Requiem for Relativity

Suppose you use a rocket to hover motionless above the surface of Sol, adjust your altitude to be 1 AU, and wait for Earth to fly past you.

As it does you and another observer (on Earth) take simultaneous measurements of the aberration of light from the same star. He gets a value of 20" (because of his tangental speed), you get a value of 0" (because of your tangental speed). Whether there is a light carrying medium or not.

Aberration does not occur in space or in the telescope tube. It occurs in your eyeball. Or in your CCD camera.

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Suppose there is an LCM, and parts of it are rotating with Sol and other parts of it are co-moving with the planets. The observer on the rocket is then probably not going to get a reading of exacty zero.

This, it seems to me, is the effect we need to be wondering about. A variation in observed aberration that is not a result of " ... just the velocity of the observer relative to the direction of where the light is coming from."

Supose we observe (from near Earth's equator) a star nearly overhead at midnight, and another nearly overhead at noon. And suppose there is an LCM. Light from the first star will be carried sideways, in one direction only, by the orbiting LCM, causing a small change in the direction it comes from. (This is a physical change in direction, whereas aberration is an apparent change in direction, but both require us to adjust our telescope a little.)

Light from the second star will be carried sideways first in one direction, then in the opposite direction, causing two small changes in the direction it comes from. Since these two changes are of opposite sign, they will tend to cancel. But they are not likely to be the same magnitude so they are not likely to cancel to zero.

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If we assume that the LCM near the ecliptic is moving at the same speed as each planet at any given distance from Sol (even if that planet is presently on the other side of Sol), it ought to be possible to estimate the magnitude of this "drift effect". Then it ought to be possible to estimate how precise our observations must be, in order to detect this effect.

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I suspect that this effect is too small to be detectable right now. But I'm not familliar with how aberration is measured by astronomers, so I could be wrong. There are a number of unknowns involved as well, such as how far out Sol's statically entrained LCM bubble extends (probably not way-far beyond Neptune/Pluto), and what happens at the transition zone between static entrainment and dynamic entrainment (probably similar to turbulence, in some ways, but not in other ways).

I still owe you a more accurate and complete discussion of my thoughts about the physical nature of the elyson particle field, so you can better understand some of my conclusions.

On the topic of stellar aberration, you may want to read how James Bradley measured the effect (while in search for the effect of parallax) gsjournal.net/Science-Journals/Essays/View/2441 .

An eyeball or CCD Camera has a lens and a sensor which are physically separated from each other.
As such, these are the equivalent of a telescope tube.

Once the light hits the sensor, the light hits a different place then what you would expect without aberration.
So aberration must occur before hitting the sensor.

If it did, the observer in the hovering rocket would get the same reading as the observer right next to him on the orbiting planet.

<b>[Bart] "An eyeball or CCD Camera has a lens and a sensor which are physically separated from each other.
As such, these are the equivalent of a telescope tube."</b>

OK, I'll concede the point. Thank you.

Aberration is an APPARENT change in the direction of a particle or wave caused by the motion of the observer. In the case of a particle it can exist whether or not the particle travels through a medium of some sort.

Aberration occurs at the point of observation. A single particle or wave, observed by three different observers in mutual relative motion, can simultaneously have three different aberration values.

<ul>EDIT -

A single particle or wave, observed by three different observers in mutual relative motion, MUST simultaneously have three different aberration values. </ul>
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The phenomenon you are talking about - a phenomenon that also changes the angle of arrival of a light beam, <u>but that occurs out in space</u> - is independent from the phenomenon of aberration.

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This other phenomenon, a drift phenomenon, is a PHYSICALLY REAL change in the arrival direction of a particle or wave caused by the motion of a physically real medium through which the particle or wave has traveled or propagated.

Our three observers in mutual motion will all measure the same drift angle, after each corrects for his (ususally larger) individual aberration angle.

"Aberration is an APPARENT change in the direction of a particle or wave caused by the motion of the observer. "

I understand that this is how stellar aberration described, but this description does not explain the following paradox:

Suppose a star is just behind the border of the moon and that the magnitude and direction of stellar aberration are as such that the star appears right next to the moon: how can a star (that is supposed to be obscured) become visible through a local (apparent) effect?

Instead of using the moon as a reference object, one could observe stars passing behind an object on a mountain.
The object on the mountain is not subject to stellar aberration wheras the stars passing behind are.
The effect of stellar aberration does not cause stars to be displayed on top of the object.
Rather: the stars are visible/invisible based on their apparent direction relative to the object (on not based on their true direction).
This effect can only be explained if the aberration takes place before reaching the object and goes hand-in-hand with a true physical displacement.

I agree that the observers travelling in mutual relative motion must observe different aberration values ...
An observer on Earth would measure the drift angle while the other observers would need to correct for their relative motion.
The Earth and the Moon are both 'static' relative to surrounding medium and that's why observers on both of them see each other without aberration.

<b>[Bart] "Suppose a star is just behind the border of the moon and that the magnitude and direction of stellar aberration are as such that the star appears right next to the moon: how can a star (that is supposed to be obscured) become visible through a local (apparent) effect?"</b>

Our imaginations frequently fail us, but let me give this another try.

I'll use our three observers (A, B and C) again, but this time all three are in rockets. This change is not needed, but perhaps it will make a diference in how the example is processed in your mind?

All three are observing the light arriving from star S.

A is still hovering above Sol, stationary with respect to the incoming light beam.

B (who was previously our observer on Earth) is now orbiting Sol in a ship at one AU, with speed of 30 kps perpendicular to the incoming beam from S, in the same direction as Earth orbits.

C (who was previously not described in much detail) is now orbiting Sol in a ship at one AU, with speed of 30 kps perpendicular to the incoming beam from S, in the opposite direction as Earth orbits.

A sees the beam moving radially inward toward Sol (aberration angle = zero)
B sees the beam moving in at an angle from in front of him (aberration angle = +X)
C also sees the beam moving in at an angle from in front of him (but remember he is in retrograde orbit, so aberration angle = -X)


The orbits are timed so that B and C pass closest to A at the same instant, as shown above in Fig 1.

(
I'm trying to inject a little bit of a 3-D effect into my artwork. None of my coordinate axes are shown in either drawing, so I will describe them for you.

(A is at the origin of my coordinate system. )

The X axis passes through A and extends horizontally to the left and right.

The Y axis passes through A, but it slants up/left so that it also passes through B and down/right so that it also passes through C.

The Z axis passes through A, extending vertically up and down, and is the path followed by the light beam from S to A (shown by the vertial dashed line).

The diagonal dashed line from B to S_b is that same beam, seen from B's moving frame.
The diagonal dashed line from C to S_c is that same beam, seen from C's moving frame.
)

Even though all three observers are observing the same star from the same place at the same time, aberration causes each to see the star S at a different position in the sky.

Aberration does not change the path of the light beam (so the direction change is apparent, not physical), but it does require the observer to point his telescope in a different direction (so the aiming change is physical, not apparent).

Aberration has both apparent and physical effects.

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Let there be an occultation event:

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Earth and Luna are somewhere else in their orbits, so to create an occultation event I will suddenly invoke a fourth rocket, O, moving between the observers and the star with a speed of 31 kps (1 kps faster than perpendicular to the incoming beam from S, in the same direction as Earth orbits. (O is large relative to the distance between the observers and about 400,000 km from them, meaning that parallax can be neglected as a source of timing difference among the observations.)


At the instant when the leading edge of O blocks the light beam for A, observer B (simulating the Earth based observer from the previous version of this example) can still see the beam and observer C (who actually observed the occultation event begin a bit earlier) is just now seeing S re-appear on the back side of O

FIG 2 is an attempt to depict this new situation.

(I could have chosen the size of O to be larger, in which case C would still not be able to see S at the time A first observes occultation. And so on.)