Problems with Relativity

[vuquta]

Just ripped off from wiki, the second postulate.

 

"As measured in any inertial frame of reference, light is always propagated in empty space with a definite velocity c that is independent of the state of motion of the emitting body."

 

All references to the second postulate sound similar. Note as measured in any inertial reference frame.

 

The mathematical statement is that the free parameter in the Lorentz transformations is numerically equal to the speed of propagation of light as measured in an inertial reference frame.

 

 

Nope this is not the light pistulate. Since so many are confused, I only accept Einstein's version.

 

Any ray of light moves in the ``stationary'' system of co-ordinates with the determined velocity c, whether the ray be emitted by a stationary or by a moving body

http://www.fourmilab.ch/etexts/einstein/specrel/www/

 

You cannot find any measure logic in this postulate. It is talking about motion.

It says light moves through space at c. Now, how do you measure it. See how these are different issues.

 

However, what I will grant you is that Einstein used this postulate and all of a sudden out of nowhere, he concluded the light path is the same as the path between the emission point in the frame and the receiver.

 

So, here is the real question now. Given Einstein's version of the light postulate, can you prove the light path is the same as the path between the emission point in the frame and the receiver? This is how it is claimed to be measured.

 

I will tell you how Einstein proved it.

 

In agreement with experience we further assume the quantity

 

2AB/(t'A - tA) = c.

http://www.fourmilab.ch/etexts/einstein/specrel/www/

 

See, he simply asserted it and did not prove it. There has been no experiments done with clocks which t'A and tA reference.

 

There is a 3rd hidden postulate based on his statement above.

 

Postulate 3 - The light path is the same as the path between the emission point in the frame and the receiver.

 

Normally, when folks attack relativity, they make assertions they cannot prove.

 

Well, this is exactly what I found in SR based on Einstein's statement above.

 

 

So, what I am I really saying?

 

The distance light travels from emission to reception is not logically decidable.

 

 

Do you ever say what light is moving relative to?

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My experiments don't measure frequency, the detectors are simply photodiodes. They have no (well very limited) frequency dependence, and certainly none over the laser frequency range.

 

it is not directly measuring the speed of light but if the speed was different in different directions the two orthogonal delay set ups would produce different results. Which they do not.

 

Well, I look it up and signal is known to be frequency. Where are the clocks?

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Light is a wave. Frequency is a property of the wave. I don't understand what the problem is, vuquta. It's like saying knowing mass of the object is not related to measuring its weight on earth. They're related.

 

Of course they are related. That is a far cry from saying they are equivalent which they are not.

 

I showed an MMX experiment with different length armatures and a null result.

This can never happen in a clock based environment since the path lengths of light would be different.

 

This demonstrates, as measuring techniques, they are different.

[Klaynos]

Well, I look it up and signal is known to be frequency. Where are the clocks?

 

I don't know what you mean by "signal is known to be frequency" that makes little to no sense. The 'clocks' are because we are varying the delay, increasing the travel distance and therefore from that can calculate the time it takes the light to travel. As the delays are orthoginal to each other from what you are saying about distances the time difference from the same distance moved would be different, they are not different they are the same, this shows your proposal that c is different in different directions to be false.

 

We don't measure frequency, the experiment can be conducted with 800nm or 400nm light from the same laser. We measure intensity, and a change in path length.

[ajb]

Nope this is not the light pistulate. Since so many are confused, I only accept Einstein's version.

 

So forget everything that has been done since and go back to Einstein's original postulates?

 

I tend to think about all this much more geometrically than Einstein originally did.

 

To measure anything one picks coordinates, sensible coordinates in special relativity are the inertial ones. This is synonymous with inertial observer. The speed of light is defined in terms of such a coordinate system.

 

Now in Klaynos' lab we see that the effect of the Earth's rotation and the gravitational field are tiny and well beyond his experimental errors. We take Klaynos' lab to be an inertial reference frame. He can then do what ever experiments he likes. If he infers the speed of light from his experiments it is made clear that this is with respect to the inertial frame of his lab.

 

Klaynos, being a great thinker decides he wants to try the experiment on a train, travelling at constant speed, with respect to his lab. What does he find out?

[vuquta]

I don't know what you mean by "signal is known to be frequency" that makes little to no sense. The 'clocks' are because we are varying the delay, increasing the travel distance and therefore from that can calculate the time it takes the light to travel. As the delays are orthoginal to each other from what you are saying about distances the time difference from the same distance moved would be different, they are not different they are the same, this shows your proposal that c is different in different directions to be false.

 

We don't measure frequency, the experiment can be conducted with 800nm or 400nm light from the same laser. We measure intensity, and a change in path length.

 

 

this shows your proposal that c is different in different directions to be false

 

I never said this and do not believe this. From the emission point in space, light moves c in all directions.

 

That is my view.

 

therefore from that can calculate the time it takes the light to travel

 

You are calculating time with what?

 

Also,

 

As the pulse energies for femtosecond pulses are usually small, the measured signal has to be obtained from the overlap region of two focused laser beams.

http://spie.org/x648.html?product_id=723954

 

This description is comparing two signals ie frequencies. How is this what you are saying?

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So forget everything that has been done since and go back to Einstein's original postulates?

 

I tend to think about all this much more geometrically than Einstein originally did.

 

To measure anything one picks coordinates, sensible coordinates in special relativity are the inertial ones. This is synonymous with inertial observer. The speed of light is defined in terms of such a coordinate system.

 

Now in Klaynos' lab we see that the effect of the Earth's rotation and the gravitational field are tiny and well beyond his experimental errors. We take Klaynos' lab to be an inertial reference frame. He can then do what ever experiments he likes. If he infers the speed of light from his experiments it is made clear that this is with respect to the inertial frame of his lab.

 

Klaynos, being a great thinker decides he wants to try the experiment on a train, travelling at constant speed, with respect to his lab. What does he find out?

 

Wait, I am not refuting any experiment. How did you get that?

I am saying there is no experiments that times the speed of light with clocks. Einstein claimed it is true, yet it is false. It has been verified that light travels through space at one speed. Now we need a way to time this.

 

 

Yes, you may put an MMX experiment on a train and it will produce null result. You may put it on the earth or sun or wherever and it will produce a null result.

That is the nature of frequency, it matches the frame.

 

So, this is very good to depend on frequency since it is very dependable.

 

That does not measure the speed of light though since MMX is consistent with Ritz's theory.

[ajb]

You are calculating time with what?

 

It is true that unless you measure a "round trip" i.e. use a single clock, you have problems with synchronization of clocks. Einstein defined a method/convention of synchronisation.

[Klaynos]

this shows your proposal that c is different in different directions to be false

 

I never said this and do not believe this. From the emission point in space, light moves c in all directions.

 

That is my view.

 

therefore from that can calculate the time it takes the light to travel

 

You are calculating time with what?

 

Also,

 

As the pulse energies for femtosecond pulses are usually small, the measured signal has to be obtained from the overlap region of two focused laser beams.

http://spie.org/x648.html?product_id=723954

 

This description is comparing two signals ie frequencies. How is this what you are saying?

 

We create some decaying effect that will effect the signal. In our case photo excited electrons in a semiconductor. The signal we measure will decrease over time.

 

We are calculating time delays, so we move the delay line by x amount and measure the signal, move x and measure etc...

 

We repeat that on the other set up, the results match each other.

 

Now if c was varying in direction the two decaying traces will be different widths, they are not.

 

I don't see them mention anything about frequency, the overlap they are talking about is between the pump (to excite what you are measuring) and the probe, they must over lap in space so you are actually measuring something, and at some point during your scan they will overlap in time. This is not dependent on frequency, although for experimental reasons (you can use band pass filters) you often use different frequencies for pump and probe pulses.

[vuquta]

To measure anything one picks coordinates, sensible coordinates in special relativity are the inertial ones. This is synonymous with inertial observer. The speed of light is defined in terms of such a coordinate system.

 

 

OK, let's pick the earth frame. Is it moving around the sun?

 

So, how do you measure light with a set of coordinates that are moving through space since light moves though space at c?

[ajb]

It is locally close enough to an inertial reference frame for us to verify special relativity.

[vuquta]

We create some decaying effect that will effect the signal. In our case photo excited electrons in a semiconductor. The signal we measure will decrease over time.

 

We are calculating time delays, so we move the delay line by x amount and measure the signal, move x and measure etc...

 

We repeat that on the other set up, the results match each other.

 

Now if c was varying in direction the two decaying traces will be different widths, they are not.

 

I don't see them mention anything about frequency, the overlap they are talking about is between the pump (to excite what you are measuring) and the probe, they must over lap in space so you are actually measuring something, and at some point during your scan they will overlap in time. This is not dependent on frequency, although for experimental reasons (you can use band pass filters) you often use different frequencies for pump and probe pulses.

 

When you say you measure the signal, you are measuring frequency.

 

So, this statement should read

 

Now if the light frequency were not constant and was varying in direction the two decaying traces will be different widths, they are not.

 

I already agree the freqeuncy of light does not change in a single frame.

 

Also, if your experiment is clock based, you would not need two lasers.

You are just doing one way MMX.

 

If you look at this paper,

 

In particular, double-probe frequency domain interferometry (FDI), which has come into widespread use in high-field laser-plasma experiments

 

Also, look at figure 2 and it is clear this is an MMX derivative.

 

http://w3fusion.ph.utexas.edu/ifs/ifsreports/1051_Zgadzaj.pdf

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It is locally close enough to an inertial reference frame for us to verify special relativity.

 

Wait.

Do you agree your coordinates are moving in some unknown way?

 

If so, Einstein's assertion is false.

[ajb]

Coordinates don't move. You measure things with reference to them.

 

Does the Earth move with respect to the Sun? Does the Sun move with respect to the galactic centre? etc. Of course.

 

But this is not the issue.

 

Special relativity says that there is a preferred class of coordinates in the neighbourhood of every point on space-time. In fact, you can extend this to global coordinates.

 

You have two kinds of coordinate transformation.

 

1) Passive, that is changing the coordinates in the neighbourhood of a point.

2) Active, that is you move the point.

 

In special relativity both types are used.

[Klaynos]

When you say you measure the signal, you are measuring frequency.

 

No, the detectors are frequency independent, they are photodiodes, I explain this above. The laser frequency is stable (we can actually measure it and it is stable), yet the signal is not stable, it is reproducable.

 

So, this statement should read

 

Now if the light frequency were not constant and was varying in direction the two decaying traces will be different widths, they are not.

 

No, that would make no sense. The detectors are frequency independent.

 

I already agree the freqeuncy of light does not change in a single frame.

 

Also, if your experiment is clock based, you would not need two lasers.

 

No, not really, the clock would just add more error. The system is acting so that it is possible to measure the same time difference independent of each other.

 

You are just doing one way MMX.

 

Not really, the two 'arms' are making individual time difference measurements.

 

If you look at this paper,

 

In particular, double-probe frequency domain interferometry (FDI), which has come into widespread use in high-field laser-plasma experiments

 

Also, look at figure 2 and it is clear this is an MMX derivative.

 

http://w3fusion.ph.utexas.edu/ifs/ifsreports/1051_Zgadzaj.pdf

 

That is a frequency domain experiment, we are doing time domain experiments.

 

Figure 2 also doesn't look much like MMX other than it has a diffraction pattern, but it's cause by a grating in this case which is completely different to MMX.

[vuquta]

Coordinates don't move. You measure things with reference to them.

 

Does the Earth move with respect to the Sun? Does the Sun move with respect to the galactic centre? etc. Of course.

 

But this is not the issue.

 

Special relativity says that there is a preferred class of coordinates in the neighbourhood of every point on space-time. In fact, you can extend this to global coordinates.

 

You have two kinds of coordinate transformation.

 

1) Passive, that is changing the coordinates in the neighbourhood of a point.

2) Active, that is you move the point.

 

In special relativity both types are used.

 

This is all fine.

 

But, since you argue that light moves through emoty space at c, and I also agree, then you have to use the coordinates of light to measure it.

 

Further, when you say light moves through space, you must decide, if your selected coordinates move through space.

 

I seriously doubt that anyone would claim objects do not move through space. Thus, coordinates of the frame are somehow moving through space.

 

Therefore, coordinates move through space and light moves through space.

 

So, unless you know how the coordinates are moving through space, you cannot use these coordinates to measure how light is moving through space.

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No, the detectors are frequency independent, they are photodiodes, I explain this above. The laser frequency is stable (we can actually measure it and it is stable), yet the signal is not stable, it is reproducable.

 

 

 

No, that would make no sense. The detectors are frequency independent.

 

 

 

No, not really, the clock would just add more error. The system is acting so that it is possible to measure the same time difference independent of each other.

 

 

 

Not really, the two 'arms' are making individual time difference measurements.

 

 

 

That is a frequency domain experiment, we are doing time domain experiments.

 

Figure 2 also doesn't look much like MMX other than it has a diffraction pattern, but it's cause by a grating in this case which is completely different to MMX.

 

This paper says your stuff is interferometry which is MMX. All logic in the paper references frequency measurements.

 

So, precisely how are you measuring time if not with clocks and not with frequency?

[mooeypoo]

This is all fine.

 

But, since you argue that light moves through emoty space at c, and I also agree, then you have to use the coordinates of light to measure it.

I thought a photon is not a valid inertial frame.

 

Further, when you say light moves through space, you must decide, if your selected coordinates move through space.

Movement is relative.. it moved relative to the frame. Isn't that the point?

 

I seriously doubt that anyone would claim objects do not move through space. Thus, coordinates of the frame are somehow moving through space.

I don't see the logic in this statement..

 

Therefore, coordinates move through space and light moves through space.

Again, logic doesn't quite follow.

 

So, unless you know how the coordinates are moving through space, you cannot use these coordinates to measure how light is moving through space.

Totally lost you.

[ajb]

But, since you argue that light moves through emoty space at c, and I also agree, then you have to use the coordinates of light to measure it.

 

Light cone coordinates can be employed. But I think that will confuse you even more.

 

Further, when you say light moves through space, you must decide, if your selected coordinates move through space.

 

Not really, simply fix the coordinate system used.

 

I seriously doubt that anyone would claim objects do not move through space. Thus, coordinates of the frame are somehow moving through space.

 

Then you can think of objects moving as describe in the now fixed coordinate system.

 

I understand what you are thinking of. However, I think you are confused by the notion of local coordinates, inertial coordinates and how to describe things in special relativity.

[vuquta]

I thought a photon is not a valid inertial frame.

I did not say light is an inertial frame

 

 

Movement is relative.. it moved relative to the frame. Isn't that the point?

 

No, we are not talking about two frames. We are talking about light and the frame. We are talking about measuring its speed.

 

So, how would you do it?

[Klaynos]

This paper says your stuff is interferometry which is MMX. All logic in the paper references frequency measurements.

 

So, precisely how are you measuring time if not with clocks and not with frequency?

 

We are measure a time delay bassed on an increase of distance, we increase the distance in both kits by the same amount, it is not an absolute measurement, but a difference measurement, we can then compare the difference between the two kits and see there is no difference.

 

Interferometry is a VERY broad term, only michalson interferometers are the same as the MMX experiment. They can be massively different to that.

 

Also as I stated that is a frequency domain pump probe experiment, I've been discussing time domain pump probe experiments, which are not interferometry.

[vuquta]

Light cone coordinates can be employed. But I think that will confuse you even more.

 

Let's go here later.

 

 

Not really, simply fix the coordinate system used.

Well, since light moves though space, how are you going to fix these in space?

 

For example, you shoot a laser from the west to the east. While light is moving toward the target, does the targety sit still in space? I am not taking about the frame, I am talking about space, since a frame is just a coordinate system. So, will the target remain in fixed in the same space as the light beam?

 

 

 

I understand what you are thinking of. However, I think you are confused by the notion of local coordinates, inertial coordinates and how to describe things in special relativity.

 

Nope, I am not having trouble understanding SR.

 

Let's prove together that the light path, which is independent of the frame, is the same as the path between the emission point in the frame and the light receiver in the frame.

 

That is what we are really working on.

 

How would you prove it?

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We are measure a time delay bassed on an increase of distance, we increase the distance in both kits by the same amount, it is not an absolute measurement, but a difference measurement, we can then compare the difference between the two kits and see there is no difference.

 

Interferometry is a VERY broad term, only michalson interferometers are the same as the MMX experiment. They can be massively different to that.

 

Also as I stated that is a frequency domain pump probe experiment, I've been discussing time domain pump probe experiments, which are not interferometry.

 

which are not interferometry

 

OK, I trust you answer here.

 

We are measure a time delay bassed on an increase of distance, we increase the distance

OK, how are you measuring distance?

 

Everything I read in that paper is frequency based and I have not yet seen how you have separated from this.

 

I found this also

http://faculty.virginia.edu/bpate-lab/Time%20Domain/Misc_Pages/PumpProbe.html

 

This is frequency based for the distance measurement.

 

Here is more using amplitude.

 

Time domain pump-probe THz spectrometer

The setup is capable of measuring the amplitude transmissivity in the frequency region 200Ghz-2.5 THz. In the pump-probe mode the time evolution of the amplitude transmissivity after excitation with an optical pump pulse on a few picosecond timescale is accessible. Maximum available excitation fluence at the sample is ~10 uJ/cm^2 with the photon energy 1.5 eV.

 

Time Resolution

At present the temporal resolution of the pump-and-probe experiments at FLASH depends on the length of the optical laser pulses, which is 120 femtoseconds at 800 nanometers in the infrared and 12 picoseconds for visible light at 523 nanometers. The width of the ATI cross-correlation signal is mainly determined by the temporal jitter of the FEL pulses with respect to the optical laser and represents the overall temporal resolution of around 250 femtoseconds (rms).

 

http://hasylab.desy.de/facilities/flash/research/timing_of_femtosecond_pump_and_probe_pulses/index_eng.html

[ajb]

Let's prove together that the light path, which is independent of the frame, is the same as the path between the emission point in the frame and the light receiver in the frame.

 

That is what we are really working on.

 

How would you prove it?

 

Light cones are preserved under Lorentz transformations. Or more specifically, null-rays are preserved.

 

I think that answers your question.

[vuquta]

Light cones are preserved under Lorentz transformations. Or more specifically, null-rays are preserved.

 

I think that answers your question.

 

Lightcones? Glad your used plural.

 

Let there are two rigid body spheres in collinear relative motion. The “moving” rigid body sphere has a light source at its center. When these spheres are coincident, the light emits. According to SR, light proceeds spherically in the stationary frame and strikes the sphere points simultaneously. Likewise, the light also proceeds spherically in the moving frame and strikes its sphere points simultaneously also.

 

Now, the light sphere in the stationary frame has an origin at (0,0)

 

The origin of the light sphere in the moving frame has an origin at (vt,0) after any time t.

 

Thus, there are two light spheres.

 

Do you know how this is hidden?

 

In the worldline map, they origin the light cones at the same 0.

 

But, the above exercise shows the light sphere is at two different origins.

 

Anyway, can you prove the light path is equal to the emission point in the frame to the light receiver? I cannot.

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Light cones are preserved under Lorentz transformations. Or more specifically, null-rays are preserved.

 

I think that answers your question.

 

Also, if you look at post #60, I give an example that c is measured at two different values under the logic of SR and GPS.

Edited January 17, 2010 by vuquta
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[Klaynos]

We measure the distance by using a stepper motor and a translation stage, we know how far the motor turns which means we know how far the stage has moved on top of the stage is a mirror set up that makes the beam longer by twice the distance the distance the stage has moved.

 

This is a different experiment to the frequency domain experiment you link to above I can't find a good clear, simple explanation of our experiment that is freely avaliable currently.

 

interestingly my main research is bassed THZ-Time domain spectroscopy and I spent last week rebuilding a THZ-TDS experiment, now these are far more complicated than we need to deal with because they measure in the time domain and then do a fourier transform to move into the frequency domain.

[ajb]

We do not have rigid bodies in special relativity.

 

The notion of "simultaneously" is highly frame dependant.

 

If you want to think about light signals etc try drawing some Minkowski diagrams.

[vuquta]

We measure the distance by using a stepper motor and a translation stage, we know how far the motor turns which means we know how far the stage has moved on top of the stage is a mirror set up that makes the beam longer by twice the distance the distance the stage has moved.

 

This is a different experiment to the frequency domain experiment you link to above I can't find a good clear, simple explanation of our experiment that is freely avaliable currently.

 

interestingly my main research is bassed THZ-Time domain spectroscopy and I spent last week rebuilding a THZ-TDS experiment, now these are far more complicated than we need to deal with because they measure in the time domain and then do a fourier transform to move into the frequency domain.

 

Yes, well I would like to see this motor thing since you used diodes before to control timing.

 

I want to know exactly how it is done.

So far, all the posts indicate they use frequencey to determine distance and you have not come up with any logical refutation to this.

I would like to see a paper or an explanation from you on exactly how you measure distance.

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We do not have rigid bodies in special relativity.

 

The notion of "simultaneously" is highly frame dependant.

 

If you want to think about light signals etc try drawing some Minkowski diagrams.

 

No you do not.

 

But, you are avoiding the issues.

First, I showed the light path is logically undecidable under SR.

Second, I showed SR requires 2 different light spheres to complete its mission

 

Finally, I showed with GPS, SR cannot measure at c in 2 frames.

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I might not have the Math to disprove E=mc^2 but I certainly have got a good discussion going...lol

 

My point is:- to measure anything you must know what you are measuring and have the instruments to measure it..(How long is a pice of string?) Depends on if you are measuring in inches or atoms, the speed of light is only a concept as I believe light to be just an occurence of excited electrons, light can be a waveform and a particle and can be many places at the same time, so what are you measuring?

Time is also related to light, but time is relative to energy so 'c' must be related to time.

also the instruments you are using to measure the speed of light are electronic, electricity is slower than light so how do you know that your measurements give you a true reading?

 

How do you have a good discussion going if you do not have the math?

[ajb]

First, I showed the light path is logically undecidable under SR.

 

Light travels along null geodesics.

 

In special relativity this means that in an inertial coordinate system light travels along straight lines. If you draw a 1+1 dimensional Minkowski diagram then light emitted from the origin travels along the lines [math]dx^{2}-dt^{2}=0[/math] into the future of the origin.

 

You can now think about changing coordinates as you will.

 

 

 

Second, I showed SR requires 2 different light spheres to complete its mission

 

I do not follow what you are saying here. Your thoughts on the two rigid spheres I think is flawed. You need to be very careful about what is measured in what frame . Also, recall no rigid bodies. I think you will have to do a Lorentz transformation very carefully to see what will be happening.

 

Finally, I showed with GPS, SR cannot measure at c in 2 frames.

 

What are you claiming here? State it very carefully.

 

We have experimental evidence that the speed of light does not change from inertial frame to inertial frame. I would agree that one does not measure c. It is defined via the definition of a meter and a second. But that is not the issue really, the point is that it is constant between inertial frames.

[vuquta]

Light travels along null geodesics.

 

In special relativity this means that in an inertial coordinate system light travels along straight lines. If you draw a 1+1 dimensional Minkowski diagram then light emitted from the origin travels along the lines [math]dx^{2}-dt^{2}=0[/math] into the future of the origin.

 

Again, you evaded showing by a math proof or experiment that d = ct in a frame which is necessary for the survival of SR.

Why?

 

 

 

 

 

 

 

I do not follow what you are saying here. Your thoughts on the two rigid spheres I think is flawed. You need to be very careful about what is measured in what frame . Also, recall no rigid bodies. I think you will have to do a Lorentz transformation very carefully to see what will be happening.

I did all this. there are 2 light spheres required to complete the mission.

 

I posted the example in post #93.

 

 

 

 

What are you claiming here? State it very carefully.

 

We have experimental evidence that the speed of light does not change from inertial frame to inertial frame. I would agree that one does not measure c. It is defined via the definition of a meter and a second. But that is not the issue really, the point is that it is constant between inertial frames.

 

As I said, post #60, and I was very specific, light is measured different speeds.

 

 

Since I was quite specific, it should be easy to refute it.

[mooeypoo]

vuquta, it was answered, read the posts following yours...