Quote:
Originally Posted by RetEng
Accelerating Universe has been much publicized in recent times.
Yet as far as we can see in distance and back in time from here-and-now,
redshifts increase. Looks more like DEceleration to me.
What am I missing here ?
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The missing link is that you are moving, as well as the objects you are looking at.
https://en.wikipedia.org/wiki/Metric_expansion_of_space
When we look at nearby galaxy clusters (e.g. the Virgo cluster ~ 50 million light years, receding at 0.4% c) we see doppler red shifts.
When we look at ancient galaxy clusters (e.g. Abell 2744 ~ 1.2 gigaparsec, 0.3c) we see expansion red shifts.
https://en.wikipedia.org/wiki/Abell_2744
Intuitively, you imagine the following:- Stuff that's far away (and hence long ago) is moving away really fast. Stuff that's nearby (and hence recent) is moving relatively slowly away. Therefore, we're decelerating.
And indeed, we sort of are co-aligned with respect to our Local Group (Andromeda, etc) but we are no longer able to see the stuff that is not local with us. So yes, the nearby stuff is at the same velocity as us, but the far away is gone forever. The evidence of expansion has fled. All that's left is the nearby. Only in the past is it there for us to see.
Regards,
Tony Barry
Penrith, Sydney