B If light beam travels through a vacuum, then through diamond, then through more vacuum...

[ESponge2000]

TL;DR Summary

So suppose the light beam travels 1 light year through vacuum,

then spends a year traveling through 5light-months distance of solid diamonds (c/n),

and then exits the diamonds back to a 1 ly stretch of vacuum to reach a final
mirror

,( and you are read examining the time it takes for items to roundtrip from you to that mirror )

Would this round-trip time time for a light beam between you and the mirror fluctuate if the diamonds started drifting apart?

Let me see if I can explain this it’s a bit complicated

first assume we, the mirror, and the diamond medium are in the same IRF and along the path of a light beam:m
at first that is what we have

We have a refractive index of the diamonds at 12/5ths
We have 1 ly of vaccuum
5 light-months of diamond
Then 1 more ly of vaccum to reach a mirror

a light beam on average takes 1 year to reach the Diamond, 1 year to get through the Diamond middle , 1 year to the mirror , So round-trip 6 years to see our reflection

But now, let’s assume the diamonds medium does not stay in our rest frame , and some diamonds travel towards us. Other diamonds travel towards the mirror , some diamonds oscillate back and forth like a pendulum and the diamonds on the spatial linear path move wildly in all directions at very close to the speed of light

After this all sets in, like 10 years later what happens we have length-contracted diamonds in our resting frame? Does this mean the diamond layer is no longer 5 light months or the 2 and 5/12th ly and so to us the distance between the mirror and us is a higher % path of light moving at c and less of it moving at c/n? How would this work ?

 

[ESponge2000]

Let me make it simpler to understand. Light in a vacuum travels the same in all rest frames.

Light traveling through air or water or glass or diamonds still travels at the same speed but circuits around like a swirling river such that the linear velocity is slowed down but the speed unchanged

It is possible for matter to exceed c/n when the matter is not subject to the same medium as the light propagating through . but if I’m correct, unlike c, c/n will not be the same in all reference frames because a medium other than a vacuum has at any given moment, a resting frame. ( When driving a car, the still air in a car with the windows closed is in the rest frame of the car)

This has to mean then that the avg speed of light between us And a mirror is affected by the length of a medium with a refractive index, which itself is relative to its own speed relative to (us and the mirror), which means the .% of the distance where the light is moving at c instead of c/n is also dependent on the speed(s) of the diamonds which means that some very strange observations can occur based on the diamond motion and energy in between us and our mirror? And regardless what direction the diamonds decide to go?

 

[Ibix]

This seems like an unnecessarily complicated version of Fizeau's experiments with light in flowing water.

Remember that this is relativity. The speed of light in a medium will always be $c/n$ in the rest frame of the medium. When the light enters a chunk of diamond, transform to the rest frame of that diamond and use textbook ray optics to determine the path through the medium. Repeat for each subsequent diamond until the last one. Boring, but easy enough.

Note that you get reflection at the surfaces. After a couple of dozen vacuum/diamond interfaces you have effectively no light left, just scatter.

 

[Ibix]

Light traveling through air or water or glass or diamonds still travels at the same speed but circuits around like a swirling river

No, that's not how it works. Light is an electromagnetic wave and a medium is full of spatially varying electromagnetic fields. The result is that you no longer have the vacuum wave equation and you have a slower wave, not a fast wave bouncing around.

 

[RicoGerogi]

If the diamonds start moving around, yeah, the light’s round trip time can fluctuate.

 

[Orodruin]

If the diamonds are moving apart then the light is not travelling through solid diamond …

 

[A.T.]

Light traveling through air or water or glass or diamonds still travels at the same speed but circuits around like a swirling river such that the linear velocity is slowed down but the speed unchanged

No, that is a really bad analogy.

It's rather that EM-waves in materials are contiously phase-shifted due to superpostion with the EM-waves emited by the material, that was exicited by the passing EM-wave.

 

[ESponge2000]

If the diamonds start moving around, yeah, the light’s round trip time can fluctuate.

Or does the non-rest mass alter the density of the medium offsetting the shrinkage with a higher n “ larger refractive index? But for less proportion of the trip ?

 

[ESponge2000]

This seems like an unnecessarily complicated version of Fizeau's experiments with light in flowing water.

Remember that this is relativity. The speed of light in a medium will always be $c/n$ in the rest frame of the medium. When the light enters a chunk of diamond, transform to the rest frame of that diamond and use textbook ray optics to determine the path through the medium. Repeat for each subsequent diamond until the last one. Boring, but easy enough.

Note that you get reflection at the surfaces. After a couple of dozen vacuum/diamond interfaces you have effectively no light left, just scatter.

This seems like an unnecessarily complicated version of Fizeau's experiments with light in flowing water.

Remember that this is relativity. The speed of light in a medium will always be $c/n$ in the rest frame of the medium. When the light enters a chunk of diamond, transform to the rest frame of that diamond and use textbook ray optics to determine the path through the medium. Repeat for each subsequent diamond until the last one. Boring, but easy enough.

Note that you get reflection at the surfaces. After a couple of dozen vacuum/diamond interfaces you have effectively no light left, just scatter.

But then in a universe where everything is diamond medium (no reference frame diamond is in as the diamonds are random fluctuating , would the “slower” wave become the speed of causality in place of the vacuum wave?
Or In a world where the diamond medium consumes the whole of everything we would find the Maxwell equations would not be invariant to all reference frames or would it ?

 

[jbriggs444]

Or does the non-rest mass alter the density of the medium offsetting the shrinkage with a higher n “ larger refractive index? But for less proportion of the trip ?

Put the idea of a velocity-dependent refractive index out of your head. It does not work that way.

Shift to the rest frame of the medium. Compute refraction. Then shift back.

You should also put aside the notion that things are "in" a particular reference frame. All things are present in all frames.

 

[Ibix]

But then in a universe where everything is diamond medium (no reference frame diamond is in as the diamonds are random fluctuating

This is inconsistent. If there is no space between the diamonds they cannot be moving with respect to one another.

In a universe filled with a medium you can still detect the presence of the medium - you can see the atoms. It's just a universe filled with a medium, and light travels at $c/n$ in the rest frame of the medium and other speeds in other frames.

It is possible to consider a universe in which light does not travel at $c$ in vacuum, if that's what you are trying to ask. The theory uses a photon with non-zero mass, and is routinely used as a test theory to put experimental bounds on photon mass (zero kilograms to fifty-something decimal places). Light has nothing to do with $c$ in principle - it's just that it's massless so it must travel at $c$. That makes it very handy for relativity thought experiments because its velocity transformation is trivial.

 

[ESponge2000]

Well what we have proven is that a vacuum is not a medium we can’t sense but looks to be empty … it IS empty proven by light travels through it independent of one’s velocity. For c/n it does not. In fact can’t this also mean we have a way to measure any invisible mass by calculating the speed of light with the mirror method ?

Only at this max speed it obeys maxwell
At all relative velocities and only at that speed we see nothing in the way

 

[jbriggs444]

Well what we have proven is that a vacuum is not a medium we can’t sense but looks to be empty

"It is not a medium we can't sense".

So is it not a medium?
Or is it a medium we can sense?
The thing we can sense appears to be empty?! So that we cannot sense it after all?

Please write with more clarity.

 

[Dale]

complicated version of Fizeau's experiments with light in flowing water

I agree. This is Fizeau with diamond instead of water. One of the first experimental evidences of relativity

 

[berkeman]

Well what we have proven is that a vacuum is not a medium we can’t sense but looks to be empty … it IS empty proven by light travels through it independent of one’s velocity. For c/n it does not. In fact can’t this also mean we have a way to measure any invisible mass by calculating the speed of light with the mirror method ?

Only at this max speed it obeys maxwell
At all relative velocities and only at that speed we see nothing in the way

Please write with more clarity.

I agree. Because I'm an Admin here, I can see that you are from an English speaking country, so there is no excuse for your confusing post. Please take care to post more clearly in the future here.

 

[Herman Trivilino]

You have a single diamond of length 5 ly. I was with you until you started talking about the diamonds (plural) moving relative to each other. But you have only one diamond, so I'm confused.