Medium entrainment considered as flow

<b>[Bart] "On the topic of "planetary displacement angle" and "stellar displacement angle".
Using the word 'drift' to explain the effect suggests that light would bend along with the direction of increased medium velocity. But the observed effect is the opposite: light bends towards the direction where the medium velocity is higher."</b>

To preclude any misunderstanding I will describe the phemomenon of drift more precisely. I'll use a sound analogy.

There are four hill tops, three in row about three sound-seconds apart and one off to the side about fifteen-sound seconds away.

I pick one of the three closer hill tops to send a signal (a firecracker). You must sit on the lone, far away hill top and decide where I was.

You hear the pop and are convinced that it came from the right most hill top. There is a very fast wind blowing through the hills, but you do not know it because your hill top is higher than mine, where the air is still.

I was actually on the middle hill top. As the sound waves from my firecracker crossed the valley between us they were blown to your right by the wind. Enough that when they arrived they seemed to be comming from the right most hill top.

You are experiencing an angular displacement in your obsevation, caused by medium drift.

We may not be sure that light travels as a wave within a medium, but we are posiive that sound does. And for sound, this medium drift effect is very real.

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An actual flow boundary between parts of the medium between us is not necessary. Suppose the wind extends upward to an altitude that is also above your hill top. Nothing changes, except now you can detect the wind and understand why the sound waves seem to come from the right most hill top, instead of where they actually came from.

If such a boundary did exist it could certainly alter a wave passing through it. But that is really not what the medium drift effect is all about. In looking back through some of my recent writings on this topic I see that I may have suggested the boundary played more of a role than it does. My apology.

LB

The "four hill top" analogy indeed explains the effect of medium drift.

But considering the effect of 'stellar aberration' : the light appears ahead of the direction the observer (and surrounding medium) is moving towards. It would be the same as hearing the sound as it came from the left most hill top (while being on the middle).

Medium particles (light carrying / gravition):
- I assume they are much, much smaller then the known particles
- I assume the known particles are (at least partially) build of medium particles
- Therefore, I assume that the medium particles are very close to each other
- A photon is not a particle a such but the combined momentum contained in many medium particles.
gsjournal.net/Science-Journals/Essays/View/1870

Entrainment is what was investigated through the Gravity Probe B experiment (validating Einsteins theory)
einstein.stanford.edu/SPACETIME/spacetime4.html
Although the effect is real it looks to be a very weak.

The Michelson Gale experiment paper:
gsjournal.net/Science-Journals/Essays/View/2582

<b>[Bart] "On the topic of "planetary displacement angle" and "stellar displacement angle".
Using the word 'drift' to explain the effect suggests that light would <u>bend along with the direction of increased medium velocity</u>.

But the observed effect is the opposite: light <u>bends towards the direction where the medium velocity is higher</u>.</b>

Perhaps I am misunderstanding you, but it seems that you have said the same thing twice.


<b>[Bart]"... the light appears ahead of the direction the observer (and surrounding medium) is moving towards. It would be the <u>same as hearing the sound as it came from the left most hill top</u> ..."</b>

Again I'm not following you. It seems like you would expect the sound waves to drift up-wind as they move across the valley toward you. Or, perhaps you are saying that <u>you think I am saying</u> they drift up-wind?

<ul>
<li>Waves propagating in a medium drift down-wind.</li>
<li>If down-wind is perpendicular to the line between you and the source, the source will appear to be down-wind of where it actually is.</li>
<li>If down-wind is parallel to the line between you and the source, the source will appear to be either closer or farther away than it actually is.</li></ul>

Note that if the source is also moving, that motion can be, and in general is, independent of any motion of the medium.

LB

Some additional thoughts.

If we look at a star or a planet or a moon, and we see it to the left of where we expect to see it, after correcting for things like propagation delay and our own motion (aberration), then we can infer that there is a medium between us and that this medium is drifting to the left.

There is more medium between us and a star than between us and a planet or moon. So the amount and direction of any medium drift for the star can be different than for the planet/moon. Even if they are visually right next to each other.

Without an accurate mental picure of how things like drift, drag and aberration can alter what we see, it would be very hard to look at an observational anomaly and understand what it means.

LB

<b>[Bart]"... the light appears ahead of the direction the observer (and surrounding medium) is moving towards. It would be the same as hearing the sound as it came from the left most hill top ..."</b>

One more possible source of misunderstanding. You talk of "observer motion" here. In my analogy, only the medium has motion. All four hill tops are stationary.

Note in particular that since neither the source nor the observer are moving,

edit*****
(more precisely, since they all have the same velocity)
/edit****

the aberation angle MUST be zero. All of the observed displacement angle must have some other cause or causes. In the modified analogy, where the wind is blowing past both of our hill tops, we will both suspect medium drift as that cause.

LB

<b>[Bart]"
Medium particles (light carrying / gravition):
- I assume they are much, much smaller then the known particles"</b>

That is our assumption as well.

<b>- I assume the known particles are (at least partially) build of medium particles</b>

Hmmm. It is not an unreasonable assumption, but there is no data to support or refute it now. Since "stuff" is infinitely divisible, we feel fairly jusified in assuming that both normal sized mater and these medium particles are made of the same (much smaller than both) stuff.

<b>- Therefore, I assume that the medium particles are very close to each other</b>

Another reasonable assumption. Again, no data either way. Consider, however, that "close to" is entirely relative.
<ul>
<li>Stars in a galaxy are "close to" each other, compared to the separation between galaxies.</li>
<li> Atoms in a glass of water are "close to" each other relative to stars in a galaxy.</li></ul>

The atoms (molecules, actually) in the glass are closER than the stars in the galaxy, simply because atoms are smaller than stars.

But they are also closER if you compare particle size with same-particle separation.

Using this as my standard for judging closeness, and some other things I have not yet shared, I predict that the average particle separation in the light carying medium will turn out to be very large compared to the average particle diameter. As I mentioned earlier I believe they repel each other (rather strongly).

Of course, from our human sized perspective my "not close" description seems to be wrong. Turns out it is and it isn't.

The particles might be separated by a million particle diameters, but if the diameter of a particle is 10^-12 meters, the particle to particle separation is only a micrometer.

To us this is a tight crowd. To them it is lonely isolation.

<b>- A photon is not a particle a such but the combined momentum contained in many medium particles."</b>

This is a decent physical description of a wave. Thanks.