I Special theory of relativity argument

[exponent137]

Some layman people are against special relativity and stubbornly persist on their theories.
One man put the model that the speed of photon is c + v, where v is speed of source. In such case Michelson interferometer is not a good anti-argument.

What is, in your opinion about the most simple and effective experimental or theoretical argument against the above model (for educated non-physicist.)
He wishes an experiment, where source of light is moving.
I gave an argument about the speed of OPERA neutrinos, but argumentation is not easy.
All physics is against the above model, but anti-argumentation is not easy.

 

[FactChecker]

If you rule out explaining the details of the Michelson-Morley experiment, there is not much that you can say scientifically. But you can describe the history. Just about everyone believed that the velocities should add. Or that aether existed. They tried really hard to find experiments and theories that would support that belief. The experimental results left no alternative to the speed of light being constant.

 

[exponent137]

It is strange to me, that no experiment exists to simply rule out c+v model. Is it something similar to OPERA, where source is moving and photons are used instead of neutrinos?

 

[jerromyjon]

One man put the model that the speed of photon is c + v, where v is speed of source. In such case Michelson interferometer is not a good anti-argument.

I thought that was the whole argument? If c+v is one direction c-v would be the opposite direction. We simply see "c" and "v" has no effect on the results.

 

[FactChecker]

You might describe briefly that light behaves like a wave going through a stationary field, unaffected by the speed of the source, but that all inertial frames measure it's speed the same in their reference frame. That can lead to a discussion of the relativity of simultaneity, distance, and time.

 

[exponent137]

You might describe briefly that light behaves like a wave going through a stationary field, unaffected by the speed of the source, but that all inertial frames measure it's speed the same in their reference frame. That can lead to a discussion of the relativity of simultaneity, distance, and time.

Yes, but I do not know an example where speed of light is measured from non-rest source?
I agree, nonsimultaneity is an important argument, but not in one step.

Or maybe, Maxwell equations are independent from speed of source, they always give result c, as speed of light?

 

[FactChecker]

Yes, but I do not know an example where speed of light is measured from non-rest source?

You mean other than the Earth?

I agree, nonsimultaneity is an important argument, but not in one step.

Only if they are interested. But it is the root cause of it all.

 

[exponent137]

You mean other than the Earth?
Only if they are interested. But it is the root cause of it all.

It is not important if source is other than earth, I think, if speed of source is minuscule, it can be measured.

And my question above: Do maxwell equations always give speed of light as c? This can be an effective answer.

 

[Nugatory]

Yes, but I do not know an example where speed of light is measured from non-rest source?

Transmission of radio signals between Earth and spacecraft

 

[exponent137]

Transmission of radio signals between Earth and spacecraft

Was this speed of "light" measured precisely enough?

 

[jtbell]

I do not know an example where speed of light is measured from non-rest source?

Tests of Light Speed from Moving Sources (from the FAQ on experimental tests of relativity which is linked at the top of this forum)

Was this speed of "light" measured precisely enough?

What is "precisely enough"?

 

[Nugatory]

Was this speed of "light" measured precisely enough?

If the actual speed of the received signal differed from the accepted invariant velocity as a result of the speed of the source, the ground locations computed by a GPS receiver would be systematically wrong. No such systematic errors have ever been seen, and we're working with distances measured in meters after the signal has traveled hundreds of kilometers.
So even before doing any statistical error analysis or considering interferometry measurements, we're talking about better than one part in ten thousand. More sophisticated measurements than this naive "how far down the off-ramp did I go before the GPS figured out that I took the wrong exit?" are orders of magnitude better than that.

 

[FactChecker]

Without corrections for relativity, GPS measurements would be wrong by about 6 miles per day.

 

[exponent137]

If the actual speed of the received signal differed from the accepted invariant velocity as a result of the speed of the source, the ground locations computed by a GPS receiver would be systematically wrong. No such systematic errors have ever been seen, and we're working with distances measured in meters after the signal has traveled hundreds of kilometers.
So even before doing any statistical error analysis or considering interferometry measurements, we're talking about better than one part in ten thousand. More sophisticated measurements than this naive "how far down the off-ramp did I go before the GPS figured out that I took the wrong exit?" are orders of magnitude better than that.

Do you think satelites, or Spacecraft? If you think satelites, you do not think geostationary satelites?

 

[exponent137]

Tests of Light Speed from Moving Sources (from the FAQ on experimental tests of relativity which is linked at the top of this forum)
What is "precisely enough"?

This link is what I wished. Thanks.
With "precise enough" I thougt more precise than velocity of source of light.

 

[exponent137]

Without corrections for relativity, GPS measurements would be wrong by about 6 miles per day.

Yes, but I think that those corrections are for general relativity, I think only about velocity of satelites, that I will not complicate.

 

[PeroK]

Yes, but I think that those corrections are for general relativity, I think only about velocity of satelites, that I will not complicate.

Well, if Special Relativity is wrong, what hope would there be for General Relativity? It's not you yourself that is unconvinced, by any chance?

The GPS corrections are for both SR and GR, by the way.

 

[exponent137]

Well, if Special Relativity is wrong, what hope would there be for General Relativity? It's not you yourself that is unconvinced, by any chance?

The GPS corrections are for both SR and GR, by the way.

I think I found:
46 us/day for general relativity, -7 us/day for special relativity. This can be translated into above 6 miles/day.

When I explain to a layman, I need as simple as possible.

 

[Nugatory]

Do you think satelites, or Spacecraft? If you think satelites, you do not think geostationary satelites?

Either satellites or spacecraft - they're both spacecraft , we just happen to use a different name for the spacecraft that are in semi-permanent Earth orbit, and they're all equally useful as moving light sources.

The GPS satellites are nowhere near geosynchronous, but even if they were... A geosynchronous satellite is moving about 2.5 km/sec faster than the point on the Earth's surface directly below it.

 

[pervect]

It is strange to me, that no experiment exists to simply rule out c+v model. Is it something similar to OPERA, where source is moving and photons are used instead of neutrinos?

I didn't read the whole thread, but I don't know why you think that no experiment rules out the c+v model, which is commonly called emission theory.

See for instance the PF Faq, "Experimental basis of Special Relativity", https://www.physicsforums.com/threads/faq-experimental-basis-of-special-relativity.229034/, and chase down through a couple levels of links to arrive at the section on "Tests of light speed from moving sources", http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html#moving-source_tests. You might also want to check out the notes on "extinction" earlier in the reference.

Basically there's plenty of tests, and they've been mentioned numerous times. But there's always someone around to ask the same old questions over again. Perhaps we'll see another question along the same lines as early as tomorrow, as someone reads the thread, and gets inspired without reading the responses. Though I can't point too much of a finger at not reading all the responses - I didn't read them all myself, as - well, I've seen this before a few times.

 

[Dale]

One man put the model that the speed of photon is c + v, where v is speed of source. In such case Michelson interferometer is not a good anti-argument.

What is, in your opinion about the most simple and effective experimental or theoretical argument against the above model (for educated non-physicist.)
He wishes an experiment, where source of light is moving.

See http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html

In particular section 3.3 Tests of Light Speed from Moving Sources.

My favorite ones are the observations of binary stars. If the speed of light were c+v then binary stars would appear to be three stars then two stars then one star as the stars went forward and backward. It would be very weird and noticeable.

Edit: I see that I am the third or later person to point to the same link. There is a good reason why it is kept as a "sticky thread" on the top of the forum.

 

[HallsofIvy]

Indeed, the only good argument, for or against a physics theory is "experimental evidence".