![]() |
| If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|||||||
| Tags: confirmed, empirically, superluminal, velocities |
|
|
Thread Tools | Display Modes |
|
#31
|
|||
|
|||
|
|
| Ads |
|
#32
|
|||
|
|||
|
Richard wrote in message ...
EL wrote: This restricts experiments to law frequency waves to guarantee that a phase shift is that of a single wave, which is based on our empirical knowledge that the wave must travel at less than [c] in caesium or any medium other than vacuum. So I was not surprised to read that they obtained a delay of 62 ns inside the tube. I tried to follow the equations but I stopped at being disgusted from the relentless attempts to fit the results to a hypothesis. Any way, thank you for your response Richard. sigh EL You are probably correct EL, but I don't believe that it's that complicated. All you need to measure is the dispersion, from there you can calculate the group velocity, as demonstrated nicely by this applet http://gregegan.customer.netspace.ne...ETS/20/20.html According to the link on that page, the group velocity is given by v_g = c / (n(v) + vdn(v)/dv) and can be greater than c. OTOH, I have a problem with their explanation of why this doesn't contradict SR. Let's suppose that wrt some given wave the speed of the group wave is less than c. That supposition contradicts SR. Thus the richard perry has assumed his conclusion. |
|
#33
|
|||
|
|||
|
|
|
#34
|
|||
|
|||
|
[EL]
Ah! The applet. ![]() It is quite an amusing view, BUT. Let us analyze that applet to find out how tricky wave mechanics can be. ![]() Firstly, that applet is simply a dynamic graph. So let us assign some physical meanings to it before we proceed. The horizontal axis should be definitely TIME. The vertical axis could be the amplitude of differently offseted waves. This is rather very easy to demonstrate on a multi-channel oscilloscope. Since our screen image is a raster then the horizontal scan time-window must be a single finite value. Now let us assume that that oscilloscope's screen is subdivided horizontally to 20 equal divisions. We now lock our time-window onto twenty cycles of the highest frequency displayed. If it was for example 100MHz then each cycle takes 10 ns and we need a horizontal sweep time of 200 ns. That highest frequency must appear stationary on the scope's screen. The applet shows a group of waves slipping backwards, which means that they are slower than the reference frequency and the wavelengths are not integer multiples of that wave length. So we have a group of waves propagating at the same speed in the same homogenous and isotropic medium but they have different frequencies and they superimpose. The group phase amplitude then is the sum of all superimposed phases at any time. Therefore at any point in time we have a summed wave propagating at [c] and the modulation is static over space while changing over time. Out of synch waves may slip backwards or forward depending on the sign of the frequency delta with respect to the time-window of the oscilloscope. We chose for our example a 5 MHz reference frequency for the oscilloscope and we choose our group to be based on a reference wave frequency of 100 MHz and a band width less than 5MHz such that all other group waves take frequencies less than 100 MHz but not less than [95 MHz + epsilon]. This guaranties that the slipping effect is distributed over a single division and is moving backwards (left side of screen). The resulting interference-modulated wave, however, may be a new frequency and we find Modulo 5 of that frequency to know the direction of the slip of the resulting wave. If it was between .1 to 2.4 it slips forward and if it was between 2.6 and to 4.9 it slips backwards. The slipping speed is directly proportional to the delta of the modulo and the horizontal scan frequency and it has absolutely nothing to do with wave propagation time. So this should take care of the fancy applet that means **** nothing relevant to the being claimed hoopla. According to the link on that page, the group velocity is given by v_g = c / (n(v) + vdn(v)/dv) and can be greater than c. [EL] What velocity is that v? If it was the modulation frequency I fail to relate propagating it at any other velocity than [c] in vacuum or less in caesium. How in hell do they ambitiously wish to make us believe that a modulation result at time [T] can appear forward at time [T- t]? All interfering waves at any moment has a finite superposition and at the next time event has another superposition that follows the first at the same space coordinates while the previous one propagates at [c] forward in space. We either monitor space from an inertial frame and observe changes to that locked space of time or we monitor time from a moving frame such that we lock time [freeze time] and inspect a paper tape graph record of changing space. Doing both concurrently is reckless and irresponsible child's play. OTOH, I have a problem with their explanation of why this doesn't contradict SR. Let's suppose that wrt some given wave the speed of the group wave is less than c. Thus wrt that wave a massive particle may be moving in tandem with that group wave. According to SR velocity addition, that particle is thus traveling at less than c wrt lab frame as well, and thus the group wave is also moving at less than c wrt lab frame because it is perpetually adjacent to the particle, which is simply an invariant condition. Thus, according to SR and simple logic, a group wave cannot move at greater than c wrt lab frame, 'unless' it is also moving at greater than c wrt any single phase wave involved in the group wave propagation. Thus the equation above cannot be relativistically correct. [EL] The equation above is meaningless because I have no freaking idea how they fill in the values of the variables. That hoopla does not shake a hair. Group velocity is an Oxymoron from scratch because there are no different wave velocities in one and the same homogenous and isotropic medium. Any phase velocity expressed in distance over time is zero because a phase change takes place at a fixed coordinate while the invariant phase-state is what propagates space over time. Therefore wave velocity in [L/T] dimensions is the same as the phase velocity in [L/T] dimensions. It is the phase rate of change in [L=0 /T] (we call it the Slew Rate) that is erroneously labelled as a velocity. It is in units of wave Amplitude/Time, like volts per second. OTOH, there is no doubt that the group wave can indeed empirically surpass c, [EL] Objection, because I have amply demonstrated that that is impossible too. so that if SR is valid, then there is a speed of the group wave that cannot be accompanied by the moving particle. Once again this can only result in the group wave propagating at greater than c wrt 'all' frames at the very instant that it exceeds c wrt any one frame. [EL] I am not a fan of SR either but c is a scalar constant of vacuum, and we should never argue a constant by definition. What is the meaning of group velocity! Tow inertially locked light sources radiating expanding spherical wavefronts must have the spherical shells approaching each other at 2c by simple arithmetic. However, each sphere's radius must be increasing length over time at [c]. I also give no flying monkey's fart to Einstein's observers and twins. snip It is easy to say, "Well, the SR speed limit applies only to massive particles and information", it is quite another to prove that statement, and to be quite honest, in retrospect, I've not only never seen such a proof, I've never even seen a citation of such a proof. This seems to be one of those, "well it sounds reasonable so it must be correct" laws. Never once questioned as it is being questioned now. And it would seem that it was very easy to discredit it all this time. Hmmm...Sometimes I wonder if man will ever actually be even half of what believes himself to be ![]() Deal with that EL, and leave your condescending tone out of it, I didn't buy. Superiority isn't a matter of one's technobabble cache'. 'sigh' Richard Perry [EL] SR has nothing to do with asserting the fact that electromagnetic waves propagate at c in vacuum. You are giving Albert the credits of Maxwell by doing so. There is nothing faster than light to accelerate anything faster than light or are we going to violate the fact that energy may not be created or destroyed now? If you are driving a truck with speed limit 200 Km/h you may catch up with a Fiat and give it a push and accelerate it to death, but when you are in a Fiat how you, can catch up with a corvette zapping by at 180 km/h? To apply a force to a particle you need to catch up with the particle first and then push. Nothing can be accelerated to more than [c] because [c] itself cannot catch up with [c]. EL |
|
#35
|
|||
|
|||
|
EL wrote: [EL] Ah! The applet. ![]() It is quite an amusing view, BUT. Let us analyze that applet to find out how tricky wave mechanics can be. ![]() Firstly, that applet is simply a dynamic graph. So let us assign some physical meanings to it before we proceed. The horizontal axis should be definitely TIME. The vertical axis could be the amplitude of differently offseted waves. This is rather very easy to demonstrate on a multi-channel oscilloscope. Since our screen image is a raster then the horizontal scan time-window must be a single finite value. Now let us assume that that oscilloscope's screen is subdivided horizontally to 20 equal divisions. We now lock our time-window onto twenty cycles of the highest frequency displayed. If it was for example 100MHz then each cycle takes 10 ns and we need a horizontal sweep time of 200 ns. That highest frequency must appear stationary on the scope's screen. The applet shows a group of waves slipping backwards, which means that they are slower than the reference frequency and the wavelengths are not integer multiples of that wave length. So we have a group of waves propagating at the same speed in the same homogenous and isotropic medium but they have different frequencies and they superimpose. The group phase amplitude then is the sum of all superimposed phases at any time. Therefore at any point in time we have a summed wave propagating at [c] and the modulation is static over space while changing over time. Out of synch waves may slip backwards or forward depending on the sign of the frequency delta with respect to the time-window of the oscilloscope. We chose for our example a 5 MHz reference frequency for the oscilloscope and we choose our group to be based on a reference wave frequency of 100 MHz and a band width less than 5MHz such that all other group waves take frequencies less than 100 MHz but not less than [95 MHz + epsilon]. This guaranties that the slipping effect is distributed over a single division and is moving backwards (left side of screen). The resulting interference-modulated wave, however, may be a new frequency and we find Modulo 5 of that frequency to know the direction of the slip of the resulting wave. If it was between .1 to 2.4 it slips forward and if it was between 2.6 and to 4.9 it slips backwards. The slipping speed is directly proportional to the delta of the modulo and the horizontal scan frequency and it has absolutely nothing to do with wave propagation time. So this should take care of the fancy applet that means **** nothing relevant to the being claimed hoopla. According to the link on that page, the group velocity is given by v_g = c / (n(v) + vdn(v)/dv) and can be greater than c. [EL] What velocity is that v? If it was the modulation frequency I fail to relate propagating it at any other velocity than [c] in vacuum or less in caesium. How in hell do they ambitiously wish to make us believe that a modulation result at time [T] can appear forward at time [T- t]? All interfering waves at any moment has a finite superposition and at the next time event has another superposition that follows the first at the same space coordinates while the previous one propagates at [c] forward in space. We either monitor space from an inertial frame and observe changes to that locked space of time or we monitor time from a moving frame such that we lock time [freeze time] and inspect a paper tape graph record of changing space. Doing both concurrently is reckless and irresponsible child's play. OTOH, I have a problem with their explanation of why this doesn't contradict SR. Let's suppose that wrt some given wave the speed of the group wave is less than c. Thus wrt that wave a massive particle may be moving in tandem with that group wave. According to SR velocity addition, that particle is thus traveling at less than c wrt lab frame as well, and thus the group wave is also moving at less than c wrt lab frame because it is perpetually adjacent to the particle, which is simply an invariant condition. Thus, according to SR and simple logic, a group wave cannot move at greater than c wrt lab frame, 'unless' it is also moving at greater than c wrt any single phase wave involved in the group wave propagation. Thus the equation above cannot be relativistically correct. [EL] The equation above is meaningless because I have no freaking idea how they fill in the values of the variables. That hoopla does not shake a hair. Group velocity is an Oxymoron from scratch because there are no different wave velocities in one and the same homogenous and isotropic medium. Any phase velocity expressed in distance over time is zero because a phase change takes place at a fixed coordinate while the invariant phase-state is what propagates space over time. Therefore wave velocity in [L/T] dimensions is the same as the phase velocity in [L/T] dimensions. It is the phase rate of change in [L=0 /T] (we call it the Slew Rate) that is erroneously labelled as a velocity. It is in units of wave Amplitude/Time, like volts per second. OTOH, there is no doubt that the group wave can indeed empirically surpass c, [EL] Objection, because I have amply demonstrated that that is impossible too. so that if SR is valid, then there is a speed of the group wave that cannot be accompanied by the moving particle. Once again this can only result in the group wave propagating at greater than c wrt 'all' frames at the very instant that it exceeds c wrt any one frame. [EL] I am not a fan of SR either but c is a scalar constant of vacuum, and we should never argue a constant by definition. What is the meaning of group velocity! Tow inertially locked light sources radiating expanding spherical wavefronts must have the spherical shells approaching each other at 2c by simple arithmetic. However, each sphere's radius must be increasing length over time at [c]. I also give no flying monkey's fart to Einstein's observers and twins. snip It is easy to say, "Well, the SR speed limit applies only to massive particles and information", it is quite another to prove that statement, and to be quite honest, in retrospect, I've not only never seen such a proof, I've never even seen a citation of such a proof. This seems to be one of those, "well it sounds reasonable so it must be correct" laws. Never once questioned as it is being questioned now. And it would seem that it was very easy to discredit it all this time. Hmmm...Sometimes I wonder if man will ever actually be even half of what believes himself to be ![]() Deal with that EL, and leave your condescending tone out of it, I didn't buy. Superiority isn't a matter of one's technobabble cache'. 'sigh' Richard Perry [EL] SR has nothing to do with asserting the fact that electromagnetic waves propagate at c in vacuum. You are giving Albert the credits of Maxwell by doing so. There is nothing faster than light to accelerate anything faster than light or are we going to violate the fact that energy may not be created or destroyed now? If you are driving a truck with speed limit 200 Km/h you may catch up with a Fiat and give it a push and accelerate it to death, but when you are in a Fiat how you, can catch up with a corvette zapping by at 180 km/h? To apply a force to a particle you need to catch up with the particle first and then push. Nothing can be accelerated to more than [c] because [c] itself cannot catch up with [c]. EL My apologies EL, apparently I misread your reply. I mistook you for the.... LOL, now I'm at a loss for a word to apply to them, I don't regard them as enemies, even if that is functionally what they are, enemies of truth, I guess. OTOH, as I said, the argument can be transferred to the superluminal light beam spot, whether or not the waves spoken of above are superluminal. Here's something interesting to play with: Suppose an observer is moving at 0.5c wrt lab frame. A superluminal beam spot is moving wrt him at 2c. Plugging these into the SR velocity equation: W = (v+w)/(1 + vw/c^2) gives W ~ 2.5c IOW we get a result that approximates normal velocity addition. I think this is enough to show that the ticking rate dilations and length contractions are now contradictory, since it is the same length of road, fence, ground, etc. being contracted wrt the moving observer, by a factor 1/gamma in the subluminal case, and virtually 1 in the superluminal case. Different contractions, even though the observer never changes speed wrt the background (lab frame). Now plug in c and 'any' value, for v and w, in either order, you get W=c Thus even though a spot may be moving at any arbitrary speed wrt the moving observer, including superluminally, then that same spot will be moving at exactly c wrt lab frame. Thus it follows that all motions occurring objectively wrt the moving observer are fictitious changes wrt lab frame, since the lab frame observer sees all of these other points (i.e. those that the moving observer sees as moving wrt him) as moving at the same speed as the moving observer. Need I continue? Once again EL, pardon my grouping you in, I plead 'temporarily at my wits end dealing with crackpots', hope you accept my sincerest apology ![]() I've always found you to be one of the most level-headed amongst us, I should've known better. Richard Perry |
|
#36
|
|||
|
|||
|
Hello holog,
Why do people think if you go faster than light you can immediately go back in time? i.e. if you could travel at twice the speed of light it would still take two years to get to alpha centuri, right? That´s from the earth´s point of view. If you could travel to alpha centauri at twice the speed of ligtht, the events "departure from earth" and "arrival at alpha centauri" would be spacelike seperated events. This means that their temporal sequence depends on the frame of reference you choose. The violation of causality becomes obvious if you immediately travel back from alpha centauri to earth, again at twice the speed of light: Then your arrival on earth would be *before* your departure from earth. SR avoids such violations of causality by limiting the maximum speed at which you possibly can travel to the speed of light. regards, Jürgen |
|
#37
|
|||
|
|||
|
Hello holog,
sorry, I made a mistake: Don´t travel to alpha centauri but rather to a star which itself recedes from earth at *almost* the speed of light. Let your speed be twice the speed of light *with respect to the earth* for your way to the star and twice the speed of light *with respect to this star* when you travel back to earth. Then you will come back before you started. regards, Jürgen |
|
#38
|
|||
|
|||
|
Hello Richard,
[...] Now as I see it, a group velocity was measured at greater than c, and thus, in contrast to the Fizeau near fit, the relativistic velocity addition equation fails in this current experiment. Not only that, but the whole of special relativity has been proved false. No, it hasn´t. SR forbids *transport of energy-momentum at superluminal speeds*, and in the case of anomalous dispersion, as in this experiment, energy-momentum is not transported with the group velocity of the wave package. So superluminal group velocities don´t violate SR. regards, Jürgen |
|
#39
|
|||
|
|||
|
|
|
#40
|
|||
|
|||
|
J?rgen Clade wrote: Hello Richard, [...] Now as I see it, a group velocity was measured at greater than c, and thus, in contrast to the Fizeau near fit, the relativistic velocity addition equation fails in this current experiment. Not only that, but the whole of special relativity has been proved false. No, it hasn´t. SR forbids *transport of energy-momentum at superluminal speeds*, and in the case of anomalous dispersion, as in this experiment, energy-momentum is not transported with the group velocity of the wave package. So superluminal group velocities don´t violate SR. Where in the lorentz transform is it implicit that v corresponds only to tangible particles? You are only repeating what you've heard over and over. This was an outright lie imposed in order to save SR from very observable superluminal speeds. It was a rationalization, it was a fabrication, it was pulled out of their asses. Tell me, If a spot (generated by a rotating laser) is moving at 2c along a fence wrt me, then what speed will that spot be moving wrt an observer moving at x m/s wrt the fence, as measured by that observer? Richard Perry regards, Jürgen |
| Thread Tools | |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| Turin Shroud confirmed as a fake! | Quantum Mirror | Physics - General Discussion | 5 | June 22nd 05 01:29 AM |
| Frame dragging confirmed. | Llanzlan Klazmon | Physics - General Discussion | 3 | October 23rd 04 09:37 AM |
| Empirically Confirmed Superluminal Velocities? | Paul R. Mays | Physics - General Discussion | 110 | November 11th 03 04:43 AM |
| Empirically Refuted Superluminal Velocities. | EL | Physics - General Discussion | 22 | October 31st 03 05:07 PM |
| NO Dark Matter: Another Confirmed SD Rodrian prediction | SDR | The Theory of Relativity | 0 | July 17th 03 11:35 PM |