Relavistic Contraction

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20 years 11 months ago #6970 by tvanflandern
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Mac</i>
<br />I agree that if we take a rod i.e. a rod 1 foot long and we observe it by a rotating a theodolite, positioned orthogonal and centered on ans at a select distance from the rod, such that the angle between the right hand end and the left hand end is 30 degrees, the length of the rod can be determined to be 3 feet.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

I don't get it. You said the rod was 1 foot long. Why is the experiment giving an incorrect length measurement?

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">If the rod is not in motion relative to the monitor then the speed at which we rotate the monitor has no bearing on our calculation (Perception of rod length).<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

The same is true if the rod is in motion. In SR, the rotation has no bearing on our perception of length, period. I mentioned rotation only to show how SR requires that time vary along the rod's length, which then makes the straight, horizontal stripes along the rod appear twisted even though the rod is rigid and clearly not twisted.

Because I did not get your setup, I cannot comment on the questions that follow. -|Tom|-

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20 years 11 months ago #6760 by 1234567890
Replied by 1234567890 on topic Reply from
Well, if light is being observed by humans, Einstein was correct:
objects moving away from an observer at any velocity will appear smaller,
and smaller, and smaller until the object disappears from sight! Since this
affects all objects moving away from us, one can then claim that space has
contracted (and hence time dilated) due to relative velocities.
However, the Lorentz transformation would be off quite a bit
in this case (it should be the refractive index of the
human eye I think).

Unfortunately, fish and other species with flat eyes will have no such luck.

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20 years 11 months ago #6791 by Mac
Replied by Mac on topic Reply from Dan McCoin
Tom,

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><b>I don't get it. You said the rod was 1 foot long. Why is the experiment giving an incorrect length measurement?


quote:
If the rod is not in motion relative to the monitor then the speed at which we rotate the monitor has no bearing on our calculation (Perception of rod length).


The same is true if the rod is in motion. In SR, the rotation has no bearing on our perception of length, period. I mentioned rotation only to show how SR requires that time vary along the rod's length, which then makes the straight, horizontal stripes along the rod appear twisted even though the rod is rigid and clearly not twisted.

Because I did not get your setup, I cannot comment on the questions that follow. -|Tom|-</b><hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Sorry, my error. I started the post with a yard stick and decided it took less typing to say rod and simply made it a one foot rod but missed changing that entry.

I agree with the added visualization of the rotating stripes. But the question becomes why Relativity predicts a compounding contraction with velocity when time desynchronation is linear with relative velocity?

Thanks.

Knowing to believe only half of what you hear is a sign of intelligence. Knowing which half to believe can make you a genius.

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20 years 11 months ago #6799 by Mac
Replied by Mac on topic Reply from Dan McCoin
123....,

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><b>Well, if light is being observed by humans, Einstein was correct:
objects moving away from an observer at any velocity will appear smaller,
and smaller, and smaller until the object disappears from sight! Since this
affects all objects moving away from us, one can then claim that space has
contracted (and hence time dilated) due to relative velocities.</b><hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

I'm not sure but it appears you have linked depth perception to time dilation. The affect you seem to be referring to doesn't require velocity at all but mere spatial seperation and affects simultaneity but not dilation.


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20 years 11 months ago #7301 by tvanflandern
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Mac</i>
<br />But the question becomes why Relativity predicts a compounding contraction with velocity when time desynchronation is linear with relative velocity?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Do you mean the vX/c^2 term? Gon't forget the gamma factor also multiplies that term.

The gamma factor [1/sqrt(1-v^2/c^2)] is a constant for any given pair of inertial frames. So the rate of passage of time in the other frame is linear with time in the observer or laboratory frame. The vX/c^2 "time slippage" term simply modifies it from slower than lab-frame time to faster than lab-frame time.

If you are asking why gamma has that form, see my "canoe paddled with and against a current" example posted elsewhere on this MB. -|Tom|-

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20 years 11 months ago #6809 by Mac
Replied by Mac on topic Reply from Dan McCoin
Tom,

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><b>If you are asking why gamma has that form, see my "canoe paddled with and against a current" example posted elsewhere on this MB.[</b><hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Yes that would seem to boil down to the question. Can you remember the string you discussed this?



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