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I stumbled upon this text which illustrates and says:

We find that as the object is moved to higher redshifts its angular size first decreases (as naively expected) but soon begins to increase after passing through a minimum value.

Is this correct for the mainstream standard model? What would an English language explanation be?

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Yes this is correct for the standard model. I believe the English language explanation would be that the angular size of a galaxy does not depend on its current distance to us, but its distance when the light we currently see from it was emitted (here using "distance" synonymous with "proper distance"). Though I also believe there are other complicating factors such as the spatial geometry of the Universe.

Look at the first diagram in Figure 1 in this paper, notice how the size of the past light cone in terms of proper distance firstly increases as we go back in time, before reaching a maximum and decreasing to zero at t = 0.

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  • $\begingroup$ Aaargh! I've actually read that paper, but didn't realize this implication. The universe is so strange. I understand Chris Impey who in a public lecture series kind of mumbled to himself: "- I should just make up mad stuff to say in these lectures. I would get away with it." $\endgroup$
    – LocalFluff
    Jan 25, 2015 at 16:16
  • $\begingroup$ Those diagrams are immensely useful, there's a lot of hidden information in them! Another way of looking at it perhaps is that, though the size of gravitationally bound objects like galaxies is not hugely affected by expansion, the light as it travels from the galaxy to us will be affected by expansion causing the angular size to expand. In a Universe with a particle horizon there will always come a point where the expansion of the angular size due to cosmological expansion overwhelms the decrease in angular size due to distance. $\endgroup$
    – John Davis
    Jan 25, 2015 at 16:44
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This is an interesting thought,but red shift was a theory that could be answered by assuming near light velocities.The belief in,this unproven idea,invokes argument of"If it is coming toward us then we will already have seen it"

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  • $\begingroup$ What "unproven idea"? $\endgroup$
    – Jim421616
    Jul 7, 2020 at 6:02

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