Does the Acceleration of the Universe Change?

[falcon32]

And every day it radiates away that energy...well, sometimes a bit more, sometimes a bit less...the former are cooling periods the latter warming periods...

talk about facetious...just don't leave this discussion thinking that I have said the heat lost with cosmological expansion powers the Sachs Wolfe...I have no idea about all those very complicated relationships...for all we know maybe there is a some gain or loss of energy...I
don' t think we have observational evidence one way or the other...

Tongue in check, I'm never serious when I joke, my friend. And you have every right to redefine your stance, there are many mysterious things in this Universe, part of why I love learning. Thanks to all who contributed to this thread, I've learned allot and will continue to do so with the information you've provided.

 

[Naty1]

Mordred: I scanned the paper linked in your post #35...lots of the detail I don't understand...terminology not all that clear to me...
If you have any specific comments...your 'good information'...I'd be interested...

I checked the conclusions and found these comments:

... there is no indication of an evolving dark energy density. By combining
these results with other cosmological data, we find a generally consistent picture of the behaviour of the Universe, which is converging towards the ΛCDM model although
the uncertainties remain considerable.

which are reassuring, but nothing unexpected...

What would have been an indication of evolving dark energy density??

 

[Mordred]

A large chunk of that paper is calibration data. In other words removal of other factors to arrive at a dataset to work from. Section vI is where they go into looking for the Sach-Wolf effect.

Sach-Wolf effect occurs in the case of integrated Sach-Wolf when photons pass through a time varying gravitational well.
This particular form is from last scattering and essentially
present time observer.
If factors such as DE and curvature vary during the period between emmision and receiving of the photons. This would cause variations in redshift. similar to how expansion does but for a
different cause.
There are a forms of Sach-Wolf non integrated(normal) and integrated described above

http://www.astro.ucla.edu/~wright/Sachs-Wolfe.html

Ned Wright describes the two better than I can.

 

[Mordred]

You may find this technical paper handy as well. I haven't fully read it however its showing the Sach-Wolfe effect in regards to the newly released Planck data

http://arxiv.org/abs/1303.5079