Invariance of Light

Well, you guys are sure in the deep doo-doo now. I have not gone there and instead have been playing with the model proposed at the beginning of tthis thread. There is a lot of very interesting information that can be amassed from this model of Jan's. For one thing both receivers are getting redshifted signals from each other even though the sent signal was blue shifted from one of them. And both receivers get the signal at very different times but there is no way for either of the receivers to know any of this so both have a misconception about the time and distance.

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[TVF] : Aberration is a consequence of relative motion, period. Ordinary (angular) aberration requires a tangential (transverse) component of motion, as distinct from radial or normal (meaning perpendicular out-of-plane) motion.

See Figure 3 in www.metaresearch.org/cosmology/speed_of_gravity.asp
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From what I understand of the link you posted is that aberration is caused by transit delay. So in the case of the laser on the border of the rotating platform, the observer in the centre will not see the actual position of the laser, only its retarded position, which is dependent on the angular speed "w". You use the same reasoning for the Sun, that is, we only see the Sun where it was 8.3 minutes ago. To come back to the platform, the aberration is clear to me, however, what is not yet clear is the following. When the platform is at rest, the laser is perfectly aligned and rigidly attached as to hit a target in the centre of the platform. Thus, the direction of the laser exit is absolutely "fixed" and points towards the centre. I understand that there is propagation delay, but I have some difficulty seeing why the centre is not being hit as soon as the platform rotates with a uniform speed. The only way I can come to terms with this is when I view the laser pulse to be a particle and contruct the resultant velocity vector, composed of the tangential component and the radial component, which equals the emission speed of the laser. From this point of view, the laser pulse is dependent on the velocity of the source with respect to the observer in the platform's centre. This is slightly confusing when considering a wave front coming from the instantaneous position of the laser, that is, the wave should be independent of the laser's motion. Thus, we cannot view this problem as an instantaneous "snapshot" and argue that the pulse is perfectly traveling along the radius to the target?

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>[Jan]: the observer in the centre will not see the actual position of the laser, only its retarded position, which is dependent on the angular speed "w".<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

A small correction: It is dependent on the linear speed v. Angular speed is irrelevant. Aberration is v/V, where V is the propagation speed of the laser (or projectile, or whatever).

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>I have some difficulty seeing why the centre is not being hit as soon as the platform rotates with a uniform speed.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

That can only be a problem if you regard the motion on the platform as absolute motion. If instead you regard the motion as relative, then the center sees the retarded position of the rim, and the rim sees the retarded position of the center. Every point regards itself as at rest.

Forget the connection between rim and center. The laser sees a center traveling past relative to a starry background. If the laser hopes to hit the moving center, it had better aim ahead of the center for the same reason a hunter must aim ahead of a flying duck.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>The only way I can come to terms with this is when I view the laser pulse to be a particle<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

For aberration purposes, there is absolutely no difference between waves and particles.

Don't think of aiming the laser at the center. Think of aiming it at a star behind the center. After the rim moves a bit, the laser beam must still be traveling toward the same star, even though the rim is no longer in the same direction as the star. -|Tom|-

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[tvf]
Reply to LB:

In the first 150 years of trying, no one could find an experiment that could distinguish aether from non-aether beyond the original evidence that light had all the known properties of waves and therefore had to have a medium to "wave".

Then it was argued that such an experiment was impossible in the light-speed & slower domain. [AJP 41, 1068-1077 (1973), "The rod contraction-clock retardation ether theory and the special theory of relativity" by Herman Erlichson.] He concluded that:
(1) no experimental difference, predicted or realized, yet exists between the Lorentzian “ether” form of relativity and Einstein’s special relativity.
(2) The only possible experimental difference between the two theories may lie in a one-way experiment that is not a direct measurement of the speed of light.
(3) It may be that no experimental difference is possible.

The elimination of one-way experiments as candidates (because of clock synchronization requiring an assumption about light-speed), and the failure for all the people in the world (thinking hard about how to do this) to come up with an experiment, has convinced me and others that no such experiment is possible. But you are welcome to keep trying. If you succeeded, it wouldn't be the first time that something thought impossible was done. <img src=icon_smile_shock.gif border=0 align=middle> -|Tom|-
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It's difficult for me to imagine that it could really be any other way. But without that "central repository" I wished for earlier there is always room to imagine that your idea hasn't been tried yet.

Are Dr Erlichson's three conclusions generally acknowledged and accepted by the physics community? I believe that my idea might fit into category two. But I can see I've got a lot more studying and thinking to do to make it presentable.

Regards,
LB

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Like so much of past physics, these conclusions are unchallenged but little known. It seems every generation starts from scratch and must re-invent the wheel. -|Tom|-

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[TVF]: A small correction: It is dependent on the linear speed v. Angular speed is irrelevant. Aberration is v/V, where V is the propagation speed of the laser (or projectile, or whatever).
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So you say that the instantaneous tangential (linear) velocity, "v", of the laser pulse should not be associated with an inducing angular speed "w"? So we can't simply equate "rw/V" to describe the aberration, where V is the pulse speed, "r" is the radius, and "w" the angular speed?

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[TVF]: That can only be a problem if you regard the motion on the platform as absolute motion.
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Of course, you are right! Why didn't I noticed this before? I "naturally" took the centre as being an absolute reference and didn't give it any other thought. I pictured a fictious medium around the centre, which again shows that I'm still in the phase of "wanting" a light transmitting medium. Having a medium for light is such a natural concept that light without medium is like sound without air. It will take a while to "divorce" myself from wanting a nurturing ocean of infinite space that is the cradle for all that exists.