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A Laboratory Experiment for Astronomers ("Look-Back")



 
 
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  #11  
Old November 5th 14, 10:40 AM posted to sci.astro.research
Eric Flesch
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Default A Laboratory Experiment for Astronomers ("Look-Back")

(Pursuant to my posting immediately above)

Ah no, the momentum should be the same because both photon speed and
wavelength are half of what we think, if the z=1 photon is travelling
at c/2. So the momentum equation yields the same result, darn it.

Modelling the z=1 photon as travelling at c/2 is (so far as I can
tell) consistent with all other observed photon properties. So we
need to do that occultation-based observation -- or whatever other
physical property that would be affected by photon speed.

By the way, I need to mention this: most people model the photon as a
physical object which travels continuously from A to B. With that
model, people might find problems with a universe in which photons are
whizzing around at different speeds. The reason I'm agnostic about
that is because I don't believe photons exist in mid-flight -- John
Wheeler's delayed-choice experiments have specifically excluded such
photons, I believe. I've occasionally posted my photon model on these
newsgroups, and it's posted at http://quasars.org/photon.txt . The
model is, of course, consistent with all observed photon properties.

Eric
  #12  
Old November 5th 14, 04:19 PM posted to sci.astro.research
Harri Tavaila[_4_]
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Default A Laboratory Experiment for Astronomers ("Look-Back")

2.11.2014 18:53, Eric Flesch kirjoitti:

Yes, and aberration was mentioned although I'm not seeing how that
would work.


The observed direction of an astronomical target will move to the
direction of the observers movement by the quantity:

a = (v/c')*sin(theta)

whe

v is observers velocity [km/s]
c' is the speed of light [km/s]
theta is the angle between the observers motion and the true position of
the object [radians].

When using the speed of light (c' = c approx 3*10**8 m/s) the maximum
aberration due to motion of Earth around the Sun is approximately 21''.
This can be readily detected and indeed has to be accounted for in some
observations.

If for some targets c' = c/2 they would show aberration that would be
twice larger than for target for which c' = c. Thus extragalactic
targets would dance around closer objects in the same exposure to the
rythm of Earths seasonal movement.

No such effect is observed.

H Tavaila
  #13  
Old November 5th 14, 04:21 PM posted to sci.astro.research
Richard D. Saam
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Default A Laboratory Experiment for Astronomers ("Look-Back")

On 11/4/14, 11:26 AM, Steve Willner wrote:
In article ,
Eric Flesch writes:
If Barbour's well-published "relative scale" is operative, then z=1
photons were emitted under an earlier "scale" state, ald it is
possible that they are travelling at speeds slower than c


I think this is pretty much ruled out by existing observations.
Optical spectrographs measure wavelength. Radio spectrographs
measure frequency. Both methods give the same redshift for high-z
galaxies; therefore the photons have to be traveling at the same
speed as any other photons to within the combined measurement
uncertainties.

Further:
This is inherent in the photon gas model
Black Body expression of observed universe CMBR
where wavelength and frequency calculation
are dependent on c within the Stefan constant
2*pi^5*Boltzmann^4/(15*c^2*hbar^3)

Richard D Saam
  #14  
Old November 6th 14, 10:24 AM posted to sci.astro.research
Eric Flesch
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Default A Laboratory Experiment for Astronomers ("Look-Back")

On Wed, 05 Nov 14, Harri Tavaila wrote:
If for some targets c' = c/2 they would show aberration that would be
twice larger than for target for which c' = c. Thus extragalactic
targets would dance around closer objects in the same exposure to the
rythm of Earths seasonal movement. No such effect is observed.


Thanks for that excellent explanation, Harri. So if the light from
z=1 quasars travel at c/2, then their maximum aberration would be 40
arcsec instead of the 20 arcsec of stars. So we would see z=1 quasars
move as much as 20 arcsec against the stellar background. Gosh, can't
say I've noticed that!

Before I raise the white flag all the way up the pole (it's mostly up
:-), one anomaly stands out in my cataloguing, and that is there is a
patch of sky at about -30 Dec covered by the 2QZ survey where DSS
plots the quasars about 4 arcsec from the 2QZ-given co-ordinates --
with plenty of scatter. I need to check that place to see if there is
any support there for my hypothesis, i.e., that the positional
variance is proportional to redshift. I'll report back if it does,
but otherwise it is my hypothesis which is stone cold dead. Thanks
very much Harri and all.

Eric
  #15  
Old November 7th 14, 01:02 PM posted to sci.astro.research
Steve Willner
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Default A Laboratory Experiment for Astronomers ("Look-Back")

In article ,
Eric Flesch writes:
Therefore if Neptune occults a z=1
quasar, the entire occultation would be seen after Neptune has passed.


Less dramatic than an occultation timing event, but 3C 273 passes
behind the Sun each year. Its position as affected by gravitational
light bending has been used as a test of GR. I wouldn't expect that
test to agree with GR if the speed of radio waves from 3C 273 differs
from c.

Aberration, as others have mentioned, also provides a strong test.
The radio astrometric reference frame is defined by quasars at a wide
range of redshifts. If they moved with respect to each other at
different times of year, that would be noticed. (Measurement
precision is at the micro-arcsec level.)

An optical spectrograph measures the wavelength of received light
relative to the grating spacing. Speed of photons doesn't matter;
it's just geometry. (Wavelengths will, of course, change between air
and vacuum, but that's known and accounted for in the calibration.)

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
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  #16  
Old November 9th 14, 10:29 AM posted to sci.astro.research
Eric Flesch
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Default A Laboratory Experiment for Astronomers ("Look-Back")

On Fri, 07 Nov 14 12, Steve Willner wrote:
An optical spectrograph measures the wavelength of received light
relative to the grating spacing. Speed of photons doesn't matter;
it's just geometry. (Wavelengths will, of course, change between air
and vacuum, but that's known and accounted for in the calibration.)


I must confess I didn't realize they worked like that, thought prisms
were used. Still unsure about detaching wavelength from c, but it
doesn't matter since aberration shows my hypothesis is false. So
whatever "spatial expansion" consists of, it overtakes whatever came
before (outside of gravity-bound galaxy groups etc).
  #17  
Old November 13th 14, 12:21 PM posted to sci.astro.research
Steve Willner
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Default A Laboratory Experiment for Astronomers ("Look-Back")

In article ,
Eric Flesch writes:
I didn't realize they worked like that, thought prisms
were used.


Nearly all astronomical spectrographs operating today use diffraction
gratings, which allow much higher dispersion than prisms can
produce. Prisms are sometimes used as cross-dispersers in "echelle
spectrographs," which spread several orders of grating spectra over a
2-d focal plane. Prisms are also used when low resolution but wide
wavelength coverage (more than an octave) is needed.

Still unsure about detaching wavelength from c


Not sure what you mean here. A grating (plus geometry) directly
measures wavelength at the grating location. For any wave, product
of frequency and wavelength is speed.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
 




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