Does the expansion of the universe affect our observations in the real world?

[pervect]

In view of a new thread in the Astrophysics forum
https://www.physicsforums.com/showthread.php?p=1008842#post1008842,
I'm amazed that the Cooperstock paper was not mentioned in this thread.
I quote from near the end of the Cooperstock paper.

http://xxx.lanl.gov/abs/astro-ph/9803097

I don't think I necessarily agree with the assumptions underlying Cooperstocks' approach as a "given". From what I can tell from Ned Wright's quote (which is where I found the Cooperstock reference in the first place), he also has similar reservations on Cooperstock's approach - i.e. Ned Wright feels that Cooperstocks approach could be justified only under certain particular conditions, such as a uniform background of "dark matter" in the universe.

Take a look at
http://www.astro.ucla.edu/~wright/cosmology_faq.html#SS

For the technically minded, Cooperstock et al. computes that the influence of the cosmological expansion on the Earth's orbit around the Sun amounts to a growth by only one part in a septillion over the age of the Solar System. This effect is caused by the cosmological background density within the Solar System going down as the Universe expands, which may or may not happen depending on the nature of the dark matter.

The thing that is probably the most important is that we can regard Cooperstocks' approach as being conservative, in the sense of giving us the biggest possible effect. And even being conservative in this manner, we can see that the effect would be very small and not measurable (parts in a septillion).To take one example, the loss of mass of the sun via radiation would have a much more significant effect on changing planetary orbits than the expansion of the universe - i.e. the sun is losing visible mass much faster than the rate at which hypothetical "dark matter" would be leaving the solar system due to cosmological expansion.