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## Measuring The Relative Velocity Of Light

 Quote by ram1024 doesn't matter than it wasn't LIGHT moving faster than LIGHT. INFORMATION did.
But the experimenters themselves never claimed that they could send information faster than light. How could you possibly claim to know it?
 there was an event on one side and a reaction on the other side, a reaction that happened 300 times faster than SHOULD have happened using light speed as a measure. think binary. a bit of information "1" was sent into the tube. a bit of information "1" was received 300 times faster than it would have been using direct light transmission over the same distance. THAT is why.

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 Quote by ram1024 there was an event on one side and a reaction on the other side, a reaction that happened 300 times faster than SHOULD have happened using light speed as a measure. think binary. a bit of information "1" was sent into the tube. a bit of information "1" was received 300 times faster than it would have been using direct light transmission over the same distance. THAT is why.
The experimenters also reported that part of the pulse was detected at the exit before it was detected at the entrance, and yet Wang (the head scientist) specifically denies that he could use the effect to send information back in time. Furthermore, every analyst of this experiment has concluded that information was not sent faster than light. Aren't you even the least bit curious as to why? Don't you feel compelled to consult the literature on the experiment? Doesn't the first hand testimony of the people who designed the experiment and witnessed the effect carry any weight with you? Or are you satisfied with your simplistic explanation based on only a partial knowledge of what actually occured in that lab?

 Aren't you even the least bit curious as to why?

they're coming to the wrong conclusion trying to intercept the whole pulse,

ANYTHING coming out the other end can be taken as that "bit" of data.

align 4 tubes <arbitrary number> and transmit using all 4, by moving to another "tube" while waiting for the one you just used to complete in rotation you can transmit data AT LEAST 4 times faster than the speed of light.

with 300 tubes you could utilize the full capabilities of this speed. course the "switching" would have to be damn complex for that ;D

in any case i'm sure they adequately realize the potential of their results, but don't want to "give" any of the technology away if they can help it.

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Somehow, I don't think you have read the articles that appeared in the research journals.

 they're coming to the wrong conclusion trying to intercept the whole pulse,
Well, you should email them right away!

Here's their Science director's webpage:

 ANYTHING coming out the other end can be taken as that "bit" of data.
But it is not the case that anything coming out can be seen as intelligible information.

 in any case i'm sure they adequately realize the potential of their results, but don't want to "give" any of the technology away if they can help it.
What they want is to make a name for themselves, not to get patents. Scientists publish their results freely in journals such as Physical Review Letters. These scientists are no exception.

 Quote by grounded Before we go on, do you agree that the Lorentz contraction was created to explain why we DID NOT measure a change in the speed of light when it traveled against the aether during the Michelson-Morley experiment?
Yes. The contraction would cancel the effect of aether resistance.

 Quote by grounded I do know that Einstein replaced the Lorentz contraction, but wasn't it still used to explain why we DID NOT measure a change in the speed of light when it traveled against the aether?
Well, since aether was dismissed, it isn't currently used to expain anything about aether. As I wrote before, if you want to assume aether exists, you can treat it like any other frame of reference, and the length contraction explanation would appy.

However, there's another issue. Suppose you simply explain MMX result with length contraction. There is no need to abandon absolute space, and all observers could agree on how their lengths would compare. But according to SR, observers will not agree. I think that's an important point.
 you don't seem to be understanding me. ANYTHING coming out the other end is "Data" it either IS or ISN'T, 1 or 0. this is the principle behind binary computing. the data coming out the other side doesn't need to do anything other than exist

 Quote by Tom Mattson No, it isn't. The length of the boxcar is contracted according to the following formula: L=L0/γ That is not the simple ratio of speed to boxcars-per-second. ....
Tom,
in post #186, Grounded already found out his assumption did not match with SR's predictions. It would help if you could help me answer his questions after that post because I'm no expert and you seem to be. Thank you.

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 Quote by ram1024 you don't seem to be understanding me. ANYTHING coming out the other end is "Data" it either IS or ISN'T, 1 or 0. this is the principle behind binary computing. the data coming out the other side doesn't need to do anything other than exist
I understand you just fine. But what you aren't understanding is that in order for "information" to travel from one spacetime point to another, the carrier of information has to do more than just "exist". It has to be causally connected to the source so that something intelligble can be communicated. If the people who did the experiment do not claim that they could send information faster than light, then who are you to claim that they can?

Do yourself a favor: Read up on this.
 the tube IS connected the receiving end to the source. i have no idea what you're talking about but if i want to transmit "Hi Mom" in binary 300 times faster than the speed of light to the target location, i take 6 bytes of data (8 bits per byte) and through the system pipe of 48 tubes this "information" is transfered to the other end 300 times faster than light speed would reach. thus if the computer on MY end was capable of deciphering those 48 bits and displaying them instantly, i could have them on MY screen before i would see them on YOUR screen, if you flashed them on YOUR screen AND transmitted them through the tube system at the same time.
 Recognitions: Gold Member Science Advisor Staff Emeritus The problem is that the experimental setup is transmitting "Hi Mom" subluminally. The "magic" is that the entry to the tube delays acknowledging the transmission until just before the exit receives it. This generates the illusion that the information went from the entry to the exit superluminally.

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 Quote by ram1024 the tube IS connected the receiving end to the source.
I know that. Just like in my streetlight example, the lights are connected to my switch. That doesn't mean I can send information faster than light with them.

 i have no idea what you're talking about but if i want to transmit "Hi Mom" in binary 300 times faster than the speed of light to the target location, i take 6 bytes of data (8 bits per byte) and through the system pipe of 48 tubes this "information" is transfered to the other end 300 times faster than light speed would reach. thus if the computer on MY end was capable of deciphering those 48 bits and displaying them instantly, i could have them on MY screen before i would see them on YOUR screen, if you flashed them on YOUR screen AND transmitted them through the tube system at the same time.
LOL, well one thing is clear: You are certainly content to make a few simplifying assumptions when the problem gets difficult! The truth is that you have no idea of what your computer screen would say. You are just guessing that your machine will be able to interpret the pulse. The real scientists who did the real experiment in a real laboratory, on the other hand, disagree.

Why are you being so stubborn about this? The experimenters themselves said that what you have proposed cannot be done. Why don't you listen to them?

Here's an excerpt from a news report in which one of the experimenters was quoted.

From http://www.msnbc.com/news/435007.asp?cp1=1

"All this might make it sound as if the NEC researchers found a way to send a message at speeds faster than 186,000 miles a second — which could theoretically open the way for a sort of time travel. But the researchers contend that is not the case. Their experiment dealt with smooth changes in a pulse, and “a smooth function cannot carry information,” Dogariu said. Sending information — for example, the flashes of a laser semaphore — would require sharper variations in frequency that could not be processed in the type of finely tuned atom chamber used by the NEC researchers.

Color added by me, for emphasis.
 i KNOW that. why do you think i said 48 chambers? because each ONE would be transmitting one BIT of information (either ON or OFF) to the destination. Code: }}| | | || | | || | ||| || | | | || || | || {{ - light in tubes }}1000101011010101101011101101010010011011001000110{{ - interpreted data assume that all that crap up there translates to "hi mom" a string of 6 character expressed in binary. each BIT of information can be transmitted to the other end of the tube 300 times faster than light speed. it is instantly processed by my computer and displayed on the screen (assume so to make a point). if you displayed the words "HI MOM" on your screen AND sent the data down the tubes AT THE SAME TIME (co-local simultaneity DOES exist) then i would receive those 48 bits of data FASTER than looking over and waiting for the light from your screen to register "HI MOM" to my eyes. we're talking 62 billionths of a second though for a 50 ft pipe of caesium, so the real result is "big deal?" but what this DOES say is using light for simultaneity DOES fail for transmission of information at superluminal speeds. in essense, if light is your limiter for this situation then the message DOES come out on the receiving end BEFORE it was sent in, calculated with light simultaneity

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 Quote by ram1024 i KNOW that.
You say that, but then you steamroll right over the troublesome part of the problem.

Right here:

 it is instantly processed by my computer and displayed on the screen (assume so to make a point).
!!!

That's exactly the problem! You can't just assume that this can be done.

Again, I ask: Why are you being so stubborn about this? Why don't you believe the people who were there, when they tell you that this sort of pulse cannot be used to do what you say it can? What makes you think you know better than them, without ever having done any work in this field?
 the crux of the argument is information being transmitted at speeds faster than can be accomplished by light. i was never arguing you that it's not feasible to do so because we lack the computing power to process that information at those speeds. not once :D

 What makes you think you know better than them, without ever having done any work in this field?
you're just unwilling to conceed towards superluminal information transfer. logically if you think about it, and you know anything about information transmission you would KNOW what i'm saying is reasonable.

they know it too since they work in the business. i'm pretty sure "it can't be done" is either fog to keep competition away from what they're going to pioneer as new technology OR their data is faulty and they have no idea what they're talking about (their experiment is a sham).

take whichever of those two conclusions makes you feel the safest... :D

 Quote by wespe True, the observer can't measure any change in his own mesauring stick (or better, there isn't any change according to him). But he does measure the measuring sticks in other frames shorter than his measuring stick. "his measuring stick has also contracted" is from the perspective of other frames. Imagine you and I are holding 1 meter measuring sticks in the direction of each other. We both agree when we are at rest wrt each other. Then let us approach at a speed. I would see your meter contracted, and you would see my meter contracted. We would both think our [own] meters didn't change [it's always the other's meter that changed] and we would not agree on whose meter is shorter. But from a third person's perspective, both of our sticks might have been contracted. Everyone is correct according to oneself
I think there may be a contradiction here and that you may have erred slightly, Let us expand the situation. Two observers wih 1 meter rods are moving such that a stationary observer will see a length contraction to .9m on each rod and these observers are moving parallel and in the same direcion to each other. Clearly the rods would look the same to both observers, agreed?

Now we have the observers moving towad each other, but each is ignorant of he oher's presence. The grouind observer will will see a contraction to both rods to .9m each. Your statement that each observer would think the other's rod has changed and no agreement could be made, I Iassume you are placing each in the position of an effective stationary observer wrt the other. With a stationary observer noting changes, she still sees the rods shoren to .9c. But let us have the rods placed parallel and close to each other when they pass (or from an SR perspective when A passess B or B passes A) by each other.

It would be physically impossible for each of the moving obsevers to claim hat their rod was longer than the other. First their relaitive speed with respect to the stationary observer is the same, and hence the stationary observer keeps the books straight from his perspective.

However when passing next to each other there could be no disagreement between the observers as any disputes could be resolved with a simple inspection. So my question is what is the value, the wort, the utility of using assumed stationary frames when measuring relative velocity? The mathematics may allow you to do that and SR may allow you to do that, but there is the physical impossibility that the assumptions could ever be realized in practice, and then what of the assumed frame changes, i.e. to the rods?

The point is that making an assumption that an observer on a moving frame is stationary and the other moving, (and vice versus) just because the mathematics appears to alllow this kind of comparison is contradicted by physical law. Moving bodies do not enjoy the arbitrary luxury of starting and stopping at the will of an observer in that particlular frame, under any circumstances, yet this seems to be a common practice among SR theorist describing reality..

Just to overkill a tad. If one rod is shortened to .9m and the other to .5m as measured by a third observer then each could claim, re SR, that the other rod had shortened to .4m? How long would this assumption be demonstrably true, if ever? Especially when they pass next to each other and see the differences? Which they would see if their eyes were a few wave lengths from herods as they slid past, agreed?

If SR maintains this posture then it would have to conclude, as you said in your post, that each sees the other as shortening, but can the rod that is .9m wrt the stationary observer appear as .4m wrt to the other moving observer? Especially at the instant the rods were located next to each other, clearly visible to both? Couldn't each observer jump in the other's shoes and see the rods from the other's perspective? Apparently SR says you can. Each observer with the mere mental decision can place themselves in the other's position or themsleves at rest, or at any velocity compatible with the observed velocity as measured by the stationary observer?

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