Re: Hubble deep field question

which, I think you will agree, is merely the most plausible
*explanation* for a universally acknowledged phenomenon, redshift, and
which involves mere kinematics.

You seem to have accepted the responsibility of providing an
explanation for Doppler redshift, but I resent your making me a party
to this hypothetical detonation.  

In any case, this dynamite thing is just an obfuscatory distraction,
which in no way undermines my assertion that z/1+z is the proper
distance modulus, not z.

You stated that recession velocity at z =1 is c, and tolerated a
reported  measurement of z = 6 making v = 6c, without considering how
you could see the redshift. Of course with D = z/1+z you get v = c*6/7
and we are back in real physics.  

The inherent error lies in failing to recognize that while the Doppler
effect has a transparent explanation as a frequency phenomenon, it is
*measured* as a wavelength phenomenon and then persisting to employ
wavelength algebra through thick and thin despite the glaring
incongruities.

You better modify all those z*c expressions to zc/1+z.

John Polasek

Dear John Polasek:

But you did invoke straight classical Doppler shift, with the inherent
energies required to blast masses away from us at significant
percentages of the speed of light.

Sure, if you completely ignore what your "model" requires.

...

You are right.  So why don't you face those consequences?

David A. Smith

I did not discuss 'center'. My statement treats of a line joining the
observer and his star- there's no explosion.

I derived the velocity for you as a function of z, but you neglected
to examine it.

No center you say, OK, but then space has no substance either, that
could stretch by 1+z, ostensibly to fend off superluminal problems.
But these problems stem from erroneous use of the illegal expression
cz leading to 2c, 3c, which are not impossible, just that there's
nothing to see past 1c and we need to see redshift.
The red shift is from Doppler alone, but a whole legend has developed
from this 1+z stretch fixation.
The paper below argues for a replacement of z with z/1+z but from
purely mathematical consideration of algebraic poles and the like.
http://arxiv.org/abs/ 0710.1887. This notion is correct as I have
shown in the prior note.

I repeat, it is a serious error with serious consequences

John Polasek

Dear John Polasek:

The Universe has no unique center, therefore the expansion is not from
an explosion in space.  So there is no theoretical support to your
"manipulations".

David A. Smith

On Thu, 22 Jan 2009 17:00:01 -0700, "N:dlzc D:aol T:com \(dlzc\)"
<dlzc1@cox.net> wrote:

I beg to differ. This is a common and grievous error, if we attribute
redshift to straight Doppler. The laboratory measurement is
    L'/L = 1 + z
Letting v/c = b (for beta), doppler causes the frequency reduction
    f'/f = 1 - b
from which the wavelength is given by the inverse
    L'/L = 1/1-b = 1 + b + b^2 + b^3 which is not 1 + z
z is not v/c.
    A little algebra shows that recession velocity is given by
c*z/1+z, so for z = 1, the recession is c/2.
    I think this has been lost sight of in the current fiction
that space stretches wavelengths by 1+z, a concept which panders to
Einsteins space-time.
    I see the graphs that routinely present v/c>1 with velocities
equal to 2 and 3c. It isn't true, and this is the reason, which should
come as a great relief, since viewing >c is impossible.

John Polasek

Dear Craig Franck:

No,, that assumes the objects look to be 12.7 Gly away "now".

... and hence further away, and with the correct intensity.

No.  A Z of 1 is "receeding" at c.

http://www.astro.ucla.edu/~wright/cosmo_01.htm
... the text below the little sketch with the text "You're
receding"

I think you are trying to get to a number that has little
meaning.

David A. Smith

I'm reading "Chasing Hubble's Shadows" by Jeff Kanipe, and he
states on page 140 that "blobjects" at redshift 6 that were
13,000 light years across would appear 0.2 seconds of arc in
size. But that's assuming the light left when the object was 12.7
billion light years away.

I had thought that the objects would have been much closer when
the light first left and it took 12.7 billion years to reach us because
of cosmic expansion, which would not have made the objects look
smaller.

At redshift 6 they would be traveling at about 0.9c, but how would
you figure out how far away they were when the light first left from
that? I thought it would be 1/6 * 12.7bly, but that's assuming the
author is wrong, which may not be warranted.