Do redshifts really indicate expansion of the universe?

[Lino]

Thanks Ich.

I think that I understand what you're saying, so I'll spend some time trying to digest it. But if I can make one comment on first read, I think I may have given the wrong impression - the viewer does not remains in a central location (i.e. on the axis but lifted of the plane of the wheel), but what is on one of the 'spokes' (i.e. between the axle and rim but on the spoke) - not on the axle itself - as an artibary example: say 20% of the distance along the spoke toward the rim (but I don't think that the actual precentage value is critical). Apologies if I was causing confusion rather than clarifying my question.


Regards,


Noel.

 

[Chronos]

Forget about the 'axis of evil', it is busted - selection effect.

 

[Lino]

Thanks Chronos. I'll keep reading about it out of interest, but it's good to kow how the story ends.

Regards,

Noel.

 

[Ich]

I think I may have given the wrong impression [...] but what is on one of the 'spokes'

I understood that part, and answered it:

If you're off the axis, you introduce further anisotropies that also not observed, like blueshift in one direction, redshift in the other. But you don't alleviate the other problem.

That's why I introduced the "effective potential", it allows you to easily calculate redshifts in this scenario. For example, it is a general result that light from bodies that orbit at the same radius as the observer is not redshifted. This is true even if the actual relative velocities are changing all the time. All you need to know is the effective potential, so you can easily prove that your scenario doesn't work.

 

[Lino]

Jambaugh, I have been reading what I can on de Sitter space, thanks again for the prompt, and can see what you were get at (... I think). Can I ask a very basic question in relation to it:

Am I correct in saying that every item of mass sits at the bottom of it's own gravity well (understandably of extremely differing depths), and given that the light from any object has to come 'out of its well', across 'flat' space and 'into my well', does this mean that 'I' am always deeper in my gravity well than everything else - since the light from that object must cross 'flat' space?

(I'm not really asking this in relation to my original rotation question - just trying to understand the deSitter model ... to some extent!)

Regards,

Noel.

 

[Chalnoth]

Am I correct in saying that every item of mass sits at the bottom of it's own gravity well

No, not at all. If that were the case, then all masses would be concentrated to a single point, and nothing would orbit anything else.

Now, what you have written here swings sort of kinda close to the truth, in that every mass is the center of the gravity well that it produces. But that well may be quite shallow compared to other nearby masses.