Special Relativity. This means the shape of the expanding shell measured by all observers is always a sphere and is never a shell derived from the rotation of an ellipse about it's long axis. This is because the observer can't "see" any other place in empty space with which to compare the position of the progress of this "flash". Later comparison of notes with accurately synchronized clocks in "other places" may expose that a "flash" was seen elsewhere at a different time and at a different place. These measurements do not change the facts that the speed of light is a constant but they are the basis of a reconciliation of these differences between the different moving frames through a Theory of Special Relativity and is not explained by a Newtonian treatment in which the speed of light is not fixed or is "infinite" or that any "aether wind" is blowing. This is not a "postulate" either ... is is an experimental measurement and in accord with "common sense" (... if there is any such thing). Other observers and their observations are of no "immediate" concern to the single observer. That &
2. To assume or assert the truth, reality, or necessity of, especially as a basis of an argument.
3. To assume as a premise or axiom; take for granted. See synonyms at presume.
You cannot answer the question "why?" by proposing a list of "postulates". You either believe "postulates" or not... it will not tell you or anyone "why" you believed it or not or even "should" you believe it or not.... like the quantum postulates for instance which are just as unintelligible. All "postulates" are arbitrary and confusing and the obvious starting point for disagreement not agreement. What I asked for is to follow normal logic ... without any postulates.
No human can "follow" the progress of a beam of light in the vacuum... it is a quantum event in progress. It is not like a bullet... I can take a synchronized double snapshot of a bullet in flight and you can triangulate it's current position by parallax. You cannot do this with a flash of light. There are several methods of determination of the velocity of light. Some of these would not convince anyone that it is a transparent means of velocity determination. That does not mean that they are incorrect but a lot of Theory is required as a starting point in order to convince anyone of validity. They are certainly not postulates though. Check out Wikipedia reference on the "Speed of Light ... Measurement of the speed of light".
Wikipedia:"Speed of Light ... Measurement of the speed of light"
The "motion" of light can only be determined by timing the arrival of the disturbance caused by electromagnetic phenomena at two separate places in the rest frame or the arrival of the event or at two separate times for the same event in the rest frame of an observer. First point is all observations to be consistent must be made in the one frame of reference. The usual way is the use of a "flash" of light. A flash of light must contain more than one photon since at least two determinations are required to determine velocity, and all the photons must ideally be on the one expanding wavefront. A "flash" ideally will exist as a partial shell of expanding EM disturbance whose "center" relative to this expanding "shell" is fixed relative to the shell surface and is a half diameter away from any point at which it is intersected... that center is determinable through a "postulate" that the speed of light is constant and lies on the surface of a geometric sphere. This postulate has been shown to be experimentally true. The "shape" of this expanding shell cannot be altered by the motion of the person who measures it's arrival at position at any later point in time after it is launched... it always "looks" like an expanding spherical shell and is simple Pythagorean Mathematics to determine where the center is and where things are relative to the center. Note that successive flashes may originate from different relative positions to the observer. That "relative position" depends only on the relative velocity since we have discussed that all velocity relative to a hypothetical "aether" is not able to be experimentally measured (therefore the postulate that the "aether wind" can distort this shell is wrong). Simple reflection on these points will indicate this is 'obvious" but inevitably leads to Special Relativity. This means the shape of the expanding shell measured by all observers is always a sphere and is never a shell derived from the rotation of an ellipse about it's long axis. This is because the observer can't "see" any other place in empty space with which to compare the position of the progress of this "flash". Later comparison of notes with accurately synchronized clocks in "other places" may expose that a "flash" was seen elsewhere at a different time and at a different place. These measurements do not change the facts that the speed of light is a constant but they are the basis of a reconciliation of these differences between the different moving frames through a Theory of Special Relativity and is not explained by a Newtonian treatment in which the speed of light is not fixed or is "infinite" or that any "aether wind" is blowing. This is not a "postulate" either ... is is an experimental measurement and in accord with "common sense" (... if there is any such thing). Other observers and their observations are of no "immediate" concern to the single observer. That &