Re: Time dilation needs Absolute Space?

From: Christophe Major (cmaj10_at_yahoo.com)
Date: 06/21/04 

Date: 21 Jun 2004 02:06:00 -0700

[I may have posted a previous reply with a typo in a math expression.
This copy is better. -- chris]

vergon_enterprises@highstream.net (V ertner Vergon) wrote in message
> Vergon:
>
> To Dr. Taylor
>
> Greetings.
>
> Re your text on Special Relativity.
> I have a comment re section 38-5, TIME STRETCHING.
> Please bear with me, I mean no disrespect but the exposition there is
> in error.
>
> I refer you to Fig 38.4. Please note that this illustration and your
> description of it are definitely that of a *transverse* velocity.
>
> You describe the observed system as going by us, not toward or away
> from - which is the condition described in Einstein's paper.
> Therefore, the time dilation result is that of transverse Doppler.
>
> Now it so happens by some strange coincidence that transverse Doppler
> is written
> f' = f sqrt(1-v^2/c^2), the same as time dilation.
>
> One must consider what the true time dilation is in the radial
> velocity and approach velocity situations.
>
> Regardless of the mechanics, a constant invariable frequency is a
> clock. If we observe that frequency to slow, then the *observed* time
> slows. If we observe the frequency to increase, then the *observed*
> time increases - is faster.
>
> Having said that, we keep in mind that clocks do not change rate in
> their respective coordinate systems. Proper time never varies. It is
> only the observation that changes.
>
> That brings us to the description of Doppler as given in your text.
>
> There you proclaim that that relativistic Doppler is caused by
> the movement of consecutive vibrations (requiring more time for
> light to transmit the event) which is further altered by time
> dilation.
>
> This description tacitly states that time is altered in the frame of
> Emitter. That is contrary to the above mentioned fact that proper time
> does not vary. Again, coincidence.
>
> I could describe what does happen but that would go beyond the scope
> of what we are covering here and enters new territory.
>
> In summary, it is clear that the variation in observed time is that of
> Doppler. I call it the time-frequency rate.
>
> Below is an article I posted in Sci.physics.relativity. You may find
> it of interest.
>
> Best regards,
> Vertner Vergon

The math behind the relativistic Doppler effect is particularly
convoluted, so it would be hard to discuss fine points of this issue
in a newsgroup, but from what I've read it seems clear to me that you
have never considered the following thought experiment: imagine that
the moving emitter blinks in such a manner that in his own frame the
light is turned on for a duration of 1 second, then it is turned off
for a duration of 1 second, etc. The stationary observer will see a
variation of colors over time depending on the directional vector to
the emitter; but the blink frequency will remain constant: each blink
will last 1/sqrt(1-(v/c)^2) seconds. The received color frequency
varies, but the periods of the blinks are constant. That contradicts
your theory that the received color frequency reflects the variation
of observed time.

Your problem with the relativistic Doppler effect is that you fail to
realize that there are two components in it: a frequency shift, and a
time dilation. The example given by Taylor is a case where the blink
duration is exactly equal to the wave's period in the emitter's frame,
instead of 1 second (as I used above). When the emitter *passes by*
the receiver, the frequency shift portion of the Doppler effect is 0
exactly like in the non-relativistic case, so all you are left with is
the time dilation portion. And since what is being dilated is the
blink duration which in this case happens to be exactly the same
duration as the wave period, the receiver will see that dilation of
the wave's period, and that's the only effect he will see.

-- chris

Relevant Pages

  • Re: Time dilation needs Absolute Space?
    ... the time dilation result is that of transverse Doppler. ... The math behind the relativistic Doppler effect is particularly ... but the blink frequency will remain constant: ...
    (sci.physics.relativity)
  • Re: Time dilation
    ... > We examine time dilation and find it leads to an unforgiving ... > examining Doppler time we find it has none of these deficiencies. ... he stated the moving clock "was slow by ...". ... earlier you said that the time dilation effect occurs regardless ...
    (sci.physics.relativity)
  • Time Dilation and Doppler Time.
    ... ON TIME DILATION AND DOPPLER TIME ... We examine time dilation and find it leads to an unforgiving ... he stated the moving clock "was slow by ...". ... were to observe a clock on a fast moving spaceship, ...
    (sci.physics.relativity)
  • Re: Time Dilation and Doppler Time.
    ... > We examine time dilation and find it leads to an unforgiving ... > examining Doppler time we find it has none of these deficiencies. ... When Einstein perceived the difference of the clock readings ... > non-relativistic Doppler rate and modifies it by the time dilation ...
    (sci.physics.relativity)
  • Clocks, Dilation Time and Doppler Time
    ... We examine time dilation and find it leads to an unforgiving ... examining Doppler time we find it has none of these deficiencies. ... he stated the moving clock "was slow by ...". ... were to observe a clock on a fast moving spaceship, ...
    (sci.physics.relativity)