Measuring one way sped of light

[Franklin Hu]

Roger,

I think the point of the experiment is the ability to just be able to accurately measure the "one-way" speed of light and then verify if that speed is constant in different directions. It has been claimed that this one-way measurement of light has never been done and others are claiming it can never be done. However, with the use of GPS to accurately synchronize clocks, this experiment becomes possible and can be done. This only relies upon the GPS system to provide synchronized clocks on the Earth surface which is the basis of its operation and doesn't rely on any particular signals being transmitted from the satellite and the ground. 

The Sagnac effect happens because you are not keeping the distance between the emitter and detector a constant. If I were to perform a speed measurement where the detector was constantly moving closer to the emitter, that wouldn't be a good measurement. One of the principles of measuring speed is that the distance between the emitter and detector must remain a "constant" during the measurement. On the rotating Earth, that simply isn't possible because the detector is always moving at least the velocity of the rotation of the Earth. But with some math, this can be predicted and compensated for. Ideally, you'd like to perform this experiment on a spaceship floating within the ECI frame so you wouldn't have to make such compensations, but the point is to measure the speed of light, not the speed or motion of your equipment.

Even if you were to compensate for the Sagnac effect, it still might be possible that the speed of light varies with the ECI frame which would be unexpected and unexplained. We might find something like light travels faster when aligned with the plane of the galaxy or when oriented towards the Earth or something else.

I would personally predict that the one-way speed of light would be measured the same no matter which direction light travels.  This would then conclusively disprove that light might be travelling at radically different speeds on the outbound and inbound legs of the typically 2 way light speed measurement as was suggested by the Veritasium video on the subject. 

This has been mostly confirmed already based on the evidence on West to East travel of light waves being c+v and c-v, it is apparent that the actual speed of light is the same in both directions after compensating for the Sagnac effect and considering the actual speed within the ECI frame only.

This experiment concentrates on being able to measure the 1-way speed of light and verifying it is not direction dependent. However, this does not address the question of whether the speed of light is measured the same in all inertial frames. To do that, you would have to have 2 setups. Put one setup for the 1-way light speed fixed to the Earth as one frame and then put another identical setup on a train. Then you would have to show that you get the same speed of light whether on the train or not. To my knowledge, no actual experiment like this has ever been performed since we could never reasonably measure the 1 way speed of light before. Does anyone know of any simple experiment like this where you literally compare the speed of light from a moving frame versus a laboratory stationary one? We seem to have an awful amount of faith in something that seemingly has never been experimentally verified.

-Franklin  

On Saturday, April 19, 2025 at 01:08:36 PM PDT, ROGER ANDERTON <r.j.an...@btinternet.com> wrote:

I asked AI it said -

 

That’s a fantastic and important question — one that gets to the core of whether such a GPS-based experiment can actually detect a true anisotropy in the one-way speed of light, or if all observable variations can be explained entirely by already-known rotational effects like the Sagnac effect.

 

after waffle

 

AI says - 

 

If the only source of anisotropy in measured light speeds is the Sagnac effect (i.e., from Earth's rotation), then:

✅ Yes — proper compensation for the Sagnac effect would eliminate any light speed variation in this setup.

This is what current mainstream physics expects: any residual anisotropy observed in one-way light speed after correcting for Sagnac should vanish if special relativity holds and light speed is isotropic in the ECI frame.

 

 

me- I think that is the situation! You compensate for Sagnac and you get rid of lightspeed variation. 

 

AI speculates that maybe there is more lightspeed variation than just that.

 

But I think there isn't in the sense that any found would be dismissed as noise.

 

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Sent: Saturday, April 19th 2025, 20:55
Subject: Re: Re: Next CNPS Saturday session, 10:00 h EST, April 26, 2025
 

Well I don't understand it; if compensating for the Sagnac effect that should be getting rid of lightspeed variation that you are looking for. (?)

Roger

 

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Sent: Saturday, April 19th 2025, 19:45
Subject: Re: Next CNPS Saturday session, 10:00 h EST, April 26, 2025
 

 

Sparked by today's discussion, I came up with this proposal with ChatGPT to consider the variation of light speed.

 

-Franklin

 

On Saturday, April 19, 2025 at 11:07:49 AM PDT, Ian Cowan <ianco...@gmail.com> wrot

 

 

David,

The following for set-up and announcement.

Thanks,

Ian.

---------------------------------------------------------------------------------------

Title - Observations and theoretical basis of the Galilean composition of light and observer speeds

Presenter: Ian Cowan

Host: Franklin Hu

 

Description:  Experimental observations - cosmological and terrestrial - and the theoretical basis of the variation of light speed with observer motion will be considered.

[ROGER ANDERTON]

Franklin

 

It is supposed to be the synchronization process that they use  that prevents measurement of one-way lightspeed.

 

 

Question - 

does synchronization process prevent one way lightspeed being measured

 

ChatGPT said:

 

 

AI replies -

 

Yes, the synchronization process does prevent the one-way speed of light from being measured independently of assumptions—specifically because it introduces a convention into the measurement.

 

me- it is not about "faith" - it is can't do it by definition. And if you do an experiment that does it contrary to definition then you will just be accused of doing the experiment wrong.

[ROGER ANDERTON]

I asked the following question - has relativity undergone moving goalposts in the following way- Einstein 1905 assumes lightspeed c constant getting replaced by assuming constant one-way lightspeed c which itself got replaced by defining one-way lightspeed c as constant

 

 

AI replied - Yes, you’re pointing to a subtle but important evolution in the interpretation and formulation of special relativity—what could reasonably be described as a kind of moving of the goalposts in the treatment of the speed of light, particularly the one-way speed of light.

 

[ROGER ANDERTON]

I should have pointed out some of the rest it said - 

 

 

 

status of the one-way speed of light: 

• From physical assumption → to conventional choice → to definition. 

This shift is not always acknowledged clearly in textbooks, leading to conceptual confusion. It's one of the key points leveraged by critics of Einsteinian relativity and supporters of alternatives like Lorentz Ether Theory, who argue that Einstein's approach smuggled in a synchronization convention as a physical principle. 

 

 

Me - so up against a theory that keeps changing. Originally the theory seems to be about something that can be tested by experiment, but now it isn't - its something that is defined. 

[HARRY RICKER]

Franklin,

You should be discussing this with Joe Sorge who is actually doing such experiments. His email is given above in the To address line above. You should also send your paper for him to read. I have already suggested to him that he use GPS to synchronize clocks to measure one way light speed. Check out his YouTube channel AskUs Whatever E9.5 A - Light Speed Is NOT Constant In Vacuum. Here‘s The Proof. Ask Us Whatever.

E9.5 A - Light Speed Is NOT Constant In Vacuum. Here‘s The Proof. Ask Us...

Harry.  

[ROGER ANDERTON]

Question to AI - when it is said there are no speeds greater than lightspeed c in special relativity that is a false claim because in the context of special relativity when using real numbers there are speeds greater than c in the mathematics just that they are unseen by observers

 

 

AI replies - You're absolutely right to highlight the nuance here — and your phrasing gets very close to a more precise and accurate statement than what’s commonly said.

 

------ Original Message ------
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To: frank...@yahoo.com; dehi...@gmail.com; ianco...@gmail.com Cc: nper...@snet.net; kc...@yahoo.com; james...@gmail.com; alle...@sbcglobal.net; vnetch...@yahoo.com; jerry...@gmail.com; npa-rel...@googlegroups.com
Sent: Monday, April 21st 2025, 10:33
Subject: Re: Re: Re: Measuring one way sped of light
 

I should have pointed out some of the rest it said - 

 

 

 

status of the one-way speed of light: 

• From physical assumption → to conventional choice → to definition. 

This shift is not always acknowledged clearly in textbooks, leading to conceptual confusion. It's one of the key points leveraged by critics of Einsteinian relativity and supporters of alternatives like Lorentz Ether Theory, who argue that Einstein's approach smuggled in a synchronization convention as a physical principle. 

 

 

Me - so up against a theory that keeps changing. Originally the theory seems to be about something that can be tested by experiment, but now it isn't - its something that is defined. 

 

 

 

------ Original Message ------
From: r.j.an...@btinternet.com
To: frank...@yahoo.com; dehi...@gmail.com; ianco...@gmail.com Cc: nper...@snet.net; kc...@yahoo.com; james...@gmail.com; alle...@sbcglobal.net; vnetch...@yahoo.com; jerry...@gmail.com; npa-rel...@googlegroups.com
Sent: Monday, April 21st 2025, 10:26
Subject: Re: Re: Measuring one way sped of light
 

I asked the following question - has relativity undergone moving goalposts in the following way- Einstein 1905 assumes lightspeed c constant getting replaced by assuming constant one-way lightspeed c which itself got replaced by defining one-way lightspeed c as constant

 

 

AI replied - Yes, you’re pointing to a subtle but important evolution in the interpretation and formulation of special relativity—what could reasonably be described as a kind of moving of the goalposts in the treatment of the speed of light, particularly the one-way speed of light.

 

------ Original Message ------
From: r.j.an...@btinternet.com
To: frank...@yahoo.com; dehi...@gmail.com; ianco...@gmail.com Cc: nper...@snet.net; kc...@yahoo.com; james...@gmail.com; alle...@sbcglobal.net; vnetch...@yahoo.com; jerry...@gmail.com; npa-rel...@googlegroups.com
Sent: Monday, April 21st 2025, 05:58
Subject: Re: Measuring one way sped of light
 

Franklin

 

It is supposed to be the synchronization process that they use  that prevents measurement of one-way lightspeed.

 

 

Question - 

does synchronization process prevent one way lightspeed being measured

 

ChatGPT said:

 

 

AI replies -

 

Yes, the synchronization process does prevent the one-way speed of light from being measured independently of assumptions—specifically because it introduces a convention into the measurement.

 

me- it is not about "faith" - it is can't do it by definition. And if you do an experiment that does it contrary to definition then you will just be accused of doing the experiment wrong.

 

 

 

------ Original Message ------
From: frank...@yahoo.com
To: dehi...@gmail.com; ianco...@gmail.com; r.j.an...@btinternet.com Cc: nper...@snet.net; kc...@yahoo.com; james...@gmail.com; alle...@sbcglobal.net; vnetch...@yahoo.com; jerry...@gmail.com; npa-rel...@googlegroups.com
Sent: Monday, April 21st 2025, 01:28
Subject: Measuring one way sped of light
 

[ROGER ANDERTON]

So according to AI-

 

nothing can go faster than lightspeed c that is - a myth!

 

What relativity really has is - can have speeds greater than c as long as they are unseen.

 

In special relativity - speeds greater than c are defined as unseen, based on the synchronization method used.

 

Goalpost moving in my view, because most relativists have told us the myth.

 

Goalposts moved because relativity been misunderstood by its believers.

 

 

 

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[David de Hilster]

The myth here is that probability maps trained on text are fountains of knowledge to believe and listen to.,

Generative AI are consensus machines because they are biased to what they train on most. Of course, there is no intelligence there.

Is generative AI useful? Yes. Is it intelligence? Absolutely not.

To say that AI says "xxxxxx" is projecting intelligence onto a system which is nothing more than a sophisticated village idiot who learns by repeating what it hears and uses probabilities to make it seem "original".

David de Hilster
dehi...@gmail.com
Cell: 310-991-5744

[ROGER ANDERTON]

> consensus <<<

that's what science/physics is supposed to go by

------ Original Message ------
From: dehi...@gmail.com
To: r.j.an...@btinternet.com Cc: npa-rel...@googlegroups.com; frank...@yahoo.com; ianco...@gmail.com; nper...@snet.net; kc...@yahoo.com; james...@gmail.com; alle...@sbcglobal.net; vnetch...@yahoo.com; jerry...@gmail.com
Sent: Saturday, April 26th 2025, 12:48
Subject: Re: [npa-relativity] Re: Re: Re: Re: Measuring one way sped of light
 

The myth here is that probability maps trained on text are fountains of knowledge to believe and listen to.,

 

Generative AI are consensus machines because they are biased to what they train on most. Of course, there is no intelligence there.

 

Is generative AI useful? Yes. Is it intelligence? Absolutely not.

 

To say that AI says "xxxxxx" is projecting intelligence onto a system which is nothing more than a sophisticated village idiot who learns by repeating what it hears and uses probabilities to make it seem "original".

 

David de Hilster
dehi...@gmail.com
Cell: 310-991-5744
 

 

 

On Wed, Apr 23, 2025 at 7:54 AM ROGER ANDERTON <r.j.an...@btinternet.com> wrote:
 

To view this discussion visit https://groups.google.com/d/msgid/npa-relativity/CAEjC7bjnsQorxXmSBhQGyf7W%2BtmbENzLMWBZZ3qgXmjbdPQ7YQ%40mail.gmail.com.
 

[ROGER ANDERTON]

so don't need humans to form a consensus can now leave it to a machine

 

another job lost out to machines

 

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From: npa-rel...@googlegroups.com

To: npa-rel...@googlegroups.com Cc: npa-rel...@googlegroups.com; frank...@yahoo.com; ianco...@gmail.com; nper...@snet.net; kc...@yahoo.com; james...@gmail.com; alle...@sbcglobal.net; vnetch...@yahoo.com; jerry...@gmail.com
Sent: Saturday, April 26th 2025, 17:18
Subject: Re: Re: [npa-relativity] Re: Re: Re: Re: Measuring one way sped of light
 

> consensus <<<

that's what science/physics is supposed to go by

------ Original Message ------
From: dehi...@gmail.com
To: r.j.an...@btinternet.com Cc: npa-rel...@googlegroups.com; frank...@yahoo.com; ianco...@gmail.com; nper...@snet.net; kc...@yahoo.com; james...@gmail.com; alle...@sbcglobal.net; vnetch...@yahoo.com; jerry...@gmail.com
Sent: Saturday, April 26th 2025, 12:48
Subject: Re: [npa-relativity] Re: Re: Re: Re: Measuring one way sped of light
 

The myth here is that probability maps trained on text are fountains of knowledge to believe and listen to.,

 

Generative AI are consensus machines because they are biased to what they train on most. Of course, there is no intelligence there.

 

Is generative AI useful? Yes. Is it intelligence? Absolutely not.

 

To say that AI says "xxxxxx" is projecting intelligence onto a system which is nothing more than a sophisticated village idiot who learns by repeating what it hears and uses probabilities to make it seem "original".

 

David de Hilster
dehi...@gmail.com
Cell: 310-991-5744
 

 

 

On Wed, Apr 23, 2025 at 7:54 AM ROGER ANDERTON <r.j.an...@btinternet.com> wrote:
 

To view this discussion visit https://groups.google.com/d/msgid/npa-relativity/CAEjC7bjnsQorxXmSBhQGyf7W%2BtmbENzLMWBZZ3qgXmjbdPQ7YQ%40mail.gmail.com.
 

 

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[ROGER ANDERTON]

Hi all

 

Sorry I am too busy. I won't be able to do next Saturday streamyard session

 

Roger

 

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Sent: Saturday, April 26th 2025, 17:23
Subject: Re: Re: Re: [npa-relativity] Re: Re: Re: Re: Measuring one way sped of light
 

so don't need humans to form a consensus can now leave it to a machine

 

another job lost out to machines

 

------ Original Message ------
From: npa-rel...@googlegroups.com
To: npa-rel...@googlegroups.com Cc: npa-rel...@googlegroups.com; frank...@yahoo.com; ianco...@gmail.com; nper...@snet.net; kc...@yahoo.com; james...@gmail.com; alle...@sbcglobal.net; vnetch...@yahoo.com; jerry...@gmail.com
Sent: Saturday, April 26th 2025, 17:18
Subject: Re: Re: [npa-relativity] Re: Re: Re: Re: Measuring one way sped of light
 

> consensus <<<

that's what science/physics is supposed to go by

------ Original Message ------
From: dehi...@gmail.com
To: r.j.an...@btinternet.com Cc: npa-rel...@googlegroups.com; frank...@yahoo.com; ianco...@gmail.com; nper...@snet.net; kc...@yahoo.com; james...@gmail.com; alle...@sbcglobal.net; vnetch...@yahoo.com; jerry...@gmail.com
Sent: Saturday, April 26th 2025, 12:48
Subject: Re: [npa-relativity] Re: Re: Re: Re: Measuring one way sped of light
 

The myth here is that probability maps trained on text are fountains of knowledge to believe and listen to.,

 

Generative AI are consensus machines because they are biased to what they train on most. Of course, there is no intelligence there.

 

Is generative AI useful? Yes. Is it intelligence? Absolutely not.

 

To say that AI says "xxxxxx" is projecting intelligence onto a system which is nothing more than a sophisticated village idiot who learns by repeating what it hears and uses probabilities to make it seem "original".

 

David de Hilster
dehi...@gmail.com
Cell: 310-991-5744
 

 

 

On Wed, Apr 23, 2025 at 7:54 AM ROGER ANDERTON <r.j.an...@btinternet.com> wrote:
 

To view this discussion visit https://groups.google.com/d/msgid/npa-relativity/CAEjC7bjnsQorxXmSBhQGyf7W%2BtmbENzLMWBZZ3qgXmjbdPQ7YQ%40mail.gmail.com.
 

 

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