Redshift

[Aqueous Id]

Doppler redshift observed using parabolic reflector telescopes is an aberration

Are you saying that the whole wold is wrong because they are using defective equipment?

In the first place, you might want to ask anybody here if they ever had to calibrate an instrument before.

Second, the purpose of a parabolic reflector is to collect a large cross section of incident light to give the collector gain. And this is because the detector has a minimum threshold due to its signal to noise ratio. The parabola has a focus. That is, any ray (within the field of view) that falls incident on any infinitesimal element of the lens will reflect at such an angle that it passes through the focus. So it allows gain to compensate for limited sensitivity.

You seem to be of the opinion that if some rays take longer to arrive at the detector than others, then red shift has occurred.

Here you are simply confusing phase shift (longer path) and frequency shift (red shift due to frame dragging).

So no, there is no frequency shift as you might imagine. Phase shift would be insignificant since the light is not coherent to begin with.

 

[kaduseus]

Second, the purpose of a parabolic reflector is to collect a large cross section of incident light to give the collector gain. And this is because the detector has a minimum threshold due to its signal to noise ratio. The parabola has a focus. That is, any ray (within the field of view) that falls incident on any infinitesimal element of the lens will reflect at such an angle that it passes through the focus. So it allows gain to compensate for limited sensitivity.

Again, parallel light focuses to a point, incident light does not, it has a series of points, the light is converging at the reflector. You just said incident light and then tried to explain the parabolic reflector in terms of parallel light.
I'm not talking about longer path although that will occur to some degree.
Optically you will only see the aberration at the limit of the optics, even though you will loose some resolution, it's when you refract the light after it passes through a series of focal points, the light will NOT be parallel, it will be divergent before it gets refracted, you've gone and designed the instrumentation based on an ideal model that only works for spherical chickens in a vacuum....

The world isn't wrong at all,

“the assumption that redshifts are not velocity shifts is more economical and less vulnerable, except for the fact that, at the moment,
no other satisfactory explanation [i.e., apart from the Doppler effect] is known.”

If through experimental observation it is found that the redshift better fits a model based on an aberration, the data collected isn't wrong, I doubt there would be much sleep lost, in fact the improvements to optics and astronomy would outweigh any losses.

It's completely testable, or are you going to not test it because light is parallel?

 

[origin]

It's completely testable, or are you going to not test it because light is parallel?

It is not going to be tested for same reason that no one is going to test to see if the redshift is due to the type of metal supporting the telescopes.


If you think your idle conjecture is worth testing, looks like you are going to have to do it yourself.

 

[kaduseus]

Which bit is idle conjecture?, light not being parallel?, parabolic caustic curves?, refraction? spectrum broadening?
Or do you not believe the angle of incidence is proportional to distance?
Take any galaxy, from the known data about it, work out the angle of the light cone hitting the reflector, then take one of similar size that is known to be twice the distance and work out the angle of the light cone hitting the reflector, you'll find the angle of the light cone from the one further away to be approximately half that of the closer galaxy.
You can go collect the data and see for yourself or normalize the dimensions and produce a general relationship, angle of incidence is proportional to distance.

Even binary stars show the relationship, the redshift changes over time as they orbit each other, you can directly see the change in angle of incidence as the light cone grows and shrinks, apparently though this is down to some crap about inelastic photon-atom interactions, nothing to do with angle of incidence, funny how it's a perfect sine wave.......

One day some amateur astronomer will go and accidentally put a collimating reflector before the 'point' of focus and end up with a bucket full of blue shift.

You know though, there should be alot of coma in the optical images, as if you looked at a star that was just offset in the mirror and then lathed it around the center, not sure what that would look like, you'd have a decent (but improvable) image in the center with a halo of light around most images, not seen that in any images though, it's all dust reflections or something. You'd probably get a few images with gradient ripples as well under certain circumstances, not seen any of them either.

 

[Aqueous Id]

Again, parallel light focuses to a point, incident light does not, it has a series of points, the light is converging at the reflector. You just said incident light and then tried to explain the parabolic reflector in terms of parallel light.

Well then we can start with some basic definitions. "Incident" light is any light that impinges upon a specified surface. "Field of view" is the extent of the viewable area of the telescope. "Coherent" means that all rays are in phase, that is, the sum of all rays produces a pure sinusoid.

As I understood your complaint, you're saying that any two rays that are phase shifted on account of the parabolic mirror combine to simulate red shift (or blue shift). My statement to you is that this is incorrect, because the star light is not coherent to begin with, and additional phase scattering by the dish will have no meaningful effect on the phase information, since it was random to begin with. Furthermore, phase shift is not equivalent to red or blue shift. Frequency shift (over the spectrum) is. Therefore, you can't simulate red or blue shift simply by introducing a parabolic mirror.

I'm not talking about longer path although that will occur to some degree.
Optically you will only see the aberration at the limit of the optics, even though you will loose some resolution, it's when you refract the light after it passes through a series of focal points, the light will NOT be parallel, it will be divergent before it gets refracted, you've gone and designed the instrumentation based on an ideal model that only works for spherical chickens in a vacuum....

This still makes no sense. All light rays within the field of view of the mirror are pseudo-randomly phase shifted upon arrival at the focus. But each and every ray retains its original frequency content. Since the phase information is random to begin with, this additional phase distortion is not going to alter the spectral content. That is, you need frequency shift, not phase shift, to simulate red or blue shift. And that's the part that is preserved in a parabolic mirror.

The world isn't wrong at all,

If through experimental observation it is found that the redshift better fits a model based on an aberration, the data collected isn't wrong, I doubt there would be much sleep lost, in fact the improvements to optics and astronomy would outweigh any losses.

It's completely testable, or are you going to not test it because light is parallel?

By you analysis, every parabolic dish in the world is inherently defective. That's a huge indictment against a large population of very smart people. It makes no sense. You seem to be assuming that nobody tests or calibrates their precision instruments which is ludicrous. Also note, if this actually occurred as you think, it would be advantageous, because passive devices could be built out of dishes which produce ultrawide band spectral shifting (such as a downconverter). It would improve signal to noise ratios in some cases and open new doors to technology.

Unless we're still speaking a different language, you would have to demonstrate a frequency shift, not a phase shift, that arises out of using a parabolic mirror. But you can't, because it doesn't, hence my remarks.

 

[kaduseus]

Yeah, realised you meant incidental when I was falling asleep.

Could you re-read the first post and replace the word diffraction with refraction, silly mistake but it does confuse the issue. I'm not talking about phase shift at all.

Thing is these very smart people who understand optics know that the parabolic dish is inherently defective, they also know light isn't parallel, which is why it's deffective, but it's the best curve there is that can be used over a range of distances.

Is there experimental evidence to discount angle of incidence as the cause for the redshift?
What happens to the redshift when you offset the object in the mirror, give it additional angle of incidence.
Redshift is a valuable tool, what happens when you set the instruments up for galaxies and then measure smaller objects, there will be a huge shift towards the red with the smaller objects, you would assume they were very far away, until you discover one sitting in front of a galaxy, quasars....