I Measuring the Speed of Light: Time of Flight Experiments

[Sandeep T S]

Is anyone expermently measured two way speed of light from moving source using time of flight?

 

[Ibix]

Moving with respect to what? All sources are moving in most frames of reference.

 

[Sandeep T S]

Moving with respect to what? All sources are moving in most frames of reference.

Moving respect to me or experimentalist

 

[Sandeep T S]

Moving respect to me or experimentalist

I searched lot in this site. http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html#Doppler_shift , but I couldn't get any information about experiment I prescribed above.

 

[Ibix]

Moving respect to me or experimentalist

Take any two way speed measurement process and walk past it. The source is now moving with respect to you. Do you expect the results to change because you are walking?

 

[Ibix]

I searched lot in this site. http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html#Doppler_shift , but I couldn't get any information about experiment I prescribed above.

The Beckmann and Mandics paper cited under Tests of Light Speed From Moving Sources would seem to fit exactly.

 

[Sandeep T S]

The Beckmann and Mandics paper cited under Tests of Light Speed From Moving Sources would seem to fit exactly.

I read that paper , here optical extinction is not a problem but here Beckman used to find violation in speed of light using fringe shift. Not directly measured speed of light. This experiment not useful for me.

I need a experiment in which two way speed of light measured from moving source, and by using time of flight.

 

[Ibix]

Then take any time of flight experiment and walk past it. Now you have a moving source in your frame. The results won't change.

 

[Ibix]

And why isn't Beckmann and Mandic's paper acceptable? If they show that the speed of light doesn't change why do you care that they don't directly measure the speed? Why would you expect it to come out different in this one experiment?

 

[Sandeep T S]

And why isn't Beckmann and Mandic's paper acceptable? If they show that the speed of light doesn't change why do you care that they don't directly measure the speed? Why would you expect it to come out different in this one experiment?

I m not arguing with the credibility of Beckman's experiment.

I need to know that anyone did experiment like Beckman with moving mirror and find speed of light by measuring time of flight.

If you know anything about this kind of experiment please share.

 

[Ibix]

My point is that Beckmann and Mandics find that the speed of light is the same whether the mirror is moving or not. For this not to count as measurement of the speed of light with a moving mirror you have to believe that it is possible that the speed of light in their experiment was some constant other than c, even when the mirror was not moving. Why would you think that? What's special about their perfectly ordinary interferometer that it changes the speed of light under conditions that have been tested elsewhere?

I don't think this paper answers your specific request. I just can't think of a way it doesn't verify what the experiment you asked for would verify.

 

[Nugatory]

Is anyone expermently measured two way speed of light from moving source using time of flight?

Aircraft radars routinely test the two-way speed of light between moving objects. They wouldn't produce accurate position information if the speed (speed relative to what?) of either the source or the target affected the two-way speed of light.

 

[Sandeep T S]

Aircraft radars routinely test the two-way speed of light between moving objects. They wouldn't produce accurate position information if the speed (speed relative to what?) of either the source or the target affected the two-way speed of light.

Can you share any link to get this experiment.

 

[Klystron]

If you prefer a longer experimental baseline, NASA left radar reflectors on the surface of the moon. You can locate published reviewed papers on experiments that bounced signals from the moving Earth off the moving moon. These experiments measured earth-moon distances and motions more precisely than optical telescopes. You can select data sets from voluminous online sources that can be used to compute speed of light in vacuum (possibly corrected for passage through Earth's atmosphere for ground based radars).

For an even longer baseline consider transmissions from interplanetary probes including Voyager 1 & 2. I seem to remember announcements years ago that Voyager data transmissions and two-way communication were used to validate several RF (radio-frequency) measurements.

Closer to earth, satellite transmission delay times might provide data for your experiments.

 

[Sandeep T S]

If you prefer a longer experimental baseline, NASA left radar reflectors on the surface of the moon. You can locate published reviewed papers on experiments that bounced signals from the moving Earth off the moving moon. These experiments measured earth-moon distances and motions more precisely than optical telescopes. You can select data sets from voluminous online sources that can be used to compute speed of light in vacuum (possibly corrected for passage through Earth's atmosphere for ground based radars).

For an even longer baseline consider transmissions from interplanetary probes including Voyager 1 & 2. I seem to remember announcements years ago that Voyager data transmissions and two-way communication were used to validate several RF (radio-frequency) measurements.

Closer to earth, satellite transmission delay times might provide data for your experiments.

These experiments seems to be fine for my criteria. As NASA did, any recent experimentalist repeat this experiment on vacuum in laboratory by measuring distance between moving body and observer.

 

[A.T.]

Aircraft radars routinely test the two-way speed of light between moving objects. They wouldn't produce accurate position information if the speed (speed relative to what?) of either the source or the target affected the two-way speed of light.

Can you share any link to get this experiment.

I wouldn't describe aircraft radars as experimental. More like routine performed continuously with thousands of lives depending on it. It would be headline news if they stopped working properly.