Re: observers in physics



Timo Nieminen wrote:
> On Tue, 20 Jun 2005, jgreenfield@xxxxxxxxxxx wrote:
>
> > In all the "explanations" of how SR is proposed to work, both for time
> > and length alterations, there is NEVER a situation where the
> > "observer", ie he that is noting the effect under discussion, EVER
> > recieves information directly;
> > the whole explanation is what he WOULD SEE, and the entire scenario
> > must be taken on FAITH.
> > How many of the diagrams, from which the "math" evolves, include a
> > light ray which actually impinges on the observer's eye????????????
> > None!...... and when the observer was placed in the correct position to
> > actually "see" what was occurring, he would NOT notice either length
> > contraction or time change, due to velocity.
>
> If you're prepared to learn something, you might want to read:
>
> Robert J. Deissler, The appearance, apparent speed, and removal of
> optical effects for relativistically moving objects, Am. J. Phys. 73(7),
> 663-669 (2005)
>
> The references given in the paper, btw, refute your claim of "NEVER".
>
> For the casual reader:
> Most treatments of special relativity and Lorentz transformations do not
> consider an observer - ie somebody who looks and sees - usually only a
> coordinate system is considered. To make matters worse, the coordinate
> system is sometimes called an "observer". The relativistic effects (length
> contraction, time dilation) are 2nd order in v/c, while the optical
> effects due to an observer looking and having to wait for the light to
> arrive are 1st order.
>
> --
> Timo

Sam W, Al S, Bjoern F, and sundry other supporters of SR seem to
disagree with you. What other interpretation is there to "appears
shortened due to velocity"? As the math and ideaology of the scenario
of a fast moving object which suffers such shortening depend on ONE
AXIS only, any observer, real or imagined, can ONLY be cognizant of the
effect if he is directly on that axis. In other words, he sees the
front or back of the object under view, and NEVER recieves information
about both ends at once (only sees the front or rear).
Where were you when discussion of objects claimed to be travelling >>c
(jets of matter ejected from some astronomical bodies) was discussed?
Are we supposed to ignore ALL objects which are not travelling directly
towards/away?

Some "learn and regurge"; others THINK, and reject "faith" as
overcoming the
impossible.

Jim G
c'=c+v

.

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