Speed of Light

No.. pretty tricky to get clocks synchronized at great distances....

https://physics.stackexchange.com/questions/205656/is-there-any-way-to-measure-the-one-way-speed-of-light#:~:text=It%20is%20hardly%20possible%20to,at%20the%20point%20of%20arrival.

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Yes, it has been measured this way.

Veritassium has a really interesting video on this.

https://www.youtube.com/watch?v=pTn6Ewhb27k

From what I've read and seen on the internet, it is not possible.

But I'm wondering how a GPS receiver could calculate accurate position if the speed of light were different in different directions. Each GPS satellite has an accurate clock and sends out a signal which can be compared with the signals from other satellites, and the receiver calculates the difference in travel times. The signals from 4 satellites are required to specify a position in 3D space. (More than 4 satellites are generally used and the resultant positions averaged to get a more accurate answer.)

It would seem to me, since the satellites move around, that there would be some measurable error that could be correlated with satellite positions to indicate a non-isotropic speed of light.

Put a modulated laser and fast photodetector on a sliding track with the same cable lengths to an oscilloscope and measure the phase time as the two are separated.

I think the problem with that is that if the speed of light varied in different directions, then the delay in the coax from your receiver to the oscilloscope would vary as you moved the receiver down the track. If the speed of light varied with direction in free space, then it would also vary in a coaxial cable.

Measuring the transmit and receive signal with an oscilloscope (bringing the transmit and receive signals together) is not any different than reflecting the light from a mirror.

But the signal propagating down the coaxial cables are slower than the speed of light (in a vacuum) and not transmitted by light. The signal velocity in those cables are dominated by the transmission line velocity factor. It is easy to demonstrate in a coaxial cable using time domain reflectometry that the transit time of the signal in each direction is identical. Thus the orientation of these cables are superfluous.

The point of my proposal is one varies only the distance that the photons travel from laser to detector. All other delays from cable lengths to detector remain constant.

I assume "speed of light" refers to any electromagnetic radiation.

The Velocity Factor (VF) of the coax is due to the permittivity of the dielectric which is greater than the permittivity of free space. So propagation velocity through the cable (c_eff) should be VF times the speed of light along the cable's path.

κ = ε/ε₀ > 1.

v=VF x c_eff

TDR measurement on the cables is a two-way delay and wouldn't detect whether the speed were different in each direction.

You seem to be making the assumption that signals in a coaxial transmission line propagate by photons. My reference textbook show that the electric and magnetic field lines that concentrically and radially align within the dielectric media between conductors form the signal. For a lossy transmission line the resistance of the conductors and the conduction of the dielectric material must be added to the equations. My point here is that while the reference maximum velocity of light in a vacuum is certainly part of the equations for coaxial transmission lines the mechanism of this signal motion is electrons not photons. (Who uses whale oil anymore and what species?) The speed, c₀, is an asymptotic limit for things with a rest mass (electrons) those electrons cannot reach this velocity. While things without a rest mass (photons) only exist at the speed of light for that media it travels in. By varying only the travel distance that photons travel in one direction my proposal can measure the speed of light in one direction.

There is another point in this discussion that should be mentioned. For the proposal that an asymmetric signal velocity of light (radio transmission) could occur means that an asymmetric value for the magnetic and/or electric permittivity must exist. This has never been observed.

Read the links from Mikey and me above.It explains the difficulty of synchronizing clocks at a distance.

A train station supervisor,in the 1890's would set his watch every day at noon and blow the whistle at exactly 12 o'clock.

At 5 till noon,he would call the operator and verify the time and,and make corrections to his watch if necessary.

20 years later,the two met at a cafe,and the conductor thanked the operator for keeping his watch on time all those years.

She acted surprised.

He asked why she was so shocked.

She said she had been using the train station whistle to set her clock.

...an asymmetric value for the magnetic and/or electric permittivity must exist.

That's a very good point, as long as the speed of light is not used in measuring these.

Hopefully I'm not beating a dead horse here but to me, my proposal to measure the one way speed of light seems an obvious solution. At the same time, this is supposedly a century old outstanding conundrum. My gut and respect for the myriad of those minds smarter than me says I have to be overlooking something but my head just cannot see where.

I do have a final, critical point I wish to add. The distance varying photonic signal path carries photons (pulsed or intensity modulated) moving only in one direction, the direction of the signal path. The fixed distance electronic signal path (always using the same coaxial cables) carries electrons moving in both directions of with and opposite the signal path direction, simultaneously. The electronic timing signal will be slower than the photonic signal but that added delay will be constant so long as the same cable is used for each measurement.

So where did I get confused?

Or should I search for a research grant?

My thinking is it is not electrons going down the coax cable, but electromagnetic radiation, Maxwell's equations with the boundary conditions of center conductor, outer sheath conductor, and dielectric. (Electrons in a conductor hardly move at all, even at very low frequencies, e.g. 60 Hz.)

If light propagation velocity were different in opposite directions, I don't think you could rule out different velocity in the coax in different directions.

Your idea of permittivity and permeability is interesting. You have variable permittivity in a piece of stressed plastic that causes interference effects in polarized light. If free space permittivity (or permeability) were variable, would we see some similar phenomenon?

Here's another idea. If you reflect a beam of light, you should have a standing wave where the two beams add and subtract. If the reflected beam is moving at a different speed, you should see a different pattern of interference, a beat pattern, because the frequency would be the same but the wavelength would be different. Just a thought...

I think we all agree that variable speed of light is highly improbable. The question is can we prove it.

Just my thoughts...

A virtual photon does propagate in the dielectric at a velocity less than the velocity of free space (vacuum). You glossed over the critical point, this all happens due to boundary conditions between the conductors. It is the geometry and characteristics of the cable that establishes this boundary condition. Thus it is the cable selection that establishes this lower propagation velocity and the fixed cable length by using the same cable that makes a fixed total delay regardless of cable orientation.

I want to emphasize that a virtual photon travels in the dielectric. I mean virtual in that the existing boundary conditions of the cable allow for this photon to exist at all. When an air dielectric cable (ε=ε₀ and μ=μ₀) abruptly ends at free space the photon(s) do not now exit the region between conductors to propagate into free space. The photon is reflected back into the coaxial cable where suitable boundary conditions exist for the photon. It is the boundary conditions of the cable that allow for this virtual photon.

This virtual photon does "wiggle" electrons forward and back as it propagates down the cable. This is why in a real, lossy cable equation analysis the unit length conductor resistance and dielectric conductance values are included.

Yes, it me again.

If there were a difference in propagation velocities depending on forward or reverse signals in a coaxial cable then standing waves from a reflected signal could not occur for the frequencies of the two signals would never match.

If the propagation velocity were different in opposite directions, a reflected signal would have the same frequency but different wavelength.

λ = v/f

Adding the original and reflected signal, you get a beat signal which doesn't vary in time, only in position as illustrated below:

Since we don't see this beat frequency, it would seem to prove that the velocity is the same in both directions, that the 1-way velocity is the same as the 2-way velocity.

Therefore the coaxial cable does provide a fixed time delay. The one way speed of light has been measured.

This is far beyond my pay grade.

You guys can argue with A.E. if you wish.

If my reasoning is sound...It's hard to prove something we consider obvious (e.g. 1-way c = 2-way c) avoiding assumptions that follow from what we're trying to prove. Circular reasoning is insidious.

a few years ago, I have read that there was an experiment that did this, by having the light focused through a medium (I believe it was a gas medium) that slowed down the speed of light, where the light actual travel was slowed down and was able to be picked up the actually travel of light through the medium with high speed CCD cameras.

I have looked for a link of this experiment, and I haven’t found it as of yet.

Found video of this experiment... pretty cool.

Here is a link that explains my point rather well:

https://phys.org/news/2021-01-there-no-way-to-measure.html

Nice article. Pretty much the same point made in the link in my earlier post.

Reality,and all measurements,is subjective and an illusion.

We all exist within our own subjective reality.We cannot escape it,try as we may.

So don't worry..be happy.!

Hakuna Matata!

Should that not have been:

Reality is, and all measurements are, subjective ...

No it shouldn't..

It is correct as written.

Go back 10 spaces. Do not collect $300.

Repeat English 101.

Outline (diagram) the sentence.

Fer shure, fer shure, thar Jethro, wahtevah yew aul say...

...an juss haud yew aul suhg jess othas goe 'bout doin thet measurin thang yew been duin awl thet ahskin 'bout, ahnyhoo?...

IMHO:

If I wished to offend you,I would say:

It is not my responsibility to educate the pitiful pismires in this world.

At least you speak fluent Appalachian without an accent.

Not a single error,but then again,I could be wrong;I am not a pedantic,didactic person,and I can ignore minor discrepancies.

It seems to come naturally to you.Who are you trying to fool?

Come on,fess up!

I still don't think you can diagram a sentence.

And it does not matter,unless it is for an elementary English exam.

But I will not say that,as I do not wish to offend you.

One thing still ''is'', while two things still ''are''...

It's hard to pin down light, because light is a flux, and the results that you measure, will be average results.

If you want to see and measure the relative velocity of EM radiation, (and light has this just like the motion of mass, except it is expressed in a different form)....... use a low frequency radio wave, and emit one wave at a time. Can you emit one wave from a dipole?

Then you will measure in the proper manner, and see that Einstein was correct........EM radiation is discreet and intermittent, coming from an instant emission event. The propagation, without relative velocity.....has a 50% duty cycle. The duty cycle not only tells you the relative velocity between emitter and absorber.......but tells you how much of that relative velocity belongs to the emitter and how much belongs to the absorber. Emitter v causes a phase change at the absorber(allowing a plot of emitter v) and the absorber v causes a frequency change(allowing a plot of absorber v). Could you use such a tool?

With our current switching rates, we can see this on low frequency radio. We need higher switching rates to see this with light. And the need for a ONE RAY filter.

OLD Classical Science......answered the mystery of light and mass,100 years ago. Parson's Magneton 1917. This model shows how an instant event physically occurs.

AND after you see this, you will know that time and length are omnipresent.
Now, can modern science and engineering figure out, how to emit one wave from a dipole?

Feed-lines and antennas are NOT conventional circuits. In regular electrical and electronic circuits, the current is pushed and pulled by TWO poles.

Feed-lines and antennas are ONE pole currents. In one pole currents(polarization current)......the current is 180 degrees out of phase.

In normal circuits, the negative electron flow, is from negative to positive pole. In polarization currents, the negative electron flow is from the positive to the negative. It flows backwards.

At the end of a positive excitation to an element, the voltage at the end of that element......is 2 times the excitation voltage. To acquire that voltage, the negative electron flow......has to flow away from the positive pole. That's what makes it positive. That dynamic is 180 degrees out, compared to conventional flow.

This 180 degree out of phase.......is what allows the instant dislocation of the antenna current, which separates the emission field from the current field. The emission is a snap.....a strobe. For every 360 degree input to feedpoint, two strobes are emitted. One instant emission for every 180 input. That dislocation and emission leaves the element neutral for the next input.

Feed-lines are like polarization charge boxes. Dipoles(1/4 WL element) are anti-resonant.....and break the field.......when the voltage at the tip is max.

A string of charge makes a field.......an instant jerk or dis-location, breaks that field from the charge.....and the field propagates away. The velocity of that charge field is c and is radial......when it breaks.....the field goes linear.....with the c velocity.

Emission.

I don't understand why you say antennas and feed lines (transmission lines) are not conventional circuits. Look into Oliver Heaviside's brilliant work in transcribing Maxwell's electromagnetic theories. In particular look at his telegrapher's equations that describe transmission line theory. Yes, the old telegraph that first broad commercial use of electricity.

What amazes me is this theoretical work came years before the invention of the Crookes tube into a functioning oscilloscope that can allow for measuring voltages faster than an analog needle can move.

"I don't understand why you say antennas and feed lines (transmission lines) are not conventional circuits. Look into Oliver Heaviside's brilliant work in transcribing Maxwell's electromagnetic theories. In particular look at his telegrapher's equations that describe transmission line theory. Yes, the old telegraph that first broad commercial use of electricity."

I have. I did. For many years. Then several years back I saw ferrofluids. And that gave me the true mechanical understanding of current phase shift. After all these years.

Phase shift comes from current spin. Giving the current a longer distance then voltage. You can now see the motion and direction of the electric and magnetic fields with ferrofluids. If you have the experience and discernment. Where is that in the equation?

And then I saw a moon flying thru volcanic debris. And the spinning, helical orbit it truly has. After centuries of preaching elliptics. That alone, kills all G equations.

This led to a review of all the physics I had been taught.....which led me to the Parson's Magneton.

That updated model.....explains everything together in the proper manner and proportion. That dynamic explains all. It fits. It's solid. No mystery.

With omnipresent time and length.