Measuring The Relative Velocity Of Light

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Let me understand: you don't seem to realy understand relativity, you do not understand what Grounded said. In order to blindly support him, you gave the flaws of his assumption by thinking that you found the flaws of SR. In fact what you should have say is that:

The hate of Special Relativity is a house of cards that is doomed
to fall, but it is still now surrounded by many, many knights in shining armor convinced
they are protecting it against the heretics.

 

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Put quite a few words in my mouth there, didn't you 1100f? Let me understand, you do not understand what Grounded said, you do not really
know what Special Relativity actually is, but you support it blindly anyway.
You hate any heretic that opposes your religion.

 

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Grounded said:

You said

So I don't know why you support his claim.

Finally, you said:

While you never gave anything that support this claim.

 

Einstein gave a defintion of simultaneity: Events that ae simultaneous in a stationary frame are not simultaneous in a moving frame." He uses the train station and moving train as his example definition. The moving observer O' passes the midpoint of photon sources A and B in the stationary frame just as the photons are emitted from A and B.

Code:

|A-----------M------------B|
             O' 

The B photon is detected first then A is detected.

Code:

|-------------M------B----A-|
              t0    t1    t2

O' is at each time indicated. As the photons are observed sequentially Einstein says that the passenmgers "must, therefore" conclude the photons are not emitted simultaneously in the moving frame.

Ok but the train is lengthy. Just as the photons from A and B arrive at the midpoint M after being detected at t1 but before detection at t2, the passengers P, sitting adjacent to M when the photons arrive simultaneously, the P observe the photons simultaneously arriving in the moving frame.

Code:

           A ->|<-B
|--------------M------B--------]
               P     t1

Do you see a problem with SR now, like a glaring contradiction between defintion and observation??

And does it not seem strange that such weight is placed on this definition, like loss of absolute time, insertion of time dilation and mass shrinking?

If you replace the photons with NASCARs moving at 300km/hr and the 0bserver O' moving at 100 km/hr and the distance between AB is 800 meters, then the B Nascar will intercept O' at 100 meters passed M and the A NASCAR will intercept O' 100 metees from where B intecepted O'. Now here everbody on the rack can see the NASCAR emitting into the moving frame as soon as they leave A and B simultaneously? Will you, or anybody else conclude the two NASCARS were not emitted into the O' frame simultaneously, that is when they entered, that is left the A and B positions, not when they were detected?

So what is the difference here? Photons vs NASCARS? So what is the difference in the conclusions you draw? Saying photons aren't NASCARS begs the question because the beginning of SR starts with the simultaneity definition. Read Relativity by A Einstein, a very readable math free book.

 

I was looking for someplace to post this question and since this thread is quite developed ill try here...

In special relativity it is my understanding that an observer measuring the velocity of llight will always come stumble upon the same answer because when the observer is approaching the light, time must slow down because C≠ 299,792,458 m/s - V. If the observer were to instead of walking toward the light, back pedal and again try to measure the velocity of the light will time indeed speed up?
because surely C≠ 299,792,458 m/s + V

 

No, because there is a flaw in your reasoning: time does not speed up to keep the speed of light constant. If you look at it properly, you can say that it is actually the other way around. If you were to look at another, moving observer, his time slows down with respect to yours because of the constancy of the speed of light (there is an important difference in cause and effect here). That other observer himself would not see something strange btw, for him it would appear as if time were ticking normally.

This effect (time dilatation) is independent of the direction of motion, and depends only on the speed of the observer. If it puzzles you, do a search for "time dilatation" on this forum and you'll find many, many threads on it (but beware, also many, many misinterpretations of it).

 

2inquisitive - why don't you read up on special relativity, and learn what it says before you try to prove it wrong?
from your posts it seems that you don't really know SR.

 

It makes no sense to say that an observer is moving toward or away from light, since light has no unique frame of reference associated with it. With respect to what is the observer moving?

If we choose an arbitrary frame of reference, then we need to replace your vtotal = v1 + v2 formula with the relativistic formula:

vtotal = (v1 + v2)/(1 + v1*v2/c^2)

and we see that if one of the velocities is c, then the total velocity will always be c, regardless of the magnitude or sign of the other velocity.

 

Shoffsta, me thinks tis yourself that needs to "read up on special relativity".

From Einstein's definition of simultaneity as described in "Relativity": Events simultaneous in a stationary freame are not simultaneous in a moving frame." This a bogus definition and is the very heart and soul of special relativity. If the definition goes, so too special relativity.
In the train gedunken the obsever O' detects the photon from B then the photon from A from behind.

Code:

A                        B
|__________M_______B___A_|
a0     0,2 O'    1,O'<---0b
 ---------------------3O'

We use numbers for the event times.

• 0 is the time the photons were emitted by A and B and when O' was at M the midpoint of A and B and recorded by a and b in the moving frame.
• 1 is the time the B photon was detected by O' and the arrival of the time the B photon was emitted by B and recorded by b in the moving frame.
• 2 is the time the A and B photon arrived simultaneously at M and recorded by a|b in the moving frame, passengers sitting there when the train passed by M.
• 3 the time the A photon detected by O'. and the time of arrival of the recorded time the A photon was emitted at A - recorded by a.

From this Einstein tells us that the passengers using the train as an inertial frame "must, therefore come to the conclusion" that the photons emitted simultaneously in the stationary frame were not emitted simultaneously in the moving frame. This conclusion comes from the staggered arrival time of the B, then the A photon as detected by the moving observer O', period.

It is clear enough even before we begin that the the B photon will be detected first as the observer O' is moving toward the oncoming B photon and away from the A photon catching up from behind. Duh.

Taking Einstein at his word, and with a little incisive logic we can infer, as did Einstein, that the mere staggered detection of the B and A photons is the reason the passengers "must" conclude the photons were not emitted simultaneously in the moving frame. Or, in other words, as a corollary, observers observing the simultaneous arrival of the A and B photon in the moving frame will conclude the photons were emitted simultaneously in the moving frame.

1 The first flaw: The train is lengthy and observers at A and B in the moving frame a and b each record the emission time of the simultaneously emitted photons from A and B. The clocks in the moving frame are synchronized within the moving frame. Therefore when the a and b data are scrutinized by O' after the arrival of the final A photon she will see the a and b observers recorded the first simultaneous emission of the A and B emitted photons.

2. The second flaw: Observers on the moving frame a|b at t2, at M when the A and B photons arrive there simultaneously (after the B photon was detected by O') record the simultaneous arrival of the A and B photons at M. Here is the second detection of simultaneous arrival of photons in the moving frame.

3. From symmetry we can determine that t3, the time of detection of the A photon by O' can be expressed as t3 = t1(C + v)/(C - v). As t3 and t1 are measured moving frame values and as v is known, t3 can be checked. t3 is measured and if the photons were emitted simultaneously in the moving frame the calculated right hand side will agree with the measured left hand t3 value.

These are just three contradictions of the Einstein conclusion that the passengers "must" conclude the photons were not emitted simultaneously in the moving frame. Virtually all the passengers are able to determine the photons were emitted simultaneously in the moving frame.

Einstein did not use any postulates of light propagation other than the speed of light is a measured constant value of c = 3 x 10^8 m/sec. For this reason we could have used NASCARS with v = 300km/hr for the photons and a 1979 Ford Fairlane with v = 100 km/hr as the moving frame.

From the loss of simultaneity we discard absolute time, insert time dilation, insert contraction of physical length, and the ever constant measurement of the speed of light in all inertial frames (using time dilaltion and contraction of physical length, of course, in order to arrive at the constant measurement of c). From SR we are told we can "consider" physical impossibilities with abandon. Space ships moving with relative velocities of .0001c and .9999c can each consider themsleves at rest and the other ship moving. Each clock on the respective ships will show time dilation and each will consider the others clocks as slower than his own, and each will be correct as per SR that is. Train stations move and trains stand still, physical impossibilities , but mathematical junk. There is more but the story is much too sad to be told in one setting.
We get the postulates of Special Relativity based on the conclusion that passengers must conclude the photons were not emitted simultaneously in the moving frame. A tremendous burden for such a naively defined characteristic, isn't it?

 

This is not a definition of simultaneity, and Einstein did not define the word since its meaning is obvious. He simply stated that simultaneity is frame variant, which is not the heart and soul of special relativity, but rather a consequence of the two postulates.

The problem with this claim is that no frame of reference is specified. The statement that "O' is moving toward the oncoming B photon and away from the A photon" is true in the embankment's frame, but not in O's frame. According to O', O' is stationary and not moving toward or away from either photon.

Two common missteps when analyzing thought experiments like this one are:

1) Subconsciously working from the "stationary" (the ground) frame of reference without specifying it explicitly.

2) Assuming that the frame of the light source is the "correct" frame for the light itself. In other words, assuming that since O' is moving with respect to the light sources, then O's view of the light itself must be invalid.

I think that if you avoid these two problems, then your objections to relativity will disappear.

 

"Events simultaneous in a stationary freame are not simultaneous in a moving frame. This a bogus definition and is the very heart and soul of special relativity. If the definition goes, so too special relativity."

I still don't see why this should be bogus; just because it does not seem to be that way at slow velocities, it doesn't mean it's not true at high velocities.

 

One reason i called it bogus is because of how he used the definition to explain the sequential arrival of photons to show a confirmation of what he had just defined.

 

The reason light is always measued as C is from the moving observer putting herself at v = 0, therefore c is a guaranteed answer, with time diltion, frame contraction, and all the rest.

As light has not exhibited any anisotropic properties from all angles wrt to the planet earth the orb qualifies as a righteous preferred frame for v=0. Taking measurements wrt to the zero frame for all frames the relative velocity of all frames can be univesally determined.

I prefer the earth as a body of reference, a coordinate frame.

 

2inquisitive, what if you were really at rest and the rock you thought you were heading for was really moving at you?

In any event take the case of all the light experiments easured from planet earth where the motion of the light has never exhibited any anisotropic properties, meaning one always measures C as the speed for light wrt the earth frame. The direction vector is changing at a rate of some 10^-8 radians per second. The difference in velocity is 4 orders of magnitude proportionally removed. Measure the speed of light wrt planet earth, then take the relative velocity of a frame wrt the earth and subtract these terms. Every thing taken wrt the earth an inertial frame and you get a righteous SR supported relative velocity. And look where we are, right in the middle of it all, just like the olden days, take a look up, well maybe.

It is the SR theorists that gave us Mother Earth as a reference frame, a zero velocity reference frame, and for personal reasons I prefer the earth frame as my body of reference. I wonder what eveilm plots they are scheming to unleash upon us, who only seek peace with our body of reference, our coordinate frame, yes our universal frame and our frame of preference.
SR made the error of the century, relatively speaking when they assumed that because frame earth gave a relative velocity of C that all frames, even those not at rest would be slaved to perform the same way. This is what you get when you go away for the weekend and someone gives a box of chalk to the mathematicians. Didn't those fools know what they were doing?

I am starting to choke in pity for the poor and lonely disinfranchiosed SRists, now idle minded and cast upon the tempest boiling sea, without boat nor oar, but I'm sure somene gave them a compass.

 

The earth is an effective Velicty zero body of reference. This works for light and material as no experiment has resulted in light exhibting any nonisotropic proerties.

 

I quote yopu your own words. tell me the the physics of assuming all inertial frames need necessarily consider measuring the velocityu of light C wrt to any inertial frame?